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arXiv 1104.0097astro-ph.HE
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来自X射线双星喷流的快速多波长变率

Fast multiwavelength variability from jets in X-ray binaries

Piergiorgio Casella, Thomas J. Maccarone, Kieran O'Brien

摘要:

虽然喷流似乎是X射线双星中致密天体吸积过程的基本结果,但其基本物理学还没有标准模型。所观察到的磁盘射流耦合的起源也仍然在很大程度上未知。X射线变异性研究揭示了恒星质量黑洞和中子星上吸积流的复杂变异性,其时间尺度短至毫秒。相关的宽带快速时间变化的射流排放的检测将提供有价值的信息,如何沿射流的可变性转移,并在这些射流中的物理过程的时间尺度,最终有助于约束内部射流物理,探测盘射流耦合和推断吸积几何形状。近年来,光学快速变率的间接证据来自一个强大的喷流。然而,在可见光中,来自外盘的发射会强烈地污染喷射信号,导致对可变性来源的模糊识别。另一方面,在更长的波长下,来自喷流远处的可变性将随着时间的推移而模糊。因此,红外可变性研究是在尽可能快的时间尺度上观察射流可变性的理想方法。得益于新推出的探测器和快速读出模式,快速红外和中红外测光现在成为可能。这为研究相对论喷流的几何和物理以及它们与吸积流的联系打开了一扇令人兴奋的新窗口。在这里,我们提出的第一个结果,从一个大的正在进行的快速定时多波长项目,显示了第一个明确的证据,亚秒射流可变排放。我们展示了这种类型的数据如何使我们能够对喷流速度,几何和物理进行定量约束,并讨论了在不久的将来新观测的巨大潜力。

英文摘要:

While jets appear as a fundamental result of accretion processes onto compact objects in X-ray binaries, there is as yet no standard model for their underlying physics. The origin of the observed disk-jet coupling also remains largely unknown. X-ray variability studies have revealed complex variability in the accretion flow onto stellar-mass black holes and neutron stars, on timescales as short as milliseconds. The detection of correlated broad-band rapid time variability in the jet emission would provide valuable information on how the variability is transferred along the jet and on the timescales of physical processes operating in these jets, ultimately helping to constrain internal jet physics, probe disk-jet coupling and infer accretion geometry. In recent years there have been indirect evidences for optical fast variability arising from a powerful jet. However, in optical light the emission from the outer disk can strongly contaminate the jet signal, resulting in an ambiguous identification of the source of the variability. On the other hand, at much longer wavelengths the variability, coming from far out in the jet, will be smeared out in time. Infrared variability studies are thus ideal for looking at jet variability on the fastest possible timescales. Thanks to newly available detectors and fast-readout modes, fast infrared and mid-infrared photometry is now possible. This is opening a new exciting window to study the geometry and the Physics of relativistic jets and their connection with the accretion flow. Here we present the first results from a large ongoing fast-timing multi-wavelength project, showing the first unambiguous evidence for sub-second jet variable emission. We show how this type of data already allows us to put quantitative constraints to the jet speed, geometry and physics, and discuss the great potential of new observations in the near future.

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