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Related papers: Lighting the dark molecular gas: H$_{2}$ as a dire…

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Hot ionized interstellar medium interlinks star formation and stellar feedback processes, redistributing energy, momentum, and material throughout galaxies. We use X-ray data from $Chandra$ to extract the hot gas emission from 78 of the…

Astrophysics of Galaxies · Physics 2025-09-01 Chunyi Zhang , Junfeng Wang

There is a robust polyatomic chemistry in diffuse, partially-molecular interstellar gas that is readily accessible in absorption at radio/mm/sub-mm wavelengths. Accurate column densities are derived owing to the weak internal excitation, so…

Astrophysics of Galaxies · Physics 2023-02-15 Harvey Liszt , Maryvonne Gerin

The relative abundances of atomic and molecular species in planet-forming disks around young stars provide important constraints on photochemical disk models and provide a baseline for calculating disk masses from measurements of trace…

Solar and Stellar Astrophysics · Physics 2015-06-22 Kevin France , Gregory J. Herczeg , Matthew McJunkin , Steven V. Penton

Using IRAM 30m, SEST 15m, and Nancay radiotelescopes, we have gathered the 1mm continuum emission, spectra of the J=1--0 CO line and of the HI line at 21cm for two samples of IRAS galaxies. Using these data, we have estimated the HI masses,…

Astrophysics · Physics 2016-08-30 Paola Andreani , Fabienne Casoli , Maryvonne Gerin

We aim to derive the electron temperature Te in the gas of metal-rich star-forming galaxies, which can be obtained from their ratios of auroral lines [O II]7320,7330 to nebular lines [O II]3727, in order to establish a more robust…

Astrophysics · Physics 2009-11-13 Y. C. Liang , F. Hammer , S. Y. Yin , H. Flores , M. Rodrigues , Yanbin Yang

There is now strong evidence suggesting that the 12CO J = 1-0 transition, widely used to trace H2 gas, significantly underestimates its mass in metal-poor regions. In spiral disks such regions are found in large galactocentric distances…

Astrophysics · Physics 2009-11-07 P. P. Papadopoulos , W. -F. Thi , S. Viti

We investigate the atomic (HI) and molecular (H_2) Hydrogen content of normal galaxies by combining observational studies linking galaxy stellar and gas budgets to their host dark matter (DM) properties, with a physically grounded galaxy…

Astrophysics of Galaxies · Physics 2010-05-25 M. Cook , C. Evoli , E. Barausse , G. L. Granato , A. Lapi

We use a suite of hydrodynamics simulations of the interstellar medium (ISM) within a galactic disk, which include radiative transfer, a non-equilibrium model of molecular hydrogen, and a realistic model for star formation and feedback, to…

Astrophysics of Galaxies · Physics 2024-05-07 Ava Polzin , Andrey V. Kravtsov , Vadim A. Semenov , Nickolay Y. Gnedin

We combine the latest observationally motivated constraints on stellar properties in dark matter haloes, along with data-driven predictions for the atomic (HI) and molecular (H$_2$) gas evolution in galaxies, to derive empirical…

Astrophysics of Galaxies · Physics 2020-06-10 Hamsa Padmanabhan , Abraham Loeb

Almost all the physics of star formation critically depends on the number density of the molecular gas. However, the methods to estimate this key property often rely on uncertain assumptions about geometry, depend on overly simplistic…

Astrophysics of Galaxies · Physics 2025-06-04 A. Giannetti , S. Leurini , E. Schisano , V. Casasola , T. G. S. Pillai , C. Sanna , S. Ferrada-Chamorro

We analyze $Chandra$ observations of the hot atmospheres of 40 early spiral and elliptical galaxies. Using new temperature, density, cooling time, and mass profiles, we explore relationships between their hot atmospheres and cold molecular…

Astrophysics of Galaxies · Physics 2020-01-08 Iu. V. Babyk , B. R. McNamara , P. D. Tamhane , P. E. J. Nulsen , H. R. Russell , A. C. Edge

We report the results of initial FUSE observations of molecular hydrogen (H2) in translucent clouds. These clouds have greater optical depth than any of the diffuse clouds previously observed for far-UV H2 absorption, and provide new…

Emission from the pure rotational transitions of H$_2$ traces warm molecular gas, providing insight into its temperature distribution and local heating conditions. We have extended previous power-law H$_2$ temperature models to account for…

We study the connection of star formation to atomic (HI) and molecular hydrogen (H$_2$) in isolated, low metallicity dwarf galaxies with high-resolution ($m_{\rm gas}$ = 4 M$_\odot$, $N_{\rm ngb}$ = 100) SPH simulations. The model includes…

Astrophysics of Galaxies · Physics 2016-03-23 Chia-Yu Hu , Thorsten Naab , Stefanie Walch , Simon C. O. Glover , Paul C. Clark

We report on strong H2 and CO absorption from gas within the host galaxy of gamma-ray burst (GRB) 080607. Analysis of our Keck/LRIS afterglow spectrum reveals a very large HI column density (NHI = 10^22.70 cm^-2) and strong metal-line…

We present numerical computations and analysis of atomic to molecular (HI-to-H$_2$) transitions in cool ($\sim$100 K) low-metallicity dust-free (primordial) gas, in which molecule formation occurs via cosmic-ray driven negative ion…

Astrophysics of Galaxies · Physics 2021-10-27 Amiel Sternberg , Alon Gurman , Shmuel Bialy

We present an initial result from the 12CO (J=1-0) survey of 79 galaxies in 62 local luminous and ultra-luminous infrared galaxy (LIRG and ULIRG) systems obtained using the 45 m telescope at the Nobeyama Radio Observatory. This is the…

Aims: We searched for the molecular outflows from fifteen molecular clouds associated with ultra-compact and compact HII (UCHII/HII) regions and discussed possible gas heating mechanism. Methods: Mapping observations of CO $J=3-2$ and…

Astrophysics · Physics 2009-11-13 Sheng-Li Qin , Jun-Jie Wang , Gang Zhao , Martin Miller , Jun-Hui Zhao

We present CO velocity fields and rotation curves for a sample of nearby galaxies, based on data from the HERACLES survey. We combine our data with literature THINGS, SINGS and KINGFISH results to provide a comprehensive sample of mass…

Astrophysics of Galaxies · Physics 2016-04-06 Bradley S. Frank , W. J. G. de Blok , F. Walter , A. Leroy , C Carignan

Using a source selection biased towards high mass star forming regions, we used a Large Velocity Gradient (LVG) code to calculate the H2 densities and CS column densities for a sample of Midcourse Space Experiment (MSX) 8 micron infrared…

Astrophysics of Galaxies · Physics 2015-05-13 David Gibson , Rene Plume , Edwin Bergin , Sarah Ragan , Natalie Evans