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(abridged) The case can be made for a rather universal stellar IMF form that can be approximated by a two-part power-law function in the stellar regime. However, there exists a possible hint for a systematic variation with metallicity. A…

Astrophysics · Physics 2007-05-23 Pavel Kroupa

We present the results of numerical experiments designed to evaluate the usefulness of near-infrared luminosity functions for constraining the Initial Mass Function (IMF) of young stellar populations. From this numerical modeling, we find…

Astrophysics · Physics 2009-10-31 August A. Muench , Elizabeth A. Lada , Charles J. Lada

The hypothesis of a universal initial mass function (IMF) -- motivated by observations in nearby stellar systems -- has been recently challenged by the discovery of a systematic variation of the IMF with the central velocity dispersion,…

We present new evidence for a variable stellar initial mass function (IMF) in massive early-type galaxies, using high-resolution, near-infrared spectroscopy from the Folded-port InfraRed Echellette spectrograph (FIRE) on the Magellan Baade…

Recent results suggest that the initial mass function (IMF) of globular clusters (GCs) is metallicity and density dependent. Here it is studied how this variation affects the initial masses and the numbers of core collapse supernovae…

Astrophysics of Galaxies · Physics 2022-09-21 Henriette Wirth , Pavel Kroupa , Jaroslav Haas , Tereza Jerabkova , Zhiqiang Yan , Ladislav Šubr

Aims. We study how IMF sampling affects the ionizing flux and emission line spectra of low mass stellar clusters. Methods. We performed 2 x 10^6 Monte Carlo simulations of zero-age solar-metallicity stellar clusters covering the 20 - 10^6…

Cosmology and Nongalactic Astrophysics · Physics 2013-07-02 Marcos Villaverde , Miguel Cervino , Valentina Luridiana

The initial mass function (IMF) is an essential tool with which to study star formation processes. We have initiated the photometric survey of young open clusters in the Galaxy, from which the stellar IMFs are obtained in a homogeneous way.…

Astrophysics of Galaxies · Physics 2015-11-05 Beomdu Lim , Hwankyung Sung , Hyeonoh Hur , Byeong-Gon Park

The stellar initial mass function (IMF) regulates the baryonic cycle within galaxies, and is a key ingredient to translate observations into physical quantities. Although for decades it was assumed to be universal, there is now growing…

The stellar initial mass function (IMF) is expressed by $\phi(m) \propto m^{-\alpha}$ with the slope $\alpha$, and known as the poorly-constrained but very important function in studies of star and galaxy formation. There are no sensible…

Astrophysics of Galaxies · Physics 2023-04-13 Shohei Aoyama , Masami Ouchi , Yuichi Harikane

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

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…

A robust stellar initial mass function (IMF) is crucial in any studies related to star formation. However, the direct measurement of the stellar IMF is confined to the local universe, limited by the resolving power of telescopes. Recently,…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-12 Sung Kei Li

We present a new technique for the determination of the low-mass slope ($\alpha_1$; $M_* < 0.5 M_{\odot}$) of the present day stellar mass function (PDMF) using the pixel space fitting of integrated light spectra. It can be used to…

Instrumentation and Methods for Astrophysics · Physics 2015-06-15 Nikolay Podorvanyuk , Igor Chilingarian , Ivan Katkov

Deviations from a universal, MW-like, Stellar Initial Mass Function (IMF) have been reported for distant galaxies, although the physical reason behind the observed variations is still matter of ongoing debate. In this paper, we present an…

Astrophysics of Galaxies · Physics 2015-06-19 Fabio Fontanot

The combination of stellar population synthesis models and photoionization models allows a better understanding of the spectral features of HII regions and HII galaxies. In this work we show that sampling effects in the initial mass…

Astrophysics · Physics 2009-12-04 M. Villaverde , V. Luridiana , M. Cervino

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

Peaks and lulls in the star formation rate (SFR) over the history of the Galaxy produce plateaux and declines in the present day mass function (PDMF) where the main-sequence lifetime overlaps the age and duration of the SFR variation. These…

Astrophysics · Physics 2009-11-13 Bruce G. Elmegreen , John Scalo

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 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

Context: The Initial Mass Function (IMF) plays a crucial role on galaxy evolution and its implications on star formation theory make it a milestone for the next decade. It is in the intermediate and high mass ranges where the uncertainties…

Astrophysics of Galaxies · Physics 2018-10-09 R. Mor , A. C. Robin , F. Figueras , B. Lemasle