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17th of October 2022
Delayed launch of an outflow following a Tidal Disruption Event
by Cendes et al.
In October 2018, a small star was ripped to shreds when it wandered too close to a black hole in a galaxy located 665 million light years away from Earth. A growing number of these so-called Tidal Disruption Events (TDEs) — when encroaching stars are spaghettified by black holes — have been detected in recent years. Cendes et al. present late-time radio/millimeter, optical/UV and X-ray detections of tidal disruption event (TDE) AT2018hyz, spanning 970–1300 d after the optical discovery in 2018. In conjunction with earlier deeper limits, the observations reveal rapidly rising emission at 0.8–240 GHz. Such a steep rise cannot be explained in any reasonable scenario of an outflow launched at the time of disruption and instead points, unexpectedly, to a delayed launch. Modeling of the multifrequency data suggests that a mildly relativistic outflow was launched -750 days after optical discovery. This is the first definitive evidence for the production of a delayed mildly relativistic outflow in a TDE. The authors suggest that such delayed outflows may be common in TDEs. The team collected observations of the TDE using the Australia Telescope Compact Array, the Jansky Very Large Array in the USA, the ALMA Observatory in Chile, MeerKAT in South Africa, and the Chandra X-Ray Observatory and the Neil Gehrels Swift Observatory in space. The image above is an artist’s illustration of the tidal disruption event AT2019dsg. (Image credit: DESY, Science Communication Lab.)

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