标题： BeppoSAX 卫星 LECS 观测到的低能宇宙 X 射线背景光谱 显示英文标题

标题： The low-energy cosmic X-ray background spectrum observed by the BeppoSAX LECS

摘要： 在银纬 >|25| 度的天区，利用 BeppoSAX 低能光谱仪聚束器（LECS）测量了 0.1-7.0 keV 宇宙 X 射线背景（CXB）的能谱。高于 1 keV 的能谱与光子指数为 1.47 ± 0.10 和 1 keV 处归一化为 11.0 ± 0.8 光子 cm⁻² s⁻¹ keV⁻¹ sr⁻¹ 的幂律一致。整体能谱可以用带有 2 个热分量的幂律模型或者用一个断点幂律和单个热分量来描述。在这两种情况下，较软的热辐射在低于 0.3 keV 时占主导地位，并且通过几乘以 10¹⁹ 原子 cm⁻² 的柱密度被观测到。其它分量的柱密度与视线上的平均值一致。对于热分量的金属丰度约束较差，但与宇宙值一致。幂律加两个热分量的模型已被用于拟合最近的联合 ASCA 和 ROSAT CXB 测量数据。在这里，软热分量被解释为局部热泡的发射，而硬热分量则被解释为来自更远处吸收区域的发射。虽然这种双分量热模型与 LECS 谱一致，但这并非必需的，硬热分量可能是由于对河外贡献建模不足造成的。因此，观察到的低能谱复杂性可能主要源于局部热泡。没有证据表明存在温度 <0.1 keV 的非常软的 CXB 分量。ROSAT 观测到的发射度在 90% 的置信水平上被拒绝。 显示英文摘要

摘要： The spectrum of the 0.1-7.0 keV cosmic X-ray background (CXB) at galactic latitudes >|25| degrees has been measured using the BeppoSAX Low-Energy Spectrometer Concentrator (LECS). Above 1 keV the spectrum is consistent with a power-law of photon index 1.47 +/- 0.10 and normalization 11.0 +/- 0.8 photon cm^-2 s^-1 keV^-1 sr^-1 at 1keV. The overall spectrum can be modeled by a power-law with 2 thermal components, or by a broken power-law and a single thermal component. In both cases the softer thermal emission dominates at less than 0.3 keV and is seen through a column of a few 10^19 atom cm^-2. The other components have columns consistent with the mean line of sight value. The metal abundances for the thermal components are poorly constrained, but consistent with cosmic values. The power-law together with 2 thermal components model has been used to fit recent combined ASCA and ROSAT CXB measurements. Here, the soft thermal component is interpreted as emission from the local hot bubble and the hard thermal component as emission from a more distant absorbed region. While such a 2 component thermal model is consistent with the LECS spectrum, it is not required, and the hard thermal component may result from inadequate modeling of the extragalactic contribution. The observed low-energy spectral complexity may therefore originate primarily in the local hot bubble. There is no evidence for the presence of a very soft CXB component with a temperature <0.1 keV. The emission measure seen by ROSAT is rejected at 90% confidence.