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Compact Resolved Ejecta in the Nearest Tidal Disruption Event

Perlman, Eric S. and Meyer, Eileen T. and Wang, Q. Daniel and Yuan, Qiang and Henriksen, Richard and Irwin, Judith and Krause, Marita and Wiegert, Theresa and Murphy, Eric J. and Heald, George and Dettmar, Ralf-Jürgen (2017) Compact Resolved Ejecta in the Nearest Tidal Disruption Event. Astrophysical Journal, 842 (2). Art. No. 126. ISSN 1538-4357.

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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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Irwin, Judith0000-0003-4307-8521
Murphy, Eric J.0000-0001-7089-7325
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.
Group:Infrared Processing and Analysis Center (IPAC)
Subject Keywords:galaxies: active – galaxies: individual (NGC 4845) – galaxies: nuclei – radio continuum: galaxies
Issue or Number:2
Record Number:CaltechAUTHORS:20170623-090559624
Persistent URL:
Official Citation:Eric S. Perlman et al 2017 ApJ 842 126
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:78481
Deposited By: Tony Diaz
Deposited On:24 Jun 2017 03:09
Last Modified:09 Mar 2020 13:18

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