Looking in all the right places: the Sloan Digital Sky Survey extends its reach

At the beginning of July, the Sloan Digital Sky Survey started a new phase with three major new programmes. eBOSS will work to extend precision cosmological measurements to a critical early phase of cosmic history; APOGEE-2 will expand the survey of the Galaxy across both the northern and southern hemispheres, and MaNGA (with participation of the Max Planck Institute for Astrophysics) will for the first time be using the Sloan spectrographs to make spatially resolved maps of individual galaxies. SDSS-IV will run from 2014 to 2020.

Fig. 1: The Milky Way Galaxy as seen in infrared light. The pink shaded region is not visible from the Northern Hemisphere, so has not been studied previously by the SDSS. The new phase of the SDSS will see the entire galaxy. Credit: The SDSS collaboration, Galaxy image credit: Two Micron All Sky Survey / Infrared Processing and Analysis Center / Caltech & University of Massachusetts

Fig. 2: MaNGA galaxy plate, showing the holes for the MaNGA IFUs and sky fibers. (credit: D.R. Law)

Fig. 3: SDSS images of the galaxies observed during the March 2014 MaNGA commissioning run at the Apache Point Observatory. (credit: K. Bundy)

Building on its past successes, the Sloan Digital Sky Survey (SDSS) has launched a major new program that will expand its census of the Universe into new areas it had been unable to explore before:

- Exploring the compositions and motions of stars across the entire Milky Way in unprecedented detail, using a telescope in Chile

- Making detailed maps of the internal structure of thousands of nearby galaxies to determine how they have grown and changed over billions of years, using a cutting-edge measurement device

-Measuring the expansion of the Universe in a poorly-understood five-billion-year period of the Universe's history, using a new set of galaxies and quasars

The new survey is a collaboration of more than 200 astronomers at more than 40 institutions on four continents, and incorporates telescopes in both the Northern and Southern Hemispheres. With these two telescopes, the SDSS will be able to see the entire sky for the first time.

This new phase of the SDSS will provide a vast new database of observations that will significantly expand our understanding of the nature of the Universe at all scales, from our own galaxy to the distant universe. In our galaxy, the new SDSS will see hundreds of thousands of individual stars, including stars that were born at the birth of the Milky Way and stars that were born yesterday. Measuring the compositions, positions, and motions of individual stars will reveal how the Galaxy evolved from the distant past to today.

In addition to the Sloan Foundation 2.5-meter Telescope in New Mexico, SDSS-IV will use the 2.5-meter Irenee du Pont Telescope at Las Campanas Observatory in La Serena, high in the Chilean Andes and home to the clearest skies on the planet. In addition to providing a 360-degree view of the Milky Way, the new telescope will also observe stars in the nearby Magellanic Clouds, giving astronomers a better understanding of the Milky Way's celestial environment.

But the Milky Way is far from the only galaxy that the new SDSS will examine. The new survey will employ innovative new technology to make detailed maps of thousands of nearby galaxies. Unlike nearly all previous astronomy surveys, which looked only at small areas in the centers of other galaxies, the new SDSS will measure light from all over. These better maps are made possible through a new technique of bundling sets of fiber optic cables into tightly-packed arrays. Those collect light from across the entire face of a galaxy, enabling detailed spectral measurements of more than 10,000 nearby galaxies in less than one-twentieth of the time. MPA scientist Guinevere Kauffmann was heavily involved in planning the "Mapping Nearby Galaxies at APO" (MaNGA) survey right from the beginning. MaNGA's goal is to understand the "life cycle" of present day galaxies from imprinted clues of their birth and assembly, through their ongoing growth via star formation and merging, to their death from quenching at late times.

"MaNGA will be key to disentangling the physical processes important in the lives of galaxies," Guinevere Kauffmann points out. "In particular, we need to understand which aspects of galaxies are set by cosmological initial conditions and which are set by black holes."

And the new SDSS will continue to improve our understanding of the Universe as a whole. It will precisely measure the expansion history of the universe through 80% of cosmic history, back to when the Universe was less than three billion years old. These new detailed measurements will help to improve constraints on the nature of dark energy, the most mysterious experimental result in modern physics.

The new cosmology measurements will include a survey of nearly all the quasars, which will allow for precision measurements of the history of the Universe's expansion in ways never before possible. Other programs within the new SDSS will follow up on galaxies seen by prior X-ray surveys, and will conduct the first systematic spectral study of variable objects, yielding a critical resource astronomers can use to identify the nature of many types of time-varying light sources discovered in previous surveys.

SDSS Press Officer:
Jordan Raddick, SDSS-III Public Information Officer, Johns Hopkins University
Email: raddickjhu.edu
Phone: 1-410-516-8889

Contact at MPA
Guinevere Kauffmann
Max-Planck-Institut für Astrophysik
Karl-Schwarzschild-Str. 1
D-85748 Garching
Phone: 089 30000-2013
E-mail: gkauffmannmpa-garching.mpg.de

Hannelore Hämmerle
Presse- und Öffentlichkeitsarbeit
Max-Planck-Institut für Astrophysik
Tel: +49 (89) 30 000 3980
E-mail: prmpa-garching.mpg.de

Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation and the Participating Institutions. SDSS-IV acknowledges support and resources from the Center for High-Performance Computing at the University of Utah. The SDSS web site is www.sdss.org.
SDSS-IV is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS Collaboration including the Carnegie Institution for Science, Carnegie Mellon University, the Chilean Participation Group, Harvard-Smithsonian Center for Astrophysics, Instituto de Astrofisica de Canarias, The Johns Hopkins University, Kavli Institute for the Physics and Mathematics of the Universe (IPMU) / University of Tokyo, Lawrence Berkeley National Laboratory, Leibniz Institut für Astrophysik Potsdam (AIP),Max-Planck-Institut für Astrophysik (MPA Garching), Max-Planck-Institut für Extraterrestrische Physik (MPE), Max-Planck-Institut für Astronomie (MPIA Heidelberg), National Astronomical Observatory of China, New Mexico State University, New York University, The Ohio State University, Pennsylvania State University, Shanghai Astronomical Observatory, United Kingdom Participation Group, Universidad Nacional Autonoma de Mexico, University of Arizona, University of Colorado Boulder, University of Portsmouth, University of Utah, University of Washington, University of Wisconsin, Vanderbilt University, and Yale University.