Related papers: HD/H$_2$ ratio in the diffuse interstellar medium
The interstellar medium (ISM) has a multiphase structure characterized by gas, dust and molecules. The gas can be found in different charge states: neutral, low-ionized (warm) and high-ionized (hot). It is possible to probe the multiphase…
We present the first results on the diffuse transition clouds observed in [CII] line emission at 158 microns (1.9 THz) towards Galactic longitudes near 340deg (5 LOSs) and 20deg (11 LOSs) as part of the GOT C+ survey. Out of the total 146…
We use a pressure-based model for splitting cold hydrogen into its atomic (HI) and molecular (H2)components to tackle the co-evolution of HI, H2, and star formation rates (SFR) in ~3e7 simulated galaxies in the Millennium simulation. The…
Newly-computed collisional rate coefficients for the excitation of C$_2$ in collisions with H$_2$, presented recently by Najar and Kalugina (2020), are significantly larger than the values adopted previously in models for the excitation of…
We aim to investigate the chemistry of internal photon-dominated regions surrounding deeply embedded hypercompact and ultracompact HII regions. We search for specific tracers of this evolutionary stage of massive star formation that can be…
There are two major theoretical issues for the star formation law (the relation between the surface densities of molecular gas and star formation rate on a galaxy scale): (i) At low metallicity, it is not obvious that star-forming regions…
Although ammonia is an abundant molecule commonly observed towards the dense interstellar medium, it has not yet been established whether its main formation route is from gas-phase ion-molecule reactions or grain-surface hydrogen additions…
We have recently developed a post-processing framework to estimate the abundance of atomic and molecular hydrogen (HI and H2, respectively) in galaxies in large-volume cosmological simulations. Here we compare the HI and H2 content of…
We exploit the unprecedented depth of integral field data from the KMOS Ultra-deep Rotational Velocity Survey (KURVS) to analyse the strong (H$\alpha$) and forbidden ([NII], [SII]) emission line ratios in 22 main-sequence galaxies at…
In recent decades, significant attention has been dedicated to analytical and observational studies of the atomic hydrogen (HI) to molecular hydrogen (H2) transition in the interstellar medium. We focussed on the Draco diffuse cloud to gain…
Using IRAM 30m, SEST 15m, and Nancay radiotelescopes, we have gathered the 1mm continuum emission, spectra of the J=1--0 CO line and of the HI line at 21cm for two samples of IRAS galaxies. Using these data, we have estimated the HI masses,…
To interpret H_2 quasar absorption line observations in Damped Ly-alpha clouds (DLAs), we model the H_2 spatial distribution within a DLA. Based on numerical simulations of disk structures with parameters similar to those derived for such…
Surprisingly large column densities of H3+ have been detected using infrared absorption spectroscopy in seven diffuse cloud sightlines (Cygnus OB2 12, Cygnus OB2 5, HD 183143, HD 20041, WR 104, WR 118, and WR 121), demonstrating that H3+ is…
We study the behavior of eight diffuse interstellar bands (DIBs) in different interstellar environments, as characterized by the fraction of hydrogen in molecular form [$f$(H$_2$)], with comparisons to the corresponding behavior of various…
We study the formation of molecular hydrogen on dust grain surfaces and apply our results to the high redshift universe. We find that a range of physical parameters, in particular dust temperature and gas temperature, but not so much dust…
We present spectroscopic observations obtained with the infrared Spitzer Space Telescope, which provide insight into the H$_2$ physics and gas energetics in photodissociation Regions (PDRs) of low to moderate far-ultraviolet (FUV) fields…
The majority of hydrogen in the interstellar medium (ISM) is in atomic form. The transition from atoms to molecules and, in particular, the formation of the H$_2$ molecule, is a key step in cosmic structure formation en route to stars.…
We present a comprehensive examination of interstellar P and Cl abundances based on an analysis of archival spectra acquired with the Space Telescope Imaging Spectrograph of the Hubble Space Telescope and the Far Ultraviolet Spectroscopic…
We report initial results from the far-infrared fine structure line observations of a sample of 44 local starbursts, Seyfert galaxies and infrared luminous galaxies obtained with the PACS spectrometer on board Herschel. We show that the…
The enrichment of the intergalactic medium (IGM) with heavy elements provides us with a record of past star formation and with an opportunity to study the interactions between galaxies and their environments. We summarize current data…