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The long gamma ray bursts (GRBs) may arise from the core collapse of massive stars. However, the long GRB rate does not follow the star formation rate (SFR) at high redshifts. In this Letter, we focus on the binary merger model and consider…

High Energy Astrophysical Phenomena · Physics 2017-11-15 Tomoya Kinugawa , Katsuaki Asano

Future missions for long gammma-ray burst (GRB) observations at high redshift such as HiZ-GUNDAM and THESEUS will provide clue to the star formation history in our universe. In this paper focusing on high redshift (z>8) GRBs, we calculate…

High Energy Astrophysical Phenomena · Physics 2019-06-26 Tomoya Kinugawa , Yuichi Harikane , Katsuaki Asano

The James Webb Space Telescope (JWST) has uncovered an abundance of $z>10$ galaxies bright in the ultraviolet (UV) that has challenged traditional theoretical models at high redshifts. Recently, various new models have emerged to address…

Astrophysics of Galaxies · Physics 2025-02-19 Anne Hutter , Elie R Cueto , Pratika Dayal , Stefan Gottlöber , Maxime Trebitsch , Gustavo Yepes

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

We use a new method of analysis to determine parameters of cosmological gamma-ray bursts (GRBs), assuming that their distribution follows the star-formation history of the universe. Spectral evolution is calculated from an external shock…

Astrophysics · Physics 2015-06-24 M. Boettcher , C. D. Dermer

We present a carefully selected sub-sample of Swift Long Gamma-ray Bursts (GRBs), that is complete in redshift. The sample is constructed by considering only bursts with favorable observing conditions for ground-based follow-up searches,…

The initial mass function (IMF) succinctly characterizes a stellar population, provides a statistical measure of the end result of the star-formation process, and informs our under- standing of the structure and dynamical evolution of…

Solar and Stellar Astrophysics · Physics 2011-07-25 Kevin R. Covey , Nate Bastian , Michael R. Meyer

We model the mass distribution of long gamma-ray burst (GRB) host galaxies given recent results suggesting that GRBs occur in low metallicity environments. By utilizing measurements of the redshift evolution of the mass-metallicity (M-Z)…

Cosmology and Nongalactic Astrophysics · Physics 2009-08-17 Daniel Kocevski , Andrew A. West , Maryam Modjaz

Studies of the cosmic gamma-ray bursts (GRBs) and their host galaxies are starting to provide interesting or even unique new insights in observational cosmology. GRBs represent a new way of identifying a population of star-forming galaxies…

The observed distribution of IMF shapes can be understood as statistical sampling from a universal IMF and variations that result from stellar-dynamical processes. However, young star clusters appear to have an IMF biased towards low-mass…

Astrophysics · Physics 2007-05-23 Pavel Kroupa

We use the BD2 sample of gamma-ray bursts (GRBs) based on 5.9 years of BATSE DISCLA data with a variety of models of the luminosity function to derive characteristic GRB luminosities, space densities and redshift distributions. Previously…

Astrophysics · Physics 2009-10-31 Maarten Schmidt

In our previous work, we derive the CR-IGIMF: a new scenario for a variable stellar initial mass function (IMF), which combines numerical results on the role played by cosmic rays in setting the thermal state of star forming gas, with the…

An essential component of galaxy formation theory is the stellar initial mass function (IMF), that describes the parent distribution of stellar mass in star forming regions. We present observational evidence in a sample of early-type…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 I. Ferreras , F. La Barbera , R. R. de Carvalho , I. G. de la Rosa , A. Vazdekis , J. Falcon-Barroso , E. Ricciardelli

Due to their highly luminous nature, gamma-ray bursts (GRBs) are useful tools in studying the early Universe (up to z = 10). We consider whether the available subset of Swift high redshift GRBs are unusual when compared to analogous…

High Energy Astrophysical Phenomena · Physics 2013-08-27 O. M. Littlejohns , N. R. Tanvir , R. Willingale , P. T. O'Brien , P. A. Evans , A. J. Levan

The immense power of gamma-ray bursts (GRBs) make them ideal probes of the early universe. By using absorption lines in the afterglows of high-redshift GRBs, astronomers can study the evolution of metals in the early universe. With an…

High-redshift gamma-ray bursts (GRBs), putative counterparts of massive, low-metallicity Population III (Pop III) stars, are a promising probe of the first stars. We assess the detectability of these Pop III GRBs using a metallicity-based…

High Energy Astrophysical Phenomena · Physics 2025-12-05 Jun-Jie Wei , Qing-Bo Ma , Xue-Feng Wu

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

We investigate the cosmological evolution of the luminosity and redshift of FRBs. As is the case for all extragalactic sources, we are dealing with data that are truncated by observational selection effects, the most important being the…

Cosmology and Nongalactic Astrophysics · Physics 2025-08-05 Sujay Champati , Vahé Petrosian

With its rapid-response capability and multiwavelength complement of instruments, the Swift satellite has transformed our physical understanding of gamma-ray bursts (GRBs). Providing high-quality observations of hundreds of bursts, and…

High Energy Astrophysical Phenomena · Physics 2014-11-20 N. Gehrels , E. Ramirez-Ruiz , D. B. Fox

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