SIMBAD references

2004ApJ...616..730F - Astrophys. J., 616, 730-737 (2004/December-1)

Chandra observations of the quiescent nuclear black hole of NGC 821: evidence of nuclear activity.

FABBIANO G., BALDI A., PELLEGRINI S., SIEMIGINOWSKA A., ELVIS M., ZEZAS A. and McDOWELL J.

Abstract (from CDS):

We report the results of the Chandra ACIS-S observations of the elliptical galaxy NGC 821, which harbors a supermassive nuclear black hole (3.5x107 M) but does not show signs of active galactic nucleus activity. A small, 8".5 long (∼1 kpc at the galaxy's distance of 23 Mpc), possibly S-shaped, jetlike feature centered on the nucleus is detected in the 38 ks ACIS-S integrated exposure of this region. The luminosity of this feature is LX∼2.6x1039 ergs/s (0.3-10 keV), and its spectrum is hard (described by a power law of Γ=1.8+0.7–0.6or by thermal emission with kT>2 keV). We discuss two possibilities for the origin of this feature: (1) a low-luminosity X-ray jet, or (2) a hot shocked gas. In either case, it is a clear indication of nuclear activity, detectable only in the X-ray band. Steady spherical accretion of the mass losses from the central stellar cusp within the accretion radius, when coupled with a high radiative efficiency, already provides a power source exceeding the observed radiative losses from the nuclear region. A third possibility, that this feature may arise from a fortuitous distribution of luminous X-ray binaries in NGC 821, is also discussed.

Abstract Copyright:

Journal keyword(s): Black Hole Physics - Galaxies: Individual: NGC Number: NGC 821 - Galaxies: Nuclei - X-Rays: Galaxies

Nomenclature: Fig.2: [FBP2004] AN (Nos S1-S3), [FBP2004] WW (No. NE).

Simbad objects: 9

goto Full paper

goto View the references in ADS

To bookmark this query, right click on this link: simbad:2004ApJ...616..730F and select 'bookmark this link' or equivalent in the popup menu


2022.11.30-09:21:50

© Université de Strasbourg/CNRS

    • Contact