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Published June 20, 2017 | Published + Submitted
Journal Article Open

Compact Resolved Ejecta in the Nearest Tidal Disruption Event

Abstract

Tidal disruption events (TDEs) occur when a star or substellar object passes close enough to a galaxy's supermassive black hole to be disrupted by tidal forces. NGC 4845 (d = 17 Mpc) was host to a TDE, IGR J12580+0134, detected in 2010 November. Its proximity offers us a unique close-up of the TDE and its aftermath. We discuss new Very Long Baseline Array (VLBA) and Karl G. Jansky Very Large Array observations, which show that the radio flux from the active nucleus created by the TDE has decayed in a manner consistent with predictions from a jet-circumnuclear medium interaction model. This model explains the source's broadband spectral evolution, which shows a spectral peak that has moved from the submillimeter (at the end of 2010) to GHz radio frequencies (in 2011–2013) to <1 GHz in 2015. The milliarcsecond-scale core is circularly polarized at 1.5 GHz but not at 5 GHz, consistent with the model. The VLBA images show a complex structure at 1.5 GHz that includes an east–west extension that is ~40 mas (3 pc) long, as well as a resolved component that is 52 mas (4.1 pc) northwest of the flat-spectrum core, which is all that can be seen at 5 GHz. If ejected in 2010, the northwest component must have had ν = 0.96c over five years. However, this is unlikely, as our model suggests strong deceleration to speeds <0.5c within months and a much smaller, sub-parsec size. In this interpretation, the northwest component could have either a non-nuclear origin or be from an earlier event.

Additional Information

© 2017 The American Astronomical Society. Received 2017 February 6; revised 2017 May 2; accepted 2017 May 6; published 2017 June 22. This work is based on observations made with the Karl G. Jansky Very Large Array (JVLA) and the Very Long Baseline array (VLBA). We acknowledge an interesting conversation with Sjoert Van Velzen about this paper.

Attached Files

Published - Perlman_2017_ApJ_842_126.pdf

Submitted - 1705.01669.pdf

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August 19, 2023
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