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arXiv 2603.22239astro-ph.GA
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JWST揭示恒星形成星系在$0.5 < z < 6.0$范围内、临界恒星质量$10^{10}M_\odot$处的尺寸-质量关系弯曲

A Bending in the Size-mass Relation of Star-forming Galaxies across $0.5 < z < 6.0$ at a Critical Stellar Mass of $10^{10}M_\odot$ Revealed by JWST

School of Astronomy and Space Science, Nanjing University(南京大学天文与空间科学学院);Key Laboratory of Modern Astronomy and Astrophysics, Nanjing University, Ministry of Education(南京大学现代天文与天体物理教育部重点实验室)
Longyue Chen, Tao Wang, Hanwen Sun, Ke Xu, Luwenjia Zhou, Tiancheng Yang, Maxime Tarrasse, Houjun Mo, Zhaozhou Li, Yangyao Chen, Avishai Dekel, Emanuele Daddi, … 展开作者

Longyue Chen, Tao Wang, Hanwen Sun, Ke Xu, Luwenjia Zhou, Tiancheng Yang, Maxime Tarrasse, Houjun Mo, Zhaozhou Li, Yangyao Chen, Avishai Dekel, Emanuele Daddi, Xuheng Ding, Mauro Giavalisco, David Elbaz

AI总结:

利用JWST/NIRCam和MIRI数据,研究恒星形成星系在$0.5<z<6.0$的尺寸-恒星质量关系,发现其呈现断裂幂律,转折质量约$10^{10}M_\odot$,表明存在紧凑大质量SFGs,并支持两种尺寸增长模式。

摘要:

我们利用PRIMER巡天的深度JWST/NIRCam和MIRI成像,研究了$0.5<z<6.0$范围内星系的静止框架光学尺寸-恒星质量关系。我们发现恒星形成星系(SFGs)在所有红移处呈现断裂幂律关系,具有几乎恒定的枢轴质量($M_{ m p}$)约$10^{10} M_\odot$,且在$M_{ m p}$以上斜率变平。这突显了先前研究中未被充分代表的紧凑大质量SFGs群体的普遍存在。静止星系(QGs)的尺寸分布由混合幂律模型很好地描述,其枢轴质量从$z=0.75$时的$M_{ m p} \sim 10^{10.0} M_\odot$增加到$z=2.6$时的$M_{ m p} \sim 10^{10.5} M_\odot$,表明淬灭大质量星系所需的最小暗晕质量随红移增加。SFGs尺寸-质量关系中的弯曲支持两种不同的尺寸增长模式。在$M_{\star} < M_{ m p}$时,尺寸增长与暗晕增长紧密耦合,而在$M_{\star} > M_{ m p}$时,越来越多的SFGs与暗晕增长解耦并变得紧凑,这可能与$M_{ m h} \gtrsim 10^{12} M_{\odot}$暗晕中快速的核球(和黑洞)增长有关。这些紧凑SFGs是大质量QGs的有前途的前身,它们的质量、表面亮度轮廓和形态相似。它们的高数密度可以解释在$z > 2$处观测到的大质量QGs的积累,表明紧凑化路径而非扩展SFGs的并合主导了高红移大质量QGs的形成。

英文摘要:

We investigate the rest-frame optical size-stellar mass relation of galaxies at $0.5<z<6.0$ using deep JWST/NIRCam and MIRI imaging from the PRIMER survey. We find that star-forming galaxies (SFGs) exhibit a broken power-law relation at all redshifts, with a nearly constant pivot mass ($M_{\rm p}$) of $\sim 10^{10} M_\odot$, and a slope flattening above $M_{\rm p}$. This highlights the prevalence of a population of compact, massive SFGs that was underrepresented in previous studies. The size distribution of quiescent galaxies (QGs) is well described by a mixture power-law model, with a pivot mass that increases from $M_{\rm p} \sim 10^{10.0} M_\odot$ at $z =0.75$ to $M_{\rm p} \sim 10^{10.5} M_\odot$ at $z = 2.6$, suggesting that the minimum halo mass required to quench high-mass galaxies increases with redshift. The bending in the size-mass relation of SFGs supports two distinct size growth modes. At $M_{\star} < M_{\rm p}$, size growth is closely coupled to halo growth, while at $M_{\star} > M_{\rm p}$, an increasing fraction of SFGs decouple from halo growth and become compact, likely associated with rapid bulge (and black hole) growth in $M_{\rm h} \gtrsim 10^{12} M_{\odot}$ halos. These compact SFGs are promising progenitors of massive QGs, as evidenced by their similar masses, surface brightness profiles, and morphologies. Their high number densities can account for the observed buildup of massive QGs at $z > 2$, suggesting that the compaction pathway, rather than major mergers of extended SFGs, dominates the formation of high-z massive QGs.

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