Variations in the Star Formation Efficiency of the Dense Molecular Gas across the Disks of Star-Forming Galaxies

  title={Variations in the Star Formation Efficiency of the Dense Molecular Gas across the Disks of Star-Forming Galaxies},
  author={Antonio Usero and Adam K. Leroy and Fabian Walter and Andreas Schruba and Santiago Garc'ia-Burillo and Karin M. Sandstrom and Frank Bigiel and Elias Brinks and Carsten Kramer and Erik W Rosolowsky and Karl F. Schuster and W.J.G. de Blok},
  journal={arXiv: Astrophysics of Galaxies},
We present a new survey of HCN(1-0) emission, a tracer of dense molecular gas, focused on the little-explored regime of normal star-forming galaxy disks. Combining HCN, CO, and infrared (IR) emission, we investigate the role of dense gas in Star Formation (SF), finding systematic variations in both the apparent dense gas fraction and the apparent SF efficiency (SFE) of dense gas. The latter may be unexpected, given the popularity of gas density threshold models to explain SF scaling relations… 
The EMPIRE Survey: Systematic Variations in the Dense Gas Fraction and Star Formation Efficiency from Full-Disk Mapping of M51
We present the first results from the EMPIRE survey, an IRAM large program that is mapping tracers of high density molecular gas across the disks of nine nearby star-forming galaxies. Here, 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
Dense gas is not enough: environmental variations in the star formation efficiency of dense molecular gas at 100 pc scales in M 51
It remains unclear what sets the efficiency with which molecular gas transforms into stars. Here we present a new VLA map of the spiral galaxy M 51 in 33 GHz radio continuum, an extinction-free
Dense gas and star formation in individual Giant Molecular Clouds in M31
Studies both of entire galaxies and of local Galactic star formation indicate a dependency of a molecular cloud's star formation rate (SFR) on its dense gas mass. In external galaxies, such
Dense Gas, Dynamical Equilibrium Pressure, and Star Formation in Nearby Star-Forming Galaxies
We use new ALMA observations to investigate the connection between dense gas fraction, star formation rate, and local environment across the inner region of four local galaxies showing a wide range
Dense Gas in the Outer Spiral Arm of M51
There is a linear relation between the mass of dense gas, traced by the HCN(1-0) luminosity, and the star formation rate (SFR), traced by the far-infrared luminosity. Recent observations of galactic
EMPIRE: The IRAM 30 m Dense Gas Survey of Nearby Galaxies
We present EMPIRE, an IRAM 30-m large program that mapped $\lambda = 3{-}4$ mm dense gas tracers at $\sim 1{-}2\,$kpc resolution across the whole star-forming disk of nine nearby, massive, spiral
Dense molecular gas properties on 100 pc scales across the disc of NGC 3627
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
Dense gas in low-metallicity galaxies
Stars form out of the densest parts of molecular clouds. Far-IR emission can be used to estimate the Star Formation Rate (SFR) and high dipole moment molecules, typically HCN, trace the dense gas. A
A diversity of starburst-triggering mechanisms in interacting galaxies and their signatures in CO emission
The physical origin of enhanced star formation activity in interacting galaxies remains an open question. Knowing whether starbursts are triggered by an increase in the quantity of dense gas or an


Connecting Dense Gas Tracers of Star Formation in our Galaxy to High-z Star Formation
Observations have revealed prodigious amounts of star formation in starburst galaxies as traced by dust and molecular emission, even at large redshifts. Recent work shows that for both nearby spiral
HCN Observations of Dense Star-Forming Gas in High Redshift Galaxies
We present here the sensitive HCN ( 1 - 0) observations made with the VLA of two submillimeter galaxies and two QSOs at high redshift. HCN emission is the signature of dense molecular gas found in
A study of the gas–star formation relation over cosmic time
We use the first systematic data sets of CO molecular line emission in z∼ 1–3 normal star-forming galaxies (SFGs) for a comparison of the dependence of galaxy-averaged star formation rates on
We present a detailed analysis of the relation between infrared luminosity and molecular line luminosity, for a variety of molecular transitions, using a sample of 34 nearby galaxies spanning a broad
Variations in the Galactic star formation rate and density thresholds for star formation
The conversion of gas into stars is a fundamental process in astrophysics and cosmology. Stars are known to form from the gravitational collapse of dense clumps in interstellar molecular clouds, and
The Star Formation Rate and Dense Molecular Gas in Galaxies
HCN luminosity is a tracer of dense molecular gas, n(H(2)) greater than or similar to3 x 10(4) cm(-3), associated with star-forming giant molecular cloud (GMC) cores. We present the results and
We compare molecular gas traced by ^(12)CO (2-1) maps from the HERACLES survey, with tracers of the recent star formation rate (SFR) across 30 nearby disk galaxies. We demonstrate a first-order
Molecular Star Formation Rate Indicators in Galaxies
We derive a physical model for the observed relations between star formation rate (SFR) and molecular line (CO and HCN) emission in galaxies and show how these observed relations are reflective of
Evidence of enhanced star formation efficiency in luminous and ultraluminous infrared galaxies
We present new observations made with the IRAM 30 m telescope of the J = 1−0 and 3–2 lines of HCN and HCO + used to probe the dense molecular gas content in a sample of 17 local luminous and
What controls star formation in the central 500 pc of the Galaxy
The star formation rate (SFR) in the Central Molecular Zone (CMZ, i.e. the central 500 pc) of the Milky Way is lower by a factor of > 10 than expected for the substantial amount of dense gas it