高z射电噪类星体的低能截止和硬X射线谱：RBS315的朱雀观
Low energy cut-offs and hard X-ray spectra in high-z radio-loud quasars: the Suzaku view of RBS315
摘要：
我们给出了朱雀星对强射电噪类星体RBS 315（z=2.69）的观测结果，先前的XMM-牛顿观测显示，在10 keV以下（光子指数γ =1.26），X射线连续谱非常平坦，并显示出强的内禀吸收（假设是中性气体，N_H~10^22 cm^{-2}）。硬X射线HXD/PIN仪器允许我们检测高达50千电子伏的源。宽带连续（0.5-50 keV）可以很好地模拟与斜率伽玛=1.5（肯定比连续测量XMM-牛顿）超过1 keV的软光子的强烈赤字的幂律。低能截止可以很好地与本征吸收（在类星体静止坐标系中，柱密度N_H~10^22 cm^{-2}）或连续谱中的一个间断拟合，在1 keV以下具有极硬（γ =0.7）的幂律。我们构建的光谱能量分布的源，也使用光学紫外测量获得通过准同步UVOT/SWIFT观测。SED的形状类似于其他具有类似功率的平谱射电类星体（FSRQ），使该源成为GLAST探测伽马射线的绝佳候选者。我们模拟的同步辐射逆康普顿模型通常适用于FSRQs的SED，显示软光子的赤字可以自然地解释为由于一个固有的弯曲的光谱附近的低能量端的IC组件，而不是固有的吸收，虽然后者的可能性不能排除。我们认为，在至少一小部分的射电强类星体在高红移的截止软X射线波段可以用类似的方式来解释。需要进一步的研究来区分这两种选择。
英文摘要：
We present the results from the Suzaku observation of the powerful radio-loud quasar RBS315 (z=2.69), for which a previous XMM-Newton observation showed an extremely flat X-ray continuum up to 10 keV (photon index Gamma=1.26) and indications of strong intrinsic absorption (N_H~10^22 cm^{-2} assuming neutral gas). The instrument for hard X-rays HXD/PIN allows us a detection of the source up to 50 keV. The broad-band continuum (0.5-50 keV) can be well modeled with a power-law with slope Gamma=1.5 (definitively softer than the continuum measured by XMM-Newton) above 1 keV with strong deficit of soft photons. The low-energy cut-off can be well fitted either with intrinsic absorption (with column density N_H~10^22 cm^{-2} in the quasar rest frame) or with a break in the continuum, with an extremely hard (Gamma =0.7) power-law below 1 keV. We construct the Spectral Energy Distribution of the source, using also optical-UV measurements obtained through a quasi-simultaneous UVOT/SWIFT observation. The shape of the SED is similar to that of other Flat Spectrum Radio Quasars (FSRQs) with similar power, making this source an excellent candidate for the detection in gamma-rays by GLAST. We model the SED with the synchrotron-Inverse Compton model usually applied to FSRQs, showing that the deficit of soft photons can be naturally interpreted as due to an intrinsic curvature of the spectrum near the low energy end of the IC component rather than to intrinsic absorption, although the latter possibility cannot be ruled out. We propose that in at least a fraction of the radio-loud QSOs at high redshift the cut-off in the soft X-ray band can be explained in a similar way. Further studies are required to distinguish between the two alternatives.
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。
