Related papers: Star Formation Occurs in Dense Gas, but What Does …

We present dense-gas--tracing molecular observations of six resolved Giant Molecular Clouds (GMCs) in the Andromeda Galaxy (M31). Using the NOEMA interferometer, we observed the transitions of HCN(1-0), HCO$^+$(1-0), and HNC(1-0), as well…

We present 5 deg^2 (~250 pc^2) HCN, HNC, HCO+, and CO J=1-0 maps of the Orion B GMC, complemented with existing wide-field [CI] 492 GHz maps, as well as new pointed observations of rotationally excited HCN, HNC, H13CN, and HN13C lines. We…

We use the CARMA millimeter interferometer to map the Antennae Galaxies (NGC4038/39), tracing the bulk of the molecular gas via the 12CO(1-0) line and denser molecular gas via the high density transitions HCN(1-0), HCO+(1-0), CS(2-1), and…

In order to study the distribution of dense molecular gas and its relation to the central activities (starburst and AGN) in galaxies, we have conducted an imaging survey of HCN(1-0) and HCO+(1-0) emissions from nearby spiral galaxies with…

We present ALMA and VLA detections of the dense molecular gas tracers HCN, HCO$^+$ and HNC in two lensed, high-redshift starbursts selected from the {\it Herschel}-ATLAS survey: {\it H}-ATLAS\,J090740.0$-$004200 (SDP.9, $z \sim 1.6$) and…

We model the star formation relation of molecular clumps in dependence of their dense-gas mass when their volume density profile is that of an isothermal sphere, i.e. $\rho_{clump}(r) \propto r^{-2}$. Dense gas is defined as gas whose…

To study the high-transition dense-gas tracers and their relationships to the star formation of the inner $\sim$ 2 kpc circumnuclear region of NGC253, we present HCN $J=4-3$ and HCO$^+ J=4-3$ maps obtained with the James Clerk Maxwell…

We report a sensitive search for the HCN(J=2-1) emission line towards SDSS J1148+5251 at z=6.42 with the VLA. HCN emission is a star formation indicator, tracing dense molecular hydrogen gas (n(H2) >= 10^4 cm^-3) within star-forming…

We present observations of HCO+ and H^13CO+, N2H+, HCS+, HCN and HN^13C, SO and ^34SO, CCH, SO_2, and CH_3OH-E towards a sample of 27 high-mass clumps coincident with water maser emission. All transitions are observed with or convolved to…

The HCN, HCO+, and HNC molecules are commonly used as tracers of dense star-forming gas in external galaxies, but such observations are spatially unresolved. Reliably inferring the properties of galactic nuclei and disks requires detailed…

Recent studies have suggested that star formation (SF) in dense gas may be governed by essentially the same law in Galactic clouds and external galaxies. This conclusion remains controversial, however, because different tracers have been…

Massive stars play an important role in the Universe. Unlike low-mass stars, the formation of these objects located at great distances is still unclear. It is expected to be governed by some combination of self-gravity, turbulence, and…

It is still poorly constrained how the densest phase of the interstellar medium varies across galactic environment. A large observing time is required to recover significant emission from dense molecular gas at high spatial resolution, and…

While the best tracer of the molecular component and its dynamics in galaxies is the CO molecule, which excitation is revealed by its isotopic and (2-1)/(1-0) ratios, the denser gas is revealed by molecules such as HCN, HNC, HCO+ or CN,…

We use new HCN(1-0) data from the ALMOND (ACA Large-sample Mapping Of Nearby galaxies in Dense gas) survey to trace the kpc-scale molecular gas density structure and CO(2-1) data from PHANGS-ALMA to trace the bulk molecular gas across 25…

Optical depths of dense molecular gas are commonly used in Galactic and extragalactic studies to constrain the dense gas mass of the clouds or galaxies. The optical depths are often obtained based on spatially unresolved data, especially in…

In most galaxies like the Milky Way, stars form in clouds of molecular gas. Unlike the CO emission that traces the bulk of molecular gas, the rotational transitions of HCN and CS molecules mainly probe the dense phase of molecular gas,…

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…

Dense molecular gas tracers in the central 1 kpc region of the superwind galaxy NGC 1808 have been imaged by ALMA at a resolution of 1" (~50 pc). Integrated intensities and line intensity ratios of HCN (1-0), H$^{13}$CN (1-0), HCO$^+$…

The origin of the high SFR observed in high-z dusty star-forming galaxies is still unknown. Large fractions of dense molecular gas might provide part of the explanation, but there are few observational constraints on the amount of dense gas…