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Discovery and follow-up of ASASSN-19dj: an X-ray and UV luminous TDE in an extreme post-starburst galaxy

Hinkle, Jason T. and Holoien, T. W.-S. and Auchettl, K. and Shappee, B. J. and Neustadt, J. M. M. and Payne, A. V. and Brown, J. S. and Kochanek, C. S. and Stanek, K. Z. and Graham, M. J. and Tucker, M. A. and Do, A. and Anderson, J. P. and Bose, S. and Chen, P. and Coulter, D. A. and Dimitriadis, G. and Dong, Subo and Foley, R. J. and Huber, M. E. and Hung, T. and Kilpatrick, C. D. and Pignata, G. and Piro, A. L. and Rojas-Bravo, C. and Siebert, M. R. and Stalder, B. and Thompson, Todd A. and Tonry, J. L. and Vallely, P. J. and Wisniewski, J. P. (2021) Discovery and follow-up of ASASSN-19dj: an X-ray and UV luminous TDE in an extreme post-starburst galaxy. Monthly Notices of the Royal Astronomical Society, 500 (2). pp. 1673-1696. ISSN 0035-8711.

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We present observations of ASASSN-19dj, a nearby tidal disruption event (TDE) discovered in the post-starburst galaxy KUG 0810+227 by the All-Sky Automated Survey for Supernovae (ASAS-SN) at a distance of d ≃ 98 Mpc. We observed ASASSN-19dj from −21 to 392 d relative to peak ultraviolet (UV)/optical emission using high-cadence, multiwavelength spectroscopy and photometry. From the ASAS-SN g-band data, we determine that the TDE began to brighten on 2019 February 6.8 and for the first 16 d the rise was consistent with a flux ∝t² power law. ASASSN-19dj peaked in the UV/optical on 2019 March 6.5 (MJD = 58548.5) at a bolometric luminosity of L = (6.2 ± 0.2) × 10⁴⁴ erg s⁻¹. Initially remaining roughly constant in X-rays and slowly fading in the UV/optical, the X-ray flux increased by over an order of magnitude ∼225 d after peak, resulting from the expansion of the X-ray emitting region. The late-time X-ray emission is well fitted by a blackbody with an effective radius of ∼1 × 10¹² cm and a temperature of ∼6 × 10⁵ K. The X-ray hardness ratio becomes softer after brightening and then returns to a harder state as the X-rays fade. Analysis of Catalina Real-Time Transient Survey images reveals a nuclear outburst roughly 14.5 yr earlier with a smooth decline and a luminosity of L_V ≥ 1.4 × 10⁴³ erg s⁻¹, although the nature of the flare is unknown. ASASSN-19dj occurred in the most extreme post-starburst galaxy yet to host a TDE, with Lick HδA = 7.67 ± 0.17 Å.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Hinkle, Jason T.0000-0001-9668-2920
Holoien, T. W.-S.0000-0001-9206-3460
Auchettl, K.0000-0002-4449-9152
Shappee, B. J.0000-0003-4631-1149
Neustadt, J. M. M.0000-0001-7351-2531
Payne, A. V.0000-0003-3490-3243
Brown, J. S.0000-0002-1885-6419
Kochanek, C. S.0000-0001-6017-2961
Graham, M. J.0000-0002-3168-0139
Tucker, M. A.0000-0002-2471-8442
Anderson, J. P.0000-0003-0227-3451
Bose, S.0000-0003-3529-3854
Dong, Subo0000-0002-1027-0990
Huber, M. E.0000-0003-1059-9603
Hung, T.0000-0002-9878-7889
Kilpatrick, C. D.0000-0002-5740-7747
Pignata, G.0000-0003-0006-0188
Piro, A. L.0000-0001-6806-0673
Rojas-Bravo, C.0000-0002-7559-315X
Stalder, B.0000-0003-0973-4900
Thompson, Todd A.0000-0003-2377-9574
Tonry, J. L.0000-0003-2858-9657
Wisniewski, J. P.0000-0001-9209-1808
Additional Information:© 2020 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2020 October 8. Received 2020 September 30; in original form 2020 June 18. Published: 15 October 2020. We thank the referee for helpful comments and suggestions that have improved the quality of this manuscript. We thank the Swift PI, the Observation Duty Scientists, and the science planners for promptly approving and executing our Swift observations. We thank Decker French for providing some of the data used in Fig. 2. We thank Stephen Smartt and Kenneth Smith for helpful discussions on archival Pan-STARRS data. We also thank Jorge Anais Vilchez, Abdo Campillay, Yilin Kong Riveros, Nahir Muñoz-Elgueta, and Natalie Ulloa for conducting Swope observations. We thank Erica Bufanda for helpful discussions. We thank the Las Cumbres Observatory and its staff for its continuing support of the ASAS-SN project. LCOGT observations were performed as part of DDT award 2019B-003 to EG. ASAS-SN is supported by the Gordon and Betty Moore Foundation through grant GBMF5490 to the Ohio State University, and NSF grants AST-1515927 and AST-1908570. Development of ASAS-SN has been supported by NSF grant AST-0908816, the Mt. Cuba Astronomical Foundation, the Center for Cosmology and AstroParticle Physics at the Ohio State University, the Chinese Academy of Sciences South America Center for Astronomy (CAS- SACA), the Villum Foundation, and George Skestos. BJS, CSK, and KZS are supported by NSF grant AST-1907570/AST-1908952. BJS is also supported by NSF grants AST-1920392 and AST-1911074. CSK and KZS are supported by NSF grant AST-181440. KAA is supported by the Danish National Research Foundation (DNRF132). MJG was supported in part by the NSF grant AST-1815034 and the NASA grant 16-ADAP16-0232. MAT acknowledges support from the DOE CSGF through grant DE-SC0019323. Support for GP and JLP is provided in part by FONDECYT through the grant 1191038 and by the Ministry of Economy, Development, and Tourism’s Millennium Science Initiative through grant IC120009, awarded to The Millennium Institute of Astrophysics, MAS. TAT is supported in part by NASA grant 80NSSC20K0531. DAC acknowledges support from the National Science Foundation Graduate Research Fellowship under Grant DGE1339067. We acknowledge Telescope Access Program (TAP) funded by the NAOC, CAS, and the Special Fund for Astronomy from the Ministry of Finance. The UCSC transient 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 RJF. Parts of this research were supported by the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project number CE170100013. This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. 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. Support for ATLAS observations and data products was provided by NASA grant NN12AR55G and 80NSSC18K0284. The CSS survey is funded by the National Aeronautics and Space Administration under Grant No. NNG05GF22G issued through the Science Mission Directorate Near-Earth Objects Observations Program. The CRTS survey is supported by the U.S. National Science Foundation under grants AST-0909182. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The LBT is an international collaboration among institutions in the United States, Italy and Germany. LBT Corporation partners are: The University of Arizona on behalf of the Arizona Board of Regents; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, The Leibniz Institute for Astrophysics Potsdam, and Heidelberg University; The Ohio State University, and The Research Corporation, on behalf of The University of Notre Dame, University of Minnesota and University of Virginia. This work is based on observations made by ASAS-SN, ATLAS, Pan-STARRS, UH88, and Keck. We wish to extend our special thanks to those of Hawaiian ancestry on whose sacred mountains of Maunakea and Haleakalā, we are privileged to be guests. Without their generous hospitality, the observations presented herein would not have been possible. Data Availability: The data underlying this article are available in the article and in its online supplementary material.
Funding AgencyGrant Number
Gordon and Betty Moore FoundationGBMF5490
Mt. Cuba Astronomical FoundationUNSPECIFIED
Center for Cosmology and AstroParticle Physics (CCAPP)UNSPECIFIED
Chinese Academy of Sciences South America Center for Astronomy (CASSACA)UNSPECIFIED
Villum FoundationUNSPECIFIED
Danish National Research FoundationDNRF132
Department of Energy (DOE)DE-SC0019323
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1191038
Iniciativa Científica Milenio del Ministerio de Economía, Fomento y TurismoIC120009
NSF Graduate Research FellowshipDGE-1339067
National Astronomical Observatories, Chinese Academy of Sciences (NAOC)UNSPECIFIED
Ministry of Finance (China)UNSPECIFIED
Heising-Simons FoundationUNSPECIFIED
David and Lucile Packard FoundationUNSPECIFIED
Australian Research CouncilCE170100013
University of MarylandUNSPECIFIED
Eotvos Lorand University (ELTE)UNSPECIFIED
Los Alamos National LaboratoryUNSPECIFIED
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:accretion, accretion discs – black hole physics – galaxies: nuclei
Issue or Number:2
Record Number:CaltechAUTHORS:20210209-121602286
Persistent URL:
Official Citation:Jason T Hinkle, T W-S Holoien, K Auchettl, B J Shappee, J M M Neustadt, A V Payne, J S Brown, C S Kochanek, K Z Stanek, M J Graham, M A Tucker, A Do, J P Anderson, S Bose, P Chen, D A Coulter, G Dimitriadis, Subo Dong, R J Foley, M E Huber, T Hung, C D Kilpatrick, G Pignata, A L Piro, C Rojas-Bravo, M R Siebert, B Stalder, Todd A Thompson, J L Tonry, P J Vallely, J P Wisniewski, Discovery and follow-up of ASASSN-19dj: an X-ray and UV luminous TDE in an extreme post-starburst galaxy, Monthly Notices of the Royal Astronomical Society, Volume 500, Issue 2, January 2021, Pages 1673–1696,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107967
Deposited By: Tony Diaz
Deposited On:09 Feb 2021 20:51
Last Modified:09 Feb 2021 20:51

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