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arXiv 2401.04774astro-ph.GA
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早型星系中星际介质的命运。III. ISM移除与恒星形成淬灭的机制

The fate of the interstellar medium in early-type galaxies. III. The mechanism of ISM removal and quenching of star formation

Michał J. Michałowski, C. Gall, J. Hjorth, D. T. Frayer, A. -L. Tsai, K. Rowlands, T. T. Takeuchi, A. Leśniewska, D. Behrendt, N. Bourne, D. H. Hughes, M. P. Ko… 展开作者

Michał J. Michałowski, C. Gall, J. Hjorth, D. T. Frayer, A. -L. Tsai, K. Rowlands, T. T. Takeuchi, A. Leśniewska, D. Behrendt, N. Bourne, D. H. Hughes, M. P. Koprowski, J. Nadolny, O. Ryzhov, M. Solar, E. Spring, J. Zavala, P. Bartczak

AI总结:

本文通过CO和H I谱线观测测量早型星系冷星际介质的移除时标,发现冷ISM各成分以相似速率减少,排除了多种移除机制,并指出恒星形成淬灭不仅因气体减少,还因气体稳定化导致效率降低。

摘要:

理解星系如何淬灭其恒星形成对于星系演化研究至关重要。淬灭与冷气体的减少有关。在第一篇论文中,我们表明早型星系(ETGs)中的尘埃移除时标约为2.5 Gyr。在此,我们展示了这些星系的一氧化碳(CO)和21厘米氢(H I)谱线观测结果,并测量了冷星际介质(ISM)的移除时标。我们发现所有冷ISM成分(尘埃、分子和原子气体)以相似的速率减少。这使我们能够排除一系列广泛的潜在ISM移除机制(包括星暴驱动的外流、恒星内部核合成、渐近巨星支恒星数量的减少),以及人造效应如恒星质量-年龄相关性、环境影响、合并和选择偏差,从而留下由演化中的低质量恒星引起的电离、Ia型超新星或活动星系核引起的电离/外流作为可行的机制。我们还提供了所探测到的ISM具有内部起源的证据。此外,我们发现这些星系中恒星形成的淬灭不能仅用气体量的减少来解释,因为恒星形成率(SFRs)的下降速度(时标约为1.8 Gyr)快于冷气体量。此外,ETGs的恒星形成效率(SFE = SFR/MH2)低于正常恒星形成星系,而其气体质量分数(fH2 = MH2/M*)是正常的。这可以通过气体抵抗碎裂的稳定化来解释,例如由于形态学淬灭、湍流或磁场。

英文摘要:

Understanding how galaxies quench their star formation is crucial for studies of galaxy evolution. Quenching is related to the cold gas decrease. In the first paper we showed that the dust removal timescale in early-type galaxies (ETGs) is about 2.5 Gyr. Here we present carbon monoxide (CO) and 21 cm hydrogen (H I) line observations of these galaxies and measure the timescale of removal of the cold interstellar medium (ISM). We find that all the cold ISM components (dust, molecular and atomic gas) decline at similar rates. This allows us to rule out a wide range of potential ISM removal mechanisms (including starburst-driven outflows, astration, a decline in the number of asymptotic giant branch stars), and artificial effects like stellar mass-age correlation, environmental influence, mergers, and selection bias, leaving ionization by evolved low-mass stars and ionization/outflows by supernovae Type Ia or active galactic nuclei as viable mechanisms. We also provide evidence for an internal origin of the detected ISM. Moreover, we find that the quenching of star formation in these galaxies cannot be explained by a reduction in gas amount alone, because the star formation rates (SFRs) decrease faster (on a timescale of about 1.8 Gyr) than the amount of cold gas. Furthermore, the star formation efficiency of the ETGs (SFE = SFR/MH2) is lower than that of star-forming galaxies, whereas their gas mass fractions (fH2 = MH2/M*) are normal. This may be explained by the stabilization of gas against fragmentation, for example due to morphological quenching, turbulence, or magnetic fields.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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