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We examine the cosmic evolution of a stellar initial mass function (IMF) in galaxies that varies with the Jeans mass in the interstellar medium, paying particular attention to the K-band stellar mass to light ratio (M/L_K) of present-epoch…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 Desika Narayanan , Romeel Davé

I present a new Galactic chemical evolution model motivated by and grounded in the hierarchical theory of galaxy formation, as expressed by a halo merger history of the Galaxy. This model accurately reproduces the "metallicity distribution…

Astrophysics · Physics 2009-11-13 Jason Tumlinson

A universal stellar initial mass function (IMF) should not be expected from theoretical models of star formation, but little conclusive observational evidence for a variable IMF has been uncovered. In this paper, a parameterization of the…

Astrophysics of Galaxies · Physics 2022-06-01 Albert Sneppen , Charles L. Steinhardt , Hagan Hensley , Adam S. Jermyn , Basel Mostafa , John R. Weaver

An essential component of galaxy formation theory is the stellar initial mass function (IMF), that describes the parent distribution of stellar mass in star forming regions. We present observational evidence in a sample of early-type…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 I. Ferreras , F. La Barbera , R. R. de Carvalho , I. G. de la Rosa , A. Vazdekis , J. Falcon-Barroso , E. Ricciardelli

We investigate the impact of an environment-dependent galaxy-wide stellar initial mass function (gwIMF) on the baryonic Tully-Fisher relation (BTFR). The integrated galaxy-wide IMF (IGIMF) theory, which incorporates variations in stellar…

Astrophysics of Galaxies · Physics 2025-07-18 Akram Hasani Zonoozi , Hosein Haghi , Pavel Kroupa , Sara Yousefizadeh , Zhiqiang Yan , Tereza Jerabkova , Eda Gjergo

We calculate the integrated galactic initial stellar mass function (IGIMF) in the presence of IMF variations in clusters. IMF Variations for a population of clusters are taken into account in the form of Gaussian distributions of the IMF…

Astrophysics of Galaxies · Physics 2022-10-19 Sami Dib

Recent results form the James Webb Space Telescope (JWST) report space densities for bright and massive galaxies at z>7 that far exceed expectations of theoretical models of galaxy formation, prompting a revision of our understanding of the…

The universality or non-universality of the initial mass function (IMF) has significant implications for determining star formation rates and star formation histories from photometric properties of stellar populations. We reexamine whether…

Astrophysics of Galaxies · Physics 2024-01-17 R. P. V. Rautio , A. E. Watkins , H. Salo , A. Venhola , J. H. Knapen , S. Comerón

Few topics in astronomy initiate such vigorous discussion as whether or not the initial mass function (IMF) of stars is universal, or instead sensitive to the initial conditions of star formation. The distinction is of critical importance:…

Solar and Stellar Astrophysics · Physics 2010-12-01 Nate Bastian , Kevin R. Covey , Michael R. Meyer

The stellar initial mass function (IMF) is predicted to depend upon the temperature of gas in star-forming molecular clouds. The introduction of an additional parameter, $T_{IMF}$ , into photometric template fitting, allows galaxies to be…

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

The manner in which the stellar initial mass function (IMF) scales with global galaxy properties is under debate. We use two hydrodynamical, cosmological simulations to predict possible trends for two self-consistent variable IMF…

Astrophysics of Galaxies · Physics 2018-10-22 Christopher Barber , Joop Schaye , Robert A. Crain

[abridged] Stars are thought to be formed predominantly in clusters. The clusters are formed following a cluster initial mass function (CMF) similar to the stellar initial mass function (IMF). Both the IMF and the CMF favour low-mass…

Astrophysics of Galaxies · Physics 2012-05-31 M. R. Haas , P. Anders

The functional form of the galaxy-wide stellar initial mass function is of fundamental importance for understanding galaxies. So far this stellar initial mass function has been assumed to be identical to the IMF observed directly in star…

Cosmology and Nongalactic Astrophysics · Physics 2010-11-11 Jan Pflamm-Altenburg , Carsten Weidner , Pavel Kroupa

We investigate the origin of a bottom-heavy stellar initial mass function (IMF) recently observed in elliptical galaxies by using chemical evolution models with a non-universal IMF. We adopt the Kroupa IMF with the three slopes (alpha_1,…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Kenji Bekki

Interpreting galactic luminosity requires assumptions about the galaxy-wide initial mass function (gwIMF), often assumed invariant in most stellar population synthesis (SPS) models. If stars form in clusters with metallicity- and…

Astrophysics of Galaxies · Physics 2025-02-07 Akram Hasani Zonoozi , Hosein Haghi , Pavel Kroupa

One of the most robust observations of the stellar initial mass function (IMF) is its near-universality in the Milky Way and neighboring galaxies. But recent observations of early-type galaxies can be interpreted to imply a bottom-heavy…

Astrophysics of Galaxies · Physics 2019-03-26 David Guszejnov , Philip F. Hopkins , Andrew S. Graus

We discuss the star formation history of the Galaxy, based on the observations of extremely metal-poor stars (EMP) in the Galactic halo, to gain an insight into the evolution and structure formation in the early universe. The initialmass…

Astrophysics · Physics 2008-11-26 Yutaka Komiya , Takuma Suda , Asao Habe , Masayuki Y. Fujimoto

We derive a semi-empirical galactic initial mass function (IMF) from observational constraints. We assume that the star formation rate in a galaxy can be expressed as the product of the IMF, $\psi (m)$, which is a smooth function of mass…

Astrophysics of Galaxies · Physics 2015-05-20 Antonio Parravano , Christopher F. McKee , David J. Hollenbach

Cosmological simulations are reaching the resolution necessary to study ultra-faint dwarf galaxies. Observations indicate that in small populations, the stellar initial mass function (IMF) is not fully populated; rather, stars are sampled…

Astrophysics of Galaxies · Physics 2020-02-24 Elaad Applebaum , Alyson M. Brooks , Thomas R. Quinn , Charlotte R. Christensen