黑洞GX 339 - 4的光学和近红外光谱：I.关注低/硬和高/软状态下的连续体
Optical and near-infrared spectroscopy of the black hole GX 339-4: I. A focus on the continuum in the low/hard and high/soft states
摘要：
微类星体GX 339 - 4，已知展示出强大的紧凑喷流，主导其无线电到近红外辐射，在2010年进入爆发，这是大约15年来的第五次。一个广泛的无线电到X射线多波长活动立即被触发，我们在这里报告ESO/FORS 2 + ISAAC光学和近红外光谱观测，由ATCA无线电和RXTE/Swift X射线准同步数据支持。GX 339 - 4在三个不同的时期被观察到，一次在软态，两次在硬态。在软态下，光学和近红外连续谱在很大程度上与热过程的瑞利-金斯尾部一致。作为一种解释，我们赞成照射外吸积盘的内部地区，增强光盘翘曲。在低频率下也存在过量，可能是由于M次巨星伴星。在第一个硬态，光学/近红外连续被很好地描述的光学薄的同步辐射发射的紧凑型喷气机结合光盘照射，也许另一个组件在紫外线峰值。光谱中断的射流从光学厚过渡到薄制度，低于1.20e14赫兹，没有检测到的光学薄同步加速器的扩展是一致的3 - 50 keV的光谱。相比之下，在第二硬态的排放是更难以理解的，并指向一个更复杂的射流连续。在这两种情况下，近红外连续被发现是可变的时间尺度至少短至20秒，虽然这些可变性被平滑超过几百秒。这意味着光谱突变位置的通量和频率的快速变化，即射流底部的物理条件（例如磁场和/或基半径）的急剧的短时间尺度变化。
英文摘要：
The microquasar GX 339-4, known to exhibit powerful compact jets that dominate its radio to near-infrared emission, entered an outburst in 2010 for the fifth time in about fifteen years. An extensive radio to X-ray multi-wavelength campaign was immediately triggered, and we report here on ESO/FORS2+ISAAC optical and near-infrared spectroscopic observations, supported by ATCA radio and RXTE/Swift X-ray quasi-simultaneous data. GX 339-4 was observed at three different epochs, once in the soft state and twice in the hard state. In the soft state, the optical and near-infrared continuum is largely consistent with the Raleigh-Jeans tail of a thermal process. As an explanation, we favour irradiation of the outer accretion disc by its inner regions, enhanced by disc warping. An excess is also present at low frequencies, likely due to a M subgiant companion star. During the first hard state, the optical/near-infrared continuum is well-described by the optically thin synchrotron emission of the compact jet combined with disc irradiation and perhaps another component peaking in the ultraviolet. The spectral break where the jet transits from the optically thick to thin regimes, located below 1.20e14 Hz, is not detected and the extension of the optically thin synchrotron is consistent with the 3-50 keV spectrum. In contrast, the emission during the second hard state is more difficult to understand and points toward a more complex jet continuum. In both cases, the near-infrared continuum is found to be variable at timescales at least as short as 20 s, although these variabilities are smoothed out beyond a few hundred seconds. This implies rapid variations - in flux and frequency - of the location of the spectral break, i.e. dramatic short timescale changes of the physical conditions at the base of the jet, such as the magnetic field and/or the base radius.
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