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太庞大无法熄灭?I. 限制银河系类似宿主晕中的矮卫星星际介质剥离

Too Big to Quench? I. Constraining ISM Stripping of Dwarf Satellites in Milky Way-like Halos

Columbia University(哥伦比亚大学);Flatiron Institute(平顿研究所)

Jingyao Zhu, Stephanie Tonnesen, Greg L. Bryan, Mary E. Putman

AI总结:

研究通过高分辨率模拟揭示银河系类似宿主晕中矮卫星星际介质剥离效率与卫星质量的关系,发现剥离效率在特定质量阈值以下较高,但更高质量卫星需其他机制如潮汐剥离或气体晕剥离来熄灭星形成。

摘要:

银河系环境在熄灭矮星系的恒星形成中起关键作用。在银河系类似环境中,矮卫星熄灭主要由风压剥离(RPS)驱动,即宿主晕气体直接移除卫星气体。利用20 pc分辨率的流体动力学风隧道模拟,我们约束了卫星质量尺度,使得矮星系星际介质(ISM)剥离在银河系类似晕中变得无效。模拟包括多相卫星ISM的辐射冷却、恒星形成和恒星反馈,并在首次进入和过近日点轨道上变化卫星质量(M*=10^6.2, 10^6.8, 10^7.2 M☉)和宿主晕气体密度。我们发现我们的矮星系ISM剥离程度与McCarthy等人(2008)的分析预测一致。当RPS有效时,恒星形成迅速熄灭,但当RPS不完整时,恒星形成可能被轻微增强或暂时熄灭并随后重新点燃。对于M* ≲ 10^7 M☉(或M200 ≲ 10^10 M☉)的卫星,ISM剥离效率较高,但在此尺度以上效率极低。此过渡质量(M* ≈ 10^7 M☉)比观测和宇宙学模拟发现的低0.5-1个数量级,表明需要额外机制如卫星暗物质的潮汐剥离或来自致密气体晕的RPS来熄灭更高质量的卫星。

英文摘要:

Galaxy environment plays a crucial role in quenching star formation in dwarf galaxies. In Milky Way (MW)-like environments, dwarf satellite quenching is primarily driven by ram pressure stripping (RPS), the direct removal of satellite gas by the host halo gas. Using a suite of 20-pc resolution hydrodynamical wind tunnel simulations, we constrain the satellite mass scale at which the stripping of a dwarf galaxy's interstellar medium (ISM) becomes inefficient in MW-like halos. The simulations include radiative cooling in a multiphase satellite ISM, star formation, and stellar feedback, and vary both satellite masses ($M_{\star}=10^{6.2}, 10^{6.8}, 10^{7.2}\ M_{\odot}$) and host halo gas densities along a first-infall and post-pericentric orbit. We find that the degree of ISM stripping in our dwarf galaxies is consistent with the analytical prediction by McCarthy et al. (2008). Star formation is rapidly quenched when RPS is effective, but can be mildly enhanced or temporarily quenched and subsequently reignited when RPS is incomplete. ISM stripping is efficient for satellites with $M_{\star} \lesssim 10^{7}\ M_{\odot}$ (or $M_{200} \lesssim 10^{10}\ M_{\odot}$) but highly inefficient above this scale. This transitional mass ($M_{\star} \approx 10^{7}\ M_{\odot}$) is 0.5-1 dex lower than that found in observations and cosmological simulations, suggesting that additional mechanisms are needed to quench more massive satellites, such as tidal stripping of the satellite dark matter or RPS from a clumpy gaseous halo.

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