MaNGA Puts Department on Leading Edge of Integral Field Unit Science

by Barb Sanford | Development Specialist, UW-Madison Department of Astronomy
Posted May 30, 2013

It may seem odd that a scientific project’s acronym is the same as a Japanese comic book. But once you know that the project leader lives in Japan and is a punster, it all makes sense.

Mapping Nearby Galaxies at APO (MaNGA) is an ambitious new project that aims to uncover the internal structure and formation history of 10,000 galaxies and characterize the diversity of their evolutionary histories. It is part of the Sloan Digital Sky Survey IV (SDSS-IV), a multi-institutional project that will operate the Sloan Foundation’s 2.5-meter telescope at Apache Point Observatory (New Mexico) from July 2014 to July 2020.

The UW is in the process of finalizing the Astronomy Department’s buy-in to SDSS-IV, which will provide the university with access to data from three surveys—APOGEE-2, MaNGA and eBOSS—aimed at furthering our understanding of stars, Galactic structure, galaxy evolution and cosmology. “Membership in SDSS-IV is a really big deal for the department,” says Professor Christy Tremonti. “It represents a significant investment of resources in a very exciting new direction.”

Department scientists have been involved in SDSS-IV since its inception. Tremonti and new Associate Scientist David Wake helped to craft the original proposal for the survey. Professor Matt Bershady was subsequently asked to serve as SDDS-IV Project Scientist, a position that gives him responsibility for the overall scientific integrity of the project. He is also overseeing the design and testing of a critical piece of hardware for MaNGA, the fiber Integral Field Units (IFUs)—small bundles of optical fibers that will enable the survey to obtain spatially resolved spectra of galaxies.

The original Sloan survey (SDSS-I: 2000-2005) transformed astronomy by providing multi-color optical imaging of a quarter of the sky and spectra of more than a million objects, ushering in a new era of large, searchable astronomical databases, and a more statistical approach to science. As a young graduate student, Tremonti was one of the first to utilize the statistical power of SDSS for galaxy evolution studies. However, she was always aware of a major limitation of the survey: SDSS-I placed a single optical fiber on the center of each galaxy and typically sampled less than 20 percent of its total light, providing an incomplete picture of the galaxy’s average properties, and no information on variations within the galaxy.

MaNGA’s innovation is to deploy numerous IFUs, in place of individual fibers, and to provide spatially resolved spectroscopy. This will enable astronomers to make maps of an individual galaxy’s gas and star motions, chemical abundances and stellar populations. UW scientists have been building and using IFUs on the WIYN telescope for well over a decade. However, with the WIYN IFUs, galaxies must be observed one at a time, making it challenging to build up large samples. “Great science has been done here at the UW with IFU observations of 10 to 50 galaxies. Having a sample of 10,000 galaxies will be a game changer,” says Tremonti.

UW’s heavy involvement with MaNGA was enabled by the newly fledged Washburn Astronomical Laboratories. Bershady, graduate student Arthur Eigenbrot, and staff members Mike Smith (mechanical engineer), Jeff Percival (senior research scientist), Kurt Jaehnig (instrument designer) and Scott Buckley (instrument maker) are designing and testing the IFUs and building an automated fiber-optic testing system. “The MaNGA project has provided Washburn Labs with an opportunity to show how it can enhance and add value to the department’s observing interests,” says Percival. “The team has done a great job, and it would not have been possible without the superb technical staff that Washburn Labs provides,” Scientist/Interim Director Marsha Wolf adds.

Tremonti is particularly excited about the new opportunities that the Sloan survey will open for students. “Survey membership links us to a network of collaborators at top-tier US and international institutions. It’s a wonderful collaborative environment, and I expect it will significantly broaden our grad students’ experiences,” she says.

The department would like to thank Board of Visitors member/past chair Jere Fluno for a gift that provided the seed money for the project.

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