From The University of California-Santa Cruz (US) : “MaNGA team releases largest-ever collection of 3D maps of nearby galaxies”

From The University of California-Santa Cruz (US)

January 12, 2022
Jordan Raddick

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MaNGA measures spectra at multiple points in the same galaxy using a newly created fiber bundle technology. This image shows the Sloan Foundation Telescope and a close-up of the tip of the fiber bundle on the left, while the bottom right illustrates how each fiber observes a different section of each galaxy. The top right shows data gathered by two fibers observing two different part of the galaxy, showing how the spectrum of the central regions differs dramatically from outer regions. Credit: Dana Berry/SkyWorks Digital, David Law, SDSS Collaboration

Just over a month ago, scientists from the Sloan Digital Sky Survey (SDSS) released the complete dataset of 10,000 galaxies observed by the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) project, making MaNGA the largest galaxy survey of its kind.

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

Apache Point Observatory near Sunspot, New Mexico Altitude 2,788 meters (9,147 ft).

Kevin Bundy, assistant professor of astronomy and astrophysics at UC Santa Cruz, is MaNGA’s principal investigator.

“Observing such a large sample with MaNGA allows us to see how the detailed internal properties of galaxies vary in systematic ways with other factors, like galaxy mass or where galaxies live in the universe,” Bundy said. “These patterns are the key to understanding the physical processes that shape galaxy evolution.”

MaNGA is a special kind of galaxy survey, using an innovative fiber-bundling technology to make detailed spectral maps of thousands of nearby galaxies. Spectra are graphs that show the amount of light given off by a galaxy at different wavelengths, much like a rainbow shows the amount of sunlight in various colors. Most previous galaxy surveys have either taken detailed images in one or a handful of colors, or measured just a single spectrum for an entire galaxy, but MaNGA works differently.

With fiber-optic cables bundled into tightly-packed hexagonal arrays, the team measured spectra at tens to hundreds of separate points in each galaxy, resulting in a “datacube” containing full spectroscopic information at each point. MaNGA was able to observe seventeen galaxies at once, while similar surveys could only observe one galaxy at a time. Six years of observing in this mode created the largest sample size of this kind ever obtained.

Researchers study each data cube to reveal its galaxy’s detailed chemical composition; find the ages, chemical makeup, and motions of the stars inside it; and map ionized interstellar gas. MaNGA has created over 30 different maps for each galaxy. These maps can be used for lots of different applications, for example, to estimate how many baby stars are being formed at every position in the galaxy, or to find the influence of the central supermassive black hole. MaNGA dramatically increases the number of galaxies with this detailed information, and a sister project, the MaNGA Stellar Library (MaStar), helped it along.

Galaxies are made of stars, so understanding them in detail requires a detailed library of spectra of stars. Alongside the complete release of MaNGA, SDSS scientists announced the completion of MaStar, which made use of otherwise unused time on the MaNGA instrument to observe over 24,000 stars, enabling the scientists to more accurately extract information from the MaNGA data.

The leader of the MaStar project, Renbin Yan of The Chinese University of Hong Kong [香港中文大学](HK), explained, “MaStar is a special kind of library that includes spectra for as many types of stars as possible. Using these data, we can figure out how many of each type of star add up to make each of the many spectra from a MaNGA galaxy and reconstruct the most accurate view ever of when and where stars formed in that galaxy’s cosmic history.”

For example, MaNGA data have been used to make movies showing how the location where baby stars form moves around through spiral arms and other features in galaxies. Identifying which spectra came from which internal structure turns out to be tricky for computers, but with the help of citizen scientists, the MaNGA team have been able to do this, providing in this release maps showing where the structures are. And the kinematics of galaxies can reveal previously unknown galaxy interactions.

All of this MaNGA data has been made publicly available, and the SDSS team have also created a specially designed tool dubbed “Marvin” to help with data access. Marvin allows anyone to have a quick look at the data of each galaxy in an easy-to-use web interface, and is also available as a powerful set of python modules which allow anyone familiar with coding to access and visualize this complex data. Brian Cherinka at The Space Telescope Science Institute (US), one of the lead developers of Marvin, explains, “Marvin was designed specifically to access the complex MaNGA data and help researchers to avoid some of the common pitfalls in data visualization and access.”

Using MaNGA data and an early version of Marvin, scientists have already been discovering many new things about galaxies, with over 500 papers already published using the data. For example, MaNGA team members discovered a new class of galaxy, dubbed a red geyser, in which outflows from the supermassive black hole, revealed in MaNGA maps of ionized gas, are preventing new stars from forming. And to scientists’ surprise, this happens even in the smallest galaxies.

Making MaNGA data publicly available and accessible will fuel science analyses for years to come and puts the full power of MaNGA data into the hands of anyone who wants to use it. “It’s important to us that the data is not just available, but also accessible, so that anyone with an interest in galaxies can use MaNGA data for their research, education, or just for fun, can explore the cubes, spectra, and maps to learn more about these galaxies,” said Anne-Marie Weijmans of The University of St. Andrews (SCT), who led the part of the SDSS team in charge of data releases. “You don’t need to be a galaxy expert to work with MaNGA data: we have many tutorials on our website to get you started.”

The instrumentation innovations developed for MaNGA will reverberate into the future. The next generation of SDSS (SDSS-V) is expanding on the novel fiber-packing methods developed for MaNGA to construct even larger fiber bundles for its Local Volume Mapper program. This survey will also study gas and newly-formed stars, but in an environment much closer to home—our own Milky Way and its nearby smaller neighbors. By combining these data with what MaNGA has learned from thousands of more distant galaxies, astronomers will gain a much deeper understanding of how gas and stars coexist and interact throughout a galaxy’s lifetime.

See the full article here .


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UC Santa Cruz (US) campus.

The University of California-Santa Cruz (US) , 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.

UCO Lick Observatory’s 36-inch Great Refractor telescope housed in the South (large) Dome of main building.

UC Santa Cruz (US) Lick Observatory Since 1888 Mt Hamilton, in San Jose, California, Altitude 1,283 m (4,209 ft)

UC Observatories Lick Automated Planet Finder fully robotic 2.4-meter optical telescope at Lick Observatory, situated on the summit of Mount Hamilton, east of San Jose, California, USA.

The UCO Lick C. Donald Shane telescope is a 120-inch (3.0-meter) reflecting telescope located at the Lick Observatory, Mt Hamilton, in San Jose, California, Altitude 1,283 m (4,209 ft).

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.)
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.

Alumna Shelley Wright, now an assistant professor of physics at UC San Diego (US), discusses the dichroic filter of the NIROSETI instrument, developed at the U Toronto Dunlap Institute for Astronomy and Astrophysics (CA) and brought to UCSD and installed at the UC Santa Cruz (US) Lick Observatory Nickel Telescope (Photo by Laurie Hatch). “Infrared light would be an excellent means of interstellar communication,” said Shelley Wright, an assistant professor of physics at The University of California-San Diego (US) who led the development of the new instrument while at the U Toronto Dunlap Institute for Astronomy and Astrophysics (CA).

Shelley Wright of UC San Diego with (US) NIROSETI, developed at U Toronto Dunlap Institute for Astronomy and Astrophysics (CA) at the 1-meter Nickel Telescope at Lick Observatory at UC Santa Cruz
NIROSETI team from left to right Rem Stone UCO Lick Observatory Dan Werthimer, UC Berkeley; Jérôme Maire, U Toronto; Shelley Wright, UCSD; Patrick Dorval, U Toronto; Richard Treffers, Starman Systems. (Image by Laurie Hatch).

Wright worked on an earlier SETI project at Lick Observatory as a UC Santa Cruz undergraduate, when she built an optical instrument designed by University of California-Berkeley (US) 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.

Frank Drake with his Drake Equation. Credit Frank Drake.

Drake Equation, Frank Drake, Seti Institute (US).

“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 scan the skies several times a week on the Nickel 1-meter telescope at Lick Observatory, located on Mt. Hamilton east of San Jose.