The FR-I radio galaxies NGC 315 and NGC 4261 observed with ASCA

Citation
Y. Matsumoto et al., The FR-I radio galaxies NGC 315 and NGC 4261 observed with ASCA, PUB AST S J, 53(3), 2001, pp. 475-481
Citations number
46
Categorie Soggetti
Space Sciences
Journal title
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN
ISSN journal
00046264 → ACNP
Volume
53
Issue
3
Year of publication
2001
Pages
475 - 481
Database
ISI
SICI code
0004-6264(2001)53:3<475:TFRGN3>2.0.ZU;2-X
Abstract
FR-I radio galaxies NGC 315 and NGC 4261 were observed in X-rays with ASCA for similar to 37 ks and similar to 54 ks, respectively. Hard X-ray emissio n from a point-like source at the nucleus was detected at a 2-10 keV lumino sity of 3.1 x 10(41) and 9.2 x 10(40) erg s(-1), respectively, for assumed distances of 66 Mpc and 29 Mpc (for H-0 = 75 km s(-1) Mpc(-1)). The 2-10 ke V spectra of NGC 315 and NGC 4261 were both fitted successfully with a powe r-law of photon index 2.02 +/- 0.34 and 1.45 +/- 0.11, respectively, plus e mission from hot gas. The NGC 315 nucleus is mildly absorbed. No X-ray vari ability was detected from either object, with typical upper limits of sever al tens per cent. These results imply the presence of a low-luminosity acti ve galactic nucleus in both galaxies, and reconfirm the previous recognitio n that the FR-I nuclei are significantly less X-ray luminous than the FR-II ones.