Using the Bulge of M31 as a Template for the Integrated X-Ray Emission from Low-Mass X-Ray Binaries
Using the Bulge of M31 as a Template for the Integrated X-Ray Emission from Low-Mass X-Ray Binaries
复制标题
使用 M31 核球作为低质量 X 射线双星集成 X 射线发射的模板
DOI：
10.1086/308081
复制
发表时间：
1999
期刊：
影响因子：
--
通讯作者：
J. Bregman
中科院分区：
文献类型：
--
作者：
J. Irwin;J. Bregman
我们对M31核团内部5 '区进行了ASCA + ROSAT PSPC联合光谱拟合。我们发现，单组分光谱模型提供了一个不充分的适合的频谱，在爱因斯坦和Ginga以前的研究。虽然2 - 10 keV的光谱可以用kT = 7.4 ± 0.3 keV的韧致辐射模型充分拟合，但需要kT = 0.38 ± 0.03 keV的附加软分量来拟合低于2 keV的光谱。该软分量包括0.1 - 2.0 keV频带中的总发射的38% ± 6%，并且可能更多，这取决于拟合中使用的吸收值。由于先前对M31的空间研究表明，在这个波段中，只有不到25%的X射线来自扩散气体成分，这意味着恒星源，即低质量X射线双星（LMXB），是部分（如果不是全部）软成分的原因。M31的光谱特性与X射线微弱的早型星系NGC 4382非常相似。这支持了先前在这些星系中看到的无法解释的软X射线发射也来自LMXB的说法。
We have performed joint ASCA + ROSAT PSPC spectral fitting on the inner 5' of the bulge of M31. We find that single-component spectral models provide an inadequate fit to the spectrum, in contrast to previous studies by Einstein and Ginga. Although the 2-10 keV spectrum can be fitted adequately with a bremsstrahlung model with kT = 7.4 ± 0.3 keV, an additional soft component with kT = 0.38 ± 0.03 keV is required to fit the spectrum below 2 keV. This soft component comprises 38% ± 6% of the total emission in the 0.1-2.0 keV band, and possibly more depending on the absorption value used in the fit. Since previous spatial studies of the bulge of M31 indicate that less than 25% of the X-ray emission from the bulge in this band is from a diffuse gaseous component, this implies that stellar sources, namely, low-mass X-ray binaries (LMXBs), are responsible for some if not all of the soft component. The spectral properties of M31 are very similar to those of the X-ray-faint early-type galaxy NGC 4382. This supports the claim that the unexplained soft X-ray emission seen previously in these galaxies also emanates from LMXBs.