EDP Sciences Journals List
Advanced Search
Subscriber Authentication Point
Home All issues Volume 462/3 Article
Free access article

Issue A&A
Volume 462, Number 3, February II 2007
Page(s) L49 - L52
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20066072



A&A 462, L49-L52 (2007)
DOI: 10.1051/0004-6361:20066072

Letter

Candidate tidal disruption events from the XMM-Newton slew survey

P. Esquej1, 2, R. D. Saxton2, M. J. Freyberg1, A. M. Read3, B. Altieri2, M. Sanchez-Portal2, and G. Hasinger1

1  Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, 85748 Garching, Germany
    e-mail: pili@mpe.mpg.de
2  European Space Agency (ESA), European Space Astronomy Centre, Villafranca, Apartado 50727, 28080 Madrid, Spain
3  Dept. of Physics and Astronomy, Leicester University, Leicester LE1 7RH, UK

(Received 20 July 2006 / Accepted 11 December 2006)

Abstract
Context.In recent years, giant amplitude X-ray flares have been observed from a handful of non-active galaxies. The most plausible scenario of these unusual phenomena is tidal disruption of a star by a quiescent supermassive black hole at the centre of the galaxy.
Aims.Only a small number of these type of events have been observed and confirmed to date. The discovery of more cases would allow a number of fundamental conclusions to be drawn about properties such as the frequency of tidal disruption events, the distribution of quiescent black hole masses and their influence in the context of galaxy/AGN formation and evolution among others.
Methods.Comparing the XMM-Newton Slew Survey Source Catalogue with the ROSAT PSPC All-Sky Survey five galaxies have been detected a factor of up to 88 brighter in XMM-Newton with respect to ROSAT PSPC upper limits and presenting a soft X-ray colour. X-ray luminosities of these sources derived from slew observations have been found in the range 1041-1044 erg s-1, fully consistent with the tidal disruption model. This model predicts that during the peak of the outburst, flares reach X-ray luminosities up to 1045 erg s-1, which is close to the Eddington luminosity of the black hole, and afterwards a decay of the flux on a time scale of months to years is expected. Multi-wavelength follow-up observations have been performed on these highly variable objects in order to disentangle their nature and to investigate their dynamical evolution.
Results.Here we present sources coming from the XMM-Newton Slew Survey that could fit in the paradigm of tidal disruption events. X-ray and optical observations revealed that two of these objects are in full agreement with that scenario and three other sources that, showing signs of optical activity, need further investigation within the transient galactic nuclei phenomena.


Key words: surveys -- galaxies: general -- X-rays: general



© ESO 2007


What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.
  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.