Rebrightening in the Radio: Secondary Flares from Tidal Disruption Events AT2019ehz and AT2019eve
Authors: Natalie K. Velez, Yvette Cendes, Jimmy Lynch, Kate D. Alexander, Edo Berger, Ryan Chornock, Adelle J. Goodwin, Tanmoy Laskar, Raffaella Margutti
Abstract
We present the discovery of new secondary delayed radio flares from two tidal disruption events (TDEs), AT2019ehz and AT2019eve from observations ranging 1-18 GHz using the Karl G. Jansky Very Large Array. For AT2019ehz, we find a secondary flare in radio emission began at 1545 days post-disruption, 770 days after the first radio flare detected at 775 days post-disruption, and for AT2019eve the secondary flare was detected at 1594 days post-disruption, 825 days after its initial radio detection at 769 days post-disruption. Through spectral modeling of the multi-frequency observations, we extract physical parameters of the new flares to constrain the origin of the rebrightening. We find the secondary flare of AT2019ehz is likely produced by a second outflow launched at roughly 1000 days. For AT2019eve, the secondary flare reveals unexpected spectral evolution with a self-absorbed peak increasing from 1325 to 2173 days post-disruption, which is not well explained with most models of expanding outflows and instead suggests a more complex physical geometry. This inconclusive origin of AT2019eve highlights the need for more complex models to explain observed TDE radio evolution.
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Abstract
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Abstract
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Abstract
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Abstract
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