CaltechAUTHORS
Published June 10, 2015 | Version Published
Journal Article Open

ALMA Resolves the Properties of Star-forming Regions in a Dense Gas Disk at z ~ 3

Creators

  • 1. ROR icon Durham University
  • 2. ROR icon University of Nottingham
  • 3. ROR icon Coordenação de Aperfeicoamento de Pessoal de Nível Superior
  • 4. ROR icon California Institute of Technology
  • 5. ROR icon University of Vienna
  • 6. ROR icon University of Canterbury
  • 7. ROR icon Royal Observatory
  • 8. ROR icon Cardiff University
  • 9. ROR icon Institut d'Astrophysique de Paris
  • 10. ROR icon National Radio Astronomy Observatory
  • 11. ROR icon European Southern Observatory
  • 12. ROR icon Osservatorio Astronomico di Padova
  • 13. ROR icon Leiden University
  • 14. ROR icon Atacama Large Millimeter Submillimeter Array

Abstract

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 ^(12)CO gas within this system are well described by a rotationally supported disk with an inclination-corrected rotation speed, v_(rot) = 320 ± 20 km s^(−1), and a dynamical mass of M_(dyn) = (3.5 ± 1.0)× 10^(10) M_☉ 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_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_(tot)/k_B ~ 40_(-20^(+30) × 10^7 K cm^(−3), which is ~10^4× 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.

Additional Information

© 2015 American Astronomical Society. Received 2015 May 1; accepted 2015 May 18; published 2015 June 9. We would like to thank the anonymous referee for a constructive report on this paper. A.M.S. acknowledges an STFC Advanced Fellowship (ST/H005234/1) and the Leverhume foundation. I.R.S. acknowledges STFC (ST/I001573/1), the ERC Advanced Grant DUSTYGAL 321334, and a Royal Society/Wolfson Merit Award. C.F. acknowledges CAPES funding (proc. 12203-1). We also thank Padelis Papadopoulos for useful discussions. This paper uses data from ALMA program ADS/JAO.ALMA#2011.0.00016.SV. ALMA is a partnership of ESO, NSF (USA), NINS (Japan), NRC (Canada), NSC and ASIAA (Taiwan), and KASI (Republic of Korea) and the Republic of Chile. The JAO is operated by ESO, AUI/NRAO and NAOJ.

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Additional details

Identifiers

Eprint ID
58838
Resolver ID
CaltechAUTHORS:20150710-090446481

Funding

Science and Technology Facilities Council (STFC)
ST/H005234/1
Leverhulme Foundation
Science and Technology Facilities Council (STFC)
ST/I001573/1
European Research Council (ERC)
DUSTYGAL 321334
Royal Society
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
12203-1

Dates

Created
2015-07-10
Created from EPrint's datestamp field
Updated
2021-11-10
Created from EPrint's last_modified field