The statistical properties of stars at redshift, z = 5, compared with the present epoch
Abstract
We report the statistical properties of stars and brown dwarfs obtained from three radiation hydrodynamical simulations of star cluster formation with metallicities of 1, 1/10, and 1/100 of the solar value. The star-forming clouds are subjected to cosmic microwave background radiation that is appropriate for star formation at a redshift z = 5. The results from the three calculations are compared to each other, and to similar previously published calculations that had levels of background radiation appropriate for present-day (z = 0) star formation. Each of the calculations treats dust and gas temperatures separately and includes a thermochemical model of the diffuse interstellar medium. We find that whereas the stellar mass distribution is insensitive to the metallicity for present-day star formation, at z = 5 the characteristic stellar mass increases with increasing metallicity and the mass distribution has a deficit of brown dwarfs and low-mass stars at solar metallicity compared to the Galactic initial mass function. We also find that the multiplicity of M-dwarfs decreases with increasing metallicity at z = 5. These effects are a result of metal-rich gas being unable to cool to as low temperatures at z = 5 compared to at z = 0 due to the hotter cosmic microwave background radiation, which inhibits fragmentation at high densities.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- February 2023
- DOI:
- 10.1093/mnras/stac3481
- arXiv:
- arXiv:2211.15727
- Bibcode:
- 2023MNRAS.519..688B
- Keywords:
-
- hydrodynamics;
- radiative transfer;
- stars: abundances;
- binaries: general;
- stars: formation;
- stars: luminosity function;
- mass function;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Cosmology and Nongalactic Astrophysics;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- Accepted for publication in MNRAS. 21 pages, 15 figures. 12 animations available at: http://www.astro.ex.ac.uk/people/mbate/Cluster/clusterRedshift5.html. arXiv admin note: substantial text overlap with arXiv:1901.03713