High-resolution CO and radio imaging of ULIRGs: extended CO structures and implications for the universal star formation law

2009/12/31 by M. S. Bothwell, S. C. Chapman, L. Tacconi +20 · 1 citation
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Astrophysics and Star Formation Studies #Context (archaeology) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Luminous infrared galaxy #Physics #RADIUS #Star formation #astro-ph.CO

paper · pdf · doi:10.1111/j.1365-2966.2010.16480.x

17 pages, 10 figures; revised version accepted for publication in MNRAS

arxiv created 2010/02/09 · openalex publication_date 2010/04/01 · arxiv updated 2015/05/14 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05

Abstract

We present high spatial resolution (0.4 arcsec, kpc) Plateau de Bure Interferometer interferometric data on three ultraluminous infrared galaxies (ULIRGs) at ⁠: two submillimetre galaxies (SMGs) and one submillimetre faint star-forming radio galaxy. The three galaxies have been robustly detected in CO rotational transitions, either 12CO (J= 43) or 12CO (J= 32), allowing their sizes and gas masses to be accurately constrained. These are the highest spatial resolution observations observed to date (by a factor of 2) for intermediate-excitation CO emission in ULIRGs. The galaxies appear extended over several resolution elements, having a mean radius of 3.7 kpc. High-resolution (0.3 arcsec) combined Multi-Element Radio-Linked Interferometer Network-Very Large Array observations of their radio continua allow an analysis of the star formation behaviour of these galaxies, on comparable spatial scales to those of the CO observations. This ‘matched beam’ approach sheds light on the spatial distribution of both molecular gas and star formation, and we can therefore calculate accurate star formation rates and gas surface densities: this allows us to place the three systems in the context of a Kennicutt–Schmidt (KS)-style star formation law. We find a difference in size between the CO and radio emission regions, and as such we suggest that using the spatial extent of the CO emission region to estimate the surface density of star formation may lead to error. This size difference also causes the star formation efficiencies within systems to vary by up to a factor of 5. We also find, with our new accurate sizes, that SMGs lie significantly above the KS relation, indicating that stars are formed more efficiently in these extreme systems than in other high-z star-forming galaxies.

Citations

• Evidence for Extended, Obscured Starbursts in Submillimeter Galaxies
• High-resolution radio observations of submillimetre galaxies
• Intense Star Formation and Feedback at High Redshift: Spatially Resolved Properties of thez= 2.6 Submillimeter Galaxy SMM J14011+0252
• The rapid formation of a large rotating disk galaxy three billion years after the Big Bang
• The nature of faint submillimetre-selected galaxies
• The formation and assembly of a typical star-forming galaxy at redshift z ≈ 3
• Interferometric Observations of Powerful CO Emission from Three Submillimeter Galaxies at z =2.39, 2.51, and 3.35
• A CO EMISSION LINE FROM THE OPTICAL AND NEAR-IR UNDETECTED SUBMILLIMETER GALAXY GN10
• Deep multi-frequency radio imaging in the Lockman Hole using the GMRT and VLA - I. The nature of the sub-mJy radio population
• SCUBA: a common-user submillimetre camera operating on the James Clerk Maxwell Telescope
• The Global Schmidt Law in Star‐forming Galaxies
• On the interstellar medium and star formation demographics of galaxies in the local universe
• STAR FORMATION IN GALAXIES ALONG THE HUBBLE SEQUENCE
• HCN Observations of Dense Star-forming Gas in High-Redshift Galaxies
• An interferometric CO survey of luminous submillimetre galaxies
• A Catalog of Neighboring Galaxies

Cited by

• MOLECULAR GAS IN LENSEDz>2 QUASAR HOST GALAXIES AND THE STAR FORMATION LAW FOR GALAXIES WITH LUMINOUS ACTIVE GALACTIC NUCLEI