Hard X-Ray Emission from the Galactic Ridge
Hard X-Ray Emission from the Galactic Ridge
复制标题
银河脊发射的硬 X 射线
DOI：
10.1086/304097
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
M. Nomachi
中科院分区：
文献类型：
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作者：
N. Yamasaki;T. Ohashi;F. Takahara;S. Yamauchi;K. Koyama;T. Kamae;H. Kaneda;K. Makishima;Y. Sekimoto;M. Hirayama;T. Takahashi;T. Yamagami;S. Gunji;T. Tamura;S. Miyazaki;M. Nomachi
利用Ginga卫星上的大面积比例计数器（LAC）和气球探测器Welcome-1研究了银河脊的硬x射线和γ射线发射。在LAC的扫描观测中，在l = -20°和l = 40°之间沿银道面探测到漫射硬x射线。实测光谱表明，在10 keV以上的星系脊发射中，除了热等离子体成分外，还存在一种硬成分。银河系脊发射的估计亮度在3-16 keV波段约为2 × 1038 ergs -1。Welcome-1在50 ~ 600 keV之间的l ~ 345°附近观测到γ射线脊发射。这两个结果和最近的一项COMPTEL研究表明，漫射星系脊发射的光谱延伸到k - mev范围。从观测到的光谱斜率来看，电子的轫致辐射是主要的发射机制。这意味着低能电子必须连续供应，以维持在硬x射线波段的发射。我们提出了一种场景，其中热等离子体中的热电子负责强Fe - K - x射线发射，在超新星遗迹（SNRs）中连续激波加速，产生观测到的银河系脊的硬x射线和γ射线发射。
Hard X-ray and γ-ray emissions from the Galactic ridge were studied with the large area proportional counter (LAC) on the Ginga satellite and a balloon-borne detector Welcome-1. In the scanning observations with the LAC, diffuse hard X-rays were detected along the Galactic plane between l = -20° and l = 40°. The measured spectrum shows that a hard component exists in the Galactic ridge emission above 10 keV, in addition to the hot plasma component. The estimated luminosity of the Galactic ridge emission is around 2 × 1038 ergs s-1 in the 3-16 keV band. Welcome-1 observed the γ-ray ridge emission at around l ~ 345° between 50 and 600 keV. These two results and a recent COMPTEL study suggest that the spectrum of the diffuse Galactic ridge emission extends over the keV-MeV range. From the observed spectral slope, bremsstrahlung by electrons is shown to be the dominant emission mechanism. This implies that low-energy electrons must be supplied continuously to sustain emission in the hard X-ray band. We propose a scenario in which the thermal electrons in the hot plasma responsible for the strong Fe K X-ray emission are shock-accelerated continuously in supernova remnants (SNRs), producing the observed hard X-ray and γ-ray emissions from the Galactic ridge.