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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

We apply gravity-based and density-based methods to identify clouds in numerical simulations of the star-forming, three-phase interstellar medium (ISM), and compare their properties and their global correlation with the star formation rate…

Astrophysics of Galaxies · Physics 2020-07-29 S. Alwin Mao , Eve C. Ostriker , Chang-Goo Kim

We try to constrain the cosmic molecular gas mass density at $z =1-1.5$ and that in the local universe by combining stellar mass functions of star-forming galaxies and their average molecular gas mass fractions against the stellar mass. The…

Astrophysics of Galaxies · Physics 2017-02-01 Fumiya Maeda , Kouji Ohta , Akifumi Seko

[abridged] While observations of Local Group galaxies show a very simple, local star formation law in which the star formation rate per unit area in each patch of a galaxy scales linearly with the molecular gas surface density, recent…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Mark R. Krumholz , Avishai Dekel , Christopher F. McKee

It appears that the majority of rapidly-, well-localized gamma-ray bursts with undetected, or dark, optical afterglows, or `dark bursts' for short, occur in clouds of size R > 10L_{49}^{1/2} pc and mass M > 3x10^5L_{49} M_{sun}, where L is…

Astrophysics · Physics 2009-11-07 Daniel E. Reichart , Paul A. Price

Some of the youngest stars (age $\lesssim 10$ Myr) are clustered, while many others are observed scattered throughout star forming regions or in complete isolation. It has been intensively debated whether the scattered or isolated stars…

Astrophysics of Galaxies · Physics 2022-04-20 František Dinnbier , Pavel Kroupa , Richard I. Anderson

Dense, star-forming gas is believed to form at the stagnation points of large-scale ISM flows, but observational examples of this process in action are rare. We here present a giant molecular cloud (GMC) sandwiched between two colliding…

Astrophysics of Galaxies · Physics 2015-06-23 J. R. Dawson , E. Ntormousi , Y. Fukui , T. Hayakawa , K. Fierlinger

Most stars in the Galaxy are believed to be formed within star clusters from collapsing molecular clouds. However, the complete process of star formation, from the parent cloud to a gas-free star cluster, is still poorly understood. We…

Astrophysics of Galaxies · Physics 2017-10-23 Elena Gavagnin , Andreas Bleuler , Joakim Rosdahl , Romain Teyssier

The fragmentation of gas to form stars in molecular clouds is intrinsically linked to the turbulence within them. These internal motions are set at the birth of the cloud and may vary with galactic environment and as the cloud evolves. In…

Astrophysics of Galaxies · Physics 2024-07-29 Jiten Dhandha , Zoe Faes , Rowan J. Smith

We performed sub-parsec (~0.06pc) scale simulations of two idealised molecular clouds with different masses undergoing a collision. Gas clumps with density greater than 1e-20 g/cm3 (0.3e4 cm-3) were identified as pre-stellar cores and…

Astrophysics of Galaxies · Physics 2015-06-22 Ken Takahira , Elizabeth J. Tasker , Asao Habe

Observations of magnetic field strengths imply that molecular cloud fragments are individually close to being in a magnetically critical state, even though both magnetic field and column density measurements range over two orders of…

Astrophysics · Physics 2007-05-23 Shantanu Basu

One of the outstanding puzzles about star formation is why it proceeds so slowly. Giant molecular clouds convert only a few percent of their gas into stars per free-fall time, and recent observations show that this low star formation rate…

Astrophysics · Physics 2015-06-24 Mark R. Krumholz

The impact of winds and jet-inflated bubbles driven by active galactic nuclei (AGN) are believed to significantly affect the host galaxy's interstellar medium (ISM) and regulate star formation. To explore this scenario, we perform a suite…

The current generation of millimeter interferometers have revealed a population of compact (r <~ 0.1 pc), massive (M ~ 100 Msun) gas cores that are the likely progenitors of massive stars. I review models for the evolution of these objects…

Astrophysics · Physics 2007-05-23 Mark R. Krumholz

We present a theoretical framework in which bound stellar clusters arise naturally at the high-density end of the hierarchy of the interstellar medium (ISM). Due to short free-fall times, these high-density regions achieve high local star…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 J. M. Diederik Kruijssen

The gas clouds of the interstellar medium have a fractal structure, the origin of which has generally been thought to lie in turbulence. The energy of turbulence could come from galactic rotation at large-scale, then cascade down to be…

Astrophysics · Physics 2016-08-30 H. J. de Vega , N. Sánchez , F. Combes

Young massive clusters (YMCs) are the most compact, high-mass stellar systems still forming at the present day. The precursor clouds to such systems are, however, rare due to their large initial gas mass reservoirs and rapid dispersal…

We present an analysis of 55 central galaxies in clusters and groups with molecular gas masses and star formation rates lying between $10^{8}-10^{11}\ M_{\odot}$ and $0.5-270$ $M_{\odot}\ yr^{-1}$, respectively. We have used Chandra…

Astrophysics of Galaxies · Physics 2018-02-21 F. A. Pulido , B. R. McNamara , A. C. Edge , M. T. Hogan , A. N. Vantyghem , H. R. Russell , P. E. J. Nulsen , I. Babyk , P. Salomé

Understanding how stars form, evolve and impact molecular clouds is key to understanding why star formation is such an inefficient process globally. In this paper, we use the infrared bright fraction, $f_\text{IRB}$ (the fraction of a given…

Astrophysics of Galaxies · Physics 2024-12-12 E. J. Watkins , N. Peretto , A. J. Rigby , R. J. Smith , K. Kreckel , G. A. Fuller

The morphology of gas-rich disc galaxies at redshift ~1-3 is dominated by a few massive clumps. The process of formation or assembly of these clumps and their relation to molecular clouds in contemporary spiral galaxies are still unknown.…

Astrophysics of Galaxies · Physics 2021-09-22 Florent Renaud , Alessandro B. Romeo , Oscar Agertz