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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 derive a physical model for the observed relations between star formation rate (SFR) and molecular line (CO and HCN) emission in galaxies, and show how these observed relations are reflective of the underlying star formation law. We do…

Volume density is a key physical quantity controlling the evolution of the interstellar medium (ISM) and star formation, but it cannot be accessed directly by observations of molecular clouds. We aim at estimating the volume density…

Astrophysics of Galaxies · Physics 2025-05-15 Jan H. Orkisz , Jouni Kainulainen

We present a global study of low mass, young stellar object (YSO) surface densities in nearby (< 500 pc) star forming regions based on a comprehensive collection of Spitzer Space Telescope surveys. We show that the distribution of YSO…

We examine several different simplified approaches for modelling the chemistry of CO in three-dimensional numerical simulations of turbulent molecular clouds. We compare the different models both by looking at the behaviour of integrated…

Astrophysics of Galaxies · Physics 2015-05-27 S. C. O. Glover , P. C. Clark

We develop a simple analytic model for the gravitational clustering of dark matter haloes to understand how their spatial distribution is biased relative to that of the mass. The statistical distribution of dark haloes within the initial…

Astrophysics · Physics 2015-06-24 H. J. Mo , S. D. M. White

Context: Understanding how protostars accrete their mass is a central question of star formation. One aspect of this is trying to understand whether the time evolution of accretion rates in deeply embedded objects is best characterised by a…

Solar and Stellar Astrophysics · Physics 2016-02-17 Søren Frimann , Jes K. Jørgensen , Paolo Padoan , Troels Haugbølle

We introduce a model for the large-scale, global 3D structure of molecular clouds. Motivated by the morphological appearance of clouds in surface density maps, we model clouds as cylinders, with the aim of backing out information about the…

Astrophysics of Galaxies · Physics 2023-09-12 Nia Imara , John C. Forbes

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 use deep adaptive mesh refinement simulations of isothermal self-gravitating supersonic turbulence to study the imprints of gravity on the mass density distribution in molecular clouds. The simulations show that the density distribution…

Astrophysics of Galaxies · Physics 2011-01-05 Alexei G. Kritsuk , Michael L. Norman , Rick Wagner

We investigate the relation between star formation rate (SFR) and gas surface densities in Galactic star forming regions using a sample of YSOs and massive clumps. Our YSO sample consists of objects located in 20 molecular clouds from the…

Astrophysics of Galaxies · Physics 2015-05-19 Amanda Heiderman , Neal J. Evans , Lori E. Allen , Tracy Huard , Mark Heyer

The probability distribution function (PDF) of the mass surface density of molecular clouds provides essential information about the structure of molecular cloud gas and condensed structures out of which stars may form. In general, the PDF…

Astrophysics of Galaxies · Physics 2015-06-22 Jörg Fischera

The formation of stars is inextricably linked to the structure of their parental molecular clouds. Here we take a number of nearby giant molecular clouds (GMCs) and analyse their column density and mass distributions. This investigation is…

Astrophysics of Galaxies · Physics 2015-05-18 D. Froebrich , J. Rowles

With a goal toward deriving the physical conditions in external galaxies, we present a survey of formaldehyde (H2CO) and ammonia (NH3) emission and absorption in a sample of starburst galaxies using the Green Bank Telescope. By extending…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Jeffrey G. Mangum , Jeremy Darling , Karl M. Menten , Christian Henkel , Meredith MacGregor

Abridged Context: Snowlines during star and disk formation are responsible for a range of effects during the evolution of protostars, such as setting the chemical composition of the envelope and disk. This in turn influences the formation…

Solar and Stellar Astrophysics · Physics 2022-09-14 Nadia M. Murillo , Tien-Hao Hsieh , Catherine Walsh

{It has recently been proposed that giant molecular complexes form at the sites where streams of diffuse warm atomic gas collide at transonic velocities.} {We study the global statistics of molecular clouds formed by large scale colliding…

Astrophysics · Physics 2009-11-13 P. Hennebelle , R. Banerjee , E. Vazquez-Semadeni , R. Klessen , E. Audit

Describing how the properties of the interstellar medium combine across size-scales is crucial for understanding star formation scaling laws and connecting Galactic and extragalactic data of molecular clouds. We describe how the statistical…

Astrophysics of Galaxies · Physics 2021-09-15 Andri Spilker , Jouni Kainulainen , Jan Orkisz