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arXiv 2006.08623astro-ph.HEastro-ph.GA
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M82热气体流出物中的温度和金属丰度因子

Temperature and Metallicity Gradients in the Hot Gas Outflows of M82

Laura A. Lopez, Smita Mathur, Dustin D. Nguyen, Todd A. Thompson, Grace M. Olivier

摘要:

我们利用深钱德拉X射线天文台成像和光谱的M82,一个多相风的星爆星系的原型,映射沿短轴的星系的热等离子体的属性。我们提取光谱从11个区域高达2.5千秒差距的恒星爆发中平面和模型的数据作为一个多温度,光学薄的热等离子体的贡献,从非热(幂律)组件和电荷交换(CX)。我们研究了最佳拟合参数的梯度,包括本征柱密度,等离子体温度,金属丰度和热气体的数密度作为距离M82核的函数。我们发现,温热和高温等离子体的温度和数密度在星暴脊处达到峰值,并沿短轴逐渐减小。的温度和密度分布是不一致的球形绝热膨胀的过热风,并建议质量加载和混合的热相较冷的材料。在所有考虑的区域中检测到非热发射,并且CX包括总吸收校正的宽带(0.5-7 keV)X射线通量的8-25%。我们发现,O,Ne,Mg和Fe的丰度在所考虑的区域大致恒定,而Si和S的峰值在500 pc的中央星爆。这些发现支持了M82超级风和温暖、富含金属的环星系介质(CGM)之间的直接联系。

英文摘要:

We utilize deep Chandra X-ray Observatory imaging and spectra of M82, the prototype of a starbursting galaxy with a multiphase wind, to map the hot plasma properties along the minor axis of the galaxy. We extract spectra from 11 regions up to 2.5 kpc from the starbursting midplane and model the data as a multi-temperature, optically thin thermal plasma with contributions from a non-thermal (power-law) component and from charge exchange (CX). We examine the gradients in best-fit parameters, including the intrinsic column density, plasma temperature, metal abundances, and number density of the hot gas as a function of distance from the M82 nucleus. We find that the temperatures and number densities of the warm-hot and hot plasma peak at the starbursting ridge and decreases along the minor axis. The temperature and density profiles are inconsistent with spherical adiabatic expansion of a super-heated wind and suggest mass loading and mixing of the hot phase with colder material. Non-thermal emission is detected in all of the regions considered, and CX comprises 8-25% of the total absorption-corrected, broad-band (0.5-7 keV) X-ray flux. We show that the abundances of O, Ne, Mg, and Fe are roughly constant across the regions considered, while Si and S peak within 500 pc of the central starburst. These findings support a direct connection between the M82 superwind and the warm-hot, metal-rich circumgalactic medium (CGM).

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