ASCA spectroscopy of IRAS 23060+0505: penetrating the torus of a type 2 quasar with X-rays
Abstract
We report on a pointed ASCA observation of the powerful (L_bol~1.3x10^46 erg s^-1) type 2 infrared luminous galaxy IRAS 23060+0505. This galaxy has been the subject of detailed spectroscopic and spectropolarimetric studies which have revealed a hidden broad-line region and have been used to construct a detailed model of the light paths in this source. Our observation detects IRAS 23060+0505 in the X-ray band for the first time and complements the optical and infrared studies. We detect hard X-ray emission that can be modelled as a power law with a 2-10 keV luminosity of 1.5x10^44 erg s^-1, thereby verifying the existence of an accreting supermassive black hole in IRAS 23060+0505. The obscuring torus of IRAS 23060+0505 appears to be Compton thin along our line of sight, and we measure a column to the nuclear X-ray source of about 8x10^22 cm^-2. Comparison of the X-ray column with the A_V=30+/-4 mag extinction measurement by Young et al. suggests that the torus may have a dust-to-gas ratio rather similar to that in the interstellar medium of the Milky Way. We also find some evidence for iron K-line emission. The apparent X-ray to bolometric luminosity ratio for IRAS 23060+0505 is <~1 per cent, a rather low value, and we consider possible explanations for this low ratio.
- Publication:
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Monthly Notices of the Royal Astronomical Society
- Pub Date:
- October 1997
- DOI:
- 10.1093/mnras/290.4.617
- Bibcode:
- 1997MNRAS.290..617B
- Keywords:
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- GALAXIES: INDIVIDUAL: IRAS 23060+0505;
- GALAXIES: SEYFERT;
- X-RAYS: GALAXIES