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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

We have undertaken the largest systematic study of the high-mass stellar initial mass function (IMF) to date using the optical color-magnitude diagrams (CMDs) of 85 resolved, young (4 Myr < t < 25 Myr), intermediate mass star clusters…

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 conditions that affect the formation of stars in radiatively and mechanically active environments are quite different than the conditions that apply to our local interstellar neighborhood. In such galactic environments, a variety of…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-19 S. Hocuk , M. Spaans

Using integral field spectroscopy, we demonstrate that gravity-sensitive absorption features in the zJ-band (0.9--1.35 \micron) can constrain the low-mass stellar initial mass function (IMF) in the cores of two elliptical galaxies, M85 and…

Astrophysics of Galaxies · Physics 2019-05-01 R. Elliot Meyer , Suresh Sivanandam , Dae-Sik Moon

Star formation in the early Universe has left its imprint on the chemistry of observable stars in galaxies. We derive elemental abundances and the slope of the low-mass end of the initial mass function (IMF) for a sample of 25 very massive…

Astrophysics of Galaxies · Physics 2024-04-08 Mark den Brok , Davor Krajnović , Eric Emsellem , Wilfried Mercier , Matthias Steinmetz , Peter M. Weilbacher

We present observational evidence of the correlation between the high-mass slope of the stellar initial mass function (IMF) in young star clusters and their stellar surface density, $\sigma_{*}$. When the high-mass end of the IMF is…

Astrophysics of Galaxies · Physics 2023-11-03 Sami Dib

The stellar initial mass function (IMF) is a fundamental astrophysical quantity that impacts a wide range of astrophysical problems from heavy element distribution to galactic evolution to planetary system formation. However, the origin and…

Solar and Stellar Astrophysics · Physics 2017-01-11 S. S. R. Offner

Observations of both galaxies in the distant Universe and local starbursts are showing increasing evidence for very hard ionizing spectra that stellar population synthesis models struggle to reproduce. Here we explore the effects of the…

Astrophysics of Galaxies · Physics 2019-01-23 E. R. Stanway , J. J. Eldridge

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

We present orbit-based dynamical models and stellar population analysis of galaxy SDSS J151741.75-004217.6, a low-redshift (z=0.116) early-type galaxy (ETG) which, for its moderate luminosity, has an exceptionally high velocity dispersion.…

The Initial Mass Function (IMF) for massive galaxies can be constrained by combining stellar dynamics with strong gravitational lensing. However, this method is limited by degeneracies between the density profile of dark matter and the…

The aim of this paper is to quantify the amplitude of the predicted plateau in [alpha/Fe] ratios associated with the most metal-poor stars of a galaxy. We assume that the initial mass function in galaxies is steeper if the star formation…

Astrophysics of Galaxies · Physics 2015-06-17 S. Recchi , F. Calura , B. K. Gibson , P. Kroupa

Statistical sampling from the stellar initial mass function (IMF) for all star-forming regions in the Galaxy would lead to the prediction of ~1000 Msun stars unless there is a rapid turn-down in the IMF beyond several hundred solar masses.…

Astrophysics · Physics 2009-10-31 Bruce G. Elmegreen

We present a new approach in the study of the Initial Mass function (IMF) in external galaxies based on quasar microlensing observations. We use measurements of quasar microlensing magnifications in 24 lensed quasars to estimate the average…

Astrophysics of Galaxies · Physics 2019-11-05 J. Jiménez-Vicente , E. Mediavilla

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…

Astrophysics of Galaxies · Physics 2015-06-23 G. Chabrier , P. Hennebelle , P. Charlot

Growing evidence suggests that the stellar initial mass function (IMF) varies systematically across galaxies, deviating from the canonical Milky Way form. Such variations would modify the integrated nucleosynthetic yields, and hence the…

In the last decade, growing evidence has emerged supporting a non-universal stellar Initial Mass Function (IMF) in massive galaxies, with a larger number of dwarf stars with respect to the Milky-Way (bottom-heavy IMF). However, a consensus…

It has been shown recently that the dynamical V-band mass-to-light ratios of compact stellar systems with masses from 10^6 to 10^8 Solar masses are not consistent with the predictions from simple stellar population (SSP) models. Top-heavy…

Astrophysics of Galaxies · Physics 2010-02-25 J. Dabringhausen , P. Kroupa , H. Baumgardt

Many results in modern astrophysics rest on the notion that the Initial Mass Function (IMF) is universal. Our observations of HI selected galaxies in the light of H-alpha and the far-ultraviolet (FUV) challenge this notion. The flux ratio…