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arXiv 2102.02206astro-ph.GA
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哪一个AGN喷流淬灭了大质量星系中的恒星形成?

Which AGN Jets Quench Star Formation in Massive Galaxies?

Kung-Yi Su, Philip F. Hopkins, Greg L. Bryan, Rachel S. Somerville, Christopher C. Hayward, Daniel Anglés-Alcázar, Claude-André Faucher-Giguère, Sarah Wellons, … 展开作者

Kung-Yi Su, Philip F. Hopkins, Greg L. Bryan, Rachel S. Somerville, Christopher C. Hayward, Daniel Anglés-Alcázar, Claude-André Faucher-Giguère, Sarah Wellons, Jonathan Stern, Bryan A. Terrazas, T. K. Chan, Matthew E. Orr, Cameron Hummels, Robert Feldmann, Dušan Kereš

摘要:

在没有额外加热的情况下,大质量星系(银河系及以上)晕中气体的辐射冷却会产生超过观测到的冷气体或恒星。以前的工作表明,活动星系核喷流可能是必要的,但喷流能量的形式所需的淬火仍然不清楚。这对于星系模拟来说尤其具有挑战性,因为在星系模拟中,分辨率比形成和演化喷流所需的分辨率要粗几个数量级。在这样的尺度上,不确定的参数包括:喷流能量形式(动能、热能和宇宙射线(CR)能量)、能量、动量和质量通量、磁场强度和几何形状、喷流进动角和周期、张开角和占空比。我们调查所有这些参数在$10^{14}\,{\rm M}_{\odot}$晕使用高分辨率非宇宙学MHD模拟与FIRE-2(反馈在现实环境中)恒星反馈模型,传导和粘度。我们探讨了哪些情况下符合观测约束,并表明CR主导的射流可以最有效地淬火中央星系通过CR压力支持和修改的热不稳定性相结合。在温和相对论性($\sim$ MeV或$\sim10^{10}$ K)热等离子体中具有大部分能量的射流工作,但需要$\sim 10$更大的能量输入。对于固定的能量通量,具有较高比能(较长冷却时间)的射流更有效地淬火。对于这种晕圈尺寸,动力射流在淬火中效率较低,除非它们具有宽的开口或旋进角。磁场起着次要的作用,除了当磁通量达到$\gtrsim 10^{44}$ erg s $^{-1}$在动力学射流模型,这导致射流茧显着扩大,淬火成为爆炸性的。我们得出结论,一个成功的射流模型的标准是一个最佳的能量通量和足够宽的射流茧足够长的冷却时间在冷却半径。

英文摘要:

Without additional heating, radiative cooling of gas in the halos of massive galaxies (Milky Way and above) produces cold gas or stars in excess of that observed. Previous work suggested that AGN jets are likely required, but the form of jet energy required to quench remains unclear. This is particularly challenging for galaxy simulations, in which the resolution is orders of magnitude coarser than necessary to form and evolve the jet. On such scales, the uncertain parameters include: jet energy form (kinetic, thermal, and cosmic ray (CR) energy), energy, momentum, and mass flux, magnetic field strength and geometry, jet precession angle and period, opening-angle, and duty cycle. We investigate all of these parameters in a $10^{14}\,{\rm M}_{\odot}$ halo using high-resolution non-cosmological MHD simulations with the FIRE-2 (Feedback In Realistic Environments) stellar feedback model, conduction, and viscosity. We explore which scenarios match observational constraints and show that CR-dominated jets can most efficiently quench the central galaxy through a combination of CR pressure support and a modification of the thermal instability. Jets with most energy in mildly relativistic ($\sim$ MeV or $\sim10^{10}$ K) thermal plasma work, but require a factor $\sim 10$ larger energy input. For a fixed energy flux, jets with higher specific energy (longer cooling times) quench more effectively. For this halo size, kinetic jets are less efficient in quenching unless they have wide opening or precession angles. Magnetic fields play a minor role except when the magnetic flux reaches $\gtrsim 10^{44}$ erg s$^{-1}$ in a kinetic jet model, which causes the jet cocoon to significantly widen, and the quenching to become explosive. We conclude that the criteria for a successful jet model are an optimal energy flux and a sufficiently wide jet cocoon with long enough cooling time at the cooling radius.

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