ASCA observations of two ultra-luminous compact x-ray sources in the edge-on spiral galaxy NGC 4565

Tsunefumi Mizuno, Tomohisa Ohnishi, Aya Kubota, Kazuo Makishima, Makoto Tashiro

研究成果査読

30 被引用数 (Scopus)

抄録

The edge-on spiral galaxy NGC 4565 was observed for ∼ 35 ks with ASCA in the 0.5-10 keV energy band. The X-ray emission was dominated by two bright sources, which could be identified with two point-like X-ray sources seen in the ROSAT HRI image. The observed 0.5-10 keV fluxes of these sources, 1.7 × 10-12 erg s-1 cm-2 and 0.7 × 10-12 erg s-1 cm-2, imply bolometric luminosities of 1.2 × 1040 erg s-1 and 4.6 × 1039 erg s-1, respectively. They exhibit similar spectra, which can be explained by emission from optically thick accretion disks with inner-disk temperature of 1.4-1.6 keV. One of them, coincident in position with the nucleus, shows too low absorption to be the active nucleus seen through the galaxy disk. Their spectra and high luminosities suggest that they are both mass-accreting black-hole binaries. However the black-hole mass required by the Eddington limit is rather high (≥ 50M(Fisheye)), and the observed disk temperature is too high to be compatible with the high black-hole mass. Several attempts have been made to solve these problems.

本文言語English
ページ(範囲)663-671
ページ数9
ジャーナルPublications of the Astronomical Society of Japan
51
5
DOI
出版ステータスPublished - 1999
外部発表はい

ASJC Scopus subject areas

  • 天文学と天体物理学
  • 宇宙惑星科学

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