From UC Santa Cruz: “MaNGA data release includes detailed maps of thousands of nearby galaxies”

UC Santa Cruz

From UC Santa Cruz

January 29, 2019
Tim Stephens

Major data release from Sloan Digital Sky Survey includes galaxy maps, new data access and visualization tools, and a huge ‘stellar library’.

The MaNGA data set will eventually include more than 10,000 nearby galaxies, and the survey is already more than half way toward that goal. (Image credit: SDSS/MaNGA collaboration)

The latest data release from the Sloan Digital Sky Survey (SDSS) includes observations revealing the internal structure and composition of nearly 5,000 nearby galaxies observed during the first three years of a program called Mapping Nearby Galaxies at Apache Point Observatory (MaNGA).

SDSS 2.5 meter Telescope at Apache Point Observatory, near Sunspot NM, USA, Altitude 2,788 meters (9,147 ft)

MaNGA uses a technique called resolved spectroscopy to study galaxies in much greater detail than previous surveys. Spectroscopy is a powerful tool for astronomers, yielding a wealth of information by measuring how much light an object emits at different wavelengths. In the past, astronomers typically acquired just one spectrum for each galaxy, but resolved spectroscopy (also called integral field spectroscopy) obtains hundreds of separate spectra covering every location within the galaxy.

“Resolved spectroscopy allows us to dissect a galaxy and study its internal composition and the motions of its stars and gas,” explained MaNGA principal investigator Kevin Bundy, an associate researcher at UC Observatories and adjunct professor of astronomy and astrophysics at UC Santa Cruz.

The Marvin web site offers easy access to a wealth of information about each galaxy in the MaNGA survey, including maps of key features such as star formation, stellar motion, emission lines, and dozens of other properties important to astronomers. View larger image here. (Image credit: SDSS/MaNGA collaboration)

The MaNGA survey obtains spectra across the entire face of target galaxies using custom-designed fiber bundles. The bottom right illustrates how the array of fibers spatially samples a particular galaxy. The top right compares spectra observed by two fibers at different locations in the galaxy, showing how the spectrum of the central regions differs dramatically from outer regions. (Image Credit: Dana Berry/SkyWorks Digital Inc., David Law, and the SDSS collaboration)

“People have been doing resolved spectroscopy for individual galaxies, but we’ve never had it for thousands of galaxies, so MaNGA gives us the statistical power to address a lot of important questions,” Bundy said.

MaNGA’s goal is to understand the “life history” of present-day galaxies, from their initial birth and assembly, through their ongoing growth via star formation and mergers, to their death from “quenching” of star formation at late times. Bundy and his students at UC Santa Cruz, for example, have discovered evidence in the MaNGA data for outflows of hot ionized gas in “dead” galaxies, supporting the idea that powerful winds driven out from a galaxy’s central black hole can shut down star formation. Bundy’s team is also finding clues to how galaxies were assembled over time by studying the motions of their stars and gas and by analyzing the chemical signatures of stars in different parts of galaxies.

One of three programs in the fourth phase of SDSS, MaNGA will eventually study a representative sample of some 10,000 nearby galaxies. Bundy said the survey is more than half way toward that goal and on track to reach it by 2020. Data from 4,621 galaxies are now publicly available as part of the 15th SDSS data release (the third data release for SDSS-IV).

“This data release is a major milestone for us,” Bundy said. “MaNGA is already by far the largest survey of its kind, and this release includes both the data and the analytical tools the project has developed.”

A powerful new interface called Marvin provides access to the MaNGA data and galaxy maps based on analyses of the data. Marvin includes a wide range of tools for searching, accessing, and visualizing the data. The Marvin web site offers easy access to a wealth of information about each galaxy, including maps of key features such as star formation, stellar motion, emission lines, and dozens of other properties important to astronomers. Kyle Westfall, a project scientist at UC Observatories, led the development of the data analysis pipeline that produced the maps and other data products now publicly available for the first time.

Another important part of this data release is the MaNGA Stellar Library containing spectra of more than 3,000 stars in our Milky Way galaxy. When complete, it will include 5,000 to 6,000 stars. Researchers can use the spectra of these individual stars to try to reconstruct the spectrum of a galaxy and thereby figure out that galaxy’s unique mix of different star types.

“The MaNGA Stellar Library is the largest library of stars ever compiled, with spectra from the same instruments used for the galaxies, so it’s a very powerful tool for understanding the nature of the stellar populations in these galaxies,” Bundy said.

MaNGA Survey Scientist Renbin Yan of the University of Kentucky led the development of the Stellar Library.

The MaNGA survey uses the two BOSS spectrographs at the 2.5-meter Sloan Foundation Telescope at Apache Point Observatory in New Mexico in a novel way.

BOSS Spectrograph – SDSS-III

Specially designed “integral field units,” each composed of tightly packed arrays of optical fibers, enable the measurement of spectra at multiple points in the same galaxy. The MaNGA spectra provide continuous coverage from optical to near-infrared wavelengths.

Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation, the U.S. Department of Energy Office of Science, and the Participating Institutions.

See the full article here .


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UCSC Lick Observatory, Mt Hamilton, in San Jose, California, Altitude 1,283 m (4,209 ft)


UCO Lick Shane Telescope
UCO Lick Shane Telescope interior
Shane Telescope at UCO Lick Observatory, UCSC

Lick Automated Planet Finder telescope, Mount Hamilton, CA, USA

Lick Automated Planet Finder telescope, Mount Hamilton, CA, USA

UC Santa Cruz campus
The University of California, Santa Cruz, opened in 1965 and grew, one college at a time, to its current (2008-09) enrollment of more than 16,000 students. Undergraduates pursue more than 60 majors supervised by divisional deans of humanities, physical & biological sciences, social sciences, and arts. Graduate students work toward graduate certificates, master’s degrees, or doctoral degrees in more than 30 academic fields under the supervision of the divisional and graduate deans. The dean of the Jack Baskin School of Engineering oversees the campus’s undergraduate and graduate engineering programs.

UCSC is the home base for the Lick Observatory.

Lick Observatory's Great Lick 91-centimeter (36-inch) telescope housed in the South (large) Dome of main building
Lick Observatory’s Great Lick 91-centimeter (36-inch) telescope housed in the South (large) Dome of main building

Search for extraterrestrial intelligence expands at Lick Observatory
New instrument scans the sky for pulses of infrared light
March 23, 2015
By Hilary Lebow
The NIROSETI instrument saw first light on the Nickel 1-meter Telescope at Lick Observatory on March 15, 2015. (Photo by Laurie Hatch) UCSC Lick Nickel telescope

Astronomers are expanding the search for extraterrestrial intelligence into a new realm with detectors tuned to infrared light at UC’s Lick Observatory. A new instrument, called NIROSETI, will soon scour the sky for messages from other worlds.

“Infrared light would be an excellent means of interstellar communication,” said Shelley Wright, an assistant professor of physics at UC San Diego who led the development of the new instrument while at the University of Toronto’s Dunlap Institute for Astronomy & Astrophysics.

Wright worked on an earlier SETI project at Lick Observatory as a UC Santa Cruz undergraduate, when she built an optical instrument designed by UC Berkeley researchers. The infrared project takes advantage of new technology not available for that first optical search.

Infrared light would be a good way for extraterrestrials to get our attention here on Earth, since pulses from a powerful infrared laser could outshine a star, if only for a billionth of a second. Interstellar gas and dust is almost transparent to near infrared, so these signals can be seen from great distances. It also takes less energy to send information using infrared signals than with visible light.

Frank Drake, professor emeritus of astronomy and astrophysics at UC Santa Cruz and director emeritus of the SETI Institute, said there are several additional advantages to a search in the infrared realm.

“The signals are so strong that we only need a small telescope to receive them. Smaller telescopes can offer more observational time, and that is good because we need to search many stars for a chance of success,” said Drake.

The only downside is that extraterrestrials would need to be transmitting their signals in our direction, Drake said, though he sees this as a positive side to that limitation. “If we get a signal from someone who’s aiming for us, it could mean there’s altruism in the universe. I like that idea. If they want to be friendly, that’s who we will find.”

Scientists have searched the skies for radio signals for more than 50 years and expanded their search into the optical realm more than a decade ago. The idea of searching in the infrared is not a new one, but instruments capable of capturing pulses of infrared light only recently became available.

“We had to wait,” Wright said. “I spent eight years waiting and watching as new technology emerged.”

Now that technology has caught up, the search will extend to stars thousands of light years away, rather than just hundreds. NIROSETI, or Near-Infrared Optical Search for Extraterrestrial Intelligence, could also uncover new information about the physical universe.

“This is the first time Earthlings have looked at the universe at infrared wavelengths with nanosecond time scales,” said Dan Werthimer, UC Berkeley SETI Project Director. “The instrument could discover new astrophysical phenomena, or perhaps answer the question of whether we are alone.”

NIROSETI will also gather more information than previous optical detectors by recording levels of light over time so that patterns can be analyzed for potential signs of other civilizations.

“Searching for intelligent life in the universe is both thrilling and somewhat unorthodox,” said Claire Max, director of UC Observatories and professor of astronomy and astrophysics at UC Santa Cruz. “Lick Observatory has already been the site of several previous SETI searches, so this is a very exciting addition to the current research taking place.”

NIROSETI will be fully operational by early summer and will scan the skies several times a week on the Nickel 1-meter telescope at Lick Observatory, located on Mt. Hamilton east of San Jose.

The NIROSETI team also includes Geoffrey Marcy and Andrew Siemion from UC Berkeley; Patrick Dorval, a Dunlap undergraduate, and Elliot Meyer, a Dunlap graduate student; and Richard Treffers of Starman Systems. Funding for the project comes from the generous support of Bill and Susan Bloomfield.