EDP Sciences
Free access
Issue
A&A
Volume 431, Number 2, February IV 2005
Page(s) 465 - 475
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20041701


A&A 431, 465-475 (2005)
DOI: 10.1051/0004-6361:20041701

The supermassive black hole in the Seyfert 2 galaxy NGC 5252

A. Capetti1, A. Marconi2, D. Macchetto3, 4 and D. Axon5

1  INAF - Osservatorio Astronomico di Torino, Strada Osservatorio 20, 10025 Pino Torinese, Italy
    e-mail: capetti@to.astro.it
2  INAF - Osservatorio Astrofisico di Arcetri Largo E. Fermi 5, 50125 Firenze, Italy
    e-mail: marconi@arcetri.astro.it
3  Space Telescope Science Institute 3700 San Martin Drive, Baltimore, MD 21218, USA
4  Affiliated with ESA's Space Telescope Division
    e-mail: macchetto@stsci.edu
5  Department of Physics, Rochester Institute of Technology, 85 Lomb Memorial Drive, Rochester, NY 14623, USA
    e-mail: djasps@rit.edu

(Received 27 July 2004 / Accepted 20 October 2004 )

Abstract
We present results from HST/STIS long-slit spectroscopy of the gas motions in the nuclear region of the Seyfert 2 galaxy NGC 5252. The observed velocity field is consistent with gas in regular rotation with superposed localized patches of disturbed gas. The dynamics of the circumnuclear gas can be accurately reproduced by adding to the stellar mass component a compact dark mass of $M_{{\rm BH}} =
0.95~(-0.45;+1.45)$   $\times$ $10^9~M_{\odot}$, very likely a supermassive black hole (BH). Contrarily to results obtained in similar studies rotational broadening is sufficient to reproduce also the behaviour of line widths. The BH mass estimated for NGC 5252 is in good agreement with the correlation between  $M_{{\rm BH}}$ and bulge mass. The comparison with the $M_{{\rm BH}}$ vs. $\sigma_{\rm c}$ relationship is less stringent (mostly due to the relatively large error in  $\sigma_{\rm c}$); NGC 5252 is located above the best fit line by between 0.3 and 1.2 dex, i.e. 1-4 times the dispersion of the correlation. Both the galaxy's and BH mass of NGC 5252 are substantially larger than those usually estimated for Seyfert galaxies but, on the other hand, they are typical of radio-quiet quasars. Combining the determined BH mass with the hard X-ray luminosity, we estimate that NGC 5252 is emitting at a fraction ~0.005 of  $L_{{\rm Edd}}$. In this sense, this active nucleus appears to be a quasar relic, now probably accreting at a low rate, rather than a low black hole mass counterpart of a QSO.


Key words: black hole physics -- galaxies: active -- galaxies: bulges -- galaxies: nuclei -- galaxies: Seyfert

SIMBAD Objects



© ESO 2005

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.