发表机构
Lund University; University of Bath; University of Sydney; University of Surrey; Sorbonne Université; University of Oxford（隆德大学; 巴斯大学; 悉尼大学; 萨里大学; 索邦大学; 牛津大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
利用 VINTERGATAN 模拟发现恒星反馈驱动银河系质量星系热 CGM 的早期形成（z≈3），远早于仅吸积激波预测（z≲1），并揭示其伪演化现象。
AI 中文摘要
热冕是银河系（MW）型星系形成中的关键调节者，被认为是在星系的暗物质晕跨越临界质量阈值（$M_{\mathrm{vir}}\sim10^{12} {\mathrm{M}}_\odot$）后出现的，此时吸积激波可以将下落气体加热至维里温度（$T_{\mathrm{vir}}$）。我们利用 VINTERGATAN 宇宙学模拟套件研究了恒星反馈和吸积激波在建立银河系质量星系周围 circumgalactic 介质（CGM）中的作用。我们发现恒星反馈驱动了热 CGM 的早期形成，其 $T_{\mathrm{CGM}}\sim T_{\mathrm{vir}}$。相比之下，在无反馈的模拟中，仅靠吸积激波在早期阶段（$z>2$）无法产生具有可比拟高平均温度的 CGM，且与气体金属丰度无关。我们表明，CGM 的维里化（定义为晕气体冷却时间超过自由落体时间）始于热冕（$T>10^5$ K）的出现，在包含反馈时，该热冕最早可于 $z\approx3$ 时在维里半径（$R_{\mathrm{vir}}$）处出现。这远早于吸积激波理论或无反馈模型所预测的时间（$z\lesssim1$）。虽然仅吸积激波会产生由内而外的维里化模式，但反馈可以改变这种行为，驱动一种快速转变（$\lesssim0.5$ Gyr），这种转变要么是由外向内，要么在整个晕中近乎同时发生。最后，这些早期形成的冕从形成至今基本保持稳定，但可能看似演化，仅仅是因为 $R_{\mathrm{vir}}$ 的定义随时间增长。这种“CGM 伪演化”类似于暗物质晕的伪演化，在解释热冕演化时应予以考虑。
英文摘要
Hot coronae are key regulators in Milky Way (MW)-type galaxy formation and are thought to emerge once a galaxy's dark matter halo crosses a critical mass threshold, $M_{\mathrm{vir}}\sim10^{12} {\mathrm{M}}_\odot$, so that accretion shocks can heat infalling gas to virial temperatures, $T_{\mathrm{vir}}$. Here we investigate the roles of stellar feedback and accretion shocks in establishing the circumgalactic medium (CGM) around MW-mass galaxies using the VINTERGATAN cosmological simulation suite. We find that stellar feedback drives the early formation of a hot CGM, with $T_{\mathrm{CGM}}\sim T_{\mathrm{vir}}$. By contrast, in feedback-free simulations, accretion shocks alone do not produce a CGM with comparably high average temperatures at early epochs ($z>2$), independent of gas metallicity. We show that CGM virialisation (defined when halo-gas cooling time exceeds the free-fall time) begins with the emergence of a hot corona ($T>10^5$ K) that can appear as early as $z\approx3$ at virial radius, $R_{\mathrm{vir}}$, when feedback is included. This is much earlier than predicted by accretion-shock theory or feedback-free models ($z\lesssim1$). While accretion shocks alone produce an inside-out virialisation pattern, feedback can alter this behaviour, driving a rapid transition ($\lesssim0.5$ Gyr) that is either outside-in or nearly simultaneous throughout the halo. Finally, these early-forming coronae are largely stable from formation through to the present day, but can appear to evolve simply because the definition of $R_{\mathrm{vir}}$ grows with time. This 'CGM pseudo-evolution' is analogous to the pseudo-evolution of dark matter haloes and should be taken into account when interpreting the evolution of hot coronae.
CommentsAccepted for publication in MNRAS
