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The integrated galaxial initial mass function (IGIMF) is the relevant distribution function containing the information on the distribution of stellar remnants, the number of supernovae and the chemical enrichment history of a galaxy. Since…

Astrophysics · Physics 2009-11-10 C. Weidner , P. Kroupa

We present a pilot method to estimate the high-mass initial mass function (IMF) across the arm, interarm, and spur regions in galaxies and apply it to NGC 628. We extracted star-forming complexes (SFCs) from H$\alpha$ VLT/MUSE and UVIT (FUV…

Astrophysics of Galaxies · Physics 2025-06-24 S Amrutha , Mousumi Das

We examine whether existing data in clusters, both old and young, and in the field of the Galactic disk and halo is consistent with a universal slope for the initial mass function (IMF). The most reasonable statement that can be made at the…

Astrophysics · Physics 2009-10-28 Harvey B. Richer , Gregory G. Fahlman

It is frequently debated in literature whether a "standard" Initial Mass Function (IMF) - meaning an IMF of the kind usually adopted to explain the chemical evolution in the local Solar Neighbourhood - can account for the observed metal…

Astrophysics · Physics 2009-11-10 L. Portinari , A. Moretti , C. Chiosi , J. Sommer-Larsen

It has been shown before that the high mass-to-light ratios of ultra compact dwarf galaxies (UCDs) can be explained if their stellar initial mass function (IMF) was top-heavy, i.e. that the IMF was skewed towards high mass stars. In this…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Jörg Dabringhausen , Pavel Kroupa , Jan Pflamm-Altenburg , Steffen Mieske

(abridged) The stellar initial mass function (IMF) can be conveniently represented as a canonical two-part power law function and is largely invariant for star formation regions evident in the Local Group of galaxies. The IMF is a…

Astrophysics of Galaxies · Physics 2018-12-27 Pavel Kroupa , Tereza Jerabkova

Crucial for star formation is the interplay between gravity and turbulence. The observed cloud virial parameter, $\alpha_{\mathrm{vir}}$, which is the ratio of twice the turbulent kinetic energy to the gravitational energy, is found to vary…

Astrophysics of Galaxies · Physics 2025-01-07 Sajay Sunny Mathew , Christoph Federrath , Amit Seta

Within a galaxy the stellar mass-to-light ratio $\Upsilon_*$ is not constant. Spatially resolved kinematics of nearby early-type galaxies suggest that allowing for a variable initial mass function (IMF) returns significantly larger…

Astrophysics of Galaxies · Physics 2018-04-11 M. Bernardi , R. K. Sheth , H. Dominguez-Sanchez , J. -L. Fischer , K. -H. Chae , M. Huertas-Company , F. Shankar

Cosmological simulations of disc galaxy formation, when compared to the observed Tully-Fisher relation, suggest a low Mass-to-Light (M/L) ratio for the stellar component in spirals. We show that a number of "bottom-light" Initial Mass…

Astrophysics · Physics 2007-05-23 L. Portinari , J. Sommer-Larsen , R. Tantalo

We measure the high-mass stellar initial mass function (IMF) from resolved stars in M33 young stellar clusters. Leveraging \textit{Hubble Space Telescope's} high resolving power, we fully model the IMF probabilistically. We first model the…

Recent observations and theories have presented a strong challenge to the universality of the stellar initial mass function (IMF) in extreme environments. A notable example has been found for starburst conditions, where evidence favours a…

Astrophysics of Galaxies · Physics 2024-05-10 Ziyi Guo , Zhi-Yu Zhang , Zhiqiang Yan , Eda Gjergo , Allison Man , R. J. Ivison , Xiaoting Fu , Yong Shi

A low mass-to-light ratio for the stellar component of spiral galaxies (M/L<1 in the I-band) is advocated by various dynamical arguments and by recent cosmological simulations of the formation of these systems. We discuss this possibility…

Astrophysics · Physics 2009-11-07 L. Portinari , J. Sommer-Larsen , R. Tantalo

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

Stars do not form continuously distributed over star forming galaxies. They form in star clusters of different masses. This nature of clustered star formation is taken into account in the theory of the integrated galactic stellar initial…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 Jan Pflamm-Altenburg , Pavel Kroupa

The rotation curves of low surface brightness (LSB) galaxies suggest that they possess significantly higher mass-to-light (M/L) ratios than their high surface brightness counterparts, indicating that LSB galaxies may be dark matter…

Astrophysics · Physics 2009-11-10 Hyun-chul Lee , Brad K. Gibson , Chris Flynn , Daisuke Kawata , Michael A. Beasley

We study the recent star formation histories (SFHs) of 575 intermediate-mass galaxies (IMGs, $10^{9} \leq M/M_{\odot} \leq 10^{10}$) in COSMOS at $0.3<z<0.4$ by comparing their H$\alpha$ and UV luminosities. These two measurements trace…

Astrophysics of Galaxies · Physics 2023-03-15 Shannon G. Patel , Daniel D. Kelson , Louis E. Abramson , Zahra Sattari , Brian Lorenz

There are various ways of measuring the slope of the upper end of the IMF. Arguably the most direct of these is to place stars on the H-R diagram and compare their positions with stellar evolutionary models. Even so, the masses one infers…

Solar and Stellar Astrophysics · Physics 2010-08-10 Philip Massey

Three component models of the IMF are made to consider possible origins for the observed relative variations in the numbers of brown dwarfs, solar-to-intermediate mass stars, and high mass stars. Three distinct physical processes are noted.…

Astrophysics · Physics 2009-11-10 Bruce G. Elmegreen

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 stellar initial mass function is of great significance for the study of star formation and galactic structure. Observations indicate that the IMF follows a power-law form. This work derived that when the expected number of stars formed…

Astrophysics of Galaxies · Physics 2025-03-20 Yu-Fu Shen