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Title

PTF10iya: a short-lived, luminous flare from the nuclear region of a star-forming galaxy

Author(s)

Cenko, S. Bradley;  Bloom, Joshua S.;  Kulkarni, S. R.;  Strubbe, Linda E.;  Miller, Adam A.;  Butler, Nathaniel R.;  Quimby, Robert M.;  Gal-Yam, Avishay;  Ofek, Eran O.;  Quataert, Eliot;  Bildsten, Lars;  Poznanski, Dovi;  Perley, Daniel A.;  Morgan, Adam N.;  Filippenko, Alexei V.;  Frail, Dale A.;  Arcavi, Iair;  Ben-Ami, Sagi;  Cucchiara, Antonio;  Fassnacht, Christopher D.;  Green, Yoav;  Hook, Isobel M.;  Howell, D. Andrew;  Lagattuta, David J.;  Law, Nicholas M.;  Kasliwal, Mansi M.;  Nugent, Peter E.;  Silverman, Jeffrey M.;  Sullivan, Mark;  Tendulkar, Shriharsh P.;  Yaron, Ofer

Abstract

We present the discovery and characterization of PTF10iya, a short-lived (Δt≈ 10 d, with an optical decay rate of ∼0.3 mag d−1), luminous ( mag) transient source found by the Palomar Transient Factory. The ultraviolet/optical spectral energy distribution is reasonably well fitted by a blackbody with T≈ (1–2) × 104 K and peak bolometric luminosity LBB≈ (1–5) × 1044 erg s−1 (depending on the details of the extinction correction). A comparable amount of energy is radiated in the X-ray band that appears to result from a distinct physical process. The location of PTF10iya is consistent with the nucleus of a star-forming galaxy (z= 0.224 05 ± 0.000 06) to within 350 mas (99.7 per cent confidence radius), or a projected distance of less than 1.2 kpc. At first glance, these properties appear reminiscent of the characteristic ‘big blue bump’ seen in the near-ultraviolet spectra of many active galactic nuclei (AGNs). However, emission-line diagnostics of the host galaxy, along with a historical light curve extending back to 2007, show no evidence for AGN-like activity. We therefore consider whether the tidal disruption of a star by an otherwise quiescent supermassive black hole may account for our observations. Though with limited temporal information, PTF10iya appears broadly consistent with the predictions for the early ‘super-Eddington’ phase of a solar-type star being disrupted by a ∼107 M⊙ black hole. Regardless of the precise physical origin of the accreting material, the large luminosity and short duration suggest that otherwise quiescent galaxies can transition extremely rapidly to radiate near the Eddington limit; many such outbursts may have been missed by previous surveys lacking sufficient cadence.

Publication type

Journal article

Source

Monthly Notices of the Royal Astronomical Society, Vol. 420, no. 3 (Mar 2012), pp. 2684-2699

Publication year

2012

FOR Code(s)

0201 Astronomical and Space Sciences

Keyword(s)

Accretion;  Accretion discs;  Active galaxies;  Black hole physics;  Nuclei

Publisher

Wiley-Blackwell

ISSN

0035-8711

Publisher URL

http://dx.doi.org/10.1111/j.1365-2966.2011.20240.x

Copyright

Copyright © 2012 The Authors. Journal copyright © 2012 Royal Astronomical Society. The accepted manuscript is reproduced in accordance with the copyright policy of the publisher. The definitive publication is available at www.interscience.wiley.com.

Full text

Peer reviewed