X-ray and lensing results on the cluster around the powerful radio galaxy 4C+55.16
Abstract
We present results from ASCA and ROSAT HRI observations of the powerful radio galaxy 4C+55.16 at redshift 0.24. Extended soft X-ray emission is imaged by the ROSAT HRI. The X-ray brightness profile is sharply peaked on the radio galaxy, characteristic of a strong cooling flow. The X-ray spectrum obtained from ASCA is consistent with multiphase intracluster gas. There is evidence for an absorbed cool component as well as ambient cluster medium in the ASCA spectrum. A spectral fit, taking a cooling-flow component into account, gives a temperature of kT = 5.4_-0.9^+1.4 keV, metal abundance (0.5 +/- 0.1) Z_solar, excess absorption on the cool component, Delta N_H = 4.9_-1.3^+3.4 x 10^21 cm^-2, and an absorption-corrected bolometric luminosity of 2.2 x 10^45 erg s^-1 (H_0 = 50 km s^-1 Mpc^-1, q_0 = 0.5). The mass-deposition rate is estimated to be ~ 1100 M_solar yr^-1 from the spectral analysis, in good agreement with that derived from imaging analysis of the ROSAT data when corrected for absorption. We tentatively identify a blue feature, seen ~ 15 arcsec from the centre of the radio galaxy in a published optical image, as a gravitationally lensed arc. The inferred lensing mass is consistent with the gravitational mass derived from the X-ray data. The best estimate of the redshift of the lensed object is ~ 1.5 (>0.7). All the observed properties suggest that the environment of 4C+55.16 is similar to known massive cooling-flow clusters. This is the first massive cooling flow to be found around a powerful, radio source with a compact, GHz-peaked spectrum core.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- June 1999
- DOI:
- 10.1046/j.1365-8711.1999.02529.x
- arXiv:
- arXiv:astro-ph/9902159
- Bibcode:
- 1999MNRAS.306..467I
- Keywords:
-
- GALAXIES: CLUSTERS: INDIVIDUAL: 4C+55.16;
- COOLING FLOWS;
- GRAVITATIONAL LENSING;
- X-RAYS: GALAXIES;
- Astrophysics
- E-Print:
- 6 pages, 4 Postscript figures, accepted for publication in MNRAS