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In this paper, we present a new derivation of the shape and evolution of the integrated galaxy-wide initial mass function (IGIMF), incorporating explicitly the effects of cosmic rays (CRs) as regulators of the chemical and thermal state of…

Astrophysics of Galaxies · Physics 2018-07-18 Fabio Fontanot , Francesco La Barbera , Gabriella De Lucia , Anna Pasquali , Alexandre Vazdekis

We investigate the time evolution and spatial variation of the stellar initial mass function (IMF) in star-forming disk galaxies by using chemodynamical simulations with an IMF model depending both on local densities and metallicities…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Kenji Bekki , Gerhardt R. Meurer

Chemical and photometric models of elliptical galaxies with infall of primordial gas, and subsequent ejection of processed material via galactic winds, are described. Ensuring that these models are consistent with the present-day…

Astrophysics · Physics 2016-01-13 Brad K. Gibson , Francesca Matteucci

The stellar initial mass function (IMF) of early-type galaxies is the combination of the IMF of the stellar population formed in-situ and that of accreted stellar populations. Using as an observable the effective IMF $\alpha_{IMF}$, defined…

Astrophysics of Galaxies · Physics 2017-01-18 Alessandro Sonnenfeld , Carlo Nipoti , Tommaso Treu

The mean alpha-to-iron abundance ratio ([$\alpha$/Fe]) of galaxies is sensitive to the chemical evolution processes at early time, and it is an indicator of star formation timescale ($\tau_{{\rm SF}}$). Although the physical reason remains…

Astrophysics of Galaxies · Physics 2016-10-05 Yiqing Liu , Luis C. Ho , Eric Peng

We study the origin of the stellar $\alpha$-element-to-iron abundance ratio, $[\alpha/\mathrm{Fe}]_{\ast}$, of present-day central galaxies, using cosmological, hydrodynamical simulations from the Evolution and Assembly of GaLaxies and…

Astrophysics of Galaxies · Physics 2016-06-08 Marijke C. Segers , Joop Schaye , Richard G. Bower , Robert A. Crain , Matthieu Schaller , Tom Theuns

The recent finding that the IGIMF (integrated galaxial initial stellar mass function) composed of all newly formed stars in all young star clusters has, in dependence of the SFR, a steeper slope in the high mass regime than the underlying…

Astrophysics · Physics 2009-11-13 Jan Pflamm-Altenburg , Carsten Weidner , Pavel Kroupa

Several independent lines of evidence suggest that the stellar initial mass function (IMF) in early-type galaxies becomes increasingly `bottom-heavy' with increasing galaxy mass and/or velocity dispersion, sigma. Here we consider evidence…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 Charlie Conroy , Aaron A. Dutton , Genevieve J. Graves , J. Trevor Mendel , Pieter G. van Dokkum

The spectral absorption lines in early-type galaxies contain a wealth of information regarding the detailed abundance pattern, star formation history, and stellar initial mass function (IMF) of the underlying stellar population. Using our…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Charlie Conroy , Pieter van Dokkum

(Abridged) The abundance ratios between key elements such as iron and alpha-process elements carry a wealth of information on the star formation history (SFH) of galaxies. So far, simple chemical evolution models have linked [alpha/Fe] with…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Ignacio G. de la Rosa , Francesco La Barbera , Ignacio Ferreras , Reinaldo de Carvalho

Observations with JWST have revealed an unexpected high abundance of bright z>10 galaxy candidates. We explore whether a stellar initial mass function (IMF) that becomes increasingly top-heavy towards higher redshifts and lower gas-phase…

The stellar initial mass functions (IMFs) for the Galactic bulge, the Milky Way, other galaxies, clusters of galaxies, and the integrated stars in the Universe are composites from countless individual IMFs in star clusters and associations…

Astrophysics · Physics 2008-11-26 Bruce G. Elmegreen

We investigate the chemical properties of local galaxies within a cosmological framework in the hierarchical picture of galaxy formation. To this aim, we use a hierarchical semi-analytic model which includes the contribution from (i) low…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Francesco Calura , Nicola Menci

We determine an absolute calibration of the initial mass function (IMF) of early-type galaxies, by studying a sample of 56 gravitational lenses identified by the SLACS Survey. Under the assumption of standard Navarro, Frenk & White dark…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 T. Treu , M. W. Auger , L. V. E. Koopmans , R. Gavazzi , P. J. Marshall , A. S. Bolton

The integrated galactic initial mass function (IGIMF) is computed from the combination of the stellar initial mass function (IMF) and the embedded cluster mass function, described by a power law with index beta. The result of the…

Astrophysics of Galaxies · Physics 2015-03-18 Francesco Calura , Simone Recchi , Francesca Matteucci , Pavel Kroupa

Metals enhance the cooling efficiency of molecular clouds, promoting fragmentation. Consequently, increasing the metallicity may boost the formation of low-mass stars. Within the integrated galaxy initial mass function (IGIMF) theory, this…

The stellar initial mass function (IMF) describes the distribution of stellar masses that form in a given star formation event. The long main-sequence lifetimes of low-mass stars mean that the IMF in this regime (below $\sim 1…

The recently inferred variations in the stellar initial mass function (IMF) among local high-mass early-type galaxies may require a reinterpretation of observations of galaxy populations and may have important consequences for the…

Astrophysics of Galaxies · Physics 2018-07-17 Christopher Barber , Robert A. Crain , Joop Schaye

We investigate the effect of a metallicity-dependent stellar initial mass function (IMF), as deduced observationally by Martin-Navarro et al. (2015c), on the inferred stellar masses and star formation rates (SFRs) of a representative sample…

Astrophysics of Galaxies · Physics 2016-08-31 Bart Clauwens , Joop Schaye , Marijn Franx

I discuss the formation of alpha-enhanced metal-rich stellar populations in the nuclei of luminous ellipticals. Based on hierarchical clustering, different galaxy formation scenarios, which imply different star formation histories, are…

Astrophysics · Physics 2007-05-23 D. Thomas