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arXiv · 1909.10817

Quenching as a Contest between Galaxy Halos and their Central Black Holes

Zhu Chen·S. M. Faber·David. C. Koo·Rachel S. Somerville·Joel R. Primack·Avishai Dekel·Aldo Rodríguez-Puebla·Yicheng Guo·Guillermo Barro·Dale D. Kocevski·A. van der Wel·Joanna Woo·Eric F. Bell·Jerome J. Fang·Henry C. Ferguson·Mauro Giavalisco·Marc Huertas-Company·Fangzhou Jiang·Susan Kassin·Lin Lin·Fengshan Liu·Yifei Luo·Zhijian Luo·Camilla Pacifici·Viraj Pandya·Samir Salim·Chenggang Shu·Sandro Tacchella·Bryan A. Terrazas·Hassen M. Yesuf
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Abstract

Existing models of galaxy formation have not yet explained striking correlations between structure and star-formation activity in galaxies, notably the sloped and moving boundaries that divide star-forming from quenched galaxies in key structural diagrams. This paper uses these and other relations to ``reverse-engineer'' the quenching process for central galaxies. The basic idea is that star-forming galaxies with larger radii (at a given stellar mass) have lower black-hole masses due to lower central densities. Galaxies cross into the green valley when the cumulative effective energy radiated by their black hole equals $\sim4\times$ their halo-gas binding energy. Since larger-radii galaxies have smaller black holes, one finds they must evolve to higher stellar masses in order to meet this halo-energy criterion, which explains the sloping boundaries. A possible cause of radii differences among star-forming galaxies is halo concentration. The evolutionary tracks of star-forming galaxies are nearly parallel to the green-valley boundaries, and it is mainly the sideways motions of these boundaries with cosmic time that cause galaxies to quench. BH-scaling laws for star-forming, quenched, and green-valley galaxies are different, and most BH mass growth takes place in the green valley. Implications include: the radii of star-forming galaxies are an important second parameter in shaping their black holes; black holes are connected to their halos but in different ways for star-forming, quenched, and green-valley galaxies; and the same BH-halo quenching mechanism has been in place since $z \sim 3$. We conclude with a discussion of black hole-galaxy co-evolution, the origin and interpretation of BH scaling laws.

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Zhu Chen, S. M. Faber, David. C. Koo, Rachel S. Somerville, Joel R. Primack, Avishai Dekel, Aldo Rodríguez-Puebla, Yicheng Guo, Guillermo Barro, Dale D. Kocevski, A. van der Wel, Joanna Woo, Eric F. Bell, Jerome J. Fang, Henry C. Ferguson, Mauro Giavalisco, Marc Huertas-Company, Fangzhou Jiang, Susan Kassin, Lin Lin, Fengshan Liu, Yifei Luo, Zhijian Luo, Camilla Pacifici, Viraj Pandya, Samir Salim, Chenggang Shu, Sandro Tacchella, Bryan A. Terrazas, Hassen M. Yesuf. 2019-09-24. Quenching as a Contest between Galaxy Halos and their Central Black Holes. https://doi.org/10.3847/1538-4357/ab9633

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