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首页> 外文期刊>The Astrophysical journal >STUDY OF THE LARGEST MULTIWAVELENGTH CAMPAIGN OF THE MICROQUASAR GRS 1915+105
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STUDY OF THE LARGEST MULTIWAVELENGTH CAMPAIGN OF THE MICROQUASAR GRS 1915+105

机译：MICROQUASAR GRS 1915 + 105的最大多波长运动研究

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摘要

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 (approx= 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, respec-tively. 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 approx= 5-30 minutes. This implies that the infrared-emitting region is located far from the black hole by approx> 10~(13) cm, while its size is approx< 10~(12) 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.
机译：我们介绍了从2000年4月16日到4月25日进行的GRS 1915 + 105多波长运动的结果。这是有史以来对该信号源进行的最大规模的协调观测之一，覆盖了无线电的宽能带（13.3-0.3厘米），近红外（J，H和K波段），X射线和伽马射线（从1 keV到10 MeV）。在战役期间，GRS 1915 + 105主要处于“高原”（或低/硬）状态，但有时显示出柔和的X射线振荡：4月20.3日之前，快速，准周期（约45分钟）的耀斑浸没周期是观测到的。在高原状态的光谱能量分布中，光学厚的同步加速器发射和康普顿化分别在无线电和X射线至γ射线波段中占主导地位。相对于X射线，无线电波段的发光度较小，表明GRS 1915 + 105属于“无线电安静”的微类星体。在三个时期中，我们在振幅为10-20兆焦耳的无线电或红外波段中检测到微弱的耀斑。 4月17日观测到的无线电耀斑显示出与频率有关的峰值延迟，这与同步辐射发射区的扩展一致，该范围从X射线从硬浸状态到软耀斑状态的转变开始。另一方面，4月20日的红外耀斑似乎紧随X射线振荡的开始（或之前），并具有大约5-30分钟的恒定时间延迟。这意味着红外发射区位于距黑洞约10〜（13）cm的位置，而其大小受时间变化的限制约为<10〜（12）cm。我们发现在近红外波段和X射线波段的准稳态通量水平之间具有良好的相关性。据此，我们估计X射线的再处理可能发生在吸积盘的外部，约占高原状态下观测到的K量的20％-30％。 0.05-10 MeV波段的OSSE光谱由单幂定律表示，光子指数3.1扩展到〜1 MeV，没有截止。我们可以通过多色圆盘模型，经高能截止修正的断能定律和反射分量的总和来建模覆盖1-200 keV的GIS-PCA-HEXTE组合光谱。尽管软X射线的通量变化很大，但在〜30 keV以上的幂律斜率在不同状态之间仍然非常相似，这表明电子能量分布不受吸积盘中状态变化的影响。

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