Related papers: Dense molecular gas toward W49A: A template for ex…

We present a study of dense gas emission in the Milky Way in order to serve as a basis for comparison with extragalactic results. This study combines new observations of HCN, CS, and CO in individual GMCs and in the Milky Way plane with…

A sample of 30 H2O extra-galactic maser galaxies with their published HCN(J=1-0) and HCO+(J=1-0) observations has been compiled to investigate the dense gas correlation with H2O maser emission. Our sample number exceeds the size of the…

Observations of molecular clouds, prestellar cores, and protoplanetary disks have established that the HNC/HCN ratio may be a potent diagnostic of molecular gas physical conditions. The processes that govern the relative abundances of these…

We present 3 mm observations obtained with the IRAM 30-m telescope for ten nearby gas-rich active galaxies spanning three orders of magnitude in infrared luminosity. Emission lines of HCO+(1-0), HCN(1-0), and C2H(1-0) were simultaneously…

We present the first survey of dense gas towards Planck Galactic Cold Clumps (PGCCs). Observations in the J=1-0 transitions of HCO+ and HCN towards 621 molecular cores associated with PGCCs were performed using the Purple Mountain…

We summarize our comprehensive gas surveys of some of the most luminous, deeply embedded (optically obscured) star formation regions in the Milky Way, which are the local cases of massive star clusters and/or associations in the making. Our…

We study the relationship between dense gas and star formation in the Antennae galaxies by comparing ALMA observations of dense gas tracers (HCN, HCO$^+$, and HNC $\mathrm{J}=1-0$) to the total infrared luminosity ($\mathrm{L_{TIR}}$)…

The aim of this study is to investigate systematic chemical differentiation of molecules in regions of high mass star formation. We observed five prominent sites of high mass star formation in HCN, HNC, HCO+, their isotopes, C18O, C34S and…

We present ALMA observations of the dwarf starburst galaxy Henize 2-10 in combination with previous SMA CO observations to probe the molecular environments of natal super star clusters. These observations include the HCO$^+$(1-0), HCN(1-0),…

We model emissivities of the HCN and CO $J=1-0$ transitions using measured properties of clouds found in normal star forming galaxies and more extreme systems. These models are compared with observations of HCN and CO $J=1-0$ transitions.…

We present a theoretical investigation of CN and HCN molecule formation in dense interstellar clouds. We study the gas-phase CN and HCN production efficiencies from the outer photon-dominated regions (PDRs) into the opaque cosmic-ray…

(abridged) In this work we have a closer look at the gas content or fraction and the associated star formation rate in main sequence and starburst galaxies at z=0 and z~1-2 by applying an analytical model of galactic clumpy gas disks to…

Certain planetary nebulae contain shells, filaments, or globules of cold gas and dust whose heating and chemistry are likely driven by UV and X-ray emission from their central stars and from wind-collision-generated shocks. We present the…

We report observations of the ground state transitions of $^{12}$CO, $^{13}$CO C$^{18}$O, HCN, and HCO$^+$ at 88-115 GHz in the inner region of the nearby galaxy IC 342. These data were obtained with the 16-pixel spectroscopic focal plane…

We present high resolution H41a hydrogen recombination line observations of the 1.2' (3 pc) region surrounding Sgr A* at 92 GHz using the OVRO Millimeter Array with an angular resolution of 7" x 3" and velocity resolution of 13 km/s. New…

HOCN and HNCO abundance ratio in molecular gas can tell us the information of their formation mechanism. We performed high-sensitivity mapping observations of HOCN, HNCO, and HNC$^{18}$O lines around Sagittarius B2 (Sgr B2) with IRAM 30m…

We made CO and HCN simultaneous observations of lenticular galaxies, NGC 404, NGC 3593 and NGC 4293, and detected HCN emission in NGC 3593 and NGC 4293 as well as CO in all the galaxies. The I(HCN)/I(CO) ratios were 0.025+-0.006 and…

We present new ALMA Band 7 ($\sim340$ GHz) observations of the dense gas tracers HCN, HCO$^+$, and CS in the local, single-nucleus, ultraluminous infrared galaxy IRAS 13120-5453. We find centrally enhanced HCN (4-3) emission, relative to…

Protostellar outflows are considered a signpost of star formation. These outflows can cause shocks in the molecular gas and are typically traced by the line wings of certain molecules. HNCO (4--3) has been regarded as a shock tracer because…

We present new 2 cm and 6 cm maps of H2CO, radio recombination lines, and the radio continuum in the W51 star forming complex acquired with Arecibo and the Green Bank Telescope at ~50" resolution. We use H2CO absorption to determine the…