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Extragalactic radio transients in the VLA Sky Survey

Presentation #409.09 in the session Gravitational Wave and Multi-messenger Missions.

Published onJun 29, 2022
Extragalactic radio transients in the VLA Sky Survey

The VLA Sky Survey (VLASS), is mapping > 80% of the 3 GHz sky at ~2 arcsecond resolution over multiple epochs, providing a ~2 order of magnitude increase in the volume available for blind radio transient searches. By comparing the first two VLASS epochs with archival radio surveys, I have identified thousands of radio sources that are strongly variable or transient on a timescale of ~years. Many of these sources can be associated with multiwavelength counterparts in archival and follow up data, providing useful clues in diagnosing their origin. In this talk, I will present a sample of transients associated with galaxies within 200 Mpc. Unlike in purely flux-limited surveys, which are dominated by variable active galactic nuclei (AGN), the local-universe sample is split roughly evenly between nuclear transients in quenched galaxies consistent with AGN or tidal disruption events (TDEs) and predominantly non-nuclear transients associated with star forming dwarf galaxies. Among the latter sample, I will highlight two subclasses: supernovae interacting with dense shells that were eruptively ejected in the centuries before explosion, and a flat-spectrum radio transient consistent with an emerging pulsar wind nebula. Together, these results highlight the potential of wide field radio surveys in identifying new transient populations.

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