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arXiv 0705.3611astro-ph
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喷流对中子星X射线双星光学/红外线贡献的证据

Evidence for a jet contribution to the optical/infrared light of neutron star X-ray binaries

D. M. Russell, R. P. Fender, P. G. Jonker

摘要:

低质量中子星X射线双星(NSXB)在爆发时发出的光学/近红外(optical/near-infrared; OIR)光,传统上认为是吸积盘的热辐射。在这里,我们提出了一个全面的收集准同时OIR和X射线数据从19个低磁场NSXB,包括新的观测三个来源:4U 0614+09,LMC X-2和GX 349+2。当观测到射电喷流时,NSXB的平均射电OIR光谱至少在高光度下为α ~ +0.2(其中L_nu propto nu^alpha)。这与黑洞X射线双星的α ~ 0.0相当,但比它稍微倒置一些。OIR光谱和OIR和X射线通量之间的关系进行比较,如果OIR发射是由热发射从X射线或粘性加热盘,或同步辐射从内部区域的射流占主导地位。我们发现,热发射由于X射线后处理可以解释所有的数据,除了在高光度的一些NSXB,即环礁和毫秒X射线天体(MSXP)。在这些系统中,来自喷流的光学薄同步辐射(观测到的OIR光谱指数α_thin < 0)在L_x ~ 10^36 erg/s以上的近红外光和L_x ~ 10^37 erg/s以上的光学光中占主导地位。对于NSXB Z源,OIR观测可以单独用X射线后处理来解释,尽管同步辐射对NIR的贡献可能很小,并且在一两种情况下可能主导OIR。

英文摘要:

Optical/near-infrared (optical/NIR; OIR) light from low-mass neutron star X-ray binaries (NSXBs) in outburst is traditionally thought to be thermal emission from the accretion disc. Here we present a comprehensive collection of quasi-simultaneous OIR and X-ray data from 19 low-magnetic field NSXBs, including new observations of three sources: 4U 0614+09, LMC X-2 and GX 349+2. The average radio-OIR spectrum for NSXBs is alpha ~ +0.2 (where L_nu propto nu^alpha) at least at high luminosities when the radio jet is detected. This is comparable to, but slightly more inverted than the alpha ~ 0.0 found for black hole X-ray binaries. The OIR spectra and relations between OIR and X-ray fluxes are compared to those expected if the OIR emission is dominated by thermal emission from an X-ray or viscously heated disc, or synchrotron emission from the inner regions of the jets. We find that thermal emission due to X-ray reprocessing can explain all the data except at high luminosities for some NSXBs, namely the atolls and millisecond X-ray pulsars (MSXPs). Optically thin synchrotron emission from the jets (with an observed OIR spectral index of alpha_thin < 0) dominate the NIR light above L_x ~ 10^36 erg/s and the optical above L_x ~ 10^37 erg/s in these systems. For NSXB Z-sources, the OIR observations can be explained by X-ray reprocessing alone, although synchrotron emission may make a low level contribution to the NIR, and could dominate the OIR in one or two cases.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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