A list of our papers is available here.
Half of the energy produced since recombination has been absorbed and reemitted by dust. This radiation, the cosmic infrared background (CIB), is produced primarily by dusty, star-forming galaxies (DSFGs) at z~1-3, with a tail extending beyond z>6. These objects were first identified in submillimeter-wavelength (submm) surveys of the extragalactic sky and found to be orders of magnitude more abundant in the early Universe than the present day. These studies upended our view of cosmic star formation, demonstrating that the bulk of star formation activity in the Universe could be taking place in DSFGs that were invisible in optical and ultraviolet surveys due to dust obscuration.
Recently, large-area millimeter/submillimeter surveys have become available and proven to be efficient for selecting rare (<0.1 per sq. deg.), gravitationally lensed DSFGs. Due to the strong gravitational lensing, these objects typically appear an order of magnitude more luminous than the bulk DSFG population, with a corresponding increase in their solid angle on the sky. This provides a spectacular reduction in the integration times required to detect lensed sources, makes weak spectral lines accessible, and magnifies the resolving power of our telescopes.
The South Pole Telescope (SPT) has systematically identified a large number of high-redshift strongly gravitationally lensed starburst galaxies in a 2500 square degree cosmological survey of the millimeter (mm) sky. These sources are selected by their extreme mm flux, which is largely independent of redshift and lensing configuration. The flux magnification provided by the gravitational lensing enabled us to perform a spectroscopic redshift survey with the recently commissioned Atacama Large Millimeter Array (ALMA). We targeted 26 SPT sources and obtained redshifts via molecular carbon monoxide (CO) lines. With a 90% detection rate, our ALMA+SPT CO redshift survey is the most complete DSFG survey to date. We determine that roughly 35% of these sources lie at z>4, indicating the fraction of dusty starburst galaxies at high-redshift is far higher than previously thought. Two sources are at z=5.7, placing them among the highest redshift starbursts known, and demonstrating that large reservoirs of molecular gas and dust can be present in massive galaxies near the end of the epoch of cosmic reionization. These sources were additionally targeted with high resolution imaging with ALMA, unambiguously demonstrating them to be strongly gravitationally lensed by foreground structure, and enabling us to make detailed and robust lens models.
The SPT has identified the brightest high-redshift sources in the extragalactic sky visible from ALMA, and assembled a sample of ~100 strongly lensed, dusty, starburst galaxies. We are undertaking a comprehensive and systematic followup campaign to use these “cosmic magnifying glasses” to study the infrared background in unprecedented detail, inform the condition of the interstellar medium in starburst galaxies at high redshift, and place limits on dark matter substructure.
Bitten Gullberg, European Southern Observatory (Garching), Advisor Carlos de Breuck
Kate Husband, University of Bristol, Advisor Malcolm Bremer
Jingzhe Ma, University of Florida, Advisor Anthony Gonzales
Kaja Rotermund, Dalhousie University, Advisor Scott Chapman
Justin Spilker, University of Arizona, Advisor Dan Marrone
Maria Strandet, Max Planck Institute for Radio Astronomy, Advisor Axel Weiss
Matthieu Bethermin, ESO Fellow, European Southern Observatory (Garching)
Matt Bothwell, University of Cambridge
Yashar Hezaveh, Hubble Fellow, Stanford University
Niraj Welikala, Beecroft Fellow, University of Oxford
Faculty and Research Astronomers
James Aguirre, University of Pennsylvania
Manuel Aravena, Universidad Diego Portales
Matt Ashby, Harvard-Smithsonian Center for Astrophysics
Mark Brodwin, University of Missouri – Kansas City
John Carlstrom, University of Chicago
Scott Chapman, Dalhousie University
Tom Crawford, University of Chicago
Carlos de Breuck, European Southern Observatory
Chris Fassnacht, University of California – Davis
Anthony Gonzales, University of Florida
Thomas Greve, University College London
Matt Malkan, University of California – Los Angeles
Dan Marrone, University of Arizona
Eric Murphy, California Institute of Technology
Brian Stalder, Harvard
Antony Stark, Harvard-Smithsonian Center for Astrophysics
Joaquin Vieira, University of Illinois
Axel Weiss, Max Planck Institute for Radio Astronomy