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NTT, Spitzer, and Chandra Spectroscopy of SDSSJ095209.56+214313.3: The Most Luminous Coronal-line Supernova Ever Observed, or a Stellar Tidal Disruption Event?

Komossa, S. and Zhou, H. and Rau, A. and Dopita, M. and Gal-Yam, A. and Greiner, J. and Zuther, J. and Salvato, M. and Xu, D. and Lu, H. and Saxton, R. and Ajello, M. (2009) NTT, Spitzer, and Chandra Spectroscopy of SDSSJ095209.56+214313.3: The Most Luminous Coronal-line Supernova Ever Observed, or a Stellar Tidal Disruption Event? Astrophysical Journal, 701 (1). pp. 105-121. ISSN 0004-637X.

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The galaxy SDSSJ095209.56+214313.3 (SDSSJ0952+2143 hereafter) showed remarkable emission-line and continuum properties and strong emission-line variability first reported in 2008 (Paper I). The spectral properties and low-energy variability are the consequence of a powerful high-energy flare which was itself not observed directly. Here we report follow-up optical, near-infrared (NIR), mid-infrared (MIR), and X-ray observations of SDSSJ0952+2143. We discuss outburst scenarios in terms of stellar tidal disruption by a supermassive black hole, peculiar variability of an active galactic nucleus (AGN), and a supernova (SN) explosion, and possible links between these scenarios and mechanisms. The optical spectrum of SDSSJ0952+2143 exhibits several peculiarities: an exceptionally high ratio of [Fe VII] transitions over [O III], a dramatic decrease by a factor of 10 of the highest-ionization coronal lines, a very unusual and variable Balmer line profile including a triple-peaked narrow component with two unresolved horns, and a large Balmer decrement. The MIR emission measured with the Spitzer IRS in the narrow 10-20 mu m band is extraordinarily luminous and amounts to L_(10-20 mu m) = 3.5 x 10^(43) erg s^(-1). The IRS spectrum shows a bump around similar to 11 mu m and an increase toward longer wavelengths, reminiscent of silicate emission. The strong MIR excess over the NIR implies the dominance of relatively cold dust. The pre- and post-flare NIR host galaxy colors indicate a nonactive galaxy. The X-ray luminosity of L_(x, 0.1-10 keV) = 10^(41) erg s^(-1) measured with Chandra is below that typically observed in AGNs. Similarities of SDSSJ0952+2143 with some extreme SNe suggest the explosion of a SN of Type IIn. However, an extreme accretion event in a low-luminosity AGN or inactive galaxy, especially stellar tidal disruption, remain possibilities, which could potentially produce a very similar emission-line response. If indeed a SN, SDSSJ0952+2143 is one of the most distant X-ray- and MIR-detected SNe known so far, the most MIR luminous, and one of the most X-ray luminous. It is also by far the most luminous (> 10^(40) erg s^(-1)) in high-ionization coronal lines, exceeding previous SNe by at least a factor of 100.

Item Type:Article
Related URLs:
URLURL TypeDescription
Rau, A.0000-0001-5990-6243
Gal-Yam, A.0000-0002-3653-5598
Salvato, M.0000-0001-7116-9303
Ajello, M.0000-0002-6584-1703
Additional Information:© 2009. The American Astronomical Society. Received 2009 February 17; accepted 2009 June 10; published 2009 July 20. Print publication: Issue 1 (2009 August 10). We thank Lee Armus, Dirk Grupe, Stefan Immler, Gottfried Kanbach, Jean-Pierre Luminet, Dieter Lutz, Ximena Mazzalay, Hagai Netzer, Nathan Smith, and Eckhard Sturm for very useful discussions, Thomas Krühler for running the GROND pipeline data reduction, and our referee for his/her insightful comments. Part of this research was carried out while M.D., S.K., A.R., and M.S. stayed at the Aspen Centre for Physics, and we thank the Centre for its support and hospitality. We acknowledge use of the SDSS, GALEX, 2MASS, NVSS, ROSAT, Swift BAT, and XMM-Newton data base and of NED and ADS. We have acquired new data with ESO's NTT, the Xinglong telescope, GROND, Spitzer and Chandra. We thank all instrument teams, and especially the SDSS team for making available to the whole astrophysics community their outstanding data base on which the discovery of this galaxy was based. A.R. thanks Lee Armus for discussing the IRS data reduction. We acknowledge Spitzer grant P483. H.Z. acknowledges support from the Alexander von Humboldt Foundation, the Chinese Natural Science Foundation through CNSF-10533050, 10573015, the CAS knowledge innovation project No. 1730812341, and the national 973 project (2007CB815403). A.G. acknowledges support by the Israeli Science Foundation, an EU Seventh Framework Programme Marie Curie IRG fellowship, and the Benoziyo Center for Astrophysics, a research grant from the Peter and Patricia Gruber Awards, and the William Z. and Eda Bess Novick New Scientists Fund at the Weizmann Institute. D.X. acknowledges support from the Chinese National Science Foundation (NSFC) under grant NSFC 10873017, and from program 973 (2009CB824800).
Funding AgencyGrant Number
Spitzer Space TelescopeP483
Alexander von Humboldt FoundationUNSPECIFIED
National Natural Science Foundation of ChinaCNSF-10533050
National Natural Science Foundation of ChinaCNSF-10573015
Chinese Academy of Science1730812341
National Basic Research Program of China (973 Program)2007CB815403
Israel Science FoundationUNSPECIFIED
Benoziyo Center for AstrophysicsUNSPECIFIED
Weizmann InstituteUNSPECIFIED
National Natural Science Foundation of ChinaNSFC 10873017
National Basic Research Program of China (973 Program)2009CB824800
Subject Keywords:circumstellar matter; galaxies: general; galaxies: individual (SDSSJ095209.56+214313.3); supernovae: general
Issue or Number:1
Record Number:CaltechAUTHORS:20090808-142505024
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Official Citation:NTT, Spitzer, and Chandra Spectroscopy of SDSSJ095209.56+214313.3: The Most Luminous Coronal-line Supernova Ever Observed, or a Stellar Tidal Disruption Event? S. Komossa, H. Zhou, A. Rau, M. Dopita, A. Gal-Yam, J. Greiner, J. Zuther, M. Salvato, D. Xu, H. Lu, R. Saxton, and M. Ajello 2009 ApJ 701 105-121 doi: 10.1088/0004-637X/701/1/105
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:14905
Deposited By: George Porter
Deposited On:01 Sep 2009 23:42
Last Modified:22 Nov 2019 05:27

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