The james clerk maxwell telescope nearby galaxies legacy survey. II. Warm molecular gas and star formation in three field spiral galaxies
Astrophysical Journal 714:1 (2010) 571-588
Abstract:
We present the results of large-area 12COJ = 3-2 emission mapping of three nearby field galaxies, NGC628, NGC3521, and NGC3627, completed at the James Clerk Maxwell Telescope as part of the Nearby Galaxies Legacy Survey. These galaxies all have moderate to strong 12COJ = 3-2 detections over large areas of the fields observed by the survey, showing resolved structure and dynamics in their warm/dense molecular gas disks. All three galaxies were part of the Spitzer Infrared Nearby Galaxies Survey sample, and as such have excellent published multiwavelength ancillary data. These data sets allow us to examine the star formation properties, gas content, and dynamics of these galaxies on sub-kiloparsec scales. We find that the global gas depletion time for dense/warm molecular gas in these galaxies is consistent with other results for nearby spiral galaxies, indicating this may be independent of galaxy properties such as structures, gas compositions, and environments. Similar to the results from The H I Nearby Galaxy Survey, we do not see a correlation of the star formation efficiency with the gas surface density consistent with the Schmidt-Kennicutt law. Finally, we find that the star formation efficiency of the dense molecular gas traced by 12COJ = 3-2 is potentially flat or slightly declining as a function of molecular gas density, the 12COJ = 3-2/J = 1-0 ratio (in contrast to the correlation found in a previous study into the starburst galaxy M83), and the fraction of total gas in molecular form. © 2010. The American Astronomical Society. All rights reserved.HARP/ACSIS: a submillimetre spectral imaging system on the James Clerk Maxwell Telescope
Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 399:2 (2009) 1026-1043
HARPACSIS: A submillimetre spectral imaging system on the James Clerk Maxwell Telescope
Monthly Notices of the Royal Astronomical Society 399:2 (2009) 1026-1043
Abstract:
This paper describes a new Heterodyne Array Receiver Program (HARP) and Auto-Correlation Spectral Imaging System (ACSIS) that have recently been installed and commissioned on the James Clerk Maxwell Telescope. The 16-element focal-plane array receiver, operating in the submillimetre from 325 to 375 GHz, offers high (three-dimensional) mapping speeds, along with significant improvements over single-detector counterparts in calibration and image quality. Receiver temperatures are ∼120 K across the whole band, and system temperatures of ∼300 K are reached routinely under good weather conditions. The system includes a single-sideband (SSB) filter so these are SSB values. Used in conjunction with ACSIS, the system can produce large-scale maps rapidly, in one or more frequency settings, at high spatial and spectral resolution. Fully sampled maps of size can be observed in under 1 h. The scientific need for array receivers arises from the requirement for programmes to study samples of objects of statistically significant size, in large-scale unbiased surveys of galactic and extra-galactic regions. Along with morphological information, the new spectral imaging system can be used to study the physical and chemical properties of regions of interest. Its three-dimensional imaging capabilities are critical for research into turbulence and dynamics. In addition, HARPACSIS will provide highly complementary science programmes to wide-field continuum studies and produce the essential preparatory work for submillimetre interferometers such as the Submillimeter Array (SMA) and Atacama Large MillimeterSubmillimeter Array (ALMA). © 2009 RAS.A large-scale CO survey of the Rosette Molecular Cloud: assessing the effects of O stars on surrounding molecular gas
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 395:4 (2009) 1805-1821
THE JAMES CLERK MAXWELL TELESCOPE NEARBY GALAXIES LEGACY SURVEY. I. STAR-FORMING MOLECULAR GAS IN VIRGO CLUSTER SPIRAL GALAXIES
ASTROPHYSICAL JOURNAL 693:2 (2009) 1736-1748