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首页> 外文期刊>The Astrophysical journal >THE HOT INTERSTELLAR MEDIUM OF NORMAL ELLIPTICAL GALAXIES. I. A CHANDRA GAS GALLERY AND COMPARISON OF X-RAY AND OPTICAL MORPHOLOGY
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THE HOT INTERSTELLAR MEDIUM OF NORMAL ELLIPTICAL GALAXIES. I. A CHANDRA GAS GALLERY AND COMPARISON OF X-RAY AND OPTICAL MORPHOLOGY

机译：正常椭圆星系的星际热介质。一，CHANDRA气体展示厅以及X射线和光学形态的比较

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We present an X-ray analysis of 54 normal elliptical galaxies in the Chandra archive and isolate their hot gas component from the contaminating point-source emission, allowing us to conduct, for the first time, a morphological analysis on the gas alone. A comparison with optical images and photometry shows that the hot gas morphology has surprisingly little in common with the shape of the stellar distribution. We observe no correlation between optical and X-ray ellipticities in the inner regions where stellar mass dominates over dark matter. A shallow correlation would be expected if the gas had settled into hydrostatic equilibrium with the gravitational potential. Instead, observed X-ray ellipticities exceed optical ellipticities in many cases. We exclude rotation as the dominant factor to produce the gas ellipticities. The gas appears disturbed, and hydrostatic equilibrium is the exception rather than the rule. Nearly all hydrostatic models can be ruled out at 99% confidence, based on their inability to reproduce the optical—X-ray correlation and large X-ray ellipticities. Hydrostatic models not excluded are those in which dark matter either dominates over stellar mass inside the inner half-light radius or has a prominently cigar-shaped distribution, both of which can be ruled out on other grounds. We conclude that, even for rather X-ray-faint elliptical galaxies, the gas is at least so far out of equilibrium that it does not retain any information about the shape of the potential, and that X-ray-derived radial mass profiles may be in error by factors of order unity.
机译：我们对钱德拉档案馆中的54个正常椭圆星系进行了X射线分析，并从污染点源发射中分离出了它们的热气体成分，这使我们首次对气体进行了形态分析。与光学图像和测光法的比较表明，热气体形态与恒星分布的形状几乎没有共同点。我们没有观察到恒星质量主导暗物质的内部区域的光学和X射线椭圆率之间没有相关性。如果气体已经沉降到具有重力势的静水平衡中，则将具有浅的相关性。相反，在许多情况下，观察到的X射线椭圆率超过光学椭圆率。我们排除旋转是产生气体椭圆率的主要因素。气体似乎受到干扰，静液压平衡是例外而不是规则。几乎所有静水力学模型都无法再现，因为它们无法再现光学X射线相关性和较大的X射线椭圆率。不排除流体静力学模型是其中暗物质在内部半光半径内占主导地位的恒星质量或具有明显的雪茄形分布的模型，这两者都可以从其他方面排除。我们得出的结论是，即使对于相当微弱的X射线椭圆形星系，气体至少也是如此不平衡，以至于它不保留有关势能形状的任何信息，并且X射线衍生的径向质量分布可能由于订单统一性因素而出错。

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