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In this paper we present an attempt to estimate the redshift evolution of the molecular to neutral gas mass ratio within galaxies (at fixed stellar mass). For a sample of five nearby grand design spirals located on the Main Sequence (MS) of…

Astrophysics of Galaxies · Physics 2021-01-27 Laura Morselli , Alvio Renzini , Andrea Enia , Giulia Rodighiero

We examine the abundance of molecular hydrogen (H2) in the spectra of gamma ray burst afterglows (GRBs). In nearby galaxies H2 traces the cold neutral medium (CNM) and dense molecular star-forming interstellar gas. Though H2 is detected in…

Models of hierarchical galaxy formation predict that large numbers of low-mass, dark matter halos remain around galaxies today. These models predict an order of magnitude more halos than observed stellar satellites in the Local Group. One…

Astrophysics · Physics 2009-11-10 D. J. Pisano

We derive radial and vertical distributions of HI and H2 gas densities in our Galaxy by using the terminal velocity method. We calculate the molecular fraction (f_mol) defined as the ratio of the molecular hydrogen to total hydrogen gas…

Astrophysics · Physics 2007-05-23 K. Imamura , Y. Sofue

A sample of 69 galaxies with radial velocities less than 2500 km/s was selected from the HI Parkes All Sky Survey (HIPASS) to deduce details about star formation in nearby disk galaxies selected with no bias to optical surface brightness…

Astrophysics · Physics 2009-11-11 J. F. Helmboldt , R. A. M. Walterbos , G. D. Bothun , K. O'Neil

New HI observations are presented for a complete sample of 109 low luminosity star-forming galaxies taken from the KPNO International Spectroscopic Survey (KISS), the first CCD-based wide-field objective-prism survey for emission-line…

We compare atomic gas, molecular gas, and the recent star formation rate (SFR) inferred from H-alpha in the Small Magellanic Cloud (SMC). By using infrared dust emission and local dust-to-gas ratios, we construct a map of molecular gas that…

Stars form in the dense interiors of molecular clouds. The dynamics and physical properties of the atomic interstellar medium (ISM) set the conditions under which molecular clouds and eventually stars will form. It is, therefore, critical…

We have studied a mass model for spiral galaxies in which the dark matter surface density is a scaled version of the observed HI surface density. Applying this mass model to a sample of 24 spiral galaxies with reliable rotation curves one…

Astrophysics · Physics 2009-10-31 H. Hoekstra , T. S. van Albada , R. Sancisi

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

Molecular hydrogen (H$_2$) formation and dissociation are key processes that drive the gas lifecycle in galaxies. Using the SImulating the LifeCycle of Molecular Clouds (SILCC) zoom-in simulation suite, we explore the utility of future…

Cosmic gas makes up about 90% of baryonic matter in the Universe and H$_2$ is the closest molecule to star formation. In this work we study cold neutral gas and its H$_2$ component at different epochs, exploiting state-of-the-art…

Astrophysics of Galaxies · Physics 2022-01-05 Umberto Maio , Céline Péroux , Benedetta Ciardi

The process of atomic-to-molecular (HI-to-H$_2$) gas conversion is fundamental for molecular-cloud formation and star formation. 21 cm observations of the star-forming region W43 revealed extremely high HI column densities, of 120-180…

Astrophysics of Galaxies · Physics 2017-02-01 Shmuel Bialy , Simon Bihr , Henrik Beuther , Thomas Henning , Amiel Sternberg

Understanding the molecular gas content in the interstellar medium (ISM) is crucial for studying star formation and galaxy evolution. The CO-to-H$_2$ ($X_{\rm CO}$) and the [CI]-to-H$_2$ ($X_{\rm CI}$) conversion factors are widely used to…

We have observed 70 galaxies belonging to 45 Hickson compact groups in the CO(1-0) and CO(2-1) lines, in order to determine their molecular content. We detected 57 galaxies, corresponding to a detection rate of 81%. We compare the gas…

Astrophysics · Physics 2007-05-23 S. Leon , F. Combes , T. K. Menon

We investigate the star formation and neutral atomic hydrogen (HI) gas properties of galaxies along three large-scale filaments and two galaxy groups in the wide field around the Virgo cluster. Our goal is to understand how galaxies are…

Astrophysics of Galaxies · Physics 2025-05-28 Hyein Yoon , O. Ivy Wong , Aeree Chung , Shan Huang

We present the results of a single-dish beam-matched survey of the three lowest rotational transitions of CO in a sample of 20 local (D < 70 Mpc) Luminous Compact Blue Galaxies (LCBGs). These ~L*, blue, high surface brightness, starbursting…

Astrophysics · Physics 2009-11-10 C. A. Garland , J. P. Williams , D. J. Pisano , R. Guzman , F. J. Castander , J. Brinkmann

We present CO(1-0) maps of 12 warm H$_2$-selected Hickson Compact Groups (HCGs), covering 14 individually imaged warm H$_2$ bright galaxies, with CARMA. We found a variety of molecular gas distributions within the HCGs, including regularly…

We present an analysis of the sky distribution of neutral hydrogen (HI) deficiency and spectral asymmetry for galaxies detected by the HI Parkes All-Sky Survey (HIPASS) as a function of projected environment density. Previous studies of…

Astrophysics of Galaxies · Physics 2020-10-21 T. N. Reynolds , T. Westmeier , L. Staveley-Smith

We investigate the atomic gas (HI) content of galaxies in groups using early data from the FAST All Sky HI survey (FASHI). Taking advantage of FAST's blind, wide-area coverage and uniform sensitivity, we assemble a sample of $230$ group…

Astrophysics of Galaxies · Physics 2026-01-29 Shulan Yan , Andrew Ma , Qingzheng Yu , Taotao Fang , Chuan He , Ming Zhu