ACTIVE DISK BUILDING IN A LOCAL H I-MASSIVE LIRG: THE SYNERGY BETWEEN GAS, DUST, AND STAR FORMATION

Journal Article · Mon Dec 20 00:00:00 EST 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/725/2/1550· OSTI ID:21476693

Cluver, M E; Jarrett, T H ^[1]; Kraan-Korteweg, R C; Woudt, P A ^[2]; Koribalski, B S; Emonts, B ^[3]; Appleton, P N ^[4]; Melbourne, J ^[5]

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1. IPAC, California Institute of Technology, Pasadena, CA 91125 (United States)
2. Astronomy Department, Centre for Astrophysics, Cosmology and Gravity, University of Cape Town, Rondebosch 7700 (South Africa)
3. Australia Telescope National Facility, CSIRO, Epping, NSW 1710 (Australia)
4. NASA Herschel Science Center, California Institute of Technology, Pasadena, CA 91125 (United States)
5. Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)

HIZOA J0836-43 is the most H I-massive (M{sub H{sub I}} = 7.5 x 10{sup 10} M{sub sun}) galaxy detected in the HIPASS volume ({delta} = -90{sup 0} to + 25{sup 0}, v<12,700 km s{sup -1}) and lies optically hidden behind the Milky Way. Markedly different from other extreme H I disks in the local universe, it is a luminous infrared galaxy (LIRG) with an actively star-forming disk (>50 kpc), central to its {approx}130 kpc gas disk, with a total star formation rate (SFR) of {approx}20.5 M{sub sun} yr{sup -1}. Spitzer spectroscopy reveals an unusual combination of powerful polycyclic aromatic hydrocarbon (PAH) emission coupled to a relatively weak warm dust continuum, suggesting photodissociation-region-dominated emission. Compared to a typical LIRG with similar total infrared luminosity (L{sub TIR} = 10{sup 11} L{sub sun}), the PAHs in HIZOA J0836-43 are more than twice as strong, whereas the warm dust continuum ({lambda}>20 {mu}m) is best fit by a star-forming galaxy with L{sub TIR} = 10{sup 10} L{sub sun}. Mopra CO observations suggest an extended molecular gas component (H{sub 2} + He>3.7 x 10{sup 9} M{sub sun}) and a lower limit of {approx}64% for the gas-mass fraction; this is above average compared to local disk systems, but similar to that of z {approx} 1.5 BzK galaxies ({approx}57%). However, the star formation efficiency (SFE = L{sub IR}/L'{sub CO}) for HIZOA J0836-43 of 140 L{sub sun} (K km s{sup -1} pc{sup 2}){sup -1} is similar to that of local spirals and other disk galaxies at high redshift, in strong contrast to the increased SFE seen in merging and strongly interacting systems. HIZOA J0836-43 is actively forming stars and building a massive stellar disk. Its evolutionary phase of star formation (M{sub stellar}, SFR, and gas fraction) compared to more distant systems suggests that it would be considered typical at redshift z {approx} 1. This galaxy provides a rare opportunity in the nearby universe for studying (at z {approx} 0.036) how disks were building and galaxies evolving at z {approx} 1, when similarly large gas fractions were likely more common.

• OSTI ID: 21476693
• Journal Information: Astrophysical Journal, Vol. 725, Issue 2; Other Information: DOI: 10.1088/0004-637X/725/2/1550; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
DUSTS
EMISSION
LUMINOSITY
MILKY WAY
PHOTOLYSIS
POLYCYCLIC AROMATIC HYDROCARBONS
RED SHIFT
SPECTROSCOPY
STARS
UNIVERSE
AROMATICS
CHEMICAL REACTIONS
DECOMPOSITION
GALAXIES
HYDROCARBONS
OPTICAL PROPERTIES
ORGANIC COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHYSICAL PROPERTIES