近日，意大利博洛尼亚大学的Sirio Belli及其研究团队取得一项新进展。经过不懈努力，他们发现在一个红移为2.45的星系中，多相气体流出使恒星形成过程终止。相关研究成果已于2024年4月22日在国际权威学术期刊《自然》上发表。

该研究团队报道了在红移z=2.445处，经历快速淬灭的大质量星系的JWST光谱分析结果。研究人员探测到微弱的电离气体流出和强烈的中性气体流出，其质量流出率足以使恒星形成熄灭。他们没有检测到X射线或射电电活动; 然而，电离气体发射谱线的特性暗示了超大质量黑洞的存在。因此，研究人员得出结论，超大质量黑洞能够通过高效地喷出中性气体，迅速抑制大质量星系中恒星的形成。

据悉，超大质量黑洞驱动的大规模外流被认为在抑制大质量星系的恒星形成中起着重要作用。然而，这一假设的直接观测证据仍然缺乏，特别是在年轻的宇宙中，恒星形成的淬灭速度非常快，因此需要有效地移除气体，而非缓慢的气体加热过程。虽然在遥远的大质量星系中通常可以检测到电离气体的流出，但喷出的质量太少，无法抑制恒星的形成。据预测，气体喷出在中性和分子阶段会更为有效，但在高红移时，这些现象主要只在星暴和类星体中被观察到。

附：英文原文

Title: Star Formation Shut Down by Multiphase Gas Outflow in a Galaxy at a Redshift of 2.45

Author: Belli, Sirio, Park, Minjung, Davies, Rebecca L., Mendel, J. Trevor, Johnson, Benjamin D., Conroy, Charlie, Benton, Chlo, Bugiani, Letizia, Emami, Razieh, Leja, Joel, Li, Yijia, Maheson, Gabriel, Mathews, Elijah P., Naidu, Rohan P., Nelson, Erica J., Tacchella, Sandro, Terrazas, Bryan A., Weinberger, Rainer

Issue&Volume: 2024-04-22

Abstract: Large-scale outflows driven by supermassive black holes are thought to play a fundamental role in suppressing star formation in massive galaxies. However, direct observational evidence for this hypothesis is still lacking, particularly in the young universe where star formation quenching is remarkably rapid, thus requiring effective removal of gas as opposed to slow gas heating. While outflows of ionized gas are commonly detected in massive distant galaxies, the amount of ejected mass is too small to be able to suppress star formation. Gas ejection is expected to be more efficient in the neutral and molecular phases, but at high redshift these have only been observed in starbursts and quasars. Here we report JWST spectroscopy of a massive galaxy experiencing rapid quenching at redshift z=2.445. We detect a weak outflow of ionized gas and a powerful outflow of neutral gas, with a mass outflow rate that is sufficient to quench the star formation. Neither X-ray or radio activity are detected; however, the presence of a supermassive black hole is suggested by the properties of the ionized gas emission lines. We thus conclude that supermassive black holes are able to rapidly suppress star formation in massive galaxies by efficiently ejecting neutral gas.

DOI: 10.1038/s41586-024-07412-1

Source: https://www.nature.com/articles/s41586-024-07412-1