Timing and Imaging of compact sources with SKA pathfinders
Kerastari June 2023

Abstracts


Name: Tzioumis, Tasso
E-mail: tasso.tzioumis@csiro.au
Affiliation: CSIRO Space & Astronomy
Type of presentation: Oral
Title: Introduction
Abstract: To be decided closer to the date.


Name: Basu, Avishek
E-mail: avishekbs3@gmail.com
Affiliation: Jodrell Bank Centre for Astrophysics, University of Manchester
Type of presentation: Oral
Title: Timing and profile evolution of young pulsars.
Abstract: In this presentation, I will present the results of the profile evolution and timing of a few young pulsars, observed by the thousand pulsar array project of MeerTIME.


Name: Stinebring, Dan
E-mail: dan.stinebring@oberlin.edu
Affiliation: Oberlin College, USA
Type of presentation: Oral
Title: Correcting for ISM delays in high precision pulsar timing
Abstract: TBD


Name: Limaye,Pranav
E-mail: s6prlima@uni-bonn.de
Affiliation: Argelander Institute for Astronomy, Bonn Germany
Type of presentation: None
Title:
Abstract:


Name: Stappers, Ben
E-mail: ben.stappers@manchester.ac.uk
Affiliation: University of Manchester
Type of presentation: Oral
Title: FRBs and Galactic Transients with MeerKAT on the road to the SKA
Abstract: MeerTRAP is a project running on MeerKAT which searches for transient radio emission with durations from milliseconds to seconds. I will discuss the status of the project after almost 3 years of fully commensal operation. I'll discuss the FRBs that we have discovered and also some of the Galactic transients. I will also use it as a chance to discuss some opportunities and challenges for the SKA.


Name: Wang, Yuanming
E-mail: ywan3191@uni.sydney.edu.au
Affiliation: University of Sydney
Type of presentation: Oral
Title: High-time resolution imaging pipeline for extreme transients detection with ASKAP
Abstract: We developed a new pipeline (so called VAST fast imaging pipeline) dedicated to deep fields observed by Australian Square Kilometre Array Pathfinder (ASKAP), e.g. GW S190814bv field or the Evolutionary Map of the Universe (EMU) survey, to search for radio transients and variables on image domain at shorter timescales (seconds to minutes). The main scientific targets include enhanced scintillation, flaring stars, radio pulsars, and peculiar transients. The prototype pipeline resulted in the first discovery of a group of extreme scintillating AGNs in a linear arrangement on the sky - uncovering the existence of a Galactic plasma filament. We conducted a pilot survey on ~40 deep fields from ASKAP archival data at a central frequency of ~GHz using the prototype fast imaging pipeline. The total area of the pilot survey footprint is ~1600 square degrees, revealing 34 highly variable and/or transient sources: 7 of them are known pulsars, including 3 millisecond pulsars, and 7 of them are flaring stars. We also detected an unknown transient with substantial polarisation. More follow-up investigations are underway to understand its nature. This is the first radio transients survey that covered a large sky area at seconds-minutes timescales down to sub-mJy sensitivity level. The results presented here demonstrate pipeline’s capability to detect transients once future ASKAP surveys such as full EMU (covering the entire sky < +30 deg in declination) begins operations -- it will result in more findings on the poorly-explored parameter space.


Name: Maan, Yogesh
E-mail: ymaan@ncra.tifr.res.in
Affiliation: National Centre for Radio Astrophysics (NCRA - TIFR)
Type of presentation: Oral
Title: Identifying the true nature of compact, steep spectrum sources
Abstract: Sensitive all sky imaging surveys have been uncovering interesting new sources, including compact sources with steep spectra that are strong candidates for interesting galactic as well as extra-galactic objects. A good fraction of the steep spectrum sources that are of Galactic origin are expected to be radio pulsars, some of which potentially also as parts of exotic binary systems or surrounded by dense environments. There are also clues adding up to the possibility that some of these sources might constitute a new, earlier unknown Galactic population of sources. Some of the steep spectrum sources might also be 'dead' or remnant radio galaxies, or high-redshift radio galaxies. Identifying the true nature of these compact, steep spectrum sources requires a multitude of observing efforts, often amounting to interferometric characterization at a range of spatial resolution scales as well as radio pulsation searches in the beam-formed data at a wide range of frequencies. I will present characterization of a sizable sample of such sources in the Galactic plane using interferometric observations with the SKA pathfinder GMRT, time-domain searches for radio pulsations covering the frequency range 300 MHz - 5 GHz using multiple telescopes, and very high-resolution probes with the European VLBI Network (EVN). In addition to uncovering interesting exotic sources, such characterization at a larger, population scale will enable efficient searches for interesting sources, such as exotic pulsars and high-redshift galaxies, using samples selected from the imaging surveys in the SKA era.


Name: John Antoniadis
E-mail: john@ia.forth.gr
Affiliation: FORTH Institute of Astrophysics
Type of presentation: Oral
Title: ARGOS: A European "small-D big-N" interferometer for multi-messenger astrophysics
Abstract: I will describe the ARGOS project: A EU-funded initiative to design and deploy a small-D big-N interferometer that will complement and support the science envisioned for next-generation instruments such as the SKA.


Name: Rea, Nanda
E-mail: rea@ice.csic.es
Affiliation: ICE-CSIC
Type of presentation: Oral
Title: Constraining the nature of long period radio pulsars
Abstract: Long period radio pulsars are a new puzzling source class comprising about 4-5 objects, the nature of which is still debated, and possibly not unique. I will report on new multi-band observations and theoretical modelling of the most interesting members of the class, showing how we are getting close to finally constrain their nature.


Name: Law, Casey
E-mail: claw@astro.caltech.edu
Affiliation: Caltech
Type of presentation: Oral
Title: Understanding Fast Radio Burst via their Persistent Radio Countparts


Name: Qiu, Hao(Harry)
E-mail: hao.qiu@skao.int
Affiliation: SKA Observatory
Type of presentation: Poster
Title: Performance of the ASKAP FRB ICS Search Pipeline


Name: Rammala, Isabella
E-mail: irammala@mpifr-bonn.mpg.de
Affiliation: Max-Planck-Institut für Radioastronomie
Type of presentation: Oral
Title: The Discovery & Classification of Compact Sources in the MeerKAT Galactic Centre at L-Band
Abstract: The MeerKAT inaugural image of the Galactic Centre revealed a population of previously unidentified compact sources in the region. Motivated by the efforts to identify radio pulsar candidates in the continuum data, we reprocessed the data to produce high-resolution images and classify the sources based on their spectral properties, as well as the morphological nature of their environment. I will present the classes of the sources discovered and highlight some sources of note.


Name: Gourdji, Kelly
E-mail: kgourdji@swin.edu.au
Affiliation: Swinburne University of Technology
Type of presentation: Oral
Title: LOFAR observations of gravitational wave merger events
Abstract: The main challenge associated with detecting the electromagnetic counterparts of gravitational wave (GW) merger events is the large uncertainty on their locations (10s to 100s of square degrees). I will present how we are utilising LOFAR's large instantaneous field of view and high sensitivity to search for GW merger radio counterparts. In particular, using state-of-the-art data reduction techniques, we construct LOFAR mosaics covering 21 deg^2 with 0.15 mJy rms noise levels at epochs ranging from 1 week to months post-merger. We present our results from LOFAR follow-up observations of three merger events from the previous GW observing run. These constitute the deepest transient search at low radio frequencies on month time timescales. The wide coverage of our observations should probe most of the localisation region of binary neutron star merger events detected in the (upcoming) 4th GW observing run. Finally, I will show how LOFAR 2.0 can be triggered to observe GW events minutes post-merger to probe prompt FRB-like emission at unprecedented sensitivity.


Name: Kylafis, Nick
E-mail: kylafis@physics.uoc.gr
Affiliation: University of Crete & Institute of Astrophysics-FORTH
Type of presentation: Oral
Title: The role of outflows in black-hole X-ray binaries
Abstract: Contrary to the standard picture for black-hole X-ray binaries (BHXRBs), which invokes an accretion flow (hot inner flow and outer accretion disk) and a jet, it is important to stress the importance of the outflow in BHXRBs. Assuming that the outflow is the “corona”, where Compton up-scattering of soft photons from the accretion disk occurs, we have been able to explain over the years a number of observations and correlations, some of which have not been explained in any other way. In particular, the model explains quantitatively 1) the energy spectrum from radio to hard X-rays, 2) the time lag of the hard X-ray photons with respect to the softer ones, 3) the correlation between time lag and Fourier frequency in Cyg X-1 and GX 339-4, 4) the correlation between the time lag and the spectral index Gamma in GX 339-4 and other sources, 5) the fact that this correlation depends on the inclination of the source, 6) the phase-lag – cutoff-energy correlation observed in GX 339-4, 7) the narrowing of the auto-correlation function with increasing photon energy seen in Cyg X-1, 8) the correlation between the Lorentzian frequencies in the power spectrum and the spectral index Gamma in Cyg X-1 and GX 339-4, 9) the B-type QPOs in GX 339-4, and 10) the radio – X-ray correlation in GX 339-4 (unpublished work). All the above observations and correlations are explained with only two parameters: the radius R at the base of the parabolic outflow and the Thomson optical depth \tau along the axis of the outflow. For all the observations and correlations, these two parameters vary in the same narrow ranges: 10 ~< R/R_g ~< 1000 and 1 ~< \tau ~< 10, where R_g is the gravitational radius.


Name: Dimopoulos Dimitrios
E-mail: d@dimokat.gr
Affiliation: National Technological University of Athens (NTUA), National Kapodistrian University of Athens (NKUA)
Type of presentation: None
Title:
Abstract:


Name: Adam Deller
E-mail: adeller@swin.edu.au
Affiliation: Swinburne University of Technology
Type of presentation: Oral
Title: Precision astrometry of impulsive transients
Abstract: I will describe the current approaches for localising millisecond-timescale radio transients, and how this may be improved with future facilities to provide higher-precision localisation.


Name: Walker, Mark
E-mail: mark.walker@manlyastrophysics.org
Affiliation: Manly Astrophysics
Type of presentation: Oral
Title: A cascade of messages from young pulsars
Abstract: I'll provide a reinterpretation of published radio and multi-messenger data that places pulsars in a supereminent position in the Universe.


Name: Rajwade, Kaustubh
E-mail: rajwade@astron.nl
Affiliation: ASTRON
Type of presentation: Oral
Title: Searching for ultra-long period magnetars with SKA pathfinders
Abstract: Time-domain surveys for pulsars and fast transients continue to discover surprising sources that have shaped our understanding of neutron stars and fast radio bursts (FRBs). Recent discoveries of periodic sources with long rotational periods (P > 30 sec) demonstrate that there is a previously hidden population of such sources lurking in our Galaxy in large numbers. These sources are of great interest due to their implications for the radio emission mechanism in neutron stars and their potential links to the mysterious FRBs. New search techniques are crucial in detecting these sources and SKA pathfinder telescopes like MeerKAT and LOFAR, with their excellent sensitivity, wide field-of-view are the right instruments for the job. In this talk, I will present the recent search efforts and discoveries of ultra-long period neutron stars with these telescope. I will discuss the tools and techniques that have been developed in order to perform this search effectively and efficiently and the relevance of these techniques in the era of next-generation facilities.


Name: Li, Di
E-mail: dili@nao.cas.cn
Affiliation: National Astronomical Observatories, Chinese Academy of Sciences
Type of presentation: Oral
Title: Toward a statistical view of repeating pulses from active FRBs
Abstract: Designed to rival the point-source sensitivity of SKA1 with filled aperture, the FAST telescope has limited field of view, but has been productive in monitoring active FRBs. FAST has obtained sets of pulses numbered in thousands, for FRB 121102 and FRB 20201124A. FAST has discovered and accumulated hundreds of pulses for FRB 20190520B. In conjunction with GBT, Parkes, and Effelsberg, our multi-band monitoring efforts are starting to review key characteristics of active FRBs. The lack of RM detection at lower frequency bands (L-band by FAST, Chime band, etc) can be well explained by RM scatter, for example. These data sets start to quantify repeaters' behaviours with statistical sign ificance. Combined analysis of the power, pulse shape (drift, etc), polarization, and scattering are building an evolutionary picture for active FRBs.


Name: Jiwoong Jang
E-mail: jjang@mpifr-bonn.mpg.de
Affiliation: Max-Planck Institute für Radioastronomie
Type of presentation: Oral
Title: Constraining the orbital parameters of PSR J1439-5501 using a first detection of Shapiro delay and scintillation
Abstract: The pulsar-white dwarf binary, J1439-5501, was first discovered in the Parkes Multibeam survey (Faulkner et al. 2004 and Lorimer et al. 2006) in a circular orbital with a period of 2.12 days. In 2013 Pallanca et al. were able to detect the white dwarf in the optical and constrained the mass range to be 1-1.3 MSun based on white dwarf cooling models. This work presents the results of a timing campaign using the MeerKAT telescope combined with the earlier Parkes data. The considerable increase in sensitivity has allowed the Shapiro delay to be detected for the first time, providing a measurement of the white dwarf mass and inclination angle of the orbit. When combined with the Chandra Shekhar mass limit, this gives a companion mass of 1.27(+8, -23) Msun, a pulsar mass of 1.57(+22,-47) Msun, and an inclination angle of 77.3(+1,-2) deg. The strong scintillation seen in the pulsar also allowed the longitude of ascending node and the orientation, velocity and distance to the screen to be measured when combined with the timing results. The scintillation results also suggest that the distance is 1.0(2) kpc, which is well above the DM derived distance of 603-655 pc (YMW, NE2001), and at the upper end of the optical estimation of 650-1200 pc. A measurement of Pbdot would provide a significant improvement in the constraint of the masses in the system. Simulations based on the current timing precision, expected upgrades to MeerKAT, and eventually using the SKA, suggest that Pbdot should be measurable in approximately 2028.


Name: Kendrick Smith
E-mail: kmsmith@perimeterinstitute.ca
Affiliation: Perimeter Institute for Theoretical Physics
Type of presentation: Oral
Title: Searching for FRBs with CHIME and CHORD
Abstract: I'll give an update on the CHIME FRB search, including both high-level science results and algorithmic/implementation details. I'll also describe improvements that are in progress for the CHORD FRB search, scheduled to start in 2024.


Name: Posselt, Bettina
E-mail: bettina.posselt@physics.ox.ac.uk
Affiliation: University of Oxford
Type of presentation: Oral
Title: Does RX J0806.4-4123 spin up or spin down?
Abstract: The radio-quiet isolated neutron star RX J0806.4-4123 is associated with unique extended near-infrared emission, detected by the Hubble Space Telescope. One possible explanation for the infrared emission is a surrounding disk made of supernova fallback material. RX J0806.4-4123 is a slowly rotating (P~11s), thermal X-ray source and a member of the so-called Magnificent Seven (Mag7), a distinct group of neutron stars that are located between the magnetars and rotation-powered radio pulsars in the period--period-derivative diagram. An accurate timing solution of RX J0806.4-4123 can clarify whether this neutron star is different from its Mag7 siblings. I will present our multi-year X-ray timing campaign of RX J0806.4-4123 with the NICER instrument and what we can learn from it about the changing spin of this pulsar.


Name: Karastergiou, Aris
E-mail: aris.karastergiou@physics.ox.ac.uk
Affiliation: Oxford
Type of presentation: Oral
Title:
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Name: Marta Burgay
E-mail: marta.burgay@inaf.it
Affiliation: INAF - OACagliari
Type of presentation: Oral
Title: Search and timing of pulsars in unidentified Fermi sources with MeerKAT
Abstract: The TRAPUM (Transients and Pulsars with MeerKAT) large survey project, now in its third year of operations, has already discovered more than a hundred pulsars. In this talk I will report on the multi-wavelength timing of 20+ millisecond pulsars found targeting Fermi unidentified point sources. A large fraction of these discoveries are exotic "spider" binary systems with low mass irradiated companion stars, which exhibit a rich phenomenology across the electromagnetic spectrum.


Name: Tarraneh Eftekhari
E-mail: teftekhari@northwestern.edu
Affiliation: Northwestern University
Type of presentation: Oral
Title: Opening a Window into the Transient Millimeter Sky with Next-Generation CMB Surveys
Abstract: The next generation of CMB surveys are poised to open a new window for transient discovery in the millimeter band. These surveys will cover a large fraction of the sky to unprecedented sensitivity and with high cadence, complementing existing and future wide-field radio and optical surveys. Using theoretical and empirical light curves for a wide range of extragalactic transients (including gamma-ray bursts, tidal disruption events, fast blue optical transients, neutron star mergers) in conjunction with known and estimated volumetric event rates, I will present the discovery phase space for millimeter transients in existing and near-term CMB surveys (ACT, SPT-3G, Simons Observatory, CMB-S4, CMB-HD), and discuss the synergy with SKA pathfinders and precursors, leading to a comprehensive view of the transient sky from radio to millimeter wavelengths.


Name: Law, Casey
E-mail: claw@astro.caltech.edu
Affiliation: Caltech
Type of presentation: Oral
Title: FRB Persistent Radio Sources
Abstract: New instruments are making precision localization of Fast Radio Bursts seem easy. Roughly twenty FRBs have been localized well enough to robustly identify host galaxies and search for multiwavelength counterparts. Dozens more are expected as purpose-built instruments come on line, such as DSA-110 and CHIME with outriggers. Yet the even the first localization, FRB 20121102A, has opened an unresolved problem in FRB and extragalactic science: what are persistent radio sources (PRS)? Two compact (<1 pc), luminous (>1e29 erg/s/Hz) radio counterparts have been associated with FRBs. At this luminosity, they are detectable at distances of hundreds of Mpc with all-sky radio surveys. This discovery mirrors theoretical and other observational work that is demonstrating that there are new populations of compact, extragalactic radio sources. I will present a summary of new extragalactic science at the confluence of new theoretical predictions, large radio surveys, and FRB discoveries.


Name: Main, Robert
E-mail: ramain@mpifr-bonn.mpg.de
Affiliation: Max-Planck-Institut für Radioastronomie
Type of presentation: Oral
Title: Scintillation of pulsars in dense local environments with MeerKAT
Abstract: TBD


Name: Marcote, Benito
E-mail: marcote@jive.eu
Affiliation: Joint Institute for VLBI ERIC (JIVE)
Type of presentation: Oral
Title: Precise localizations of Fast Radio Bursts and their local environments
Abstract:


Name: Evangelia (Lilia) Tremou
E-mail: etremou@nrao.edu
Affiliation: NRAO
Type of presentation: Oral
Title: Dense radio and X-ray monitoring of the black hole X-Ray binary GX339--4
Abstract: I will be presenting the longest-standing and the most dense quasi-simultaneous radio and X-ray monitoring campaign of the low mass X-ray binary GX 339-4, covering three years of weekly radio and X-ray observations with MeerKAT radio telescope and the Swift/XRT, respectively.


Name: Limaye, Pranav
E-mail: s6prlima@uni-bonn.de
Affiliation: Argelander Institute for Astronomy/ Max Planck Institute for Radio Astronomy
Type of presentation: None
Title:
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Name: van der Wateren, Emma
E-mail: wateren@astron.nl
Affiliation: ASTRON / Radboud University
Type of presentation: Oral
Title: The LOFAR Tied-Array All-Sky Survey: Timing of 35 radio pulsars and an overview of the LOFAR pulsar properties
Abstract: The LOFAR Tied-Array All-Sky Survey (LOTAAS) is the most sensitive untargeted radio pulsar survey performed at low radio frequencies (119−151 MHz) to date and has discovered 76 new radio pulsars, including the 23.5-s pulsar J0250+5854, which up until recently was the slowest spinning radio pulsar known. In this paper, we report on the timing solutions of 35 pulsars discovered by LOTAAS, which include a nulling pulsar and a mildly recycled pulsar, and thereby complete the full timing analysis of the LOTAAS pulsar discoveries. We give an overview of the findings from the full LOTAAS sample of 76 pulsars, discussing their pulse profiles, radio spectra, and timing parameters. We found that the pulse profiles of some of the pulsars show profile variations in time or frequency, and while some pulsars show signs of scattering, a large majority display no pulse broadening. The LOTAAS discoveries have on average steeper radio spectra and longer spin periods (1.4×), as well as lower spin-down rates (3.1×) compared to the known pulsar population. We discuss the cause of these differences and attribute them to a combination of selection effects of the LOTAAS survey as well as previous pulsar surveys, though we cannot rule out that older pulsars tend to have steeper radio spectra.


Name: Mawson Sammons
E-mail: mawson.sammons@postgrad.curtin.edu.au
Affiliation: Curtin University
Type of presentation: Oral
Title: Two Screen Scattering in CRAFT FRBs
Abstract: Using high spectral and temporal resolution dynamic spectra rendered from baseband data I will present the scintillation and scattering properties of a handful of CRAFT FRBs. This includes several FRBs which show evidence of scattering by more than one screen.


Name: Sachin Pradeep Etakkepravan Thulicheri
E-mail: s6saprad@uni-bonn.de
Affiliation: Argelander-Institut für Astronomie
Type of presentation: None
Title:
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Name: Atri, Pikky
E-mail: atri@astron.nl
Affiliation: ASTRON, the Netherlands
Type of presentation: Oral
Title: High-resolution imaging to unearth black hole birth mechanisms
Abstract: Accreting X-ray binaries are excellent laboratories to study extreme physics in our universe and provide unique opportunities to understand exotic neutron stars and black holes. It is thought that black hole X-ray binaries are small-scale Active Galactic Nuclei whose radio jets vary on human timescales. High-resolution radio imaging and astrometry are powerful tools that allow us to directly probe the evolution of these jets. In this talk, I will review the study of compact X-ray binaries and how Very Long Baseline Interferometry is enabling exciting breakthroughs in understanding their birth, evolution and advancing the search for new X-ray binary systems.


Name: Gizani, Nectaria
E-mail: ngizani@eap.gr
Affiliation: Hellenic Open University, School of Science and Technology
Type of presentation: Oral
Title: The Hellenic Radio TelescopeTHERMOpYlae
Abstract: N. Gizani, G. Veldes, N. Caballero
We present the Hellenic radio Telescope: materialization of inspiration, the infrastructure, the scientific importance of the instrument, what has been done so far in spite of issues, update on conversion.


Name: Carli, Emma
E-mail: emma.carli@postgrad.manchester.ac.uk
Affiliation: The University of Manchester
Type of presentation: Oral
Title: Searching for pulsars in Nearby Galaxies with MeerKAT
Abstract: TRAPUM (TRAnsients and PUlsars with MeerKAT, Stappers & Kramer 2016) is a Large Survey Project of the MeerKAT telescope, a 64-dish radio interferometer and precursor to the Square Kilometer Array. The TRAPUM collaboration is conducting a survey of nearby galaxies, which has so far increased the extragalactic radio pulsar population by 50%. I will present the novel observing and processing methods of the survey, harnessing the capabilities of the SKA’s mid-frequency precursor. I will report on the results of the recently completed Small Magellanic Cloud survey, which revealed many young pulsars, the prolific Large Magellanic Cloud survey, and a Fast Radio Burst discovery near the Sextans group of galaxies. Our discoveries can reveal valuable information on Neutron Star formation, Gravitational Waves and Fast Radio Bursts, by effectively probing the effects of another galaxy's properties onto a neutron star population.


Name: Woudt, Patrick
E-mail: pwoudt@ast.uct.ac.za
Affiliation: University of Cape Town
Type of presentation: Oral
Title: Radio transients with MeerKAT: Five years of ThunderKAT and MeerLICHT
Abstract: I will present highlights of five years of ThunderKAT on MeerKAT, and results from the MeerLICHT telescope (abstract to be updated at time of formal registration).


Name: Oleg Smirnov
E-mail: o.smirnov@ru.ac.za
Affiliation: Rhodes University & SARAO
Type of presentation: Oral
Title: MeerKAT as a dynamic imaging machine: Jove, Saturn and the RATT RRAT
Abstract: MeerKAT observations of the Great Saturn-Jupiter Conjunction of 2020 presented a unique dynamic imaging challenge due to the bright and highly time-variable emission from Jupiter's radiation belts (themselves moving relative to background sources). Dynamic imaging of these observations yielded the discovery of a minute-timescale transient as a happy byproduct, which was later confirmed to be an RRAT-type object.


Name: Graber, Vanessa
E-mail: graber@ice.csic.es
Affiliation: Institute of Space Sciences (ICE-Barcelona)
Type of presentation: None
Title:
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Name: Celsa Pardo Araujo
E-mail: pardo@ice.csic.es
Affiliation: Institute of Space Science (ICE-CSIC)
Type of presentation: None
Title:
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Name: Ronchi Michele
E-mail: ronchi@ice.csic.es
Affiliation: Institute of Space Sciences (CSIC-IEEC)
Type of presentation: Oral
Title: Simulation-based inference for pulsar-population synthesis
Abstract: Although about a billion neutron stars are expected to exist in the Milky Way, observational constraints limit us to only observing a few thousand. Pulsar population synthesis bridges this gap by simulating the entire population and comparing it to the observed sample to constrain neutron-star physics. In this talk, we explore the possibility of using simulation-based inference based on neural networks to estimate the parameters governing the magnetic and rotational properties of isolated Galactic radio pulsars. For this purpose, we implement a population-synthesis framework able to simulate the stars' dynamical and magneto-rotational evolution as well as their radio emission and incorporate selection biases of typical radio surveys. We then generate a dataset of mock pulsar populations to train and validate a mixture-density neural network. In particular, we demonstrate how the combined information from P-Pdot diagrams from different radio surveys can help us to recover the posterior distribution of the model parameters governing the properties of neutron stars at birth.


Name: Baan, Willem
E-mail: baan@astron.nl
Affiliation: XinJiang Astronomical Observatory & ASTRON
Type of presentation: Oral
Title: tbd
Abstract: tbd


Name: Lauren Rhodes
E-mail: lauren.rhodes@physics.ox.ac.uk
Affiliation: Oxford
Type of presentation: Oral
Title: Image plane detections of FRB 121102 and its varying persistent radio counterpart as observed with MeerKAT
Abstract: As more Fast Radio Bursts (FRBs) are being localised, accompanied by persistent radio sources (PRSs), as a community, we need to improve our understanding of the nature of the PRSs, the relation to the bursts themselves as well as determine why only some bursts have PRSs. I will report on observations made of FRB 121102 from the MeerKAT radio telescope. Across five epochs, the persistent radio counterpart associated with FRB 121102, previously reported in the literature, is clearly detected and shown to vary on a timescale of years. I will also present the image plane detections of the bursts previously reported in Caleb et al (2020). Seven of the eleven bursts were detected by imaging the two-second integrations simultaneous to the bursts. Finally, I will discuss the importance of these image plane detections when considering the commensal transient searches being performed with both MeerKAT and other radio facilities.


Name: Oswald, Lucy
E-mail: lucy.oswald@physics.ox.ac.uk
Affiliation: University of Oxford
Type of presentation: Oral
Title: Understanding, explaining and using pulsar polarization
Abstract: The polarization of radio pulsars is a key probe, both of the beam structure and geometry of the pulsars themselves, and of the magnetic structure of the Milky Way. Furthermore, accounting for intrinsic variability and the impact of the interstellar medium is of key importance for accurate pulsar timing. Continued improvements in observational capabilities have shown that the conventional picture of pulsar polarization behaviour is insufficient to explain the complex frequency- and phase-dependent signatures seen in broad-band observations. In this talk I will describe how such observations reveal key relationships between polarization variability, circular polarization and pulsar spin-down energy. I will explain how I developed the partial-coherence model of pulsar polarization to account for these relationships, illustrating this with some straightforward examples of individual and collective pulsar behaviours. I will also explain how we can apply understanding of pulsar polarization to large-scale pulsar surveys to map the structures of the interstellar medium. I will describe this in the context of the Thousand-Pulsar-Array survey on the MeerKAT telescope and look towards future prospects for developing our understanding of both pulsars and the structure of the galaxy with polarization observations in the era of the SKA.


Name: Jankowski, Fabian
E-mail: fabian.jankowski@cnrs-orleans.fr
Affiliation: CNRS Orléans, Université d'Orléans
Type of presentation: Oral
Title: FRBs and pulsars with MeerKAT and the Nançay Radio Observatory telescopes
Abstract: TBD


Name: Keith Bannister
E-mail: keith.bannister@csiro.au
Affiliation: CSIRO
Type of presentation: Oral
Title: CRACO results
Abstract: Rresults from CRACO - hopefully we have some


Name: Blanchard Clara
E-mail: clara.blanchard@cnrs-orleans.fr
Affiliation: LPC2E and University of Orleans
Type of presentation: Oral
Title: Black widow pulsar binaries with the Nançay Radio Telescope
Abstract: TBD


Name: Majid, Wali
E-mail: majidw@gmail.com
Affiliation: JPL, Caltech
Type of presentation: Poster
Title: Joint Radio/Optical Observation of FRBs with Novel DSN Instrument
Abstract: FRBs are bright, milli-second duration radio pulses of unknown origin. Since their discovery in 2007, FRBs have been shown to have extragalactic origins and enormous energy outputs in the radio band alone. Hunting for FRBs and understanding their physical origin(s) have become a leading scientific goal in astrophysics. As neither the progenitors nor their emission mechanisms are known, simultaneous multi-wavelength studies of repeating FRBs would enable new tests of emission models. In this presentation, we will describe a novel experiment currently under development at the NASA Deep Space Complex in Goldstone, CA, where we are planning on conducting simultaneous long-term radio and optical monitoring of repeating FRBs using a newly developed hybrid radio/optical system. The planned observations with the new facility once the instrument has been commissioned will enable precise measurements of the relative optical to radio energy flux of the bursts, a key observable for discriminating between the various proposed progenitors and emission mechanisms for FRBs.


Name: Venkatraman Krishnan, Vivek
E-mail: vkrishnan@mpifr-bonn.mpg.de
Affiliation: Max Planck Institute for Radio Astronomy, Bonn, Germany
Type of presentation: Oral
Title: The MeerKAT relativistic binary timing programme
Abstract: Timing relativistic binary pulsar systems have enabled the measurements of precise neutron star masses and fundamental tests of gravity in the strong field regime. The measurement of neutron star masses not only provide insight into the elusive neutron star interior, but also help constrain binary evolution theories and supernova physics. For many binary systems in the southern hemisphere, the precision of these measurements have so far been limited by the sensitivity of radio telescopes. The new MeerKAT telescope, a 64-dish interferometer in South Africa that is an SKA-mid precursor, has overcome this limitation with its unparalleled sensitivity in the southern sky. The ongoing "RelBin" observing programme with MeerKAT is a part of the MeerTime large survey project that observes relativistic binary systems. In this talk, I will provide an overview of the RelBin programme and discuss ongoing results from the last 3 years of its operation.


Name: Voraganti Padmanabh, Prajwal
E-mail: prajwal.voraganti.padmanabh@aei.mpg.de
Affiliation: Max Planck Institute for Gravitational Physics, Hannover
Type of presentation: Oral
Title: The MPIfR-MeerKAT Galactic Plane Survey
Abstract: Wide field-of-view interferometric radio surveys covering both imaging and time-domain science are rare. The Max-Planck-Institut f\"{u}r Radioastronomie (MPIfR) MeerKAT Galactic Plane survey (MMGPS) is the only SKA pathfinder survey with such a capability. Covering science cases for pulsars and fast transients, Galactic and extragalactic magnetism and Galactic star formation, the MMGPS is an ongoing commensal survey, that aims to maximise the the scientific return per unit of MeerKAT observing time. In this talk, on behalf of the MMGPS collaboration, I will describe the observing infrastructure, processing strategy and the results obtained across different domains. Observing the Galactic plane at L-band (856-1712 MHz) and S-band (1968 - 2844 MHz) the survey has already yielded more than 75 pulsar discoveries of which 16 are rapidly rotating millisecond pulsars. These include potential double neutron star systems and a binary pulsar also found to have pulsations in Gamma rays. Commensal imaging has been able to produce total intensity images down to a 30 uJy rms and an angular resolution of 7 arcseconds. Additional features planned for the future include a Full Stokes polarisation capability which would further enhance and enable synergistic science between Galactic magnetism and pulsar emission.


Name: Andersson, Alex
E-mail: alexander.andersson@physics.ox.ac.uk
Affiliation: University of Oxford
Type of presentation: Oral
Title: Discovering radio transients using the power of humans and machines
Abstract: The study of radio transients probes an immense range of astrophysical regimes - from flare stars to FRBs - and with the advent of current interferometers we can sample wide swathes of the radio sky with unprecedented sensitivity and cadence. Firstly, I will discuss recent, serendipitous discoveries being made with the MeerKAT radio telescope and how we can make the best of new facilities coming online. This includes how citizen scientists have scoured our data and uncovered 100s of new variable sources - this is the first ever crowd sourcing project dedicated to radio transients in this manner. Secondly, I will discuss novel machine learning techniques being developed to speed up the search for interesting and anomalous sources, methods that will prove invaluable as we look towards observatories such as the SKA.


Name: Kundu, Esha
E-mail: kunduesh@msu.edu
Affiliation: Michigan State University
Type of presentation: Oral
Title: The MAVERIC Survey: Nature of compact objects in globular clusters M22 and M4
Abstract: It is established that globular clusters (GCs) are over-abundant in compact binaries: those containing a white dwarf, neutron star, or black hole (BH). While the existence of some of these classes of objects was known for a long time, the presence of stellar-mass BHs in GCs has only been revealed in the last decade. With the fact that BH-BH binaries are common in the local universe, as indicated by the detection of gravitational waves from the merging events of BH-BH binaries, there are broad scientific implications of the presence of stellar-mass BHs in globular clusters. Through our MAVERIC survey, we have acquired deep radio continuum images of a significant number of Milky Way GCs. I have carried out a detailed study of radio variability along with a multi-wavelength (optical and X-ray) examination of compact objects in GCs M22 and M4 to uncover the true nature of primary accretors. We found there exists a mixed population of compact objects in both globular clusters with at least one new BH candidate in one of these GCs.


Name: Kazantsev Christine
E-mail: christine.kazantsev@ens-paris-saclay.fr
Affiliation: Institute of Space Sciences, Barcelona, Spain
Type of presentation: Oral
Title: Two new double-neutron-star binary candidates
Abstract: We will discuss two new partially recycled radio pulsars in binary systems. Timing observations carried out with the Arecibo and FAST telescopes over the past several years have led to the measurement of post-keplerian effects. The measured orbital properties of these systems are similar to other known double-neutron-star systems (DNSs) in the Galactic field. Should the neutron-star (NS) nature of the companions be confirmed, our current timing measurements imply that one of the systems contains the lowest-mass NS and one of the most asymmetric DNSs systems known. As for the second system, the spin and orbital properties of the pulsar make for an unusual system and offer a different viewpoint for investigating evolution pathways, recycling processes, pre-supernova properties and supernova kicks in DNSs.


Name: Natasha Hurley-Walker
E-mail: nhw@icrar.org
Affiliation: Curtin University, International Centre for Radio Astronomy Research
Type of presentation: Oral
Title: Long-period transients with the MWA
Abstract: Most known neutron stars have been detected via periodic radio or X-ray signals correlated with their rotational period, which are generated either by a conversion of a fraction of their spin-down dipole radiation (pulsars) or twisting and/or reorganisation of their intense magnetic fields (magnetars). The known population typically rotates with periods of milliseconds to tens of seconds, but it is postulated that there exists an older, much more slowly-rotating neutron star population. These “ultra-long period” (ULP) magnetars are candidate progenitors for Fast Radio Bursts, which themselves are now being localised to positions incompatible with young magnetars (e.g. globular clusters). ULP magnetars would explain many of the emission characteristics of FRBs, such as the quasi-periodic windows of emission, but were thought to be impossible to observe directly. Using the low-frequency radio telescope the Murchison Widefield Array, we have detected two long-period radio transients, with periods of 18 and 21 minutes, potentially the first direct detections of ULP magnetars. Timing estimates place the sources below the conventional “death lines” of emission mechanisms that explain radio emission in neutron stars. The sources also show surprisingly diverse characteristics, with different pulse morphologies, polarisation behaviour, and staggeringly different activity windows. These sources are just the tip of the iceberg of a new population, the exploration of which will illuminate the behaviour of neutron stars and therefore physics in extreme environments. I will conclude the talk with future survey plans across a range of telescopes.


Name: Anjana Ashok
E-mail: anjana.ashok@aei.mpg.de
Affiliation: Max Planck Institute for Gravitational Physics
Type of presentation: Oral
Title: Targeted searches for continuous gravitational waves from known pulsars
Abstract: A rotating neutron star with a non-axisymmetric distribution of mass continuously emits nearly-monochromatic gravitational waves. These continuous gravitational wave (CW) signals have not been detected yet and searches in Advanced-LIGO data are underway. When a neutron star is observed in electromagnetic waves as a pulsar, the resulting timing solutions can inform the searches for the CW signal from the pulsar. Such targeted searches are the most sensitive among the various types of CW searches. In the event of a non-detection, our constraints on the gravitational wave strain translate to a constraint on the ellipticity - a quantitative measure of the asymmetry of the pulsar. This talk focuses on the methods, some recent results and capabilities of targeted continuous gravitational wave searches.


Name: Salal, Jitendra
E-mail: jsalal@ncra.tifr.res.in
Affiliation: National Centre for Radio Astrophysics (NCRA - TIFR)
Type of presentation: Oral
Title: Identifying pulsar candidates in radio images using scintillation
Abstract: Pulsars have been primarily detected by their narrow pulses or periodicity in time domain data. With a synthesis imaging telescope like the GMRT, typically pulsar surveys use wider incoherent beams to map large areas of the sky, but the incoherent beam is less sensitive compared to regular imaging data. Also, the detection sensitivity of time-domain searches for pulsars is affected by dispersion smearing, scattering, and rapid orbital motion of pulsars in binaries. The radio continuum images do not suffer from the limitations of time domain searches. They, therefore, are equally sensitive to all pulsars and allow us to find hard-to-detect pulsars, such as sub-millisecond pulsars, pulsar-black hole systems, and pulsars near the Galactic Centre. Building on a variance imaging technique proposed by Dai et. al. (2016), we have developed a new technique that detects pulsar candidates in standard radio images by measuring their scintillation bandwidth and timescale from the autocorrelation of dynamic spectra of sources. We use existing GMRT observations of PSR B1508+55 and its neighboring sources as a test case for our technique. We demonstrate that the technique correctly differentiates between the pulsar and other non-scintillating point sources and show that the extracted dynamical spectrum of the pulsar is equivalent to that extracted from the GMRT phased array beam. We developed an automated pipeline for processing archival data and testing it on GMRT and uGMRT data. We will show results from our analysis of known pulsar fields and challenges in dealing with interference and instrumental effects.


Name: de Ruiter, Iris
E-mail: i.deruiter@uva.nl
Affiliation: Anton Pannekoek Institute/University of Amsterdam
Type of presentation: Poster
Title: Low-frequency radio observations of recurrent nova RS Ophiuchi with MeerKAT and LOFAR
Abstract: We report low-frequency radio observations of the 2021 outburst of the recurrent nova RS Ophiuchi. These observations include the lowest frequency observations of this system to date. Detailed light curves are obtained by MeerKAT at 0.82 and 1.28 GHz and LOFAR at 54 and 154 MHz. These low-frequency detections allow us to put stringent constraints on the brightness temperature that clearly favour a non-thermal emission mechanism. The radio emission is interpreted and modelled as synchrotron emission from the shock interaction between the nova ejecta and the circumbinary medium. The light curve shows a plateauing behaviour after the first peak, which can be explained by either a non-uniform density of the circumbinary medium or a second emission component. Further modelling of the light curves allows us to constrain the red giant mass loss rate. Radio emission from stellar wind or synchrotron jets are ruled out as the possible origin of the radio emission. Finally, we suggest a strategy for future observations that would advance our understanding of the physical properties of RS Oph.


Name: de Ruiter, Iris
E-mail: i.deruiter@uva.nl
Affiliation: Anton Pannekoek Institute/University of Amsterdam
Type of presentation: Oral
Title: A coherent radio flash following a neutron star merger: The birth of a magnetar
Abstract: The mergers of two neutron stars are exceptional multi-messenger events including short gamma-ray burst (GRB), gravitational wave and kilonova/afterglow emission. These events enable us to probe fundamental physics in one of the most extreme environments in the Universe. A key outstanding question is the remnant's nature: with its expected mass and rapid spin, it could either be a black hole or a supramassive, likely highly magnetised neutron star (a magnetar). Both can power a GRB, but rapidly spinning magnetars are additionally predicted to emit coherent radio bursts following their formation and may constitute a small fraction of the progenitors of fast radio bursts. Black holes, by contrast, are not expected to emit coherent radio bursts in the time following the GRB itself. In this talk we will present rapid follow-up observations of the short GRB 201006A using LOFAR. We have detected an associated short, coherent radio flash at 144 MHz at 76.5 mins post-burst. The radio flash is tentatively shown to be highly dispersed, allowing a distance estimate, that is in the range of typical short GRB distances. This emission indicates prolonged activity from the central engine, further providing evidence that the merger remnant is a newborn magnetar and not a black hole. This discovery of a coincident radio burst with a short GRB demonstrates that searches for this emission could be highly useful for the multi-messenger campaigns following binary mergers of neutron stars and associated gravitational wave events. I'll give this talk on behalf of the first author, Dr Antonia Rowlinson, who cannot attend this meeting.


Name: Nanda Rea
E-mail: rea@ice.csic.es
Affiliation: ICE-CSIC
Type of presentation: Oral
Title: Ultra-long period radio transients challenging magnetar evolution and coherent radio emission models
Abstract: I will present recent observational and theoretical studies on long period radio pulsars. These new objects are challenging our understanding of magnetar evolution and/or coherent radio emission models. I will show how none of the current evolutionary scenarios for neutron stars or white dwarfs can easily explain the periodicities and radio emission of these sources. I will also present population synthesis models estimating how many of such sources might be discovered in the next few years with SKA.


Name: Sett,Susmita
E-mail: 20014515@student.curtin.edu.au
Affiliation: Curtin University
Type of presentation: Oral
Title: Image-based searches for pulsar candidates using MWA VCS data
Abstract: Pulsars have been proven instrumental to explore a wide variety of physics and astrophysics, ranging from probing dense-matter physics to testing strong-field gravity. They have been studied extensively and actively over the last few decades. However, there are still areas of research such as, emission mechanism, propagation effects that have not been well explored yet. These areas of research can be better studied by using a larger sample of pulsars and hence detecting more of them is helpful. Studying of pulsars at low frequencies improves the understanding of the spectral properties and propagation effects of pulsars. However, searching for pulsars at low frequencies with traditional methods is computationally expensive and time consuming. In this talk, I will explain the image-based strategies developed to detect pulsar candidates using the the unique capability of the MWA, the Voltage Capture System (VCS) which records high-time and frequency resolution voltage data (100 μs / 10 kHz). The developed strategies exploit aspects such as spectral index, polarisation and variability. We discuss the results obtained on implementation of these strategies to MWA data and the success rate of the methodologies in detection of pulsars and pulsar like candidates. As pulsar science, in particular timing applications using millisecond pulsars and binaries, is a key science driver for the Square Kilometre Array (SKA), establishing the strategies will not only help in accelerating the efforts of pulsar searching with the MWA but also in determining the future yield of pulsar surveys with the upcoming SKA.


Name: Kylafis, Nick
E-mail: kylafis@physics.uoc.gr
Affiliation: University of Crete & Institute of Astrophysics-FORTH
Type of presentation: Oral
Title: A quantitative explanation of the radio -- X-ray correlation in black-hole X-ray binaries
Abstract: Accretion of matter onto compact objects is tightly connected with ejection of matter from them. After all, it is the accretion flow that feeds the outflow. Despite many efforts, this connection has not become clear. In particular, the observed correlation between the radio and X-ray fluxes in the hard state of black-hole X-ray binaries (BHXRBs) has been around for more than two decades now. It is currently accepted that the hard X-rays in BHXRBs come from Comptonization in the corona and the radio emission from the jet. The jet and the corona, however, are separate entities with hardly any communication between them, apart from the fact that the jet is fed from the corona. It is also widely accepted that the accretion flow around black holes in BHXRBs consists of an outer thin disk and an inner hot flow. From this hot inner flow, an outflow must emanate in the hard and hard-intermediate states of the source. By considering Compton up-scattering of soft disk photons in the outflow (i.e., in an outflowing "corona") as the mechanism that produces the hard X-ray spectrum, we have been able to explain quantitatively a number of observed correlations. Here, we investigate whether this outflowing "corona" can explain the observed radio - X-ray correlation also. We consider a parabolic outflow and compute the radio emission at 8.6 GHz coming from it, as well as the power-law photon-number spectral index Gamma of the Comptonized hard X-rays produced in it. Thus, we have a correlation between the computed radio flux F_R at 8.6 GHz and the computed spectral index Gamma of the hard X-ray spectrum. This correlation is actually a theoretical prediction, since both F_R and Gamma are computed from the model and, to our knowledge, no such correlation has been constructed from observations for the hard and the hard-intermediate states. This prediction can be confirmed or rejected in future outbursts of GX 339-4. From observations of GX 339-4, we also produce a correlation between the observed X-ray flux F_X and the observed index Gamma. Thus, for each value of Gamma, observed/computed, we have the corresponding values of the observed F_X and the computed F_R, which we plot one against the other. We find that, in the hard state of GX 339-4, our idea reproduces the observed correlation of F_R ~ (F_X)^0.6 . In addition, in the hard-intermediate state of GX 339-4, we predict that, in future outbursts of the source, the F_R will exhibit first a sudden increase and then a sharp drop within a very narrow range of values of F_X . Also, since in a parabolic outflow the density is largest at its bottom, the transverse optical depth at the bottom of the outflow is very large (typically 10 to 100) and so the soft input photons, that are Comptonized there, see something like a "slab" above their emission. This may explain naturally the observed X-ray polarization from BHXRBs.


Name: Deller, Adam
E-mail: adeller@swin.edu.au
Affiliation: Swinburne University of Technology
Type of presentation: Oral
Title: From voltages to science with the ASKAP FRB post-processing pipeline
Abstract: The Australian SKA Pathfinder boasts a potent combination of field of view, sensitivity, and real-time transient detection (along with raw data buffering) which enables Fast Radio Bursts to be 1) detected, 2) localised, and 3) studied at high time resolution with full polarimetry. I will describe the post-processing pipeline that turns saved voltage dumps into calibrated visibility datasets and beamformed filterbanks in a high performance computing (HPC) environment. Using some recent ASKAP FRBs as examples, I will illustrate the current limitations on both astrometric accuracy (typically 0.5”-0.7”) and pipeline throughput (typically a few days per FRB), and the current areas of work that should mitigate these limitations and improve accuracy and throughput by factors of 2+ and 10+ respectively in the forthcoming ``CRACO” era on ASKAP where detection rates will skyrocket.


Name: Griessmeier, Jean-Mathias
E-mail: jean-mathias.griessmeier@cnrs-orleans.fr
Affiliation: LPC2E
Type of presentation: Oral
Title: Pulsar observations and pulsar timing below 100 MHz using NenuFAR
Abstract: NenuFAR (New extension in Nançay upgrading LOFAR) is a new radio telescope developed and built on the site of the Nançay Radio Observatory. It is designed to observe the frequency window from 10 to 85 MHz, offering a high sensitivity across its full bandwidth. NenuFAR is used for a variety of pulsar studies, include a low frequency pulsar census, a blind survey searching for pulsars and a pulsar timing campaign. We will present results of the pulsar census and give an update on the NenuFAR pulsar blind survey. We will also present results from our pulsar timing campaign, which include bright non-recycled pulsars as well as MSPs.


Name: Wood, Callan
E-mail: callan.m.wood@student.curtin.edu.au
Affiliation: International Centre for Radio Astronomy Research - Curtin University
Type of presentation: Oral
Title: New Techniques for Real-time Imaging of Jets Launched by Accreting Black Holes
Abstract: Over the past few decades, very long baseline interferometry (VLBI) has been a very important tool for uncovering details about the launching and evolution of black hole jets. By precisely tracking the proper motions of the jets launched by nearby stellar-mass black holes in X-ray binaries (XRBs), we can place tight constraints on the physical processes occurring in the inner accretion flow that are responsible for the launching of transient jets. These jets, however, can exhibit rapid variability and motion on a timescale as short as a few minutes, violating a fundamental assumption of interferometric aperture synthesis. As a result, past attempts to track the motions of these jets have been limited by the difficulty of making high-fidelity images of these jets. In this talk, I will describe dynamic phase-centre tracking and time-dependent visibility model fitting, two new techniques that explicitly account for the intra-observational motion and variability of jets, to track their evolution in real-time, even for sources that are far too faint or fast-moving to be recovered by the standard imaging approach. In one example, through the use of these new techniques, we were able to place the most precise constraint on the ejection date of a transient XRB jet, by over an order of magnitude. In another example, we were able to constrain the intra-observational motion and variability of multiple emission components, which were far too faint to be detected in time-binned images. Observations of XRBs with future instruments, like the next generation Event Horizon Telescope (ngEHT), the next generation Very Large Array (ngVLA), and even SKA-VLBI, will be able to track XRB jets earlier in their evolution and for longer, with higher resolution, greater sensitivity and better instantaneous coverage. The use of new imaging and modelling techniques, like the ones we are developing, that can account for the rapid intra-observational variability of jets, will be necessary to make the most of these observations, to get the best constraints of jet launching and evolution.


Name: John Reynolds
E-mail: John.Reynolds
Affiliation: CSIRO
Type of presentation: Oral
Title: The Rapid ASKAP Continuum Survey
Abstract: The Rapid ASKAP Continuum Survey (RACS) is the first large-area survey to be completed with the full 36-dish ASKAP radio telescope. ASKAP uses novel phased-array feed technology achieving a large instantaneous field view - 30 square degrees - suitable for high speed surveys and searches for transient sources. The RACS surveys is currently the most sensitive and detailed (in angular resolution) survey in cm-wave radio. This paper describes the initial and subsequent RACS epochs, and their role in enhancing ASKAP's ability to detect and follow-up transient sources of many types.


Name: Jancey, David
E-mail: David.Jauncey@csiro.au
Affiliation: CSIRO
Type of presentation: Oral
Title: Tidbinbilla and Fifty Years of Timing and Imaging
Abstract: D.L. Jauncey, J.E. Reynolds, E.A. King, J.E.J. Lovell and S. Horiuchi et. al.,
Deep Space Station DSS 43, Tidbinbilla's 64 m antenna became operational on April 13th, 1973. Since then, many high sensitivity programs of astronomy observations of compact radio sources at Tidbinbilla using DSS43 along with other DSN facilities have been underway. Such timing and imaging observations have covered a wide range of compact celestial objects from variations in the temperatures of both Jupiter and Uranus, through decades of ultra-high resolution of numerous AGN with both Earth and space VLBI baselines, pulsar timing and structure measurements, water vapor and ammonia spectral line sources, the birth and evolution of SN1987A, inter-stellar scintillation timing to current Fast Radio Burst sources. We describe these developments and their impact.


Name: Rhodes, Lauren
E-mail: lauren.rhodes@physics.ox.ac.uk
Affiliation: University of Oxford
Type of presentation: Oral
Title: FRB 20121102A: images of the bursts and the varying radio counterpart
Abstract: As more Fast Radio Bursts (FRBs) are being localised, it has been found that some have persistent radio sources (PRSs). Such a discovery motivates an improvement in our understanding of the nature of those counterparts, the relation to the bursts themselves and why only some FRBs have PRSs. I will present the results of observations made of FRB 20121102A with the MeerKAT radio telescope over a period of 1000 days. Across five epochs, we detect the PRS associated with FRB 20121102A was detected and find that the flux density varies on a timescale of years. One of the observations coincided with the detections of 11 bursts from FRB 20121102A by the MeerTRAP backend, seven of which are detected in the image plane. I will discuss the importance of image plane detections when considering the commensal transient searches being performed with MeerKAT and other radio facilities. We find that MeerKAT is so sensitive that within a two-second image, we could localise any FRB with a CHIME-like fluence at 1.3GHz.


Name: Marcote, Benito
E-mail: marcote@jive.eu
Affiliation: Joint Institute for VLBI ERIC (JIVE)
Type of presentation: Oral
Title: Precise localizations of Fast Radio Bursts and their local environments
Abstract: Fast Radio Bursts (FRBs) are millisecond-duration extremely-luminous transient events detected at radio frequencies. Despite hundreds of FRBs have been detected to date, their nature still remains unclear. Precise (very high resolution) localizations of FRBs seem to be the path to understand the mechanisms that originate these bursts, and the environments where FRBs are located. However, this is only possible via very long baseline interferometric (VLBI) observations with the European VLBI Network (EVN). I will review here the path that allowed us to pinpoint the first FRBs to their host galaxies and local environments, and the current state of the art of the conclusions that we reached from these localizations.


Name: Woudt, Patrick
E-mail: pwoudt@ast.uct.ac.za
Affiliation: University of Cape Town
Type of presentation: Oral
Title: Highlights from five years of radio transient studies with ThunderKAT and MeerLICHT
Abstract: In this talk I will present some of the highlights from five years of radio transient studies with ThunderKAT on MeerKAT, with a focus on X-ray binaries, Cataclysmic Variables, Gamma-ray Bursts and commensal transients searches. I will also highlight the added value of the real-time link with MeerLICHT, a robotic optical telescope tethered to the observing schedule of MeerKAT in terms of characterising transients discovered in the commensal data stream. Finally, I will focus on some of the exciting new results from high-speed (second-scale) imaging of astrophysical transients with MeerKAT, including the discovery of the second white dwarf pulsar.


Name: FARHAD ZADEH
E-mail: zadeh@northwestern.edu
Affiliation: Northwestern University
Type of presentation: Oral
Title: A Radio Continuum Survey of the Galactic center Region Using MeerKAT Observations
Abstract: Recent survey images of the Galactic center have been a gold mine in the study of this complex region of the Galaxy. I will present highlights of what we have recently learned about the population of radio filaments using MeerKAT data. In particular, new statistical studies of the spectral index, magnetic field strength, size distribution and the angular separation between groups of filaments have provided much insight on the nature of mysterious synchrotron-emitting radio filaments. I also give highlights of nonthermal radio filaments recent found in active Galactic nuclei. Lastly, I will present position angle distribution of Galactic center filaments which reveal a degree-scale collimated outflow from Sgr A* along the Galactic plane.


Name: Bhandari, Shivani
E-mail: shivanibhandari58@gmail.com
Affiliation: ASTRON
Type of presentation: Oral
Title: The host galaxies and local environments of fast radio bursts
Abstract: Fast Radio Bursts (FRBs) are millisecond-duration transients of intense, coherent radiation that are signposts of extreme astronomical environments. Despite 15 years of research, no conclusive consensus on the progenitor(s) of FRBs has been reached. While it is clear that some FRBs might be produced by magnetars, the diversity of FRB properties, behaviours, and locations implies that this is not the complete answer. Although there has been significant progress in localising FRBs to their hosts, we are still only scratching the surface in terms of the locations in which we can find FRBs. In this talk, I will give an outline of our current understanding of FRB host galaxies and their local surroundings. I will also discuss the latest FRB localisation discoveries from the Australian Square Kilometre Pathfinder.


Name: Kundu, Esha
E-mail: kunduesh@msu.edu
Affiliation: Michigan State University
Type of presentation: Oral
Title: The MAVERIC Survey: Nature of compact objects in globular clusters M22 and M4
Abstract: Globular clusters (GCs) are collections of stars and stellar remnants, held together within a small volume by mutual gravitational attraction. It is established that these clusters are over-abundant in compact binaries: those containing a white dwarf, neutron star, or black hole (BH). While the existence of some of these classes of objects was known for a long time, the presence of stellar-mass BHs in GCs has only been revealed in the last decade. With the fact that BH-BH binaries are common in the local universe, as indicated by the detection of gravitational waves from the merging events of BH-BH binaries, there are broad scientific implications of the presence of stellar-mass BHs in globular clusters. Through our MAVERIC survey, we have acquired deep radio continuum images of a significant number of Milky Way GCs. I have carried out a detailed study of radio variability along with a multi-wavelength (optical and X-ray) examination of compact objects in GCs M22 and M4 to uncover the true nature of primary accretors. We found there exists a mixed population of compact objects in both globular clusters with at least one new BH candidate in one of these GCs.


Name: Karastergiou, Aris
E-mail: aris.karastergiou@physics.ox.ac.uk
Affiliation: Oxford
Type of presentation: Oral
Title: The Thousand Pulsar Array project on MeerKAT: a rich dataset for understanding the pulsar population
Abstract:


Name: Vishnu Balakrishnan
E-mail: vishnu@mpifr-bonn.mpg.de
Affiliation: Max Planck Institute for Radio Astronomy
Type of presentation: Oral
Title: Title: Missing for 20 yr: MeerKAT Redetects the Elusive Binary Pulsar M30B
Abstract: TBD


Name: Ng, Cherry
E-mail: cherry.ng-guiheneuf@cnrs-orleans.fr
Affiliation: CNRS
Type of presentation: Oral
Title: SETI with SKA pathfinders
Abstract: The search for technosignatures - remotely observable indicators of advanced extraterrestrial life - addresses one of the most profound questions in science: are we alone in the universe as intelligent life? The Breakthrough Listen program is leading the most concerted search for extraterrestrial intelligence (SETI) effort to-date through radio and optical surveys of nearby stars, nearby galaxies and the Milky Way galactic plane, thus representing the best chance the human race has ever had to detect a technosignature. Currently, the Breakthrough Listen program employs some of the most sensitive radio telescope facilities around the world, including the Green Bank Telescope (GBT), Parkes, LOFAR, FAST, MeerKAT, and the Murchison Widefield Array (MWA). Breakthrough Listen also partners with the SETI Institute in next generation SETI surveys with the Allen Telescope Array (ATA) and the Very Large Array (VLA). In this talk, we will focus on the SETI survey status on a number of SKA precursors, and conclude with a refreshed outlook on SETI searches in the SKA era.


Name: Laura Driessen
E-mail: Laura.Driessen@Sydney.edu.au
Affiliation: The University of Sydney
Type of presentation: Oral
Title: Star-planet interactions at radio frequencies
Abstract: I will present the history and current status of radio searches for the period radio signatures of star-planet interactions (SPI) and what we're looking for to confirm radio exoplanet detections. Periodic radio emission from magnetic coupling between a star and its orbiting planet has been predicted between 280 MHz to 2.8 GHZ, but has yet to be conclusively detected. Candidate SPI emission has been detected from GJ 1151 with LOFAR, YZ Ceti with the VLA and Proxima Centauri with ATCA, but none of these detections have been confirmed as SPI emission. So what do we need to detect to know for sure that the emission is from SPI? I will present these candidate detections of SPI and the methods we're using to search for radio exoplanets.


Name: Lower, Marcus
E-mail: marcus.lower@csiro.au
Affiliation: CSIRO
Type of presentation: Oral
Title: How do young pulsars spin down?
Abstract: The average pulse profiles and spin-down rate of radio pulsars are often assumed to remain constant over time. However, long-term monitoring campaigns have revealed slowing rotation rates of many pulsars display substantial deviations from their expected evolutionary paths. There is also a growing sample of pulsars that exhibit correlated irregularities in their profile shape and spin-down rate. In this talk, I will present several recent and ongoing efforts to characterise the rotational and profile evolution of a large sample of young pulsars that have been observed over several decades by Murriyang, the Parkes 64-m radio telescope.


Name: Guillemot, Lucas
E-mail: lucas.guillemot@cnrs-orleans.fr
Affiliation: LPC2E and University of Orléans
Type of presentation: Oral
Title: Towards a much improved polarization calibration scheme for pulsar timing observations with the Nançay Radio Telescope
Abstract: Accurate polarimetric calibration of the radio pulse profiles from pulsars is crucial for studying their radiation properties. Also, inaccurate calibration can distort radio pulse profiles and introduce noise in time of arrival data, thereby degrading timing studies. Cross-couplings between the polarization receptors of a given telescope can be determined by observing bright polarized pulsars over wide ranges of parallactic angles, which is something that is not feasible with the Nançay Radio Telescope due to its design. I will present our efforts to overcome this limitation and improve the calibration of NRT observations. I will also show new NRT polarimetric profiles for a selection of millisecond pulsars obtained with the new calibration method, and show the impact of the improved calibration scheme on the timing of a stable millisecond pulsar over a decade.


Name: Smith, Kendrick
E-mail: kmsmith@perimeterinstitute.ca
Affiliation: Perimeter Institute for Theoretical Physics
Type of presentation: Oral
Title: Searching for FRBs with CHIME and CHORD
Abstract: The CHIME FRB search is the largest search currently operating, both in terms of computational volume, and number of sources detected. I'll give an update on the CHIME FRB search, including high-level science results, algorithmic/implementation details that make the search possible, and a status update on CHIME VLBI outrigger telescopes currently nearing completion. I'll also describe improvements in progress for CHORD, a new 512-dish Canadian telescope currently under construction.


Name: Gemma Anderson
E-mail: gemma.anderson@curtin.edu.au
Affiliation: International Centre for Radio Astronomy Research - Curtin University
Type of presentation: Oral
Title: Rapid-response observations of GRBs using Australian radio telescopes
Abstract: Only recently have sensitive radio telescopes been capable of automatically responding to transient alerts and multi-messenger events through the use of rapid observing systems. Such automated trigger systems allow the Australia Telescope Compact Array (ATCA) and the Murchison Widefield Array (MWA) to automatically begin observing GRBs on rapid (second to hours) timescales, which probe the very earliest emitted radio emission in what has previously been a poorly explored regime. In this talk, I will show results from the MWA and ATCA GRB rapid-response observing programs. The MWA automatic triggering response time of <20s is fast enough to probe for the prompt FRB-like signals predicted to be produced by GRBs. We seek to ascertain whether merging neutron stars (short GRBs and gravitational wave events) or massive stellar collapse (long GRBs) could produce supramassive neutron star remnants (magnetars), and therefore be progenitors of a sub-population of FRBs. I will then present results of the rapid follow-up ATCA observations of GRBs, which probe the very early-time radio afterglow emission produce by relativistic jets. ATCA performed rapid radio follow-up of GRB 210702A just 4 hrs post-burst, when the source had risen above the horizon. These observations showed an unexpected radio flare that started 9 hours post-burst, lasting for 5 hours. We tracked the rise and decay of this flare on 15 minute timescales in the visibility plane. Such a feature is not a characteristic of the external forward-reverse shock scenario that usually describes GRB afterglow emission. The early-time (<1 day) optical and X-ray light curves demonstrated typical afterglow (forward shock) behaviour. We therefore suggest that the radio flare is likely due to interstellar scintillation (ISS), which boosted the radio afterglow emission above the ATCA sensitivity on minute timescales. Using ISS relations, we were able to place the earliest size constraint on a GRB blast wave to date, which is comparable to theoretical forward shock size predictions. This result has motivated the instigation of a large ATCA observing program of >1000 hours over 3 years to trigger on all Swift long GRBs, obtaining the very earliest radio follow-up of a large sample of events that we will continue to monitor for months to years post-burst.


Name: Gourgouliatos, Konstantinos
E-mail: kngourg@upatras.gr
Affiliation: University of Patras
Type of presentation: Oral
Title: Neutron star magnetic fields: Beyond dipole
Abstract: The canonical pulsar model assumes that the neutron star's magnetic field is described by a magnetic dipole, whose axis of symmetry passes through its centre. However, on several occasions, it has been proposed that the magnetic field consists of multipoles, magnetic spots, magnetic arcades and off-centre dipoles. Quite remarkably, this has been related to different species of neutron stars, including magnetars, central compact objects and also the millisecond pulsar J0030+0451, whose surface temperature has been mapped in detail. I will present possible mechanisms that can lead to the spontaneous creation of non-dipolar components of the magnetic field, related to its evolution in the crust and the core. I will discuss the implications of these structures on the timing behaviour of neutron stars. Finally, I will present the impact of such off-centred magnetic fields to the spatial velocity of neutron stars, due to acceleration by asymmetric radiation, the so-called electromagnetic rocket effect and discuss it in the context of the observed velocities of young neutron stars.


Name: van der Horst, Alexander
E-mail: ajvanderhorst@gwu.edu
Affiliation: George Washington University
Type of presentation: Oral
Title: Multi-Timescale Transient Searches with MeerKAT
Abstract: MeerKAT has opened up new parts of transient parameter space, giving rise to discoveries in both the timing and imaging domain. Its characteristics and capabilities allow for deep transient searches on many different timescales. Here we will focus on some transient searches in MeerKAT images, as part of the ThunderKAT Large Survey Project. These searches probe timescales from seconds to years, with the potential of finding fast, coherent bursts as well as slowly evolving synchrotron sources with either intrinsic or extrinsic variability. We will discuss the various methodologies and tools that have been developed for these transient searches and their implications.


Name: Stinebring, Dan
E-mail: dan.stinebring@oberlin.edu
Affiliation: Oberlin College
Type of presentation: Oral
Title: Pulsar Scintillometry - Informing High-precision Timing
Abstract: New work with SKA pre-cursors such as MeerKAT, plus observations with FAST and other telescopes, has altered our picture of the distribution of scattering material in the local ISM. I will briefly review this work, highlighting the ubiquity of localized scattering structures ("screens") that may occur every ~ 10 pc or so along the line of sight to nearby pulsars. However, not all screens are created equal, and the effect on pulsar timing of the location of the screens -- and the AU-sized structures that appear common within the screens themselves -- will have differing effects based on lever-arm effects and the degree of inhomogeneity encountered. I will attempt an error budget analysis of these effects as they appear in time-varying scattering delays of pulsars, particularly for millisecond pulsars in current and projected Pulsar Timing Arrays.


Name: Dutta, Arunima
E-mail: adutta@mpifr-bonn.mpg.de
Affiliation: Max Planck Institute for Radio Astronomy
Type of presentation: Oral
Title: MeerKAT timing analysis of a massive binary pulsar in a globular cluster
Abstract: Globular clusters are old stellar systems in our Galaxy that are held together by their own gravity. These clusters have exceptionally high density of stars, allowing for dynamic interactions that result in the creation of exotic binary systems. In this talk, I will discuss a massive binary millisecond pulsar in a dense globular cluster that was recently discovered with MeerKAT. The system has an exceptionally high mass function, and both of its binary components are compact. We derived the binary's total mass using general relativity and the measured advance of periastron, and this exceeds the heaviest double neutron star known in the Galaxy and the most massive NS-NS merger candidate in LIGO/Virgo data. Additionally, the absence of a relativistic Shapiro delay suggests that the companion is too massive to be a white dwarf. This also places the companion as a compact object mass gap candidate, with a mass larger than the largest precisely measured pulsars and smaller than the lightest known stellar-mass black holes (BHs). If the companion is identified as a neutron star, it would provide valuable insights into the equation of state of dense nuclear matter, leading to new constraints. On the other hand, if it is identified as a black hole, it would signify a groundbreaking discovery of the first MSP-BH system, offering a unique opportunity to test the properties and formation mechanisms of black holes.


Name: Colom i Bernadich, Miquel
E-mail: mcbernadich@mpifr-bonn.mpg.de
Affiliation: Max-Planck-Institut für Radioastronomie
Type of presentation: Oral
Title: MMGPS-L: The eccentric double neutron star system PSR J1208 − 5936 and an update to the neutron star merger rate
Abstract: PSR J1208-5936 is a 28.71-ms recycled pulsar in a double neutron star binary which will merge within 7.2 Gyr due to the emission of gravitational waves, making it one of the few known precursors of neutron star merger events seen by LIGO and Virgo such as GW170817. Discovered during the MPIfR-MeerKAT Galactic Plane Survey at L-band, it has an orbital period of 15.16 hours and an orbital eccentricity of 0.35. Through pulsar timing, we constrain the component masses to Mpulsar=1.26(+0.13-0.25) solar masses and Mcompanion=1.32(+0.25-0.13) solar masses. Its eccentricity is larger than what is typically found in other double neutron star systems with similar orbital periods, suggesting a larger-than-usual supernova kick during the formation of the second-born neutron star. With the new information provided by this discovery, we update the upper limit on double neutron star merger rate based on known Galactic binaries to < 515 Gpc^−3 yr^−1, and predict the detection of 8(+10-4) merger events during the LIGO-Virgo-Kargra O4 run at the 90% confidence level.


Name: Keith Bannister
E-mail: keith.bannister@csiro.au
Affiliation: CSIRO
Type of presentation: Oral
Title: CRACO - the CRAFT coherent upgrade
Abstract: CRACO is a million-dollar upgrade to the ASKAP FRB search infstracture. We will form and dedipserse 2.4 million beams on the sky with a time resolution of about 1 millisecond. this is equivalent to watching uncompressed video of 1 million youtube viewers in a box the size of a fridge. I'll give an update on the design and commissioning and present some nifty new algorithms.


Name: Skiathas Dimitrios
E-mail: d.skiathas@upnet.gr
Affiliation: University of Patras
Type of presentation: Oral
Title: Magnetic Field Evolution in Neutron Stars due to Ambipolar Diffusion, Hall Effect, and Ohmic Dissipation
Abstract: Neutron stars present a large variety of behaviors and properties which give rise to various observable phenomena. A part of those behaviors and properties is attributed to their magnetic field and its evolution. The evolution of neutron star’s magnetic field is subject to the different conditions that takes place in their crusts and core. In the crust of a neutron star the magnetic field evolve through the Hall effect, the advection of the magnetic field by the moving charges and the Ohmic dissipation, the decay of the field due to finite conductivity. In the cores of neutron stars, especially the ones with strong magnetic fields, magnetars, the evolution is driven by ambipolar diffusion, a dissipative process that is due to the relative motion of the charged and uncharged particles. In our study we integrate the evolution equation of the magnetic field using a central finite difference scheme on an axisymmetric domain for a neutron star where ambipolar diffusion is the dominant mechanism in the core while the Hall effect and Ohmic dissipation participate in the evolution in the crust. We investigate the influence of these mechanisms on the magnetic field evolution under different initial magnetic field configurations, including a pure poloidal field, a pure toroidal field, a mixed field and a toroidal field confined within the region of closed poloidal field lines. Our simulations show that the impact of ambipolar diffusion leads to the containment of the toroidal field inside the region of closed poloidal magnetic field lines and pushed to the crust – core interface.


Name: Dimitris Ntotsikas
E-mail: d.ntotsikas@upnet.gr
Affiliation: Phd student, University of Patras
Type of presentation: Oral
Title: The Effect of Magnetic Twist on Neutron Star Magnetospheres
Abstract: We investigate the structure of a twisted axisymmetric magnetosphere of a relativistically rotating neutron star by numerically solving the relativistic force-free equation. The increase of the poloidal current in the closed magnetic lines affects the global structure of the magnetosphere by causing part of the magnetic field-lines to become open. We find that a displacement of the current sheet towards the surface of the star is necessary if the current in the magnetosphere exceeds a critical value. Twisting the closed magnetic field-lines makes the field more radial, causing a higher spin-down rate. The maximum value of the twist is approximately ∆φmax = π/2, after which the magnetosphere will open up completely, adopting the structure of a split monopole. These findings can provide useful conclusions related to the behavior of magnetars and neutron stars, including the possibility of a pulsar switching between twisted and untwisted states with different spin-down and current content of the magnetosphere.


Name: Limaye, Pranav
E-mail: s6prlima@uni-bonn.de
Affiliation: Argelander Institute for Astronomy/ Max Planck Institute for Radio Astronomy
Type of presentation: Poster
Title: Energy distribution study of Pulsar single pulses and its implications for FRBs
Abstract: The most physical way to characterize the emission mechanism of coherent radio sources is by studying the energy distribution of individual bursts/pulses. Pulsars are known to follow a log-normal energy distribution with an exponential cutoff at lower energies. This kind of behaviour has recently been seen in FRB121102 observations carried by FAST where they observe a power-law distribution for high energies and log-normal distribution at lower energies. There have been observations of giant pulses from Pulsars such as the Crab Pulsar, but their energy distribution power law index is very different from what we have seen from FRB121102. Moreover, the power-law index of FRB121102 energy distribution seems to vary from observation to observation. This poster will discuss the prospects of characterizing energy distribution of pulses from regular pulsars and show some preliminary results and its correspondence with FRB energy distribution.


Name: Prayag, Venumadhava
E-mail: pryven001@myuct.ac.za
Affiliation: University of Cape Town
Type of presentation: Oral
Title: Searching for and characterising radio pulsars in the Large Magellanic Cloud
Abstract: The Large Magellanic Cloud (LMC) is positioned a mere 50 kiloparsecs away from Earth, making it one of our closest galactic neighbours. This dense region exhibits distinctive traits, including a lower metallicity, a higher rate of star formation, a larger abundance of supernova remnants, and a greater presence of high-mass X-ray binaries per unit mass compared to our own Milky Way galaxy. Consequently, the LMC serves as an extraordinary astronomical laboratory for studying pulsar populations. Under the TRAPUM project, we are currently engaged in a targeted search for extragalactic radio pulsars within the LMC using MeerKAT. The latter achieves ~7 times the sensitivity of the previous LMC surveys, enabling us to probe deeper than ever before. This comes in handy given that extragalactic pulsars are hard to find, with only 34 discovered in total and all located in the Magellanic Clouds. Prior to the start of this survey, 25 pulsars had already been found in the LMC. To date, with just 4 pointings, we have made the exciting discovery of 7 new radio pulsars. With these results, MeerKAT, which will eventually become the SKA, shows its immense potential for advancing our knowledge of the universe and reinforces its significance as a valuable tool in astronomical exploration.


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Last updated: 15 May 2024