Simulations Fest (incl. 3D vis.) - Nov 20-23, 2011
Website: Click here for details and registration.
Where: ATNF Lecture Theatre - Sydney
Abstracts:
- Max Bernyk:
"Mock Galaxy Factory"
Abstract. We discuss challenges and solutions to the problem of building synthetic universes using our online Theoretical Astrophysical Observatory (TAO) Mock Galaxy Factory. This includes the real-time remapping of simulated data onto the observer light cone, and the application of stellar population synthesis models and dust prescriptions to calculate realistic galaxy SEDs that give light to simulated mass. Applications for various surveys and science uses will be given. - Florian Beutler:
"Forecasting WALLABY large-scale structure analysis"
Abstract. I will show predictions for the possible outcome of the Baryon Acoustic Oscillation (BAO) analysis and redshift space distortion analysis for WALLABY. - Chris Blake:
"Cosmology with ASKAP"
Abstract. - Barbara Catinella:
"HI properties of massive galaxies"
Abstract. The main obstacle to understand the formation and evolution of galaxies is our limited knowledge of the role played by gas. In particular we still lack measurements of the HI gas, which is the reservoir for future star formation, for large and unbiased samples for which ancillary data on stellar and star formation properties are also available. To this end we are carrying out the GALEX Arecibo SDSS Survey (GASS), an ambitious programme to assemble the first unbiased inventory of atomic hydrogen in massive galaxies. Using the Arecibo radio telescope, we are acquiring HI spectra for ~1000 galaxies selected uniquely by stellar mass (> 10^10 Msun) and redshift (0.025 < z < 0.05), covered by both SDSS spectroscopic and GALEX imaging surveys. Our selected stellar mass range allows us to probe the interesting region where galaxies transition from blue and star-forming to red and passively evolving.
In this talk I will present gas fraction scaling relations, which can be used to identify objects that might be transitioning between blue, star-forming cloud and red sequence. In particular, objects with HI excess are good candidates for systems that might have recently accreted gas from the surrounding medium. I will also talk about dynamical scaling relations, and show a relation between baryonic mass and velocity that holds for massive systems, regardless of morphology, and thus is more suited to comparison with theoretical models. Lastly, I will discuss the relevance of HI scaling relations for the future surveys that will be carried out with the SKA precursors. As an example, I will compare the properties of GASS galaxies with those of a unique sample of very HI-rich disks at redshift z~0.2 detected with Arecibo. - Darren Croton:
"Modelling Galaxy Formation, SAM-style"
Abstract. - Helga Denes:
"Global HI properties of galaxies in the southern sky"
Abstract. I am investigating the relationship between the HI content of a galaxy, and its optical and infrared properties. There are several methods to estimate the HI content of spiral galaxies, based on measuring HI content of isolated spiral galaxies and comparing them with their optical properties, most commonly with the B-band diameter or luminosity. I will present a new multiwavelength approach that I am developing, using a sample of optically identified HIPASS galaxies to compare the HI mass of the galaxies to their various optical and infrared diameters and fluxes. In a first test of the method, I identified the most HI deficient galaxies in the sample. Interestingly, 5 of the 7 most HI deficient galaxies in the sample from the Northern HIPASS survey are members of the Virgo cluster. This shows that scaling relations may make an effective tool to study the environmental dependency of the HI content of galaxies. I will apply this work to the upcoming ASKAP HI All-Sky Survey called Wallaby, by producing a catalogue of galaxies we expect to detect with Wallaby, using the 6dF catalog and other available optical and infrared data from the southern sky. This will be a valuable comparison to the simulated galaxies, which we expect to detect. - Klaus Dolag:
"Splotch: visualizing cosmological simulations" - Part 1
and Part 2
Abstract. I will present a light and fast, publicly available, ray-tracer Splotch software tool which supports the effective visualization of cosmological simulations data. I will describe what the algorithm it relies on, which is designed in order to deal with point-like data and its optimization to allow to handle huge, cosmological simulations. Realistic three-dimensional impressions are reached through a composition of the final color in each pixel properly calculating emission and absorption of individual volume elements. I will describe several scientific as well as public applications realized with Splotch. We emphasize how different data-sets and configurations lead to remarkably different results in terms of the images and animations. - Alan Duffy:
"Neutral Hydrogen in Hydrodynamical Simulations"
Abstract. The formation and evolution of Neutral Hydrogen is a basic and yet profoundly challenging question that simulations have tried to answer for decades. In this overview talk I will explain the efforts that have gone into this topic and the great strides that have been made recently. While observations have traditionally led the field of Neutral Hydrogen I will summarise some of the latest predictions from the theoretical community, marking what I hope will be a step change in this topic with robust and testable CDM predictions a priori in place of a posteriori. - Amr Hassan:
"HI Source Finding using Envelope analysis"
Abstract. I will discuss our ongoing work to develop a new HI source finding approach based on envelope analysis, which has been used previously in other fields, such as peak detection for mass spectrometry. The presented approach uses both integrated flux and peak flux values to aid source identification. The first step in this method is to determine possible source pixels using the envelope analysis method and a Gaussian local maxima filter. The method then incorporates spatial information from each spectral channel to aid rejection of non-source pixels based on single value line contouring. The pixels are then grouped and the method calculates properties of each region. These properties are used, with the aid of a decision tree, to accept or reject regions and assign percentage of confidence to them. We are in the process of porting our current implementation (in Matlab) to a Multi-GPU platform for testing on gSTAR, along with providing a suitable graphics user interface. - Alex Hill:
"MHD simulations of a supernova-driven turbulent ISM"
Abstract. Stellar feedback drives the circulation of matter from the disk to the halo of galaxies. I present 3D magnetohydrodynamic simulations of a vertical column of the interstellar medium (representative of the Milky Way solar circle) in which supernovae drive turbulence and vertical stratification of the medium. The simulations include parameterised heating and cooling appropriate for a solar metallicity plasma. After the simulations reach a statistical steady-state, the majority of the gas is contained in thermally-stable temperature regimes (``phases'') of cold (< 200 K) and warm (~ 10^4 K) gas, with million-degree gas filling largely-evacuated OB cluster remnants. The magnetic field has little impact on the vertical distribution, mass filling fraction, or volume filling fraction of each phase of the ISM. Instead, the field acts to smooth structures and clouds. - Links to movies on slide no 5: movie-1, movie-2 - Tom Jarrett:
"From Gas to Stars: A WISE Study of Galaxies Near and Far"
Abstract. WISE is an all-sky mid-infrared imaging survey that will be a unique resource for the next two decades (if not more). WISE has the dual capacity, bas I will demonstrate, of providing information for large-scale surveys, as well as uncovering detailed ISM processes previously only achievable by the Spitzer Space Telescope. By highlighting WISE's major extragalactic science results to date, I hope to illustrate the scope of science WISE can be used to study; e.g., AGN, starburst and radio galaxies, hyper-luminous galaxies, sources in cosmologically-interesting volumes (e.g., WALLABY, EMU, GAMA), and nearby resolved galaxies. Finally, as a demonstration of science that can be carried out with resolution-enhanced imaging, I will showcase the detailed, truly multiwavelength study of M83, incorporating WISE/Spitzer with the ATCA HI gas distribution and GALEX UV emission, thus tracing the evolution from gas to stars. - Gyula Jozsa:
"Tilted-ring modelling of data cubes with TiRiFiC"
Abstract. TiRiFiC is a tool to automatically fit a tilted-ring model to HI observations of galaxies. Since TiRiFiC acts directly on data cubes, it overcomes some of the difficulties when using velocity-fields for this kind of analysis. Apart from the simple tilted-ring model, TiRiFiC allows for a multitude of additional parametrisation methods, introducing deviations from cylindric symmetry, such as harmonic expansions of the disk surface brightness and the kinematics and spiral arms.
In the context of WALLABY and WNSHS, TiRiFiC, or a modified version of TiRiFiC is discussed to become one of the components of a data analysis pipeline. This contribution concentrates on a progress report and possible issues that may be solved with the aid of experts in the audience. - Russell Jurek:
"The role of visualisation in ASKAP HI Surveys"
Abstract. In this talk I will describe the anticipated role of visualisation in the WALLABY/DINGO quality control process. I will focus on the unique advantages that visualisation provides over simple quantitative measurements. I will also briefly describe the planned WALLABY HI Analysis Tool (WHAT). - Guinevere Kauffmann:
"COLD GASS, an IRAM Legacy Survey of Molecular Gas in Massive
Galaxies: Comparison with semi-analytic models of galaxy
formation"
Abstract. We compare the semi-analytic models of galaxy formation of Fu et al. (2010), which track the evolution of atomic and molecular gas in galaxies, with gas fraction scaling relations derived from a stellar mass-limited sample of 299 galaxies from the COLD GASS survey. These galaxies have measurements of the CO(1-0) line from the IRAM 30-m telescope and the HI line from Arecibo, as well as measurements of stellar masses, structural parameters and star formation rates derived from GALEX+SDSS photometry. The treatment of disk formation in the models provides a reasonable description of how condensed baryons in star-forming galaxies are partitioned into atomic gas, molecular gas and stars as a function of galaxy mass, size, and bulge-to-disk ratio. The models appear to miss a sub-population of low mass galaxies with low densities and concentrations and high atomic gas fractions. We discuss changes to the gas accretion prescriptions that may solve this problem. The implementation of ``radio-mode feedback'' in the models produces trends that disagree strongly with the data. - Hansik Kim:
"What physics processes drive the abundance and clustering of
neutral atomic hydrogen in galaxies?"
Abstract. We use semi-analytical galaxy formation modelling to investigate how the efficiency of supernovae (SNe) feedback, AGN feedback and the strength of the photo-ionizing background during cosmological reionization affect the abundance and spatial clustering of neutral atomic hydrogen (HI) in galaxies at z=0. Our model of choice is Lagos et al. (2011), which splits the interstellar medium into atomic and molecular (H2) phases and assumes that star formation is driven not by the galaxy's cold gas mass but by its H2 mass. We demonstrate that increasing the strength of SNe feedback acts to depress both the faint end of the galaxy luminosity and the low-mass end of the HI mass function. A similar effect is obtained by increasing the mass scale below which cooling is suppressed in the dark matter haloes during reionization, whereas the redshift at which reionization occurs has no measurable effect. AGN feedback strength acts mainly to the high mass end of galaxy luminosity and the HI mass function. Also the predicted clustering of HI galaxies is changed by feedback strength. - Simon Mutch:
"Spatially decomposed galaxy properties in semi-analytic
models"
Abstract. Traditionally, semi-analytic models of galaxy formation and evolution have only provided global galaxy properties such as stellar masses and star formation rates. However, recent progress has been made by introducing radial mass profiles for the disks of spiral galaxies. Building on this work, I will describe the initial stages of a new self-consistent disk+bulge+halo model of the distribution of stars, gas and metals in local and high-redshift galaxies. These enhancements are embedded into an updated version of the a Croton et al. (2006) semi-analytic model. This model will eventually be specifically tuned, using statistical parameter estimation techniques, to reproduce the observed HI mass function, thus allowing for accurate predictions for the spatial and size distributions of HI sources in the universe. - Greg Poole:
"The GiggleZ Simulations"
Abstract. I will present the simulation program of the WiggleZ redshift survey, focusing in particular on the survey's cosmology programs and high- lighting the difficulties involved in providing mock catalogs of large volumes for surveys which observe small systems. - Chris Power:
"Overview of WALLABY Numerical Simulations & Mock Surveys"
Abstract. - Jericho Revote (POSTER):
"3DALIVE: Three Dimensional Active Laboratory for Immersive
Visualisation Environments"
Abstract. 3DALIVE is an immersive virtual reality facility that has just opened and is available for use in research, teaching and industry. The facility is joint between Monash University. AuScope, and CSIRO, and in collaboration with the UC Davis KeckCaves. - Morag Scrimgeour:
"Cosmology with Peculiar Velocity Fields"
Abstract. The measurement of peculiar velocities will be an important outcome of several upcoming galaxy and SN Ia surveys, and will provide an important cosmological probe. SkyMapper will measure the peculiar velocities of thousands of nearby supernovae, and galaxy peculiar velocities will be (or are being) measured by surveys such as 2MTF, 6dFGS, and eventually WALLABY (with ASKAP) and the SKA. Peculiar velocities provide a bias-free probe of the matter distribution and growth of structure, which depend on cosmological parameters. They are also a direct probe of gravity, and can be used to test General Relativity and modified gravity models. We can use different diagnostics for investigating the peculiar velocity field, such as the power spectrum and covariance. Using cosmological N-body simulations, we can simulate these peculiar velocity surveys and make predictions for the cosmological constraints they will provide. - Sanjib Sharma:
"A tale of two tools, Galaxia and EBF"
Abstract. Galaxia is a code for synthetic modelling of the Milky Way. It can generate a synthetic catalog of stars according to a given theoretical model of the Milky Way. The model could either be analytic or one form an N-body simulation. We describe efficient algorithms for sampling both type of models. EBF, is an efficient and easy to use binary file format for scientific data. We develop APIs for reading, writing and manipulating such files in multiple programming languages. Efficiency and ease of use are the main design goals of the format and the associated routines. Currently I/O routines are available for the following 7 languages C, C++, Fortran 90/2003, Java, IDL, Matlab and Python. - Lister Staveley-Smith: "Day 1 simulation wrap-up and discussion"
- Andreas Wicenec:
"SHORE is Facing the Data Waves"
Abstract. SHORE is an ICRAR project to implement a software environment/middleware to allow applications to place, distribute and access data across a complete storage hierarchy in an optimized way. The basic idea behind SHORE is that big multi TB datasets contained in single files (like HDF5) could be distributed both horizontally and vertically across a storage hierarchy depending on the required access pattern of the applications on one side and on the availability and performance of the storage infrastructure on the other side. Since both sides will change dynamically in an independent way the environment needs to be able to react to these changes and adjust the projected data distribution. In current SC environments the vertical and horizontal distribution is usually covered with two independent approaches/products, one are Hierarchical Storage Managers (HSM) the other one are global file systems (GFS) in the clustered case and standard file systems (FS) for ! single computers. Both are virtually blind to the specifics of the content of the data files. Typically HSMs are dealing and moving complete files from one layer to another and (G)FSs are moving, replicating and copying blocks, i.e. fixed size parts of files. Applications using these data on the other side are usually constraint by the size of memory and the I/O performance. Typically the available memory is orders of magnitude smaller than the disk or tape storage and thus processing or even just accessing substantial fractions of the data in those levels of the storage hierarchy used to be prohibitive. HSM systems typically cover various layers of disk storage and tape storage in tape silos. SHORE aims to cover also various memory levels as an integrated part of the storage hierarchy. - Matthew Whiting:
"Simulating ASKAP observations"
Abstract. To assist the ASKAP Survey Science Team Design Study phase, the ASKAP computing group has been providing a number of simulated ASKAP observations. These allow the science team members to examine the results of observing particular types of astronomical sources with the ASKAP array, to gauge the quality of the imaging that will result, and to test various analysis tools such as source-finding and stacking. I will give a brief overview of how we go about creating these simulations, and describe some of the data sets that have been recently released. - Kathrin Wolfinger:
"Visualisation of the nearby Ursa Major region"
Abstract. We compiled a comprehensive catalogue of HI sources in the Ursa Major region using data from a blind HI survey - the HI Jodrell All Sky Survey (HIJASS). The surveyed area includes the high-density region as well as the less dense filament connecting the Ursa Major with the Virgo cluster. We do not find a numerous population of gas-rich dwarf galaxies with low stellar luminosity, which could have been missed in optical surveys. However, there are various previously catalogued galaxies (listed in NED/SDSS) within the surveyed area that are below the HI mass limit of the HIJASS catalogue. We are in the process of visualizing the 3D HI dataset along with optically selected galaxies to investigate the HI distribution and HI properties: Where are the most HI-rich galaxies located? Are there numerous gas-poor galaxies known from optical surveys in the high-density regions? Where are the extended and point sources (with respect to the beam size) located?