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We present cosmological, radiation-hydrodynamics simulations of galaxy formation during the epoch of reionization in an effort towards modelling the interstellar medium (ISM) and interpreting ALMA observations. Simulations with and without…

Astrophysics of Galaxies · Physics 2018-05-02 Harley Katz , Taysun Kimm , Debora Sijacki , Martin Haehnelt

We carried out synthetic observations of interstellar atomic hydrogen at 21cm wavelength by utilizing the magneto-hydrodynamical numerical simulations of the inhomogeneous turbulent interstellar medium (ISM) Inoue and Inutsuka (2012). The…

New 21cm observations with the Green Bank Telescope show that a significant fraction of the HI in the inner Galaxy's halo 1 kpc from the midplane exists in the form of discrete clouds. Some look very much like a Spitzer ``standard'' diffuse…

Astrophysics · Physics 2007-05-23 Felix J. Lockman

The observed flaring of HI disk in the outer region of galaxies has been used in the past to determine the shape of the dark matter halo. Previous studies based on this concept suggest a slightly oblate halo (axis ratio ~ 0.8) for our…

Astrophysics · Physics 2009-11-11 C. A. Narayan , K. Saha , C. J. Jog

We have obtained deep, high spatial and spectral resolution, long-slit spectra of the Halpha nebulae in the cool cores of 9 galaxy clusters. This sample provides a wealth of information on the ionization state, kinematics, and reddening of…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Michael McDonald , Sylvain Veilleux , David S. N. Rupke

The Milky Way's million degree gaseous halo contains a considerable amount of mass that, depending on its structural properties, can be a significant mass component. In order to analyze the structure of the Galactic halo, we use XMM-Newton…

Astrophysics of Galaxies · Physics 2015-06-15 Matthew Miller , Joel Bregman

We study the IR emission from flared disks with and without additional optically thin halos. Flux calculations of a flared disk in vacuum can be considered a special case of the more general family of models in which the disk is imbedded in…

Astrophysics · Physics 2009-11-10 Dejan Vinkovic , Zeljko Ivezic , Anatoly S. Miroshnichenko , Moshe Elitzur

We use a large N-body simulation to examine the detectability of HI in emission at redshift z ~ 1, and the constraints imposed by current observations on the neutral hydrogen mass function of galaxies at this epoch. We consider three…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Nishikanta Khandai , Shiv K. Sethi , Tiziana Di Matteo , Rupert A. C. Croft , Volker Springel , Anirban Jana , Jeffrey P. Gardner

We report on a comparison between 21 cm rotation measure (RM) and the optically-thin atomic hydrogen column density (N_HI) measured towards unresolved extragalactic sources in the Galactic plane of the northern sky. HI column densities…

Astrophysics of Galaxies · Physics 2015-06-16 Tyler Foster , Roland Kothes , Joanne Brown

We present Atacama Large Millimeter/sub-millimeter Array (ALMA) neutral carbon, [C I](1-0), line observations that probe molecular hydrogen gas (H$_2$) within seven radio galaxies at $z = 2.9 - 4.5$ surrounded by extended ($\gtrsim100$ kpc)…

Astrophysics of Galaxies · Physics 2023-09-04 S. Kolwa , C. De Breuck , J. Vernet , D. Wylezalek , W. Wang , G. Popping , A. W. S. Man , C. M. Harrison , P. Andreani

We explore theoretical models of the ionization ratios of the Li-like absorbers NV, OVI, and CIV, in the Galactic halo. These ions are believed to form in nonequilibrium processes such as shocks, evaporative interfaces, or rapidly cooling…

Astrophysics · Physics 2009-11-10 Remy Indebetouw , J. Michael Shull

This paper presents the study of the interstellar medium toward beta CMa, a disk sight-line known for its low neutral gas density. This study uses high and medium resolution HST-GHRS spectra including lines from many species. The line of…

Astrophysics · Physics 2016-08-30 O. Dupin , C. Gry

Various scenarios have been proposed to explain the origin of the Galactic high-velocity clouds, predicting different distances and implying widely varying properties for the Galaxy's gaseous halo. To eliminate the difficulties of studying…

Astrophysics · Physics 2007-05-23 Eric D. Miller , Joel N. Bregman

We study the column densities of neutral atomic, molecular, and warm ionized Galactic gas through their continuous absorption of extragalactic X-ray spectra at |b| > 25 degrees. For N(H,21cm) < 5x10^20 cm^-2 there is an extremely tight…

Astrophysics · Physics 2014-10-13 John S. Arabadjis , Joel N. Bregman

The interstellar medium (ISM) consists of highly ionized and neutral atomic, as well as molecular, components. Knowledge of their distribution is important for tracing the structure and lifecycle of the ISM. Here we determine the properties…

Astrophysics of Galaxies · Physics 2016-05-25 W. D. Langer , P. F. Goldsmith , J. L. Pineda

Star formation feedback can drive large-scale, multi-phase galactic outflows. The dynamical and thermodynamical interaction between the hot and cooler phases is a prime focus of both observational and theoretical work. Here, we analyze…

Astrophysics of Galaxies · Physics 2025-08-11 Sebastian Lopez , Laura A. Lopez , Todd A. Thompson , Adam K. Leroy , Alberto D. Bolatto

The extended hot X-ray emitting gaseous halo of the Milky Way has an optical depth $\sim1$ for the dominant emission lines of \ion{O}{7} and \ion{O}{8}, which are used to infer the halo properties. To improve on halo gas properties, we…

Astrophysics of Galaxies · Physics 2017-11-15 Yunyang Li , Joel Bregman

High velocity gas that does not conform to Galactic rotation is observed throughout the Galaxy's halo. One component of this gas, HI high velocity clouds (HVCs), have attracted attention since their discovery in the 1960s and remain…

Astrophysics of Galaxies · Physics 2017-08-24 Asger Grønnow , Thor Tepper-García , Joss Bland-Hawthorn , Naomi McClure-Griffiths

The Epoch of Reionization marks the last major phase transition in the early Universe, during which the majority of neutral hydrogen once filling the intergalactic medium was ionized by the first galaxies. The James Webb Space Telescope…

Instrumentation and Methods for Astrophysics · Physics 2026-01-01 Cody Carr , Renyue Cen , Brian Fleming , Sophia Flury , Stephan McCandliss , Sally Oey , Allison Strom

We show that most particle and subhalo orbits in simulated cosmological cold dark matter halos are surprisingly regular and periodic: The phase space structure of the outer halo regions shares some of the properties of the classical…

Astrophysics · Physics 2009-11-13 J. Diemand , M. Kuhlen