The redshift of the highly variable BL Lac object H0323+022
The redshift of the highly variable BL Lac object H0323+022
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DOI：
10.1086/113977
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发表时间：
1986
期刊：
影响因子：
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通讯作者：
A. Filippenko;S. Djorgovski;H. Spinrad;W. Sargent
中科院分区：
文献类型：
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作者：
A. Filippenko;S. Djorgovski;H. Spinrad;W. Sargent
新的光谱被用来推导H 0323 + 022的红移，H 0323 + 022是一种明亮的、高度可变的X射线源，其性质一直是争议的主题。大多数光谱都是由一个无特征的非恒星连续体，如BL Lac天体。仅在两天的时间间隔内就观测到^ 2等的光度变化.非恒星光有时足够微弱，可以探测到红移z = 0.1471 + 0.0005的吸收线。这些线条显然是由于宿主星系中的恒星，这在物体的深层图像中很容易看到。该星系可能是一个相对正常的椭圆星系，Mv ~ - 21至- 22，除了在一个象限内明显的延伸。在1985年2月15日，非恒星连续谱可以用指数a-0.6的幂律来描述（其中f v oc v _a）;在5460 A时，它在核中的相对强度（2”X5.2”）约为62%，而Af K ^ - 22至- 23。当幂律分量衰减时，其斜率似乎变陡。现在毫无疑问，H 0323 + 022是一个BL Lac天体，而不是一颗奇特的银河系星星。正如Feigelson等人（1986）所讨论的那样，它极其快速的变化（Δ F ^1 × 10 45 erg s-1/Δ F ^30 s）只有OJ 287的变化可以与之相媲美，而且硬x射线必须来自一个比产生射电辐射的区域小大约10 4倍的区域。
New optical spectra are used to derive the redshift of H0323 + 022, a bright, highly variable x-ray source whose nature has been the subject of controversy. Most of the spectra are dominated by a featureless nonstellar continuum, as found in BL Lac objects. Photometric variations of ^ 2 mag have been seen over a time interval of only 2 days. The nonstellar light is sometimes faint enough to allow the detection of absorption lines at a redshift z = 0.1471 + 0.0005. These lines are clearly due to stars in the host galaxy, which is easily visible in deep images of the object. The galaxy is probably a relatively normal elliptical with M v ~ — 21 to — 22, except that a noticeable extension is evident in one quad-rant. On 24.15 February 1985 UT, the nonstellar continuum could be described by a power law of index a—0.6 (wheref v oc v _a ); its relative strength in the nucleus (2" X5.2") was ~62% at 5460 A, while Af K ^ — 22 to — 23. When the power-law component fades, its slope appears to steepen. There is now no doubt that H0323 + 022 is a BL Lac object, rather than a peculiar Galactic star. As discussed by Feigelson et al. (1986), its extremely rapid variability (AL^ 1X 10 45 erg s“ 1 in Af^30 s) is matched only by that of OJ 287, and the hard x rays must come from a region roughly a factor of 10 4 smaller than that which produces the radio emission.