2010/10/31 by R. Feldmann, N. Y. Gnedin, A. V. Kravtsov · 69 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy formation and evolution #Interstellar medium #Metallicity #Radiative transfer #Redshift #Star formation #Stars #astro-ph.CO #astro-ph.GA
paper · pdf · doi:10.1088/0004-637x/732/2/115
published in The Astrophysical Journal 732(2), 115 (IOP Publishing) · 12 pages, 7 figures, updated to match the published version, extended discussion of the scale dependence of the scatter, uses emulateapj
arxiv created 2011/03/22 · openalex publication_date 2011/04/26 · arxiv updated 2011/04/28 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
It is a well-established empirical fact that the surface density of the star formation rate, Σ SFR , strongly correlates with the surface density of molecular hydrogen, , at least when averaged over large (∼kpc) scales. Much less is known, however, about whether (and how) the relation depends on environmental parameters, such as the metallicity or the UV radiation field in the interstellar medium (ISM). Furthermore, observations indicate that the scatter in the relation increases rapidly with decreasing averaging scale. How the scale-dependent scatter is generated and how one recovers a tight ∼ kpc scale relation in the first place is still largely debated. Here, these questions are explored with hydrodynamical simulations that follow the formation and destruction of H 2 , include radiative transfer of UV radiation, and resolve the ISM on ∼60 pc scales. We find that within the considered range of H 2 surface densities (10–100 M ☉ pc −2 ), the relation is steeper in environments of low-metallicity and/or high-radiation fields (compared to the Galaxy), that the star formation rate (SFR) at a given H 2 surface density is larger, and the scatter is increased. Deviations from a "universal" relation should be particularly relevant for high-redshift galaxies or for low-metallicity dwarfs at z ∼ 0. We also find that the use of time-averaged SFRs produces a large, scale-dependent scatter in the relation. Given the plethora of observational data expected from upcoming surveys such as ALMA, the scale–scatter relation may indeed become a valuable tool for determining the physical mechanisms connecting star formation and H 2 formation.