From University of Portsmouth: “Holes in the Universe sharpen cosmic measurements”

From University of Portsmouth

July 10, 2019

The change in the average shape of voids caused by Doppler distortions and the effects of dark energy and curvature.

Regions of the Universe containing very few or no galaxies – known as voids – can help measure cosmic expansion with much greater precision than before, according to new research.

The study looked at the shapes of voids found in data from the Sloan Digital Sky Survey (SDSS) collaboration.

SDSS Telescope at Apache Point Observatory, near Sunspot NM, USA, Altitude2,788 meters (9,147 ft)

Voids come in a variety shapes, but because they have no preferred direction of alignment, a large enough sample of them can on average be used as “standard spheres” – objects which should appear perfectly symmetric in the absence of any distortions.

However, the observed shapes of these spheres are distorted by Doppler shifts in the redshifts of nearby galaxies caused by the local velocity field, and by the nature and amounts of dark matter and dark energy that make up 95% of the Universe. This distortion can be theoretically modelled, and the new work shows it can now be precisely measured.

The research was led by the University of Portsmouth, a world leader in cosmology, and is published this week in Physical Review D.

The new measurement of the distortion around voids used the Baryon Oscillation Spectroscopic Survey (BOSS) of galaxies from SDSS, that was designed to measure dark energy and the curvature of space.

BOSS Spectrograph – SDSS-III

BOSS Supercluster Baryon Oscillation Spectroscopic Survey (BOSS)

For measuring a key aspect of the cosmic expansion, the new method greatly outperforms the standard baryon acoustic oscillation (BAO) technique that BOSS was designed for. The new results agree with the simplest model of a flat Universe with a cosmological constant dark energy, and tighten the constraints on alternative theories.

Lead author, Dr Seshadri Nadathur, research fellow at the University’s Institute of Cosmology and Gravitation (ICG), said: “This measurement tremendously upgrades the previous best results from BOSS – the precision is equivalent to getting data from a hypothetical survey four times as large as BOSS, completely for free. It really helps pin down the properties of dark energy.”

“These results also mean that the expected science results from facilities such as the European Space Agency’s Euclid satellite mission and the Dark Energy Spectroscopic Instrument – in which the astronomy community have invested a lot of resources – can be even better than previously thought.”

ESA/Euclid spacecraft

LBNL/DESI spectroscopic instrument on the Mayall 4-meter telescope at Kitt Peak National Observatory starting in 2018

NOAO/Mayall 4 m telescope at Kitt Peak, Arizona, USA, Altitude 2,120 m (6,960 ft)

The other authors include Portsmouth’s PhD student Paul Carter, research fellows Dr Hans Winther and Dr Julian Bautista, and former Portsmouth Professor Will Percival, who has recently taken up a new role in Canada.

See the full article here .

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We’re a New Breed of University
We’re proud to be a breath of fresh air in the academic world – a place where everyone gets the support they need to achieve their best.
We’re always discovering. Through the work we do, we engage with our community and world beyond our hometown. We don’t fit the mould, we break it.
We educate and transform the lives of our students and the people around us. We recruit students for their promise and potential and for where they want to go.
We stand out, not just in the UK but in the world, in innovation and research, with excellence in areas from cosmology and forensics to cyber security, epigenetics and brain tumour research.
Just as the world keeps moving, so do we. We’re closely involved with our local community and we take our ideas out into the global marketplace. We partner with business, industry and government to help improve, navigate and set the course for a better future.
Since the first day we opened our doors, our story has been about looking forward. We’re interested in the future, and here to help you shape it.

The University of Portsmouth is a public university in the city of Portsmouth, Hampshire, England. The history of the university dates back to 1908, when the Park building opened as a Municipal college and public library. It was previously known as Portsmouth Polytechnic until 1992, when it was granted university status through the Further and Higher Education Act 1992. It is ranked among the Top 100 universities under 50 in the world.

The university offers a range of disciplines, from Pharmacy, International relations and politics, to Mechanical Engineering, Paleontology, Criminology, Criminal Justice, among others. The Guardian University Guide 2018 ranked its Sports Science number one in England, while Criminology, English, Social Work, Graphic Design and Fashion and Textiles courses are all in the top 10 across all universities in the UK. Furthermore, 89% of its research conducted in Physics, and 90% of its research in Allied Health Professions (e.g. Dentistry, Nursing and Pharmacy) have been rated as world-leading or internationally excellent in the most recent Research Excellence Framework (REF2014).

The University is a member of the University Alliance and The Channel Islands Universities Consortium. Alumni include Tim Peake, Grayson Perry, Simon Armitage and Ben Fogle.

Portsmouth was named the UK’s most affordable city for students in the Natwest Student Living Index 2016. On Friday 4 May 2018, the University of Portsmouth was revealed as the main shirt sponsor of Portsmouth F.C. for the 2018–19, 2019–20 and 2020–21 seasons.

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

From UC Santa Cruz

January 29, 2019
Tim Stephens
stephens@ucsc.edu

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)

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Shane Telescope at UCO Lick Observatory, UCSC

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

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

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.