Alma resolves the properties of star-forming regions in a dense gas disk at z ∼ 3

Journal Article · Wed Jun 10 04:00:00 EDT 2015 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/806/1/L17· OSTI ID:22868718

Swinbank, A. M.; Smail, Ian; Smit, R. ^[1]; Dye, S.; Nightingale, J. W.; Furlanetto, C. ^[2]; Cooray, A. ^[3]; Dannerbauer, H. ^[4]; Dunne, L. ^[5]; Eales, S. ^[6]; Gavazzi, R. ^[7]; Hunter, T. ^[8]; Ivison, R. J.; Oteo-Gomez, I. ^[9]; Negrello, M. ^[10]; Werf, P. van der ^[11]

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1. Institute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom)
2. School of Physics and Astronomy, Nottingham University, University Park, Nottingham NG7 2RD (United Kingdom)
3. Astronomy Department, California Institute of Technology, MC 249-17, 1200 East California Boulevard, Pasadena, CA 91125 (United States)
4. Institut fur Astrophysik, Universitat Wien, Türkenschanzstrasse 17, 1180 Wien (Austria)
5. Department of Physics and Astronomy, University of Canterbury, Private Bag 4800, Christchurch 8140 (New Zealand)
6. School of Physics and Astronomy, Cardiff University, Queen’s Buildings, The Parade, Cardiff CF24 3AA (United Kingdom)
7. Institut d’Astrophysique de Paris, UMR7095 CNRS-Universite Pierre et Marie Curie, 98bis bd Arago, F-75014 Paris (France)
8. National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA, 22903 (United States)
9. Institute for Astronomy, Royal Observatory Edinburgh, Blackford Hill, Edinburgh, EH9 3HJ, UK. (United Kingdom)
10. INAF, Osservatorio Astronomico di Padova, Vicolo Osservatorio 5, I-35122 Padova (Italy)
11. Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden (Netherlands)

We exploit long baseline ALMA submillimeter observations of the lensed star-forming galaxy SDP 81 at z = 3.042 to investigate the properties of the interstellar medium (ISM) on scales of 50–100 pc. The kinematics of the {sup 12}CO gas within this system are well described by a rotationally supported disk with an inclination-corrected rotation speed, v{sub rot} = 320 ± 20 km s{sup −1,} and a dynamical mass of M{sub dyn} = (3.5 ± 1.0)× 10{sup 10} M{sub ⊙} within a radius of 1.5 kpc. The disk is gas-rich and unstable, with a Toomre parameter, Q = 0.30 ± 0.10, and so into star-forming regions with Jeans length L{sub J} ∼ 130 pc. We identify five star-forming regions within the ISM on these scales and show that their scaling relations between luminosity, line widths, and sizes are significantly offset from those typical of molecular clouds in local galaxies (Larson’s relations). These offsets are likely to be caused by the high external hydrostatic pressure for the ISM, P{sub tot}/k{sub B}∼ 40{sub −20}{sup +30} × 10{sup 7} K cm{sup −3}, which is ∼10{sup 4}× higher than the typical ISM pressure in the Milky Way. The physical conditions of the star-forming ISM and giant molecular clouds appear to be similar to those found in the densest environments in the local universe, such as those in the Galactic center.

• OSTI ID: 22868718
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 806; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
GALACTIC EVOLUTION
INCLINATION
LENGTH
LENSES
LINE WIDTHS
LUMINOSITY
MASS
MILKY WAY
MOLECULES
RED SHIFT
ROTATION
STARS
UNIVERSE