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Our understanding of how molecular clouds form in the interstellar medium (ISM) would be greatly helped if we had a reliable observational tracer of the gas flows responsible for forming the clouds. Fine structure emission from singly…

Astrophysics of Galaxies · Physics 2019-05-14 Paul C. Clark , Simon C. O. Glover , Sarah E. Ragan , Ana Duarte-Cabral

Stars in galaxies form in giant molecular clouds that coalesce when the atomic hydrogen is converted into molecules. There are currently two dominant models for what property of the galactic disk determines its molecular fraction: either…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Michele Fumagalli , Mark R. Krumholz , Leslie K. Hunt

We study the molecular gas content of 24 star-forming galaxies at $z=3-4$, with a median stellar mass of $10^{9.1}$ M$_{\odot}$, from the MUSE Hubble Ultra Deep Field (HUDF) Survey. Selected by their Lyman-alpha-emission and H-band…

We use the CN/CO intensity ratio to obtain the dense gas fraction, $f_{\text{dense}}$, for a sample of 16 Ultra-luminous and Luminous Infrared Galaxies and compare $f_{\text{dense}}$ with a suite of global galaxy properties. We find a…

Astrophysics of Galaxies · Physics 2025-02-05 Blake Ledger , Christine D. Wilson , Osvald Klimi , Nuria Torres-Alba , Toshiki Saito

We analyze surveys of molecular cloud structures defined by tracers ranging from CO $J = 1-0$ through $^{13}$CO $J = 1-0$ to dust emission together with NH$_3$ data. The mean value of the virial parameter and the fraction of mass in bound…

Using hydrodynamical simulations of a Milky Way-like galaxy, reaching 4.6 pc resolution, we study how the choice of star formation criteria impacts both galactic and Giant Molecular Clouds (GMC) scales. We find that using a turbulent,…

Astrophysics of Galaxies · Physics 2020-11-25 Kearn Grisdale

Current observations favour that the massive ultraviolet-bright clumps with a median stellar mass of $\sim 10^7~M_{\odot}$, ubiquitously observed in $z\sim 1-3$ galaxies, are star-forming regions formed in-situ in galaxies. It has been…

We present ALMA Band 7 dust continuum observations of 57 massive ($M_\ast \gtrsim 10^{10.8}~M_\odot$) star-forming galaxies at $1.45<z<1.70$, selected from the FMOS-COSMOS survey to provide a homogeneous sample near the main sequence (MS)…

The spatial decorrelation of dense molecular gas and young stars observed on $\lesssim 1$ kiloparsec scales in nearby galaxies indicates rapid dispersal of star-forming regions by stellar feedback. We explore the sensitivity of this…

Astrophysics of Galaxies · Physics 2021-09-15 Vadim A. Semenov , Andrey V. Kravtsov , Nickolay Y. Gnedin

We present a cross-calibration of CO- and dust-based molecular gas masses at $z \leqslant 0.2$. Our results are based on a survey with the IRAM 30-m telescope collecting CO(1-0) measurements of 78 massive ($\log M_{\star} / M_{\odot} > 10$)…

We report the detection of differential gas column densities in three gravitational lenses, MG0414+0534, HE1104-1805, and PKS1830-211. Combined with the previous differential column density measurements in B1600+434 and Q2237+0305 and the…

Astrophysics · Physics 2009-11-13 Xinyu Dai , Christopher S. Kochanek , George Chartas , Smita Mathur

The mass of molecular gas in an interstellar cloud is often measured using line emission from low rotational levels of CO, which are sensitive to the CO mass, and then scaling to the assumed molecular hydrogen H_2 mass. However, a…

Astrophysics of Galaxies · Physics 2015-05-18 Mark G. Wolfire , David Hollenbach , Christopher F. McKee

The stellar, gaseous and young stellar disks in the LITTLE THINGS sample of nearby dIrrs are fitted with functions to search for correlations between the parameters. We find that the HI radial profiles are generally flatter in the center…

The results of spectral observations in the $\sim 84-92$ GHz frequency range of six objects in the southern sky containing dense cores and associated with regions of massive stars and star clusters formation are presented. The observations…

Astrophysics of Galaxies · Physics 2024-03-06 L. E. Pirogov , P. M. Zemlyanukha , E. M. Dombek , M. A. Voronkov

We test some ideas for star formation relations against data on local molecular clouds. On a cloud by cloud basis, the relation between the surface density of star formation rate and surface density of gas divided by a free-fall time,…

Astrophysics of Galaxies · Physics 2015-06-18 Neal J. Evans , Amanda Heiderman , Nalin Vutisalchavakul

Molecular gas, as the fuel for star formation, and its relationship with atomic gas are crucial for understanding how galaxies regulate their star forming (SF) activities. We conducted IRAM 30m observations of 23 nearby spiral galaxies from…

Astrophysics of Galaxies · Physics 2025-03-31 Yan Jiang , Jiang-Tao Li , Qing-Hua Tan , Li Ji , Joel N. Bregman , Q. Daniel Wang , Jian-Fa Wang , Li-Yuan Lu , Xue-Jian Jiang

We investigate the spectral correlations between different species used to observe molecular clouds. We use hydrodynamic simulations and a full chemical network to study the abundances of over 150 species in typical Milky Way molecular…

Solar and Stellar Astrophysics · Physics 2015-06-23 Brandt A. L. Gaches , Stella S. R. Offner , Erik W. Rosolowsky , Thomas G. Bisbas

We investigate the relationship between the star formation rate (SFR) and dense molecular gas mass in the nuclei of galaxies. To do this, we utilize the observed 850 micron luminosity as a proxy for the infrared luminosity and SFR, and…

Astrophysics · Physics 2009-11-13 Desika Narayanan , Thomas J. Cox , Lars Hernquist

We present maps and spectra of the HCN(1-0) and HCO$^+$(1-0) lines in the extreme outer Galaxy, at galactocentric radii between 14 and 22 kpc, with the 13.7 meter Delingha telescope. The 9 molecular clouds were selected from a CO/$^{13}$CO…

Astrophysics of Galaxies · Physics 2023-08-09 Jonathan Braine , Yan Sun , Yoshito Shimajiri , Floris F. S. van der Tak , Min Fang , Philippe André , Hao Chen , Yu Gao

We investigate the dynamical effects of a molecular cloud complex with a mass of about 10**7 M_sun and a size of a few 100 pc on the vertical distribution of stars and atomic hydrogen gas in a spiral galactic disc. Such massive complexes…

Astrophysics · Physics 2009-11-07 Chanda J. Jog , Chaitra A. Narayan
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