标题： ROSAT 温度和丰度完整椭圆星系样本 显示英文标题

标题： ROSAT Temperatures and Abundances for a Complete Sample of Elliptical Galaxies

摘要： 我们确定了从一个完整且光学选择的样本中选取的椭圆星系的X射线温度和丰度。 这个光学视向亮度极限样本由43个星系组成，完整到校正后的B波段视向亮度为m_B^o=11.36。 在这之中，有30个星系有足够的X射线光谱计数以允许温度测定。 我们发现这些椭圆星系中X射线发射气体的温度与其中心恒星速度弥散度相关：T ~ σ^1.45；这比简单的热力学关系T ~ σ^2更为平坦。 由于对于所有具有可测量温度的星系kT > μ m_p σ^2，弥漫气体的温度显著高于发光恒星的动力学温度。 这强烈表明暗物质晕的特征是由超出发光恒星速度弥散度的弥散度所表征。 我们没有发现X射线双星系统的发射在低光度椭圆星系中逐渐占主导地位的证据。 我们发现所谓的“超软”源符合观测到的kT-σ关系，因此它们并不比预期的根据其速度弥散度更软。 我们还发现星际介质的温度和丰度是相关的，较热系统的气体比较冷星系中的气体更富集。 然而，根据Mg_2指数推断出的气相丰度和恒星丰度之间没有发现相关性。 显示英文摘要

摘要： We determine X-ray temperatures and abundances for elliptical galaxies drawn from a complete, optically selected sample. The optical magnitude-limited sample consists of 43 galaxies, complete to a (corrected) B magnitude of m_B^o=11.36. Of these, 30 have enough X-ray spectral counts to allow temperature determinations. We find that the temperatures of the X-ray emitting gas in these ellipticals are correlated with the central stellar velocity dispersions: T ~ sigma^1.45; this is a shallower trend than the simple thermal relation T ~ sigma^2. The diffuse gas is substantially hotter than the kinetic temperature of the luminous stars, since kT > mu m_p sigma^2 for all galaxies with measurable temperatures. This strongly indicates that dark matter halos are characterized by velocity dispersions which exceed those of the luminous stars. We see no evidence of emission from X-ray binaries becoming progressively more dominant in lower luminosity ellipticals. We find that so-called "supersoft" sources adhere to the observed kT-sigma relation, so they are no softer than expected for their velocity dispersions. We also find that ISM temperatures and abundances are correlated, with the gas in hotter systems being more enriched than in cooler galaxies. However, no correlation is found between gaseous abundances and stellar abundances, as inferred from Mg_2 indices.