arXiv 2509.071242025-09-08astro-ph.GA

揭示宇宙线对从矮星系到星系群尺度盘大小和外流的影响

Unveiling the Impact of Cosmic Rays on the Disc Sizes and Outflows from Dwarf Scales to Galaxy Groups

Rebekka Bieri, Rüdiger Pakmor, Freeke van de Voort, Rosie Y. Talbot, Maria Werhahn, Christoph Pfrommer, Volker Springel

AI总结：

本研究利用宇宙学zoom-in模拟，发现宇宙线在低质量星系中显著抑制恒星形成（最高达50%）、缩小星系盘并增强外流，而在高质量星系中影响有限，但普遍影响星系形态。

摘要：

宇宙线（CRs）是星际介质和星系周介质（CGM）中的一种非热能成分，可以作为除恒星和活动星系核（AGN）的热反馈和动力学反馈之外的额外反馈通道。它们通过改变气体性质、调节恒星形成和塑造星系外流来影响星系演化。我们利用一系列宇宙学zoom-in模拟来研究这些效应，这些模拟在Auriga星系形成模型的基础上加入了宇宙线输运和反馈。我们的模拟覆盖了广泛的暗物质晕质量范围，从矮星系到小星系群（$M_{200\mathrm{c}}= 10^{10} - 10^{13}~\mathrm{M}_\odot$），使我们能够评估宇宙线在宇宙学背景下的质量依赖性影响。我们发现，宇宙线在较低质量星系（$M_{200\mathrm{c}} < 10^{12}~\mathrm{M}_\odot$）中影响最为显著，它们将恒星形成率抑制了高达50%，减小了气体和恒星半光半径，并在维里半径处驱动出流达到比无宇宙线模拟更高的速度。这些由宇宙线增强的外流还将更多金属和磁场输运到星系周介质中，导致星系周介质金属丰度更高、磁化更强、温度更低。在更大质量的星系中，宇宙线对恒星形成或外流性质没有显著影响，这很可能是因为在该质量范围内恒星和活动星系核的热反馈和动力学反馈占主导地位。然而，宇宙线仍然通过减小气体半质量半径和恒星半光半径来影响所有暗物质晕质量下的星系形态。最后，宇宙线输运性质的变化，例如不同的扩散系数或排除阿尔芬冷却，会显著影响较低质量星系中的恒星形成、星系周介质性质和外流。这种敏感性使得这些星系成为测试宇宙线输运模型和深化理解其在星系演化中作用的关键环境。

英文摘要：

Cosmic rays (CRs) are a non-thermal energy component in the interstellar and circumgalactic medium (CGM) that can act as an additional feedback channel beyond thermal and kinetic feedback from stars and AGN. They influence galaxy evolution by altering gas properties, regulating star formation, and shaping galactic outflows. We investigate these effects using a suite of cosmological zoom-in simulations, which incorporate CR transport and feedback on top of the Auriga galaxy formation model. Our simulations span a wide range of halo masses, from dwarf galaxies to small groups ($M_{200\mathrm{c}}= 10^{10} - 10^{13}~\mathrm{M}_\odot$), allowing us to assess the mass-dependent impact of CRs in a cosmological setting. We find that CRs have the strongest impact in lower-mass galaxies ($M_{200\mathrm{c}} < 10^{12}~\mathrm{M}_\odot$), where they suppress star formation rates by up to 50\%, reduce gas and stellar half-light radii, and drive outflows that reach higher velocities at the virial radius compared to simulations without CRs. These CR-enhanced outflows also transport more metals and magnetic fields into the CGM, leading to higher CGM metallicities, stronger magnetisation, and lower CGM temperatures. In more massive galaxies, CRs do not significantly affect star formation or outflow properties, likely because thermal and kinetic feedback from stars and AGN dominate in this regime. However, CRs still influence galaxy morphology across all halo masses by reducing the gas half-mass radius and stellar half-light radius. Finally, variations in CR transport properties, such as different diffusion coefficients or the exclusion of Alfvén cooling, significantly affect star formation, CGM properties, and outflows in lower-mass galaxies. This sensitivity makes these galaxies key environments for testing CR transport models and refining our understanding of their role in galaxy evolution.

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摘要：

英文摘要：

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