ROSAT, ASCA, and OSSE Observations of the Broad-Line Radio Galaxy 3C 120
Abstract
We present simultaneous observations of the superluminal radio galaxy 3C 120 performed with the ASCA and GRO (OSSE) satellites in 1994 February-March, as well as an analysis of all the ROSAT archival data. The ASCA spectrum of this object can be described by an absorbed (NH = 1.6 × 1021 cm-2) power law with a photon index of Γ ASCA = 2 and a very broad (σ > 0.8 keV) intense iron line (EW > 400 eV) at ~6 keV.
The combined ASCA-OSSE data do not exclude the presence of a narrower (σ = 0.4 keV) and less intense (EW < 300 eV) iron line plus a hard component, corresponding either to reflection from an accretion disk or to a flatter power law from a jet. However, a single power law plus broad Fe line is preferred from a statistical point of view by the ASCA data. The ROSAT data yield a column density in excess of the Galactic value. The spectral slopes, ranging from Γ ROSAT = 2.5 to 3.3, are steeper than that measured by ASCA, suggesting the presence of a soft excess. The 0.1-2 keV power-law slope is variable and softer at higher intensity. These results show that the combined soft and hard X-ray spectrum of 3C 120 is rather complex. The intrinsic absorption, the soft excess, and the iron line indicate that the X-ray emission from this blazar-like radio galaxy is dominated by a Seyfert-like component, at least in the 0.1-10 keV energy band. The jet contribution, if present, becomes important only at higher energies.- Publication:
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The Astrophysical Journal
- Pub Date:
- October 1997
- DOI:
- 10.1086/304630
- arXiv:
- arXiv:astro-ph/9707078
- Bibcode:
- 1997ApJ...487..636G
- Keywords:
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- Galaxies: Individual: Alphanumeric: 3C 120;
- Galaxies: Jets;
- Galaxies: Nuclei;
- Galaxies: Seyfert;
- X-Rays: Galaxies;
- Astrophysics
- E-Print:
- 25 pages, Latex, 8 PostScript figures, to appear in The Astrophysical Journal