近日，法国巴黎萨克雷大学的Emanuele Daddi&Qing-Hua Tan及其研究团队取得一项新进展。经过不懈努力，他们揭示遥远亚毫米明亮星系中原位球状体的形成。相关研究成果已于2024年12月4日在国际权威学术期刊《自然》上发表。

本研究表明，球状天体是由遥远宇宙中高光度星暴星系核心内的恒星形成直接产生的。这一结论基于ALMA（阿塔卡马大型毫米波/亚毫米波阵列）的亚毫米波表面亮度分布，这些分布与指数盘的分布存在显著差异，并且轴比分布偏高且不对称。

这些星系大多数为完全的三轴形态，而非扁平的盘状结构：它们三个轴中最短轴与最长轴的平均比值为一半，并且随着空间紧凑度的增加而增加。这些观测结果得到了模拟的支持，揭示了一条通过星暴在原地形成球状天体的宇宙学相关途径，这一途径可能主要由非共面气体吸积流供给的星系间的相互作用（和合并）所触发。

据悉，当今宇宙中的大多数恒星都位于球状天体中，这些天体包括螺旋星系的核球和椭圆星系。它们的形成机制至今仍是未解之谜。长久以来，人们一直怀疑高红移的红外/亚毫米波明亮星系与球状天体的形成有关。然而，在聚焦于这些星系的恒星辐射时，厚重的尘埃遮挡阻碍了这一联系的证实；而在观测亚毫米波波长时，方法学的限制以及信噪比的不足也构成了障碍。

附：英文原文

Title: In situ spheroid formation in distant submillimetre-bright galaxies

Author: Tan, Qing-Hua, Daddi, Emanuele, Magnelli, Benjamin, Correa, Camila A., Bournaud, Frdric, Adscheid, Sylvia, Zhang, Shao-Bo, Elbaz, David, Gmez-Guijarro, Carlos, Kalita, Boris S., Liu, Daizhong, Liu, Zhaoxuan, Pety, Jrme, Puglisi, Annagrazia, Schinnerer, Eva, Silverman, John D., Valentino, Francesco

Issue&Volume: 2024-12-04

Abstract: Most stars in today’s Universe reside within spheroids, which are bulges of spiral galaxies and elliptical galaxies. Their formation is still an unsolved problem. Infrared/submillimetre-bright galaxies at high redshifts have long been suspected to be related to spheroid formation. Proving this connection has been hampered so far by heavy dust obscuration when focusing on their stellar emission or by methodologies and limited signal-to-noise ratios when looking at submillimetre wavelengths. Here we show that spheroids are directly generated by star formation within the cores of highly luminous starburst galaxies in the distant Universe. This follows from the ALMA submillimetre surface brightness profiles, which deviate substantially from those of exponential disks, and from the skewed-high axis-ratio distribution. Most of these galaxies are fully triaxial rather than flat disks: the ratio of the shortest to the longest of their three axes is half, on average, and increases with spatial compactness. These observations, supported by simulations, reveal a cosmologically relevant pathway for in situ spheroid formation through starbursts that is probably preferentially triggered by interactions (and mergers) acting on galaxies fed by non-coplanar gas accretion streams.

DOI: 10.1038/s41586-024-08201-6

Source: https://www.nature.com/articles/s41586-024-08201-6