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Tidal Disruption Event Hosts Are Green and Centrally Concentrated: Signatures of a Post-merger System

Hammerstein, Erica and Gezari, Suvi and van Velzen, Sjoert and Cenko, S. Bradley and Roth, Nathaniel and Ward, Charlotte and Frederick, Sara and Hung, Tiara and Graham, Matthew and Foley, Ryan J. and Bellm, Eric C. and Cannella, Christopher and Drake, Andrew J. and Kupfer, Thomas and Laher, Russ R. and Mahabal, Ashish A. and Masci, Frank J. and Riddle, Reed and Rojas-Bravo, César and Smith, Roger (2021) Tidal Disruption Event Hosts Are Green and Centrally Concentrated: Signatures of a Post-merger System. Astrophysical Journal Letters, 908 (1). Art. No. L20. ISSN 2041-8213.

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We study the properties of the galaxies hosting the first 19 tidal disruption events (TDEs) detected with the Zwicky Transient Facility (ZTF) within the context of a carefully constructed, representative host galaxy sample. We find that the ZTF sample of TDE hosts is dominated by compact "green valley" galaxies. After we restrict the comparison sample to galaxies with a similar concentration, as measured by the Sérsic index, we find this green valley overrepresentation is even larger. That is, concentrated red sequence galaxies are not producing TDEs at elevated levels. We present host galaxy spectra that show that E + A galaxies are overrepresented in the ZTF sample by a factor of ≈22, which is lower than previous TDE host galaxy studies have found. We find that this overrepresentation can be fully accounted for when taking into account the masses, colors, and Sérsic indices of the ZTF TDE hosts. The combination of both green colors and high Sérsic index of the typical TDE host galaxy could be explained if the TDE rate is temporarily enhanced following a merger that leads to a higher central concentration of stars.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Hammerstein, Erica0000-0002-5698-8703
Gezari, Suvi0000-0003-3703-5154
van Velzen, Sjoert0000-0002-3859-8074
Cenko, S. Bradley0000-0003-1673-970X
Roth, Nathaniel0000-0002-6485-2259
Ward, Charlotte0000-0002-4557-6682
Frederick, Sara0000-0001-9676-730X
Hung, Tiara0000-0002-9878-7889
Graham, Matthew0000-0002-3168-0139
Foley, Ryan J.0000-0002-2445-5275
Bellm, Eric C.0000-0001-8018-5348
Cannella, Christopher0000-0003-2667-7290
Kupfer, Thomas0000-0002-6540-1484
Laher, Russ R.0000-0003-2451-5482
Mahabal, Ashish A.0000-0003-2242-0244
Masci, Frank J.0000-0002-8532-9395
Riddle, Reed0000-0002-0387-370X
Rojas-Bravo, César0000-0002-7559-315X
Smith, Roger0000-0001-7062-9726
Alternate Title:TDE Hosts are Green and Centrally Concentrated: Signatures of a Post-Merger System
Additional Information:© 2021 The American Astronomical Society. Received 2020 October 20; revised 2021 January 7; accepted 2021 January 15; published 2021 February 15. We thank the anonymous referee for helpful comments. We thank S. Veilleux and R. Mushotzky for their valuable comments and discussion during the early stages of this paper. S.G. is funded in part by NSF CAREER grant 1454816, and NASA Swift grant 80NSSC20K0961. The UCSC team is supported in part by NSF grant AST-1518052; the Gordon & Betty Moore Foundation; the Heising-Simons Foundation; and by a fellowship from the David and Lucile Packard Foundation to R.J.F. These results made use of the Lowell Discovery Telescope at Lowell Observatory. Lowell is a private, nonprofit institution dedicated to astrophysical research and public appreciation of astronomy and operates the LDT in partnership with Boston University, the University of Maryland, the University of Toledo, Northern Arizona University and Yale University. The upgrade of the DeVeny optical spectrograph has been funded by a generous grant from John and Ginger Giovale. Based on observations obtained with the Samuel Oschin Telescope 48 inch and the 60 inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under grant No. AST-1440341 and a collaboration including Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland, the University of Washington, Deutsches Elektronen-Synchrotron and Humboldt University, Los Alamos National Laboratories, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, and Lawrence Berkeley National Laboratories. Operations are conducted by COO, IPAC, and UW. This work was supported by the GROWTH project funded by the National Science Foundation under grant No. 1545949. Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the U.S. Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSS website is The SDSS is managed by the Astrophysical Research Consortium for the Participating Institutions. The Participating Institutions are the American Museum of Natural History, Astrophysical Institute Potsdam, University of Basel, University of Cambridge, Case Western Reserve University, University of Chicago, Drexel University, Fermilab, the Institute for Advanced Study, the Japan Participation Group, Johns Hopkins University, the Joint Institute for Nuclear Astrophysics, the Kavli Institute for Particle Astrophysics and Cosmology, the Korean Scientist Group, the Chinese Academy of Sciences (LAMOST), Los Alamos National Laboratory, the Max-Planck-Institute for Astronomy (MPIA), the Max-Planck-Institute for Astrophysics (MPA), New Mexico State University, Ohio State University, University of Pittsburgh, University of Portsmouth, Princeton University, the United States Naval Observatory, and the University of Washington. The Pan-STARRS1 Surveys (PS1) and the PS1 public science archive have been made possible through contributions by the Institute for Astronomy, the University of Hawaii, the Pan-STARRS Project Office, the Max-Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, The Johns Hopkins University, Durham University, the University of Edinburgh, the Queen's University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, the National Aeronautics and Space Administration under grant No. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, the National Science Foundation grant No. AST-1238877, the University of Maryland, Eotvos Lorand University (ELTE), the Los Alamos National Laboratory, and the Gordon and Betty Moore Foundation. Software: Astropy (Astropy Collaboration et al. 2018), SciPy (Virtanen et al. 2020), ppxf (Cappellari 2017), GIM2D (Simard et al. 2002), PSFex (Bertin 2011), Source-Extractor (Bertin & Arnouts 1996).
Group:Infrared Processing and Analysis Center (IPAC), Zwicky Transient Facility
Funding AgencyGrant Number
Gordon and Betty Moore FoundationUNSPECIFIED
Heising-Simons FoundationUNSPECIFIED
David and Lucile Packard FoundationUNSPECIFIED
John and Ginger GiovaleUNSPECIFIED
ZTF partner institutionsUNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
Participating InstitutionsUNSPECIFIED
Department of Energy (DOE)UNSPECIFIED
Japanese MonbukagakushoUNSPECIFIED
Max Planck SocietyUNSPECIFIED
Higher Education Funding Council for EnglandUNSPECIFIED
University of MarylandUNSPECIFIED
Eotvos Lorand University (ELTE)UNSPECIFIED
Los Alamos National LaboratoryUNSPECIFIED
Subject Keywords:Black Hole physics ; Galaxy nuclei
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Black hole physics (159); Galaxy nuclei (609)
Record Number:CaltechAUTHORS:20210205-093224706
Persistent URL:
Official Citation:Erica Hammerstein et al 2021 ApJL 908 L20
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107930
Deposited By: George Porter
Deposited On:05 Feb 2021 23:01
Last Modified:18 Feb 2021 20:47

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