arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2004.09530astro-ph.GAastro-ph.CO
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EDGE:从静止到富含气体再到恒星形成的低质量矮星系

EDGE: From quiescent to gas-rich to star-forming low-mass dwarf galaxies

Martin P. Rey, Andrew Pontzen, Oscar Agertz, Matthew D. A. Orkney, Justin I. Read, Joakim Rosdahl

摘要:

利用宇宙学高分辨率($3 \, \text{pc}$)流体动力学模拟研究了低质量场矮星系($10^5 \leq M_{\star} \leq 10^6 \, \text{M}_{\odot}$)中恒星形成的规律。宇宙再电离淬灭了我们模拟的所有矮星中的恒星形成,但最终动力学质量为$3 \times 10^{9} \,\text{M}_{\odot}$的三个星系随后能够通过缓慢吸积气体来补充它们的星际介质。其中两个星系以平均$10^{-5} \, \text{M}_{\odot} \, \text{yr}^{-1}$的速率重新点燃并维持恒星形成,直到今天,这让人非常想起观察到的低质量恒星形成矮不规则星,如Leo T。由于恒星风和Ia型超新星的残余反馈,恒星形成的恢复被推迟了数十亿年;即使在$z=0$,第三个星系仍然处于暂时的平衡状态,有大量的气体含量,但没有任何正在进行的恒星形成。使用“遗传修饰”的方法,我们创建一个替代的质量增长的历史,这个富含气体的静止矮星,并显示如何一个小的$(0.2\,\mathrm{dex})$增加动态质量可以克服残余的恒星反馈,重新点燃恒星形成。反馈和质量积累之间的相互作用产生了低质量矮星的恒星年龄和气体含量的多样性,这将通过结合下一代HI和成像调查进行探测。

英文摘要:

We study how star formation is regulated in low-mass field dwarf galaxies ($10^5 \leq M_{\star} \leq 10^6 \, \text{M}_{\odot}$), using cosmological high-resolution ($3 \, \text{pc}$) hydrodynamical simulations. Cosmic reionization quenches star formation in all our simulated dwarfs, but three galaxies with final dynamical masses of $3 \times 10^{9} \,\text{M}_{\odot}$ are subsequently able to replenish their interstellar medium by slowly accreting gas. Two of these galaxies re-ignite and sustain star formation until the present day at an average rate of $10^{-5} \, \text{M}_{\odot} \, \text{yr}^{-1}$, highly reminiscent of observed low-mass star-forming dwarf irregulars such as Leo T. The resumption of star formation is delayed by several billion years due to residual feedback from stellar winds and Type Ia supernovae; even at $z=0$, the third galaxy remains in a temporary equilibrium with a large gas content but without any ongoing star formation. Using the "genetic modification'' approach, we create an alternative mass growth history for this gas-rich quiescent dwarf and show how a small $(0.2\,\mathrm{dex})$ increase in dynamical mass can overcome residual stellar feedback, re-igniting star formation. The interaction between feedback and mass build-up produces a diversity in the stellar ages and gas content of low-mass dwarfs, which will be probed by combining next-generation HI and imaging surveys.

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