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Published December 10, 2013 | Published + Submitted
Journal Article Open

SPT 0538–50: Physical Conditions in the Interstellar Medium of a Strongly Lensed Dusty Star-forming Galaxy at z = 2.8


We present observations of SPT-S J053816–5030.8, a gravitationally lensed dusty star-forming galaxy (DSFG) at z = 2.7817 that was first discovered at millimeter wavelengths by the South Pole Telescope. SPT 0538–50 is typical of the brightest sources found by wide-field millimeter-wavelength surveys, being lensed by an intervening galaxy at moderate redshift (in this instance, at z = 0.441). We present a wide array of multi-wavelength spectroscopic and photometric data on SPT 0538–50, including data from ALMA, Herschel PACS and SPIRE, Hubble, Spitzer, the Very Large Telescope, ATCA, APEX, and the Submillimeter Array. We use high-resolution imaging from the Hubble Space Telescope to de-blend SPT 0538–50, separating DSFG emission from that of the foreground lens. Combined with a source model derived from ALMA imaging (which suggests a magnification factor of 21 ± 4), we derive the intrinsic properties of SPT 0538–50, including the stellar mass, far-IR luminosity, star formation rate, molecular gas mass, and—using molecular line fluxes—the excitation conditions within the interstellar medium. The derived physical properties argue that we are witnessing compact, merger-driven star formation in SPT 0538–50 similar to local starburst galaxies and unlike that seen in some other DSFGs at this epoch.

Additional Information

© 2013 American Astronomical Society. Received 2013 July 3; accepted 2013 September 11; published 2013 November 26. We thank the anonymous referee who provided comments that helped improve the clarity of this manuscript. The authors would like to thank N. Rangwala for sharing the M82 CO flux densities. M.S.B. would like to acknowledge the hospitality of the Aspen Center for Physics, where some of this manuscript was written. The Submillimeter Array is a joint project between the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics and is funded by the Smithsonian Institution and the Academia Sinica. Support is provided by National Science Foundation grants AST-1009649, ANT-0638937, PHY-1125897, and PHYS-1066293. This paper makes use of the following ALMA data: ADS/JAO.ALMA #2011.0.00957. S and #2011.0.00958. S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada) and NSC and ASIAA (Taiwan), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under a cooperative agreement by Associated Universities, Inc. Partial support for this work was provided by NASA through grant HST-GO-12659 from the Space Telescope Science Institute and awards for Herschel analysis issued by JPL/Caltech for OT1_dmarrone_1, OT1_jvieira_4, and OT2_jvieira_5. Facilities: HST/WFC3, Spitzer/IRAC, ALMA, APEX, ATCA, VLT:Kueyen, SMA, Herschel

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Published - 0004-637X_779_1_67.pdf

Submitted - 1309.3275v1.pdf


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