Study of the Largest Multiwavelength Campaign of the Microquasar GRS 1915+105
Study of the Largest Multiwavelength Campaign of the Microquasar GRS 1915+105
复制标题
微类星体 GRS 1915 最大多波长活动的研究 105
DOI：
10.1086/340061
复制
发表时间：
2002
期刊：
影响因子：
--
通讯作者：
H. Inoue
中科院分区：
文献类型：
--
作者：
Y. Ueda;K. Yamaoka;C. Sanchez;V. Dhawan;S. Chaty;J. Grove;M. McCollough;A. Castro;F. Mirabel;K. Kohno;M. Feroci;P. Casella;S. Trushkin;H. Castaneda;J. Rodriguez;P. Durouchoux;K. Ebisawa;T. Kotani;J. Swank;H. Inoue
我们给出了2000年4月16日至4月25日期间进行的GRS 1915+105多波长活动的结果。这是有史以来对这一源进行的最大规模的协调观测之一，覆盖了射电(13.3-0.3厘米)、近红外(J、H和K波段)、X射线和伽马射线(从1keV到10 MeV)的宽能带。在活动期间，GRS1915+105主要处于“平台”(或低/硬)状态，但有时也表现出软X射线振荡：在4月20日之前，观测到了快速的准周期(≃45分钟)耀斑-俯冲周期。在平台态的光谱能量分布中，射电波段和X-伽马射线波段分别以光学厚的同步辐射和康普顿效应为主。射电波段相对于X射线的小光度表明，GRS 1915+105属于“射电安静”微类星体。在三个历元中，我们在10-20mJy的射电或红外波段探测到微弱的耀斑。4月17日观测到的射电耀斑显示出与频率相关的峰值延迟，这与同步辐射区域的扩展一致，从X射线中从硬浸泡状态到软耀斑状态的转变开始。另一方面，4月20日的红外耀斑似乎跟随(或先于)X射线振荡的开始，具有≃5-30分钟的不恒定时间延迟。这意味着红外发射区距离黑洞的距离为≳1013 cm，而其大小受时间变率的限制为≲1012 cm。我们发现近红外波段和X射线波段的准稳态通量能级之间有很好的相关性。由此我们估计，X射线的再处理可能发生在吸积盘的外部，约占平台态观测K星等的20%-30%。在0.05-10 MeV范围内，OSSE谱表现为一个单次幂定律，其光子指数为3.1，无截断地扩展到~1 MeV。我们可以通过多色盘模型、高能截断修正的破缺幂定律和反射分量的总和来模拟覆盖1-200keV的组合的GIS-PCA-HEXTE谱。尽管软X射线的通量变化很大，但在~30keV以上的功率定律斜率在不同状态之间非常相似，这意味着电子能量分布不受吸积盘中态的变化的影响。
We present the results from a multiwavelength campaign of GRS 1915+105 performed from 2000 April 16 to April 25. This is one of the largest coordinated set of observations ever performed for this source, covering the wide energy band in radio (13.3-0.3 cm), near-infrared (J, H, and K bands), X-rays, and gamma rays (from 1 keV to 10 MeV). During the campaign GRS 1915+105 was predominantly in the "plateau" (or low/hard) state but sometimes showed soft X-ray oscillations: before April 20.3, rapid, quasi-periodic (≃45 minutes) flare-dip cycles were observed. In the spectral energy distribution in the plateau state, optically thick synchrotron emission and Comptonization is dominant in the radio and X- to gamma-ray bands, respectively. The small luminosity in the radio band relative to that in X-rays indicates that GRS 1915+105 falls in the regime of "radio-quiet" microquasars. In three epochs we detected faint flares in the radio or infrared bands with amplitudes of 10-20 mJy. The radio flares observed on April 17 shows frequency-dependent peak delay, consistent with an expansion of synchrotron-emitting region starting at the transition from the hard-dip to the soft-flare states in X-rays. On the other hand, infrared flares on April 20 appear to follow (or precede) the beginning of X-ray oscillations with an inconstant time delay of ≃5-30 minutes. This implies that the infrared-emitting region is located far from the black hole by ≳1013 cm, while its size is ≲1012 cm constrained from the time variability. We find a good correlation between the quasi-steady flux level in the near-infrared band and in the X-ray band. From this we estimate that the reprocessing of X-rays, probably occurring in the outer parts of the accretion disk, accounts for about 20%-30% of the observed K magnitude in the plateau state. The OSSE spectrum in the 0.05-10 MeV band is represented by a single power law with a photon index of 3.1 extending to ~1 MeV with no cutoff. We can model the combined GIS-PCA-HEXTE spectra covering 1-200 keV by a sum of the multicolor disk model, a broken power law modified with a high-energy cutoff, and a reflection component. The power-law slope above ~30 keV is found to be very similar between different states in spite of large flux variations in soft X-rays, implying that the electron energy distribution is not affected by the change of the state in the accretion disk.
发光圆盘中的辐射流 II
DOI：
--
发表时间：
2006
期刊：
Publ. Astron. Soc. Japan 58,1
影响因子：
--
作者：
Y. Mimura;T. Yokoyama;H. Isobe;Chizuru Akizuki;Jun Fukue;Jun Fukue;Naoko Sumitomo;Shinji Nishiyama;Jun Fukue
通讯作者：
Jun Fukue