近日，俄罗斯圣彼得堡约菲研究所Sergei Balashev团队揭示类星体辐射改变了合并伴星星系中的气体。该研究于2025年5月21日发表在《自然》杂志上。

类星体由超大质量黑洞上的气体吸积提供动力，是宇宙中能量最高的天体之一。尽管它们被认为是由星系合并引发的，并影响周围的气体，但对这两个过程的观测限制仍然很少。 

研究组描述了红移z ≈ 2.7的一个主要合并系统，并证明一个星系中类星体的辐射直接改变了另一个星系的气体特性。该发现表明，这些星系（质心相距仅几千秒差距，以大约550 km s⁻¹的速度相互靠近）非常巨大，正在形成恒星，并含有大量的分子量。然而，在类星体核的吸收中看到的含尘分子气体被高度激发并限制在密度约为10⁵至10⁶ cm^-3、尺寸小于0.02 pc的小尘埃云内，比在中间（非类星体）环境中观测到的要紧凑几个数量级。 

这也比目前通过高红移分子线发射可分辨的小约10⁵倍。研究组推断，无论在哪里暴露于类星体辐射，分子气体都会被破坏，留下幸存的致密云，这些云太小，无法产生新的恒星。该研究结果不仅强调了主要星系合并在触发类星体活动中的作用，还揭示了局部负反馈是内部气体结构的深刻变化，这可能会阻碍恒星形成。

附：英文原文

Title: Quasar radiation transforms the gas in a merging companion galaxy

Author: Balashev, Sergei, Noterdaeme, Pasquier, Gupta, Neeraj, Krogager, Jens-Kristian, Combes, Franoise, Lpez, Sebastin, Petitjean, Patrick, Omont, Alain, Srianand, Raghunathan, Cuellar, Rodrigo

Issue&Volume: 2025-05-21

Abstract: Quasars, powered by gas accretion onto supermassive black holes1,2, rank among the most energetic objects in the Universe3,4. Although they are thought to be ignited by galaxy mergers5,6,7,8,9,10,11 and affect the surrounding gas12,13,14,15, observational constraints on both processes remain scarce16,17,18. Here we describe a major merging system at redshift z≈2.7 and demonstrate that radiation from the quasar in one galaxy directly alters the gas properties in the other galaxy. Our findings reveal that the galaxies, with centroids separated by only a few kiloparsecs and approaching each other at a speed of approximately 550kms1, are massive, are forming stars and contain a substantial molecular mass. Yet, dusty molecular gas seen in absorption against the quasar nucleus is highly excited and confined within cloudlets with densities of approximately 105 to 106cm3 and sizes of less than 0.02pc, several orders of magnitude more compact than those observed in intervening (non-quasar) environments. This is also approximately 105 times smaller than currently resolvable through molecular-line emission at high redshifts. We infer that, wherever it is exposed to the quasar radiation, the molecular gas is disrupted, leaving behind surviving dense clouds too small to give birth to new stars. Our results not only underscore the role of major galaxy mergers in triggering quasar activity but also reveal localized negative feedback as a profound alteration of the internal gas structure, which probably hampers star formation.

DOI: 10.1038/s41586-025-08966-4

Source: https://www.nature.com/articles/s41586-025-08966-4