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Research on the high-mass end of the initial mass function (IMF) has been limited due to a scarcity of samples. Recently, Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST), as the most efficient spectroscopic telescope, has…

星系天体物理 · 物理学 2025-05-21 Qida Li , Jianping Xiong , Zhenwei Li , Dan Qiu , Chao Liu , Zhanwen Han , Xuefei Chen

We perform a series of three-dimensional, magnetohydrodynamical (MHD) simulations of star cluster formation including gravity, turbulence, magnetic fields, stellar radiative heating and outflow feedback. We observe that the inclusion of…

星系天体物理 · 物理学 2021-08-25 Sajay Sunny Mathew , Christoph Federrath

The stellar initial mass function (IMF) is commonly interpreted to be a scale-invariant probability density distribution function (PDF) such that many small clusters yield the same IMF as one massive cluster of the same combined number of…

星系天体物理 · 物理学 2023-02-22 Zhiqiang Yan , Tereza Jerabkova , Pavel Kroupa

We describe the use of our chemical evolution model to reproduce the abundance patterns observed in a catalog of elliptical galaxies from the SDSS DR4. The model assumes ellipticals form by fast gas accretion, and suffer a strong burst of…

星系天体物理 · 物理学 2018-01-10 Carlo Maria De Masi , Francesca Matteucci , Fiorenzo Vincenzo

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…

星系天体物理 · 物理学 2023-04-13 Shohei Aoyama , Masami Ouchi , Yuichi Harikane

The current knowledge on the stellar IMF is documented. It appears to become top-heavy when the star-formation rate density surpasses about 0.1Msun/(yr pc^3) on a pc scale and it may become increasingly bottom-heavy with increasing…

宇宙学与河外天体物理 · 物理学 2015-06-03 Pavel Kroupa , Carsten Weidner , Jan Pflamm-Altenburg , Ingo Thies , Joerg Dabringhausen , Michael Marks , Thomas Maschberger

Some ultra-compact dwarf galaxies have large dynamical mass to light (M/L) ratios and also appear to contain an overabundance of LMXB sources, and some Milky Way globular clusters have a low concentration and appear to have a deficit of…

星系天体物理 · 物理学 2020-03-18 Pavel Kroupa

We determine an absolute calibration of stellar mass-to-light ratios for the densest \simeq 3% of early-type galaxies in the local universe (redshift z\simeq 0.08) from SDSS DR7. This sample of \sim 4000 galaxies has, assuming a Chabrier…

宇宙学与河外天体物理 · 物理学 2015-06-03 Aaron A. Dutton , J. Trevor Mendel , Luc Simard

In this work we explore the effects of adopting initial mass functions (IMFs) variable in time on the chemical evolution of the Galaxy. In order to do that we adopt a chemical evolution model which assumes two main infall episodes for the…

天体物理学 · 物理学 2009-10-31 Cristina Chiappini , Francesca Matteucci , Paolo Padoan

It is difficult to reconcile the observed evolution of the star formation rate versus stellar mass (SFR-M*) relation with expectations from current hierarchical galaxy formation models. The observed SFR-M* relation shows a rapid rise in…

宇宙学与河外天体物理 · 物理学 2010-09-01 Romeel Davé

Accurate specification of a likelihood function is becoming increasingly difficult in many inference problems in astronomy. As sample sizes resulting from astronomical surveys continue to grow, deficiencies in the likelihood function lead…

天体物理仪器与方法 · 物理学 2019-04-26 Jessi Cisewski-Kehe , Grant Weller , Chad Schafer

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…

天体物理学 · 物理学 2009-11-13 Bruce G. Elmegreen , John Scalo

Observed variations in the IMF are reviewed with an emphasis on environmental density. The remote field IMF studied in the LMC by several authors is clearly steeper than most cluster IMFs, which have slopes close to the Salpeter value.…

天体物理学 · 物理学 2015-11-11 Bruce G. Elmegreen

This work aims to study the distribution of luminous and dark matter in Coma early-type galaxies. Dynamical masses obtained under the assumption that mass follows light do not match with the masses of strong gravitational lens systems of…

宇宙学与河外天体物理 · 物理学 2015-05-27 J. Thomas , R. P. Saglia , R. Bender , D. Thomas , K. Gebhardt , J. Magorrian , E. M. Corsini , G. Wegner , S. Seitz

The stellar initial mass function (IMF) is commonly assumed to be an invariant probability density distribution function of initial stellar masses being represented by the canonical IMF. As a consequence the galaxy-wide IMF (gwIMF), defined…

星系天体物理 · 物理学 2018-11-28 T. Jerabkova , A. H. Zonoozi , P. Kroupa , G. Beccari , Z. Yan , A. Vazdekis , Z. -Y. Zhang

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…

When calculating IMFs for young clusters, one has to take into account that (a) most massive stars are born in multiple systems (b) most IMFs are derived from data that cannot resolve such systems, and (c) multiple chance superpositions…

天体物理学 · 物理学 2009-11-13 J. Maíz Apellániz

Massive stars define the upper limits of the star formation process, dominate the energetics of their local environs, and significantly affect the chemical evolution of galaxies. Their role in starburst galaxies and the early Universe is…

天体物理学 · 物理学 2015-11-11 Donald F. Figer

The distribution of stellar masses that form in one star-formation event in a given volume of space is called the initial mass function (IMF). The IMF has been estimated from low-mass brown dwarfs to very massive stars. Combining IMF…

天体物理学 · 物理学 2009-11-07 Pavel Kroupa

We investigated a volume-limited sample of LAMOST main-sequence stars with masses from 0.25 to 1 $M_{\odot}$ and distances of 150-350 pc to explore how the stellar initial mass function (IMF) varies with metallicity. We corrected the…

太阳与恒星天体物理 · 物理学 2025-11-07 Dan Qiu , Chao Liu , Jennifer A. Johnson , Jiadong Li , Bo Zhang