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Radiative processes play a pivotal role in shaping the thermal and chemical states of gas across diverse astrophysical environments, from the interstellar medium (ISM) to the intergalactic medium. We present a hybrid cooling model for…

The GMRT observations of the HI 21~cm-line emission from 13~nearby dwarf star-forming galaxies are presented. The ranges of star formation rates and stellar masses of the sample galaxies are 0.03 -- 1.7~$M_\odot~{\rm yr}^{-1}$ and 0.04 --…

Astrophysics of Galaxies · Physics 2020-09-09 Sumit Jaiswal , Amitesh Omar

Using cosmological simulations that incorporate gas dynamics and gravitational forces, we investigate the influence of photoionization by a UV radiation background on the formation of galaxies. In our highest resolution simulations, we find…

Astrophysics · Physics 2009-10-28 David H. Weinberg , Lars Hernquist , Neal Katz

We study dwarf galaxy formation at high redshift ($z\ge5$) using a suite of high- resolution, cosmological hydrodynamic simulations and a semi-analytic model (SAM). We focus on gas accretion, cooling and star formation in this work by…

Cosmology and Nongalactic Astrophysics · Physics 2018-08-07 Yuxiang Qin , Alan R. Duffy , Simon J. Mutch , Gregory B. Poole , Paul M. Geil , Andrei Mesinger , J. Stuart B. Wyithe

We present our recently developed 3-dimensional chemodynamical code for galaxy evolution. It follows the evolution of all components of a galaxy such as dark matter, stars, molecular clouds and diffuse interstellar matter (ISM). Dark matter…

Astrophysics · Physics 2007-05-23 P. Berczik , G. Hensler , Ch. Theis , R. Spurzem

Here we investigate an exemplary chemodynamical evolutionary simulation of a dwarf irregular galaxy. By means of this model we demonstrate the existence of three gas mixing cycles: 1) An inner "local cycle" mixing the metals produced in…

Astrophysics · Physics 2008-11-26 Andreas Rieschick , Gerhard Hensler

The dissociation and subsequent ionisation of molecular material in a detached, spherically symmetric stellar wind is modelled as a star evolves from the post-asymptotic giant branch phase to a planetary nebula (i.e. from a stellar…

Astrophysics · Physics 2015-06-24 G. T. Gussie , A. R. Taylor , P. E. Dewdney , R. S. Roger

We compare the gas distribution, kinematics and the current star formation in a sample of 10 very faint (-13.37 < M_B < -9.55) dwarf galaxies. For 5 of these galaxies we present fresh, high sensitivity, GMRT HI 21cm observations. For all…

Nearby dwarf irregular galaxies are ideal laboratories for studying the interstellar medium (ISM) at low metallicity, which is expected to be common for galaxies at very high redshift being observed by the James Webb Space Telescope. We…

Astrophysics of Galaxies · Physics 2023-08-02 Chia-Yu Hu , Amiel Sternberg , Ewine F. van Dishoeck

We study the ionization and thermal evolution of the intergalactic medium during the epoch of \heii reionization by means of radiation hydrodynamical cosmological simulations. We post-process baryonic density fields from a standard…

Astrophysics · Physics 2007-11-14 Pascal Paschos , Michael L. Norman , James O. Bordner , Robert Harkness

We use a large sample of galaxies at z~3 to establish a relationship between reddening, neutral gas covering fraction (fcov(HI)), and the escape of ionizing photons at high redshift. Our sample includes 933 galaxies at z~3, 121 of which…

Astrophysics of Galaxies · Physics 2016-09-21 Naveen A. Reddy , Charles C. Steidel , Max Pettini , Milan Bogosavljevic , Alice Shapley

The excursion set reionization framework is widely used, due to its speed and accuracy in reproducing the 3D topology of reionization. However, it is known that it does not conserve photon number. Here, we introduce an efficient, on-the-fly…

Cosmology and Nongalactic Astrophysics · Physics 2022-10-05 Jaehong Park , Bradley Greig , Andrei Mesinger

We study structure formation in cosmological void regions using high-resolution hydrodynamical simulations. Despite being significantly underdense, voids are populated abundantly with small dark matter halos which should appear as dwarf…

Astrophysics · Physics 2009-11-10 Matthias Hoeft , Gustavo Yepes , Stefan Gottloeber , Volker Springel

We present our recently developed 3-dimensional chemodynamical code for galaxy evolution. This code follows the evolution of different galactic components like stars, dark matter and different components of the interstellar medium (ISM),…

Astrophysics · Physics 2009-11-07 P. Berczik , G. Hensler , Ch. Theis , R. Spurzem

We analyze circumgalactic medium (CGM) in a suite of high-resolution cosmological re-simulations of a Milky-Way size galaxy and show that CGM properties are quite sensitive to details of star formation--feedback loop modelling. The…

Astrophysics of Galaxies · Physics 2016-03-09 Cameron J. Liang , Andrey V. Kravtsov , Oscar Agertz

Using the full, three-dimensional potential of galaxy cluster halos (drawn from an N-body simulation of the current, most favored cosmology), the distribution of the X-ray emitting gas is found by assuming a polytropic equation of state and…

Astrophysics · Physics 2011-02-11 Paul Bode , Jeremiah P. Ostriker , Jochen Weller , Laurie Shaw

The ionizing photon production efficiency, $\xi_{ion}$, is a critical parameter that provides a number of physical constraints to the nature of the early Universe, including the contribution of galaxies to the timely completion of the…

A thorough analysis of well studied giant HII regions on galactic discs for which we know the ionizing stellar population, the gas metallicity and the Wolf-Rayet population, leads to photoionization models which can only match all observed…

Astrophysics · Physics 2007-05-23 M. Castellanos , A. I. Diaz , G. Tenorio-Tagle

High-resolution numerical simulations including feedback and aimed at calculating the escape fraction (fesc) of hydrogen-ionizing photons often assume stellar radiation based on single-stellar population synthesis models. However, strong…

Astrophysics of Galaxies · Physics 2020-09-30 Amy Secunda , Renyue Cen , Taysun Kimm , Ylva Gotberg , Selma E. de Mink

We demonstrate a new method for measuring the escape fraction of ionizing photons using Hubble Space Telescope imaging of resolved stars in NGC 4214, a local analog of high-redshift starburst galaxies that are thought to be responsible for…