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arXiv 1604.01764astro-ph.GAastro-ph.HE
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MASSIVE调查IV .:邻近宇宙中最大质量早型星系的X射线晕

The MASSIVE Survey IV.: The X-ray halos of the most massive early-type galaxies in the nearby Universe

Andy D. Goulding, Jenny E. Greene, Chung-Pei Ma, Melanie Veale, Akos Bogdan, Kristina Nyland, John P. Blakeslee, Nicholas J. McConnell, Jens Thomas

摘要:

研究局部椭圆星系的物理性质(例如,气体温度、晕圈质量、恒星运动学)为星系形成提供了新的线索。在这里,我们提出的热X射线气体性质的33个早期类型的系统内的大规模星系调查样本,档案钱德拉X射线观测。通过仔细的X射线光谱建模,我们得到了这些星系中弥漫气体成分的X射线光度(L_X)和等离子体温度(T_gas)。我们将MASSIVE样本与来自ATLAS ^3D巡天的41个星系结合起来,研究了在广泛环境中具有统计学意义的邻近早型星系样本的X射线和光学特性。我们推断,所有早型星系(与星系质量和转动支持无关)都遵循一个普适的标度律,使得L_X~ T_gas ^[4.5]。当X射线测量在由星系恒星含量设置的孔径中一致地进行时,在标度关系内,宽尺度环境对本征散射(~0.5dex)没有贡献。我们进一步证明了K波段光度(L_K)和星系恒星速度色散的L_X散射主要是由T_气体驱动的,与晕质量、射电功率和恒星角动量没有明显的变化趋势。将气体的起源直接与恒星质量或星系势联系起来并不是一件小事。事实上,我们的数据需要L_X,L_K和sigma_e之间的关系比标准质量损失模型预测的更陡峭。最后,我们发现sigma_e和T_gas之间存在统计上显著的相关性,表明T_gas是由光学有效半径内的星系势决定的。我们的结论是,在最内部的10- 30 kpc区域内,早期类型保持压力支持的热气,最小的T_gas由维里温度设定,但大多数显示出一些额外的加热的证据。

英文摘要:

Studies of the physical properties of local elliptical galaxies (e.g., gas temperatures, halo masses, stellar kinematics) are shedding new light on galaxy formation. Here we present the hot X-ray gas properties of 33 early-type systems within the MASSIVE galaxy survey sample that have archival Chandra X-ray observations. Through careful X-ray spectral modeling, we derive X-ray luminosities (L_X) and plasma temperatures (T_gas) for the diffuse gas components in these galaxies. We combine the MASSIVE sample with 41 galaxies from the ATLAS^3D survey to investigate the X-ray and optical properties of a statistically significant sample of nearby early-type galaxies across a wide-range of environments. We deduce that all early-type galaxies (independent of galaxy mass and rotational support) follow a universal scaling law such that L_X~T_gas^4.5. When X-ray measurements are performed consistently in apertures set by the galaxy stellar content, the wide-scale environment does not contribute to the intrinsic scatter (~0.5dex) within the scaling relation. We further demonstrate that the scatter in L_X around both K-band luminosity (L_K) and the galaxy stellar velocity dispersion is primarily driven by T_gas, with no clear trends with halo mass, radio power, or angular momentum of the stars. It is not trivial to tie the origin of the gas directly to either the stellar mass or the galaxy potential. Indeed, our data require a steeper relation between L_X, L_K, and sigma_e than predicted by standard mass-loss models. Finally, we find a statistically significant correlation between sigma_e and T_gas, suggesting that T_gas is set by the galaxy potential inside the optical effective radius. We conclude that within the inner-most 10-30kpc region, early-types maintain pressure-supported hot gas, with a minimum T_gas set by the virial temperature, but the majority show evidence for some additional heating.

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