The Structure of Tidal Disruption Event Host Galaxies on Scales of Tens to Thousands of Parsecs
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Author
French, K. Decker
Arcavi, Iair
Zabludoff, Ann I.
Stone, Nicholas
Hiramatsu, Daichi
van Velzen, Sjoert
McCully, Curtis
Jiang, Ning
Affiliation
Univ Arizona, Steward ObservIssue Date
2020-03-09
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IOP PUBLISHING LTDCitation
K. Decker French et al 2020 ApJ 891 93Journal
ASTROPHYSICAL JOURNALRights
Copyright © 2020. The American Astronomical Society. All rights reserved.Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
We explore the galaxy structure of four tidal disruption event (TDE) host galaxies on 30 pc to kiloparsec scales using Hubble Space Telescope WFC3 multiband imaging. The star formation histories of these hosts are diverse, including one post-starburst galaxy (ASASSN-14li), two hosts with recent weak starbursts (ASASSN-14ae and iPTF15af), and one early-type galaxy (PTF09ge). Compared to early-type galaxies of similar stellar masses, the TDE hosts have higher central surface brightnesses and stellar mass surface densities on 30-100 pc scales. The TDE hosts do not show the large, kiloparsec-scale tidal disruptions seen in some post-starburst galaxies; the hosts have low morphological asymmetries similar to those of early-type galaxies. The lack of strong asymmetries is inconsistent with a recent major (similar to 1:1 mass) merger, although minor (less than or similar to 1:3) mergers are possible. Given the time elapsed since the end of the starbursts in the three post-burst TDE hosts and the constraints on the merger mass ratios, it is unlikely that a bound supermassive black hole binary (SMBHB) has had time to coalesce. The TDE hosts have low central (<140 pc) ellipticities compared to early-type galaxies. The low central ellipticities disfavor a strong radial anisotropy as the cause for the enhanced TDE rate, although we cannot rule out eccentric disks at the scale of the black hole gravitational radius of influence (similar to 1 pc). These observations suggest that the high central stellar densities are a more important driver than SMBHBs or radial anisotropies in increasing the TDE rate in galaxies with recent starbursts.ISSN
0004-637XVersion
Final published versionae974a485f413a2113503eed53cd6c53
10.3847/1538-4357/ab7450