A candidate of a type 2 quasi-stellar object at z = 0.9: Large X-ray absorption with a strong broad Hα emission line

Masayuki Akiyama, Yoshihiro Ueda, Kouji Ohta

研究成果: Article査読

18 被引用数 (Scopus)

抄録

Deep hard X-ray and near-infrared observations of a type 2 radio-quiet quasi-stellar object (QSO) candidate at z = 0.9, AX J08494 + 4454, are reported. The 0.5-10 keV Chandra X-Ray Observatory spectrum of AX J08494 + 4454 is hard and is explained well with a power-law continuum absorbed by a hydrogen column density of (2.3 ± 1.1) × 1023 cm-2. The 2-10 keV luminosity of the object is estimated to be 7.2 -2.0 +3.6 × 1044 ergs s-1, after correcting the absorption, and reaches hard X-ray luminosities of QSOs. The large X-ray absorption and the large intrinsic luminosity support the original identification of AX J08494 + 4454 as a type 2 radio-quiet QSO. Nevertheless, the deep Subaru/IRCS J-band spectroscopic observation suggests the presence of a strong broad Hα emission line from AX J08494 + 4454. If real, the broad Hα emission line has a velocity width of 9400 ± 1000 km s -1, which corresponds to a typical broad Balmer line velocity width of a luminous QSO. The existence of the strong broad Hα line means that the object is not a type 2 QSO but a luminous cousin of a Seyfert 1.9 galaxy in the source-frame optical spectrum. The Balmer decrement of broad lines and the broad Hα emission to the hard X-ray luminosity ratio suggest that the nucleus is affected by dust extinction with an Av of 1-3 mag in the optical wavelength. Optical colors and faint optical magnitudes of AX J08494 + 4454 are consistent with the model. The estimated amount of dust extinction is much smaller than that expected from the X-ray column density (Av = 130 ± 60 mag).

本文言語English
ページ(範囲)42-49
ページ数8
ジャーナルAstrophysical Journal
567
1 I
DOI
出版ステータスPublished - 2002 3月 1
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

フィンガープリント

「A candidate of a type 2 quasi-stellar object at z = 0.9: Large X-ray absorption with a strong broad Hα emission line」の研究トピックを掘り下げます。これらがまとまってユニークなフィンガープリントを構成します。

引用スタイル