The HASHTAG project I. A Survey of CO(3-2) Emission from the Star Forming Disc of M31

Abstract

We present a CO(3-2) survey of selected regions in the M31 disc as part of the JCMT large programme, HARP and SCUBA-2 High-Resolution Terahertz Andromeda Galaxy Survey (HASHTAG). The 12 CO(3-2) fields in this survey cover a total area of 60 square arcminutes, spanning a deprojected radial range of 2 - 14 kpc across the M31 disc. Combining these observations with existing IRAM 30m CO(1-0) observations and JCMT CO(3-2) maps of the nuclear region of M31, as well as dust temperature and star formation rate surface density maps, we are able to explore the radial distribution of the CO(3-2)/CO(1-0) integrated intensity ratio (R31) and its relationship with dust temperature and star formation. We find that the value of R31 between 2 - 9 kpc galactocentric radius is 0.14, significantly lower than what is seen in the nuclear ring at ~1 kpc (R31 ~ 0.8), only to rise again to 0.27 for the fields centred on the 10 kpc star forming ring. We also found that R31 is positively correlated with dust temperature, with Spearman's rank correlation coefficient $\rho$ = 0.55. The correlation between star formation rate surface density and CO(3--2) intensity is much stronger than with CO(1-0), with $\rho$ = 0.54 compared to -0.05, suggesting that the CO(3-2) line traces warmer and denser star forming gas better. We also find that R31 correlates well with star formation rate surface density, with $\rho$ = 0.69.

21 pages, 10 figures, accepted by MNRAS for publication

References in corpus (14)

• xCOLD GASS: the complete IRAM-30m legacy survey of molecular gas for galaxy evolution studies
• A Wide-field High Resolution HI Mosaic of Messier 31: I. Opaque Atomic Gas and Star Formation Rate Density
• The Panchromatic Hubble Andromeda Treasury XI: The Spatially-Resolved Recent Star Formation History of M31
• The JCMT Nearby Galaxies Legacy Survey I. Star Forming Molecular Gas in Virgo Cluster Spiral Galaxies
• Unveiling the Boxy Bulge and Bar of the Andromeda Spiral Galaxy
• The Herschel Exploitation of Local Galaxy Andromeda (HELGA) VII: A SKIRT radiative transfer model and insights on dust heating
• Dense gas is not enough: environmental variations in the star formation efficiency of dense molecular gas at 100pc scales in M51
• Clustering of Local Group distances: publication bias or correlated measurements? II. M31 and beyond
• ORAC-DR: A generic data reduction pipeline infrastructure
• The Survey of Lines in M31 (SLIM): Investigating the Origins of [CII] Emission
• Calibrating star-formation rate prescriptions at different scales (10 pc to 1 kpc) in M31
• The Panchromatic Hubble Andromeda Treasury XVII. Examining Obscured Star Formation with Synthetic Ultraviolet Flux Maps in M31
• Long-term X-ray Variability Study of IC342 from XMM-Newton Observations
• JCMT Mapping of CO(3-2) in the Circumnuclear Region of M31

Cited by in corpus (3)

• A Decade of SCUBA-2: A Comprehensive Guide to Calibrating 450 $\mu$m and 850 $\mu$m Continuum Data at the JCMT
• A Herschel mapping of [C ii], [O i] and [O iii] lines from the circumnuclear region of M31
• The HASHTAG project: The First Submillimeter Images of the Andromeda Galaxy from the Ground