SIMBAD references

2002ApJS..139....1T - Astrophys. J., Suppl. Ser., 139, 1-36 (2002/March-0)

X-ray properties of LINERs and low-luminosity Seyfert galaxies observed with ASCA. I. Observations and results.


Abstract (from CDS):

This paper presents a comprehensive study of the X-ray properties of low-ionization nuclear emission-line regions (LINERs) and low-luminosity Seyfert galaxies based on observations obtained with the ASCA satellite. We analyzed data of 53 observations of 21 LINERs and 17 low-luminosity Seyferts. X-ray emission has been detected in all but one object. The X-ray luminosities in the 2-10 keV band range from 4x1039 to 5x1041 ergs.s–1, which are 1-3 orders of magnitude smaller than in classical Seyfert galaxies. The X-ray spectra of most objects are well described by a canonical model which consists of (1) a soft component from a thermal plasma with kT<1 keV and (2) a hard component represented by a power law with a photon index of Γ~1.8 or thermal bremsstrahlung emission with kT~10 keV. Several objects do not require the soft thermal component, and their continua are well fitted by a single power-law model. Some objects show heavy absorption with column densities in excess of 1023 cm–2. We detect in several objects Fe K line emission with equivalent widths ranging from 50 eV to 2 keV.

Variability on timescales less than a day is uncommon in our sample. By comparing multiple observations made with ASCA or with published 2-10 keV observations from other satellites, we show that at least eight objects are variable on timescales of a week to several years. We find that the morphologies of many objects, both in the soft and hard bands, are consistent with being pointlike relative to the telescope point-spread function; a few are clearly extended in either or both energy bands.

The second paper of this series will discuss the physical interpretation of the X-ray emission and its implications for low-luminosity active galactic nuclei.

Abstract Copyright:

Journal keyword(s): Galaxies: Active - Galaxies: Nuclei - Galaxies: Seyfert - X-Rays: Galaxies

Status at CDS:  

Simbad objects: 38

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