Related papers: On the density regime probed by HCN emission
We present Jansky Very Large Array observations of 20 - 37 GHz absorption lines from nearby Galactic diffuse molecular gas seen against four cosmologically-distant compact radio continuum sources. The main new observational results are that…
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…
Both Galactic and extragalactic studies on star formation suggest that stars form directly from dense molecular gas. To trace such high volume density gas, HCN and HCO+ J=1-0 have been widely used for their high dipole moments, relatively…
H$_{\rm I}$ 21-cm and $^{12}$CO 2.6-mm line emissions respectively trace the atomic and molecular gas phases, but they miss most of the opaque H$_{\rm I}$ and diffuse H$_2$ present in the Dark Neutral Medium (DNM) at the transition between…
We provide a model for how Kennicutt-Schmidt (KS) laws, which describe the correlation between star formation rate and gas surface or volume density, depend on the molecular line chosen to trace the gas. We show that, for lines that can be…
We have observed HNC 1-0, CN 1-0 and 2-1 line emission in a sample of 13 IR luminous (LIRGs, L_IR > 10E11 Lo) starburst and Seyfert galaxies. HNC 1-0 is detected in 9, CN 1-0 is detected in 10 and CN 2-1 in 7 of the galaxies. We also report…
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…
Tracing dense molecular gas, the fuel for star formation, is essential for the understanding of the evolution of molecular clouds and star formation processes. We compare the emission of HCN(1-0), HNC(1-0) and HCO+(1-0) with the emission of…
We report observations of dense molecular gas in the star-forming galaxy EGS 13004291 (z=1.197) using the Plateau de Bure Interferometer. We tentatively detect HCN and HNC (J=2-1) emission when stacked together at ~4sigma significance,…
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…
Dense gas is important for galaxy evolution and star formation. Optically-thin dense-gas tracers, such as isotopologues of HCN, HCO+, etc., are very helpful to diagnose excitation conditions of dense molecular gas. However, previous studies…
Based on the newly acquired dense gas observations from the JCMT MALATANG survey and X-ray data from Chandra, we explore the correlation between hot gas and HCN $J=4 \rightarrow 3$, HCO$^+\ J=4 \rightarrow 3$ emission for the first time at…
We present observations of HCN 3-2 emissions towards 37 local galaxies using 10-m Submillimeter Telescope (SMT). HCN 3-2 emission is detected in 23 galaxies. The correlation of infrared luminosity (LIR) and the luminosity of HCN 3-2 line…
The Galactic Center regions $-6^\circ \le l \le 6^\circ$ and $-0.8^\circ \le b \le 0.87^\circ$ are surveyed with HCN J=1$-$0 line (88.6 GHz) on a 4$'$ grid with the 14 m telescope at the Taeduk Radio Astronomy Observatory. The data…
The star formation rate (SFR) is tightly connected to the amount of dense gas in molecular clouds. However, it is not fully understood how the relationship between dense molecular gas and star formation varies within galaxies and in…
Dense molecular gas and star formation are correlated in galaxies. The effect of low metallicity on this relationship is crucial for interpreting observations of high redshift galaxies, which have lower metallicities than galaxies today.…
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…
We present the 3 mm wavelength spectra of 28 local galaxy merger remnants obtained with the Large Millimeter Telescope. Fifteen molecular lines from 13 different molecular species and isotopologues were identified, and 21 out of 28 sources…
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 report the detection of CN(N=3-2) emission towards the Cloverleaf quasar (z=2.56) based on observations with the IRAM Plateau de Bure Interferometer. This is the first clear detection of emission from this radical at high redshift. CN…