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A luminous X-ray transient in SDSS J143359.16+400636.0: a likely tidal disruption event

Brightman, Murray and Ward, Charlotte and Stern, Daniel and Mooley, Kunal and De, Kishalay and Gezari, Suvi and van Velzen, Sjoert and Andreoni, Igor and Graham, Matthew and Masci, Frank J. and Riddle, Reed and Zolkower, Jeffry (2020) A luminous X-ray transient in SDSS J143359.16+400636.0: a likely tidal disruption event. . (Unpublished) https://resolver.caltech.edu/CaltechAUTHORS:20201203-151035641

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Abstract

We present the discovery of a luminous X-ray transient, serendipitously detected by Swift's X-ray Telescope (XRT) on 2020 February 5, located in the nucleus of the galaxy SDSS J143359.16+400636.0 at z=0.099 (luminosity distance D_L=456 Mpc). The transient was observed to reach a peak luminosity of ∼10⁴⁴ erg s⁻¹ in the 0.3--10 keV X-ray band, which was ∼20 times more than the peak optical/UV luminosity. Optical, UV, and X-ray lightcurves from the Zwicky Transient Facility (ZTF) and Swift show a decline in flux from the source consistent with t^(−5/3), and observations with NuSTAR and Chandra show a soft X-ray spectrum with photon index Γ=2.9±0.1. The X-ray/UV properties are inconsistent with well known AGN properties and have more in common with known X-ray tidal disruption events (TDE), leading us to conclude that it was likely a TDE. The broadband spectral energy distribution (SED) can be described well by a disk blackbody model with an inner disk temperature of 7.3^(+0.3)_(−0.8) × 10⁵ K, with a large fraction (>40%) of the disk emission up-scattered into the X-ray band. An optical spectrum taken with Keck/LRIS after the X-ray detection reveals LINER line ratios in the host galaxy, suggesting low-level accretion on to the supermassive black hole prior to the event, but no broad lines or other indications of a TDE were seen. The stellar velocity dispersion implies the mass of the supermassive black hole powering the event is log(M_(BH)/M_⊙)=7.41±0.41, and we estimate that at peak the Eddington fraction of this event was ∼50%. This likely TDE was not identified by wide-field optical surveys, nor optical spectroscopy, indicating that more events like this would be missed without wide-field UV or X-ray surveys.


Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription
http://arxiv.org/abs/2010.12587arXivDiscussion Paper
ORCID:
AuthorORCID
Brightman, Murray0000-0002-8147-2602
Stern, Daniel0000-0003-2686-9241
Mooley, Kunal0000-0002-2557-5180
De, Kishalay0000-0002-8989-0542
Gezari, Suvi0000-0003-3703-5154
van Velzen, Sjoert0000-0002-3859-8074
Andreoni, Igor0000-0002-8977-1498
Graham, Matthew0000-0002-3168-0139
Masci, Frank J.0000-0002-8532-9395
Riddle, Reed0000-0002-0387-370X
Additional Information:The majority of this research and manuscript preparation took place during the COVID-19 global pandemic. The authors would like to thank all those who risked their lives as essential workers in order for us to safely continue our work from home. We wish to thank the Swift PI, Brad Cenko, for approving the target of opportunity requests we made to observe SDSS J143359.16+400636.0, as well as the rest of the Swift team for carrying the observations out. We also acknowledge the use of public data from the Swift data archive. We also wish to thank the NuSTAR PI, Fiona Harrison, for approving the DDT request we made to observe SDSS J143359.16+400636.0, as well as the NuSTAR SOC for carrying out the observation. This work was also supported under NASA Contract No. NNG08FD60C. NuSTAR is a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration. This research has made use of the NuSTAR Data Analysis Software (NuSTAR-DAS) jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA). 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 paper is 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. SED Machine is based upon work supported by the National Science Foundation under Grant No. 1106171. The ZTF forced-photometry service was funded under the Heising-Simons Foundation grant #12540303 (PI: Graham). Facilities: Swift (XRT, UVOT), NuSTAR, CXO, Keck:I (LRIS), PO:1.2m PO:1.5m, VLA
Group:Infrared Processing and Analysis Center (IPAC), Space Radiation Laboratory, NuSTAR, Zwicky Transient Facility
Funders:
Funding AgencyGrant Number
NASANNG08FD60C
NASA/JPL/CaltechUNSPECIFIED
NSFAST-1440341
ZTF partner institutionsUNSPECIFIED
NSFAST-1106171
Heising-Simons Foundation12540303
Record Number:CaltechAUTHORS:20201203-151035641
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20201203-151035641
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:106902
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:03 Dec 2020 23:51
Last Modified:05 Feb 2021 20:29

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