dc.contributor.author | Chabrier, G | |
dc.contributor.author | Hennebelle, P | |
dc.contributor.author | Charlot, P | |
dc.date.accessioned | 2016-03-08T10:19:59Z | |
dc.date.issued | 2014-11-06 | |
dc.description.abstract | We examine variations of the stellar initial mass function (IMF) in extreme environments within the formalism derived by Hennebelle & Chabrier. We focus on conditions encountered in progenitors of massive early-type galaxies and starburst regions. We show that, when applying the concept of turbulent Jeans mass as the characteristic mass for fragmentation in a turbulent medium, the peak of the IMF in such environments is shifted toward smaller masses, leading to a bottom-heavy IMF, as suggested by various observations. In very dense and turbulent environments, we predict that the high-mass tail of the IMF can become even steeper than the standard Salpeter IMF, with a limit for the power-law exponent α sime –2.7, in agreement with recent observational determinations. This steepening is a direct consequence of the high densities and Mach values in such regions but also of the time dependence of the fragmentation process, as incorporated in the Hennebelle-Chabrier theory. We provide analytical parameterizations of these IMFs in such environments to be used in galaxy evolution calculations. We also calculate the star-formation rates and the mass-to-light ratios expected under such extreme conditions and show that they agree well with the values inferred in starburst environments and massive high-redshift galaxies. This reinforces the paradigm of star formation as being a universal process, i.e., the direct outcome of gravitationally unstable fluctuations in a density field initially generated by large-scale, shock-dominated turbulence. This globally enables us to infer the variations of the stellar IMF and related properties for atypical galactic conditions. | en_GB |
dc.description.sponsorship | The authors are grateful to C. Federrath for providing the data used in Figures 3 and 4. This research has received funding from the European Research Council under the European Community's Seventh Framework Programme (FP7/2007-2013 grant agreements No. 247060, No. 306483, and No. 321323NEOGAL). | en_GB |
dc.identifier.citation | Vol. 796 (2), article 75 | en_GB |
dc.identifier.doi | 10.1088/0004-637X/796/2/75 | |
dc.identifier.uri | http://hdl.handle.net/10871/20588 | |
dc.language.iso | en | en_GB |
dc.publisher | American Astronomical Society / IOP Publishing | en_GB |
dc.title | Variations of the stellar initial mass function in the progenitors of massive early-type galaxies and in extreme starburst environments | en_GB |
dc.type | Article | en_GB |
dc.date.available | 2016-03-08T10:19:59Z | |
dc.description | This is the final version of the article. Available from IOP Publishing via the DOI in this record. | en_GB |
dc.identifier.journal | Astrophysical Journal | en_GB |