Chandra observations of nuclear X-ray emission from a sample of radio sources
Abstract
We present the X-ray properties of a sample of 17 radio sources observed with the Chandra X-ray Observatory as part of a project aimed at studying the X-ray emission from their radio jets. In this paper, we concentrate on the X-ray properties of the unresolved cores. The sample includes 16 quasars (11 core-dominated and 5 lobe-dominated) in the redshift range z=0.30-1.96, and one low-power radio-galaxy at z=0.064. No diffuse X-ray emission is present around the cores of the quasars, except for the nearby low-power galaxy that has diffuse emission on a scale and with a luminosity consistent with other FRIs. No high-amplitude, short-term variability is detected within the relatively short Chandra exposures. However, 1510-089 shows low-amplitude flux changes with a timescale of ~ 25 min. The X-ray spectra of the quasar cores are generally well described by a single power law model with Galactic absorption. However, in six quasars we find soft X-ray excess emission below 1.6 keV. Interestingly, we detect an Fe K-shell emission line, consistent with fluorescent Kalpha emission from cold iron, in one lobe- and two core-dominated sources. The average X-ray photon index for the quasars in the sample is Gammasample =1.66 and dispersion sigmasample =0.23. The average spectral slope for our sample is flatter than the slope found for radio-quiet quasars and for radio-loud AGNs with larger jet orientations; this indicates that beaming affects the X-ray emission from the cores in our sample of quasars.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- April 2003
- DOI:
- 10.1051/0004-6361:20030173
- arXiv:
- arXiv:astro-ph/0302265
- Bibcode:
- 2003A&A...401..505G
- Keywords:
-
- galaxies: active;
- radio continuum: galaxies;
- galaxies: quasars: emission lines;
- X-rays: general;
- Astrophysics
- E-Print:
- 14 pages, 5 figures, Accepted for publication in Astronomy &