2004AJ....127..758I -
Astron. J., 127, 758-764 (2004/February-0)
X-ray-Underluminous active galactic nuclei relative to broad emission lines in ultraluminous infrared galaxies.
IMANISHI M. and TERASHIMA Y.
Abstract (from CDS):
We present X-ray spectra of four ultraluminous infrared galaxies (ULIRGs) with detectable broad near-infrared emission lines produced by active galactic nuclei (AGNs): Mrk 463, PKS 1345+12, IRAS 05189-2524, and IRAS 07598+6508. With the exception of IRAS 07598+6508, high-quality X-ray spectra obtained with XMM or Chandra show modest (30-340 eV) equivalent widths of the 6.4 keV Fe Kα emission line and clear signatures for absorption at a level of 4-33x1022/cm2 for the main power-law components from the AGNs. These spectral properties are typical of Compton-thin AGNs, and so we estimate absorption-corrected 2-10 keV X-ray luminosities for the AGNs, LX(2-10 keV) using the Compton-thin assumption. We compare the LX(2-10 keV) values with broad optical/near-infrared emission-line luminosities and confirm a previous finding by Imanishi & Ueno that the LX(2-10 keV) to broad emission-line luminosity ratios in ULIRGs are systematically lower than those of moderately infrared-luminous type 1 AGNs. A comparison of independent energy diagnostic methods suggests that the AGNs are underluminous in the 2-10 keV band with respect to their overall spectral energy distributions, as opposed to the broad emission lines being overluminous. This X-ray underluminosity should be taken into account when using 2-10 keV X-ray data to investigate the energetic contribution from AGNs to the large infrared luminosities of ULIRGs.
Abstract Copyright:
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Journal keyword(s):
Galaxies: Active - Galaxies: Individual: Name: Markarian 463 - Galaxies: Individual: Alphanumeric: IRAS 05189-2524 - galaxies: individual (PKS 1345+12) - Galaxies: Individual: Alphanumeric: IRAS 07598+6508 - Galaxies: Nuclei - X-rays: galaxies
Simbad objects:
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