The Complex Broadband X-Ray Spectrum of the Starburst Galaxy M82
The Complex Broadband X-Ray Spectrum of the Starburst Galaxy M82
复制标题
星爆星系 M82 的复杂宽带 X 射线光谱
DOI：
10.1086/303795
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
M. Lehnert
中科院分区：
文献类型：
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作者：
E. Moran;M. Lehnert
典型星暴星系M82的宽带x射线光谱非常复杂。在0.1-10 keV范围内，至少需要三个光谱分量来拟合ROSAT和ASCA的组合频谱。观测到的这一波段的x射线通量主要由一个坚硬的Γ = 1.7，重吸收的幂律分量控制，它起源于星系的核和近核盘。在硬x射线发射的候选来源中，最可信的似乎是M82丰富的红外光子通量与超新星产生的相对论性电子相互作用产生的逆康普顿散射发射。测量的幂律分量的固有光度与期望的逆康普顿光度的计算结果非常吻合。此外，M82核心的射电和x射线发射具有相同的光谱斜率，如果这两种类型的发射都是非热的，并且与共同的电子群有关，情况应该是这样的。另外两个光谱成分，特征温度为kT≈0.6和0.3 keV的热等离子体，与M82的恒星形成和星爆驱动的风有关。较热的热成分也被大量吸收，也一定起源于星系的中心区域。然而，较软的热成分没有被吸收，很可能代表沿着M82小轴延伸的x射线发射。三组分模型所需的吸收量表明，M82在0.1-10 keV波段的本征光度大约是其观测光度（4 × 1040 ergs -1）的4倍。
The broadband X-ray spectrum of the prototypical starburst galaxy M82 is very complex. At least three spectral components are required to fit the combined ROSAT and ASCA spectrum in the 0.1-10 keV range. The observed X-ray flux in this band is dominated by a hard Γ = 1.7, heavily absorbed power-law component which originates in the nucleus and near-nuclear disk of the galaxy. Among the candidates for the origin of this hard X-ray emission, the most plausible appears to be inverse-Compton scattered emission from the interaction of the copious infrared photon flux of M82 with supernova-generated relativistic electrons. The measured intrinsic luminosity of the power-law component agrees closely with calculations of the expected inverse-Compton luminosity. Moreover, the radio and X-ray emission in the nucleus of M82 have the same spectral slope, which should be the case if both types of emission are nonthermal and are associated with a common population of electrons. The other two spectral components, thermal plasmas with characteristic temperatures kT ≈ 0.6 and 0.3 keV, are associated with the star formation and starburst-driven wind in M82. The warmer thermal component is heavily absorbed as well and must also originate in the central region of the galaxy. The softer thermal component, however, is not absorbed, and is likely to represent the X-ray emission that extends along the minor axis of M82. The amount of absorption required in the three-component model suggests that the intrinsic luminosity of M82 in the 0.1-10 keV band is about four times greater than its observed luminosity of 4 × 1040 ergs s-1.