相关论文: Structure analysis of simulated molecular clouds w…
Stars form in cold molecular clouds. However, molecular gas is difficult to observe because the most abundant molecule (H2) lacks a permanent dipole moment. Rotational transitions of CO are often used as a tracer of H2, but CO is much less…
{It is necessary to understand the dynamics of the atomic gas to use complex modeling and to carry out detailed comparisons between theoretical models and observations.}{In a companion paper, we present high resolution bidimensional…
The diffuse and translucent molecular clouds traced in absorption along the line of sight to strong background sources have so far been investigated mainly in the spectral domain because of limited angular resolution or small sizes of the…
We investigate physical properties of molecular clouds in disc galaxies with different morphology: a galaxy without prominent structure, a spiral barred galaxy and a galaxy with flocculent structure. Our $N$-body/hydrodynamical simulations…
We present a 3-mm and 1.3-cm spectral line survey conducted with the Mopra 22-m and Parkes 64-m radio telescopes of a sample of 40 cold dust cores, previously observed with BLAST, including both starless and proto-stellar sources. 20…
The offsets between the radial velocities of the rotational transitions of carbon monoxide and the fine structure transitions of neutral and singly ionized carbon are used to test the hypothetical variation of the fine structure constant,…
In this paper, we review some of the properties of dense molecular cloud cores. The results presented here rely on three-dimensional numerical simulations of isothermal, magnetized, turbulent, and self-gravitating molecular clouds (MCs) in…
We calculate the non-linear virialization density, $\Delta_c$, of halos under spherical collapse from peaks with an arbitrary initial and final density profile. This is in contrast to the standard calculation of $\Delta_c$ which assumes…
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…
We use N-body simulations to investigate the structure of dark halos in the standard Cold Dark Matter cosmogony. Halos are excised from simulations of cosmologically representative regions and are resimulated individually at high…
We report the results of observations toward the center of the molecular cloud CO 0.02-0.02 made using the Atacama Large Millimeter/Submillimeter Array. The successfully obtained 1 arcsec resolution images of CO $J$=3-2, H$^{13}$CN $J$=4-3,…
CO(J=1-0) line emission is a widely used observational tracer of molecular gas, rendering essential the X_CO factor, which is applied to convert CO luminosity to H_2 mass. We use numerical simulations to study how X_CO depends on numerical…
$Context.$ The traditional approach to characterize the structure of molecular clouds is to map their line emission. $Aims.$ We aim to test and apply a stratified random sampling technique that can characterize the line emission from…
In this paper we examine the factors that shape the distribution of molecular gas surface densities on the 150 pc scale across 67 morphologically diverse star-forming galaxies in the PHANGS-ALMA CO (2-1) survey. Dividing each galaxy into…
Aims: We wish to separate and quantify the CO luminosity and CO-H2 conversion factor applicable to diffuse but partially-molecular ISM when H2 and CO are present but C+ is the dominant form of gas-phase carbon. Methods: We discuss galactic…
In our local Galactic neighborhood, molecular clouds are best studied using a combination of dust measurements, to determine robust masses, sizes and internal structures of the clouds, and molecular-line observations to determine cloud…
A magnetohydrodynamic model of a steady, transverse C-type shock in a dense molecular cloud is presented. A complete gas-grain chemical network is taken into account: the gas-phase chemistry, the adsorption of gas species on dust grains,…
We use ALMA and IRAM 30-m telescope data to investigate the relationship between the spectroscopically-traced dense gas fraction and the cloud-scale (120 pc) molecular gas surface density in five nearby, star-forming galaxies. We estimate…
Column-density maps of molecular clouds are one of the most important observables in the context of molecular cloud- and star-formation (SF) studies. With the Herschel satellite it is now possible to determine the column density from dust…
We use numerical simulations of critically-closed cold dark matter (CDM) models to study the effects of numerical resolution on observable quantities. We study simulations with up to $256^3$ particles using the particle-mesh (PM) method and…