论文标题
银河系介质的伽马射线和无线电背景约束
Gamma-ray and radio background constraints on cosmic rays in Milky Way circumgalactic medium
论文作者
论文摘要
我们研究了宇宙射线（CRS）与银河系（MW）银河系的弥漫性环境气体的相互作用，从而导致悬岩$γ-$ ray发射和无线电同步基发射。我们的目标是借助观察到的各向同性$γ$ ray背景（IGRB），其各向异性和无线电连续体来限制我们的环境培养基（CGM）中的CR种群。我们通过包括$η\ equiv p _ {\ rm cr}/p _ {\ rm th} $参数来修改文献中讨论的静水平衡中CGM气体的不同模型。对于最简单的等温模型，虽然IGRB强度允许$η\ Lessim 3 $，但由太阳系在MW中的中心位置产生的各向异性将所有$η$的值排除了所有值。对于降水模型，在该模型中，CGM气体的冷却以最佳的冷却时间与自由下落时间的比率调节，而观察到的IGRB强度允许$η\ Lesssim 230 $，观察到的各向异性只能允许非常大的$η$，$ \ gtrsim 100 $的$η$。无线电连续体限制了降水模型的$η\ Lessim 400 $，并且不限制等温模型，但是通过同步加速器损耗时间与CR扩散时间尺度相当，这些约束可以减轻这些约束。这些界限与当前的数值模拟有关，该数值模拟表明MW质量星系中CGM的CR群体显着。
We study the interaction of cosmic rays (CRs) with the diffuse circumgalactic gas of Milky Way (MW) galaxy that results in hadronic $γ-$ray emission and radio synchrotron emission. We aim to constrain the CR population in our circumgalactic medium (CGM) with the help of observed isotropic $γ$-ray background (IGRB), its anisotropy and radio continuum. We modify different models of CGM gas in hydrostatic equilibrium discussed in literature by including a cosmic ray population, parametrized by $η\equiv P_{\rm CR}/P_{\rm th}$. For the simplest isothermal model, while the IGRB intensity allows $η\lesssim 3$, the anisotropy resulting from the Solar system's off-center position in MW rules out all values of $η$. For the precipitation model, in which the cooling of the CGM gas is regulated with an optimum ratio of cooling time to free-fall time,while the observed IGRB intensity allows $η\lesssim 230$, the observed anisotropy allows only very large values of $η$, of order $\gtrsim 100$. The radio continuum limits $η\lesssim 400$ for precipitation model and does not constrain isothermal model, however these constraints are mitigated by synchrotron loss time being comparable to CR diffusion time scales. These bounds are relevant for current numerical simulations that indicate a significant CR population in CGM of galaxies of MW mass.
