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Date and Time of the Query: 2019-05-26 T06:19:27 PDT
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For refcode 2002ApJS..139....1T:
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2002ApJS..139....1T X-Ray Properties of LINERs and Low-Luminosity Seyfert Galaxies Observed with ASCA. I. Observations and Results Yuichi Terashima, Naoko Iyomoto, Luis C. Ho, and Andrew F. Ptak Received 2001 July 10; accepted 2001 September 14 ABSTRACT 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 4 x 10^39^ to 5 x 10^41^ 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 {GAMMA} ~ 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 10^23^ 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. Subject headings: galaxies: active - galaxies: nuclei - galaxies: Seyfert - X-rays: galaxies
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