The BIMA Survey of Nearby Galaxies (BIMA SONG). II. The CO Data

Abstract

The BIMA Survey of Nearby Galaxies is a systematic imaging study of the 3 mm CO J ¼ 1 0 molecular emission within the centers and disks of 44 nearby spiral galaxies. The typical spatial resolution of the survey is 6 00 or 360 pc at the average distance (12 Mpc) of the sample. The velocity resolution of the CO observations is 4 km s À1 , though most maps are smoothed to 10 km s À1 resolution. For 33 galaxies, multifield observations ensured that a region e190 00 (hDi ¼ 10 kpc) in diameter was imaged. For the remaining 11 galaxies, which had smaller optical diameters and were on average farther away, single-pointing observations imaged a 100 00 diameter (hDi ¼ 11 kpc) region. The sample was not chosen based on CO or infrared brightness; instead, all spirals were included that met the selection criteria of v 2000 km s À1 , ! À20, i 70 , D 25 < 70 0 , and B T < 11:0. The detection rate was 41/44 sources or 93%; of the three nondetections, one (M81) is known to have CO emission at locations outside the survey field of view. Fully sampled single-dish CO data were incorporated into the maps for 24 galaxies; these single-dish data comprise the most extensive collection of fully sampled, two-dimensional single-dish CO maps of external galaxies to date. We also tabulate direct measurements of the global CO flux densities for these 24 sources. For the remaining 20 sources, we collected sensitive single-dish spectra in order to evaluate the large-scale flux recovery. We demonstrate that the measured ratios of flux density recovered are a function of the signal-to-noise of the interferometric data. We examine the degree of central peakedness of the molecular surface density distributions and show that the distributions exhibit their brightest CO emission within the central 6 00 in only 20/44 or 45% of the sample. We show that all three Local Group spiral galaxies have CO morphologies that are represented in SONG, though the Milky Way CO luminosity is somewhat below the SONG average, and M31 and M33 are well below average. This survey provides a unique public database of integrated intensity maps, channel maps, spectra, and velocity fields of molecular emission in nearby galaxies. It also lays the groundwork for extragalactic surveys by more powerful future millimeter-wavelength interferometers like CARMA and ALMA.

Cold gas properties of theHerschelReference Survey

“…Comparison between the integrated SCO fluxes determined by Kuno et al (2007) and those determined by Helfer et al (2003; red filled dots), Chung et al (2009a; blue filled triangles), our own observations of the two galaxies NGC 4548 and NGC 4579 with the IRAM radiotelescope (green filled squares) and the extrapolated fluxes of the FCRAO survey (Young et al 1995; cyan empty circles) on logarithmic scale for all galaxies in common (left) and on linear scale for those objects with SCO in the range 100-5000 Jy km s −1 sampled by the HRS (right). The linear best fit to the data, determined assuming the Kuno et al (2007) data as independent variable in the range 100-5000 Jy km s −1 , are shown by the red dotted line (Helfer et al 2003), the blue long dashed line (Chung et al 2009a) and the cyan solid line (Young et al 1995).…”

“…The linear best fit to the data, determined assuming the Kuno et al (2007) data as independent variable in the range 100-5000 Jy km s −1 , are shown by the red dotted line (Helfer et al 2003), the blue long dashed line (Chung et al 2009a) and the cyan solid line (Young et al 1995). The short dashed black line shows the 1:1 relationships.…”

Dusty star-forming galaxies at high redshift

“…Utilizing data from the THINGS, HERACLES, and BIMA SONG surveys Leroy et al, 2009;Helfer et al, 2003), Bigiel et al (2008) investigated the resolved star formation law in nearby galaxies. These authors found that the SFR is principally correlated with H 2 gas (as traced by CO (J=2-1) in this case), and unassociated with HI in nearby galaxies.…”

What powers the starburst activity of NGC 1068? Star-driven gravitational instabilities caught in the act

“…1, the Σco and σco profiles presented here are derived up to R = 3 kpc, but we exclude the central R = 350 pc because such a region is highly disturbed by a massive AGN-driven outflow (García-Burillo et al 2014). The surface density of molecular gas is converted to physical units by adopting the standard CO-to-H2 conversion factor, Xco = 2 × 10 20 cm −2 (K km s −1 ) −1 (Bolatto et al 2013), consistent with Helfer et al (2003). We also correct for the contribution of helium multiplying by a factor of 1.36.…”