| The X—ray Background from the Warm Gas of the Galactic Halo |
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| 引用本文： | Yan－JieXue.The X—ray Background from the Warm Gas of the Galactic Halo[J].中国天文和天体物理学报,2001,1(5):383-388. |
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| 作者姓名： | Yan－JieXue |
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| 作者单位： | National Astronomical Observatories,Chinese Academy of Sciences,Beijing 100012 |
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| 摘 要： | LETTERS1 INTRODUCTIONIn the hierarchical scenario of structure formation, massive dark ha1os fOrm by gravitationalaggregation of individual low-mass objects, whi1e the stel1ar disks of spiral galaxies like theMilky Way form by accretion of gas which cools and falls onto the galaxies from an extendedsurrounding reservoir. FOr a massive galaxy of M ~ 10"MO, the surrounding gas can be heatedto temperature of T ~ 106 K by gravitational1y-driven shocks, the dominant cooling is thus dueto …
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| 关 键 词： | 银河系 X射线 晕 光环 宇宙论 热 气体 辐射 散射 |
The X-ray Background from the Warm Gas of the Galactic Halo |
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| Yan-Jie Xue.The X-ray Background from the Warm Gas of the Galactic Halo[J].Chinese Journal of Astronomy and Astrophysics,2001,1(5):383-388. |
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| Authors: | Yan-Jie Xue |
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| Institution: | NationalAstronomicalObservatories,ChineseAcademyofSciences,Beijing100012 |
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| Abstract: | Within the framework of the hierarchical scenario of galaxy formation, spiral galaxies like our own Galaxy are still growing at present. This opens a possibility that one might be able to see X-ray galactic halos from gravitationally heated gas with temperatures of -10^6 K as a result of bremsstrahlung. An interesting issue is whether the X-ray background produced by the warm gas in the halo of our Galaxy is detectable. We present a simple estimate of the strength and spectrum of the X-ray background from the Galactic halo and compare with the recent findings of a spatially variable soft X-ray component seen towards the north Galactic polar cap by Kuntz et al. (2001). It is shown that a good agreement, regardless of cosmological models, can be achieved if the gas fraction is as low as -0.01. This requirement seems to be consistent with the extrapolated result from a number of independent observational and theoretical constraints established for groups and clusters of galaxies. In particular, the expected soft X-ray background from the warm gas of the Galactic halo is comparable to, or even exceeds that produced by the warm-hot gas in massive groups, and it may constitute the major source of contamination in the search for missing baryons through the detection of their soft X-ray emission, unless we can work out a way to properly remove the X-ray background (e.g.,from anisotropy) from the halo of our Galaxy. |
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| Keywords: | cosmology: diffuse radiation - Galaxy: formation - Galaxy: halo -X-rays: galaxies |
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