A two-phase model of galaxy formation: II. The size-mass relation of dynamically hot galaxies
Fuente:
arXiv
Saved in:
| Main Authors: | , , |
|---|---|
| Format: | Preprint |
| Published: |
2023
|
| Subjects: | |
| Online Access: | |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1866911941435326464 |
|---|---|
| author | Chen, Yangyao Mo, Houjun Wang, Huiyuan |
| author_facet | Chen, Yangyao Mo, Houjun Wang, Huiyuan |
| contents | In Paper-I we developed a two-phase model to connect dynamically hot galaxies (such as ellipticals and bulges) with the formation of self-gravitating gas clouds (SGCs) associated with the fast assembly of dark matter halos. Here we explore the implications of the model for the size-stellar mass relation of dynamically hot galaxies. Star-forming sub-clouds resulting from the fragmentation of the turbulent SGC inherit its spatial structure and dynamical hotness, producing a `homologous' relation, $r_{\rm f}\approx\, 100 r_{\rm bulge}$, between the size of a dynamically hot galaxy ($r_{\rm bulge}$) and that of its host halo assembled in the fast regime ($r_{\rm f}$), independent of redshift and halo mass. This relation is preserved by the `dry' expansion driven by dynamical heating when a galaxy becomes gas-poor due to inefficient cooling, and is frozen due to the stop of bulge growth during the slow assembly regime of the halo. The size-stellar mass relation is thus a simple combination of the galaxy-halo homology and the non-linear stellar mass-halo mass relation. Using a set of halo assembly histories we reproduce all properties in the observed size-mass relation of dynamically hot galaxies, including the flattening in the low-mass end and the upturn in the massive end. The prediction matches observational data currently available to $z \approx 4$, and can be tested in the future at higher $z$. Our results indicate that the sizes of dynamically hot galaxies are produced by the dissipation and collapse of gas in halos to establish SGCs in which stars form. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2311_11713 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | A two-phase model of galaxy formation: II. The size-mass relation of dynamically hot galaxies Chen, Yangyao Mo, Houjun Wang, Huiyuan Astrophysics of Galaxies In Paper-I we developed a two-phase model to connect dynamically hot galaxies (such as ellipticals and bulges) with the formation of self-gravitating gas clouds (SGCs) associated with the fast assembly of dark matter halos. Here we explore the implications of the model for the size-stellar mass relation of dynamically hot galaxies. Star-forming sub-clouds resulting from the fragmentation of the turbulent SGC inherit its spatial structure and dynamical hotness, producing a `homologous' relation, $r_{\rm f}\approx\, 100 r_{\rm bulge}$, between the size of a dynamically hot galaxy ($r_{\rm bulge}$) and that of its host halo assembled in the fast regime ($r_{\rm f}$), independent of redshift and halo mass. This relation is preserved by the `dry' expansion driven by dynamical heating when a galaxy becomes gas-poor due to inefficient cooling, and is frozen due to the stop of bulge growth during the slow assembly regime of the halo. The size-stellar mass relation is thus a simple combination of the galaxy-halo homology and the non-linear stellar mass-halo mass relation. Using a set of halo assembly histories we reproduce all properties in the observed size-mass relation of dynamically hot galaxies, including the flattening in the low-mass end and the upturn in the massive end. The prediction matches observational data currently available to $z \approx 4$, and can be tested in the future at higher $z$. Our results indicate that the sizes of dynamically hot galaxies are produced by the dissipation and collapse of gas in halos to establish SGCs in which stars form. |
| title | A two-phase model of galaxy formation: II. The size-mass relation of dynamically hot galaxies |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2311.11713 |