The Impact of Radiation and Feedback from Stars and Supermassive Black Holes on the High-Redshift Circum-Galactic Medium

我们的标准宇宙学模型ACDM和观测之间的主要冲突之一是，宇宙中观测到的卫星星系数量和气体量少于预测。由于它在高红移星系的环银河介质（CGM）中达到了前所未有的分辨率，NEPHTHYS宇宙学变焦模拟套件揭示了这个CGM具有复杂的新颖结构，这些结构是由冷丝状流入和辐射流出的相互作用形成的，这些流出是由大质量恒星和嵌入星系本身的超大质量黑洞驱动的。据推测，这种强大的外流可能会破坏卫星星系，并显着加热流入的气体，在此过程中产生明显的温暖CGM阶段，这将是非常难以检测到与目前的望远镜。使用NEPHTHYS套件结合我们团队开发的新光子示踪算法，学生将探索这种情况的可行性，重点关注z~2的大质量星系。更具体地说，DPhil项目的目的是了解这些星系的CGM属性如何在不同的演化阶段发生变化，解决它如何被不同类别的源（恒星，活动星系核）电离，并确定这如何影响吸收线诊断，以评估流出是否可以真正解释ACDM和观测之间的差异。

One of the major conflicts between ACDM, our standard cosmological model, and observations, is that the number of satellite galaxies and amount of gas observed in the Universe is less than predicted. Thanks to the unprecedented resolution it reaches in the circum-galactic medium (CGM) of high-redshift galaxies, the NEPHTHYS suite of cosmological zoom simulations reveals that this CGM hosts complex novel structures shaped by the interplay of cold filamentary inflows and radiative outflows driven by massive stars and supermassive black holes embedded within the galaxies themselves. It is speculated that such powerful outflows could disrupt satellite galaxies and significantly heat up inflowing gas, generating in the process a pronounced warm CGM phase which would be extremely difficult to detect with current telescopes. Using the NEPHTHYS suite combined with a new photon tracer algorithm developed within our group, the student will explore the viability of this scenario, focussing on massive galaxies at z~2. More specifically, the aim of the DPhil project is to understand how the properties of the CGM of these galaxies change at different evolutionary stages,resolve how it is ionized by different classes of sources (stars, Active Galactic Nuclei) and determine how this affects absorption line diagnostics, in order to assess whether outflows can truly account for the discrepancies between ACDM and observations.