Sriharsh Tendulkar (NCRA, TIFR)

Sriharsh Tendulkar Colloquium: Multi-scale and multi-wavelength searches for FRBs (and other transients)

Online

Abstract

Fulfilling the true promise of fast radio bursts (FRBs) as cosmological probes, understanding their origins, and their association with other transients necessitates our understanding of the FRB emission mechanism, their formation channel(s), and their local environments. Most emission mechanisms expect that the prompt radio emission represents a small fraction of the total energy released — a larger fraction of the energy should be released at higher frequency wavebands: optical, UV, X-ray and in some cases, gravitational waves (GW) and neutrinos, either as prompt emission or as a longer-lived afterglow. Given that the observed rates of FRBs are two to three orders of magnitude higher than the sky rates of any other extragalactic transient, it is clear that most FRBs will not have detectable multi-wavelength counterparts. The X-ray bursts aligned with the FRB-like radio emission from SGR 1935+2154 highlight the need to be alert to the brightest and nearest FRBs since those will be the most likely to have detectable multi-wavelength counterparts. Theoretical expectations also highlight the need to search for radio transients not just in the millisecond timescale, but also at second timescales, an area of phase space that is badly ignored. In this talk, I will discuss results from CHIME/FRB in trying to constrain counterparts of FRBs, FRB-GRB connections, and FRB-GW connections and our efforts to increase the phase space of radio transients by searching for not-so-fast radio bursts. For these science cases, I will also discuss two new projects: The proposed All Sky Transient Radio Array (ASTRA), an ultra-wide field of view telescope to detect the brightest and nearest radio transients and Daksha, a proposed all-sky X-ray mission with 2-satellites in antipodal orbits to increase the detection rate of GRBs and electromagnetic counterparts of GW events.