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Related papers: The Stellar Initial Mass Function at the Epoch of …

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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…

Detection of the radiation emitted from the first galaxies at z > 10 will be made possible in the next decade, with the launch of the James Webb Space Telescope (JWST). We carry out cosmological radiation hydrodynamics simulations of…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Jarrett L. Johnson , Thomas H. Greif , Volker Bromm , Ralf S. Klessen , Joseph Ippolito

Cosmological simulations of Population III star formation suggest an initial mass function (IMF) biased toward very massive stars (M>100Msun) formed in minihalos at redshift z>20, when the cooling is driven by molecular hydrogen. However,…

Astrophysics of Galaxies · Physics 2015-05-13 Michele Trenti , Michael Shull

A method is presented here for investigating variations in the upper end of the stellar Initial Mass Function (IMF) by probing the production rate of ionizing photons in unresolved, compact star clusters with ages<10 Myr and covering a…

Cosmology and Nongalactic Astrophysics · Physics 2010-10-26 Daniela Calzetti , Rupali Chandar , Janice C. Lee , Bruce G. Elmegreen , Robert C. Kennicutt , Brad C. Whitmore

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 calculate the generic spectral signature of an early population of massive stars at high redshifts. For metal-free stars in the mass range of 100-1000 solar masses, we find that the combined spectral luminosity per unit stellar mass is…

Astrophysics · Physics 2009-10-31 Volker Bromm , Rolf P. Kudritzki , Abraham Loeb

Starlight from galaxies plays a pivotal role throughout the process of cosmic reionisation. We present the statistics of dwarf galaxy properties at z > 7 in haloes with masses up to 10^9 solar masses, using a cosmological radiation…

Cosmology and Nongalactic Astrophysics · Physics 2014-07-08 John H. Wise , Vasiliy G. Demchenko , Martin T. Halicek , Michael L. Norman , Matthew J. Turk , Tom Abel , Britton D. Smith

We discuss implications of a stellar-dominated UV background at high redshifts. The composite spectrum of 29 LBGs evaluated by Steidel etal (2000) at <z>=3.4 can be well fit by a stellar population with ongoing star formation, a Salpeter…

Astrophysics · Physics 2009-10-31 Martin G. Haehnelt , Piero Madau , Rolf P. Kudritzki , Francesco Haardt

The initial mass function (IMF) is one of the most important functions in astrophysics because it is key to reconstructing the cosmological matter cycle, understanding the formation of super-massive black holes, and deciphering the light…

Astrophysics of Galaxies · Physics 2024-12-30 Pavel Kroupa , Eda Gjergo , Tereza Jerabkova , Zhiqiang Yan

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…

Astrophysics · Physics 2015-11-11 Donald F. Figer

In this contributed talk I present recent results on the connection between stellar population properties and the normalisation of the stellar initial mass function (IMF) measured using stellar dynamics, based on a large sample of 260…

Astrophysics of Galaxies · Physics 2015-06-23 Richard M. McDermid

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…

Astrophysics of Galaxies · Physics 2025-05-21 Qida Li , Jianping Xiong , Zhenwei Li , Dan Qiu , Chao Liu , Zhanwen Han , Xuefei Chen

Measurements of stellar properties of galaxies when the universe was less than one billion years old yield some of the only observational constraints of the onset of star formation. We present here the inclusion of \textit{Spitzer}/IRAC…

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…

Using varying models for the star formation rate (SFR) of Population (Pop) III and II stars at z>6 we derive the expected redshift history of the global 21 cm signal from the inter-galactic medium (IGM). To recover the observed Thomson…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-19 Hidenobu Yajima , Sadegh Khochfar

Our understanding of galaxy properties and evolution is contingent on knowing the initial mass function (IMF), and yet to date, the IMF is constrained only to local galaxies. Individual stars are now becoming routinely detected at…

We present very faint dropout galaxies at z~6-9 with a stellar mass M* down to M*~10^6Mo that are found in deep optical/near-infrared (NIR) images of the full data sets of the Hubble Frontier Fields (HFF) program in conjunction with deep…

The fraction of ionizing photons that escape their host galaxies and so are able to ionize hydrogen in the inter-galactic medium (IGM) is a critical parameter in analyses of the reionization era and early galaxy formation. Studies of the…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 Stuart Wyithe , Andrew M. Hopkins , Matthew D. Kistler , Hasan Yuksel , John F. Beacom

The stellar masses, mean ages, metallicities, and star formation histories of galaxies are now commonly estimated via stellar population synthesis (SPS) techniques. SPS relies on stellar evolution calculations from the main sequence to…

Astrophysics · Physics 2009-08-18 Charlie Conroy , James E. Gunn , Martin White

Oxygen to iron abundance ratios of metal-poor stars provide information on nucleosynthesis yields from massive stars which end in Type II supernova explosions. Using a standard model of chemical evolution of the Galaxy we have reproduced…