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We study the relation between molecular gas and star formation in a volume‐limited sample of 222 galaxies from the COLD GASS survey, with measurements of the CO(1–0) line from the IRAM 30‐m telescope. The galaxies are at redshifts 0.025 < z < 0.05 and have stellar masses in the range 10.0 < log M★/M⊙ < 11.5. The IRAM measurements are complemented by deep Arecibo H i observations and homogeneous Sloan Digital Sky Survey and GALEX photometry. A reference sample that includes both ultraviolet (UV) and far‐infrared data is used to calibrate our estimates of star formation rates from the seven optical/UV bands. The mean molecular gas depletion time‐scale [] for all the galaxies in our sample is 1 Gyr; however,  increases by a factor of 6 from a value of ∼0.5 Gyr for galaxies with stellar masses of ∼1010 M⊙ to ∼3 Gyr for galaxies with masses of a few ×1011 M⊙. In contrast, the atomic gas depletion time‐scale remains constant at a value of around 3 Gyr. This implies that in high‐mass galaxies, molecular and atomic gas depletion time‐scales are comparable, but in low‐mass galaxies, the molecular gas is being consumed much more quickly than the atomic gas. The strongest dependences of  are on the stellar mass of the galaxy [parametrized as ], and on the specific star formation rate (sSFR). A single  versus sSFR relation is able to fit both ‘normal’ star‐forming galaxies in our COLD GASS sample and more extreme starburst galaxies (luminous infrared galaxies and ultraluminous infrared galaxies), which have  yr. Normal galaxies at z = 1–2 are displaced with respect to the local galaxy population in the  versus sSFR plane and have molecular gas depletion times that are a factor of 3–5 times longer at a given value of sSFR due to their significantly larger gas fractions.

We are conducting COLD GASS, a legacy survey for molecular gas in nearby galaxies. Using the IRAM 30‐m telescope, we measure the CO(1−0) line in a sample of ∼350 nearby ( Mpc), massive galaxies (log(M*/M⊙) > 10.0). The sample is selected purely according to stellar mass, and therefore provides an unbiased view of molecular gas in these systems. By combining the IRAM data with Sloan Digital Sky Survey (SDSS) photometry and spectroscopy, GALEX imaging and high‐quality Arecibo H i data, we investigate the partition of condensed baryons between stars, atomic gas and molecular gas in 0.1–10L* galaxies. In this paper, we present CO luminosities and molecular hydrogen masses for the first 222 galaxies. The overall CO detection rate is 54 per cent, but our survey also uncovers the existence of sharp thresholds in galaxy structural parameters such as stellar mass surface density and concentration index, below which all galaxies have a measurable cold gas component but above which the detection rate of the CO line drops suddenly. The mean molecular gas fraction  of the CO detections is 0.066 ± 0.039, and this fraction does not depend on stellar mass, but is a strong function of (NUV − r) colour. Through stacking, we set a firm upper limit of  for red galaxies with NUV − r > 5.0. The average molecular‐to‐atomic hydrogen ratio in present‐day galaxies is 0.3, with significant scatter from one galaxy to the next. The existence of strong detection thresholds in both the H i and CO lines suggests that ‘quenching’ processes have occurred in these systems. Intriguingly, atomic gas strongly dominates in the minority of galaxies with significant cold gas that lie above these thresholds. This suggests that some re‐accretion of gas may still be possible following the quenching event.

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We present a systematic analysis of two-pion interferometry in Au+Au collisions at √ s NN = 200 GeV using the STAR detector at Relativistic Heavy Ion Collider. We extract the Hanbury-Brown and Twiss radii and study their multiplicity, transverse momentum, and azimuthal angle dependence. The Gaussianness of the correlation function is studied. Estimates of the geometrical and dynamical structure of the freeze-out source are extracted by fits with blast-wave parametrizations. The expansion of the source and its relation with the initial energy density distribution is studied.