Related papers: High molecular gas fractions in normal massive sta…
I review observational studies of the large-scale star formation process in nearby galaxies. A wealth of new multi-wavelength data provide an unprecedented view on the interplay of the interstellar medium and (young) stellar populations on…
The gas accretion and star-formation histories of galaxies like the Milky Way remain an outstanding problem in astrophysics. Observations show that 8 billion years ago, the progenitors to Milky Way-mass galaxies were forming stars 30 times…
Stars are forming in our galaxy at a rate of between 1 and 4 solar masses of stars per year. In contrast to elliptical galaxies, which are largely devoid of star formation, star formation is still going on in spiral galaxies because of…
We present new mm interferometric and optical integral-field unit (IFU) observations and construct a sample of 12 E and S0 galaxies with molecular gas which have both CO and optical maps. The galaxies contain 2 x 10^7 to 5 x 10^9 M\odot of…
In the local Universe, the efficiency for converting baryonic gas into stars is very low. In dark matter halos where galaxies form and evolve, the average efficiency varies with galaxy stellar mass and has a maximum of about twenty percent…
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 it has been proposed that the resulting…
Over the past decade increasingly robust estimates of the dense molecular gas content in galaxy populations between redshift 0 and the peak of cosmic galaxy/star formation from redshift 1-3 have become available. This rapid progress has…
The molecular gas content of local early-type galaxies is constrained and discussed in relation to their evolution. First, as part of the Atlas3D survey, we present the first complete, large (260 objects), volume-limited single-dish survey…
Studies of the molecular interstellar medium that fuels star formation and supermassive black hole growth in galaxies at cosmological distances have undergone tremendous progress over the past few years. Based on the detection of molecular…
We try to constrain the cosmic molecular gas mass density at $z =1-1.5$ and that in the local universe by combining stellar mass functions of star-forming galaxies and their average molecular gas mass fractions against the stellar mass. The…
The first stars in the Universe are predicted to have been much more massive than the Sun. Gravitational condensation accompanied by cooling of the primordial gas due to molecular hydrogen, yields a minimum fragmentation scale of a few…
Young galaxies are clumpy, gas-rich, and highly turbulent. Star formation appears to occur by gravitational instabilities in galactic disks. The high dispersion makes the clumps massive and the disks thick. The star formation rate should be…
We use the first systematic data sets of CO molecular line emission in z~1-3 normal star forming galaxies for a comparison of the dependence of galaxy-averaged star formation rates on molecular gas masses at low and high redshifts, and in…
In the Milky Way and other main-sequence galaxies, stars form exclusively in molecular gas, which is traced by CO emission. However, low metallicity dwarf galaxies are often `CO-dark' in the sense that CO emission is not observable even at…
It has been known for more than 30 years that star formation in giant molecular clouds (GMCs) is slow, in the sense that only ~1% of the gas forms stars every free-fall time. This result is entirely independent of any particular model of…
We summarize cm through submm observations of the host galaxies of z ~ 6 quasars. These observations reveal the cool molecular gas (the fuel for star formation), the warm dust (heated by star formation), the fine structure line emission…
Over the last decade, observations of the cool interstellar medium in distant galaxies via molecular and atomic fine structure line emission has gone from a curious look into a few extreme, rare objects, to a mainstream tool to study galaxy…
In order to understand galaxy evolution through cosmic times it is critical to derive the properties of the molecular gas content of galaxies, i.e. the material out of which stars ultimately form. The last decade has seen rapid progress in…
Massive galaxies in the early Universe have been shown to be forming stars at surprisingly high rates. Prominent examples are dust-obscured galaxies which are luminous when observed at sub-millimeter (sub-mm) wavelengths and which may be…
We review the evolution of the cosmic average molecular gas density to large look-back times, using observations of rotational transitions of CO. Molecular gas is the fuel for star formation in galaxies. Deep searches for CO emission from…