ASCA Observation of an X-Ray-luminous Active Nucleus in Markarian 231
Abstract
We have obtained a moderately long (105 s) ASCA observation of the Seyfert 1 galaxy Markarian 231, the most luminous of the local ultraluminous infrared galaxy population. In the best-fitting model we do not see the X-ray source directly; the spectrum consists of a scattered power-law component and a reflection component, both of which have been absorbed by a column NH~3×1022 cm-2. About three-quarters of the observed hard X-rays arise from the scattered component, reducing the equivalent width of the iron Kα line. The implied ratio of 1-10 keV X-ray luminosity to bolometric luminosity, LX/Lbol~2%, is typical of Seyfert 1 galaxies and radio-quiet QSOs of comparable bolometric luminosities and indicates that the bolometric luminosity is dominated by the active galactic nucleus (AGN). Our estimate of the X-ray luminosity also moves Mrk 231 in line with the correlations found for AGNs with extremely strong Fe II emission. A second source separated by about 2' is also clearly detected and contributes about 25% of the total flux.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 2000
- DOI:
- 10.1086/317327
- arXiv:
- arXiv:astro-ph/0010125
- Bibcode:
- 2000ApJ...545L..23M
- Keywords:
-
- Galaxies: Active;
- Galaxies: Individual: Name: Markarian 231;
- Galaxies: Nuclei;
- Galaxies: Seyfert;
- X-Rays: Galaxies;
- Astrophysics
- E-Print:
- 11 pages, 3 figures