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

Yukari Matsumoto, Yasushi Fukazawa, Kazuhiro Nakazawa, Naoko Iyomoto, Kazuo Makishima

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9 Citations (Scopus)


FR-I radio galaxies NGC 315 and NGC 4261 were observed in X-rays with ASCA for ∼ 37 ks and ∼ 54 ks, respectively. Hard X-ray emission from a point-like source at the nucleus was detected at a 2-10 keV luminosity of 3.1 × 1041 and 9.2 × 1040 erg s-1, respectively, for assumed distances of 66 Mpc and 29 Mpc (for H0 = 75 km s-1 Mpc-1). The 2-10 keV spectra of NGC 315 and NGC 4261 were both fitted successfully with a power-law of photon index 2.02 ± 0.34 and 1.45 ± 0.11, respectively, plus emission from hot gas. The NGC 315 nucleus is mildly absorbed. No X-ray variability was detected from either object, with typical upper limits of several tens per cent. These results imply the presence of a low-luminosity active galactic nucleus in both galaxies, and reconfirm the previous recognition that the FR-I nuclei are significantly less X-ray luminous than the FR-II ones.

Original languageEnglish
Pages (from-to)475-481
Number of pages7
JournalPublications of the Astronomical Society of Japan
Issue number3
Publication statusPublished - Jun 25 2001
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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