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  • richardmitnick 12:10 pm on July 18, 2019 Permalink | Reply
    Tags: "Northwestern leads effort to detect new types of cosmic events", A new kind of gravitational-wave detector that is small enough to fit on a tabletop, , , Northwestern University, Physicists and astronomers begin development of miniature gravitational-wave detector.   

    From Northwestern University: “Northwestern leads effort to detect new types of cosmic events” 

    Northwestern U bloc
    From Northwestern University

    July 16, 2019
    Kayla Stoner

    Physicists and astronomers begin development of miniature gravitational-wave detector.

    1

    A team of physicists and astronomers from Northwestern University is poised to lead gravitational-wave astronomy into its next evolution. The W. M. Keck Foundation has awarded $1 million, which will be used to develop a prototype for a new kind of gravitational-wave detector that is small enough to fit on a tabletop and powerful enough to detect cosmic events that existing astronomical equipment cannot.

    “This is the start of the next phase of gravitational-wave and multi-messenger astronomy,” said Andrew Geraci, principal investigator on the project. “This tabletop sensor will be able to observe events we’ve never seen before, expanding our understanding of space and the universe.”

    Geraci is an associate professor of physics and astronomy in Northwestern’s Weinberg College of Arts and Sciences and a faculty member of the Center for Fundamental Physics (CFP) and the Center for Interdisciplinary Exploration and Research for Astrophysics (CIERA) at Northwestern.

    The Levitated Sensor Detector will extend the spectrum of detectable gravitational waves to higher frequencies, possibly opening a window to the types of events that are related to the mysterious dark matter in the universe. It will complement research being conducted at the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo observatories, which occupy several acres of land in the United States and Italy, by observing smaller cosmic events that produce waves at a frequency LIGO and Virgo cannot detect.

    “If you think of gravitational waves like sound waves, the frequency we are trying to capture with levitated sensors is sort of like a dog whistle,” said Vicky Kalogera, project co-investigator and CIERA director.

    “Dogs are capable of hearing sound frequencies that the human ear cannot perceive. Similarly, levitated sensors will pick up frequencies that LIGO and Virgo cannot detect,” said Kalogera, who also is the Daniel I. Linzer Distinguished University Professor of Physics and Astronomy and one of the foremost astrophysicists in the LIGO Scientific Collaboration (LSC).

    2

    Northwestern scientists will spend two years building and testing the levitated sensor prototype, which will consist of two arms in an L-formation, each measuring about one meter in length. The levitated sensor will then operate for a one-year observing run, the results of which will be shared with the international gravitational-wave and astronomy communities.

    Levitated sensors will be capable of detecting cosmic events that produce gravitational waves with a frequency of greater than 10 kHz. These events are thought to be the result of small cosmic events involving black holes similar in mass to Earth’s sun, and primordial black holes produced in the earliest days of the universe. Astrophysicists theorize but have so far been unable to prove that these events are responsible for the creation of dark matter. Other dark matter candidates such as axions, hypothetical particles that are predicted to be a component of cold dark matter, also can be searched for using the device.

    Development of this tabletop detector coincides with the development of a third type of detector on the opposite end of the frequency spectrum. The European Space Agency plans to launch LISA, a space-based gravitational-wave detector that spans tens of millions of miles, in the early 2030s.

    ESA/LISA Pathfinder


    ESA/NASA eLISA


    ESA/NASA eLISA space based, the future of gravitational wave research

    “Just like electromagnetic astronomy has telescopes and gamma-ray detectors and more, the gravitational-wave community is now developing the tools needed to detect events on all parts of the spectrum,” project co-investigator Shane Larson said. “LISA will detect the big events; LIGO and Virgo pick up the medium events; and LSD will detect the smallest cosmic events.”

    Larson is associate director of CIERA and a research associate professor of physics and astronomy at Northwestern. He also is a member of the LISA Consortium and the LSC.

    The project, titled “A novel tabletop gravitational-wave detector for frequencies > 10 kHz,” is supported by the W. M. Keck Foundation.

    The grant counts toward We Will. The Campaign for Northwestern. The funds raised through the “We Will” Campaign are helping realize the transformational vision set forth in Northwestern’s strategic plan and solidifying the University’s position among the world’s leading research universities. More information on the “We Will” Campaign is available at http://wewill.northwestern.edu.

    Based in Los Angeles, the W. M. Keck Foundation was established in 1954 by the late W. M. Keck, founder of the Superior Oil Company. The Foundation’s grant making is focused primarily on pioneering efforts in the areas of medical research and science and engineering. The Foundation also maintains a Southern California Grant Program that provides support for the Los Angeles community, with a special emphasis on children and youth. For more information, please visit http://www.wmkeck.org.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Northwestern South Campus
    South Campus

    On May 31, 1850, nine men gathered to begin planning a university that would serve the Northwest Territory.

    Given that they had little money, no land and limited higher education experience, their vision was ambitious. But through a combination of creative financing, shrewd politicking, religious inspiration and an abundance of hard work, the founders of Northwestern University were able to make that dream a reality.

    In 1853, the founders purchased a 379-acre tract of land on the shore of Lake Michigan 12 miles north of Chicago. They established a campus and developed the land near it, naming the surrounding town Evanston in honor of one of the University’s founders, John Evans. After completing its first building in 1855, Northwestern began classes that fall with two faculty members and 10 students.
    Twenty-one presidents have presided over Northwestern in the years since. The University has grown to include 12 schools and colleges, with additional campuses in Chicago and Doha, Qatar.

    Northwestern is recognized nationally and internationally for its educational programs.

     
  • richardmitnick 11:48 am on June 19, 2019 Permalink | Reply
    Tags: Astronomers uncover first polarized radio signals from gamma-ray burst, , , , , Northwestern University, Polarization is a property of light that indicates how a magnetic field is organized and structured in a jet   

    From Northwestern University: “Astronomers uncover first polarized radio signals from gamma-ray burst” 

    Northwestern U bloc
    From Northwestern University

    June 19, 2019

    Discovery could give insight into how and why jets are formed in gamma-ray bursts.


    Video credit: Kitty Yeung (art), Tanmoy Laskar (animation)

    An international team of astronomers has captured the first-ever polarized radio waves from a distant cosmic explosion.

    2
    Team finds detailed record of mysterious fast radio burst

    This explosive event (known as gamma-ray burst GRB 190114C) is part of a class of the most energetic explosions in the universe. It was produced when a star — much more massive than our sun — collapsed to form a black hole.

    Gamma ray bursts produce powerful jets that travel close to the speed of light and shine with the incredible luminosity of more than a billion suns combined. Astronomers have struggled to understand how these jets are formed and why they seem to appear only in gamma ray bursts — but not other explosions, such as ordinary supernovae.

    Because these jets are extremely bright at radio wavelengths, the discovery of polarized radio signals may offer new clues to help solve this mystery. Polarization is a property of light that indicates how a magnetic field is organized and structured in a jet.

    “We know that only a very tiny fraction (less than 1%) of massive stars form jets when they collapse,” said Northwestern University’s Raffaella Margutti, who contributed to the study. “But we have not known how they manage to launch these outflows with such extreme properties, and we don’t know why only a few stars do this.”

    “This measurement opens a new window into gamma-ray burst science and the studies of energetic astrophysical jets,” said Tanmoy Laskar, a postdoctoral researcher at the University of Bath in the U.K. and lead author of the study. “We would like to understand whether the low level of polarization measured in this event is characteristic of all gamma-ray bursts and, if so, what this could tell us about the magnetic structures in gamma-ray burst jets and the role of magnetic fields in powering jets throughout the universe.”

    The paper was published last week in The Astrophysical Journal Letters.

    The international team included three astrophysicists from Northwestern’s Weinberg College of Arts and Sciences: Kate Alexander, Wen-fai Fong and Margutti. All are members of Northwestern’s Center for Interdisciplinary and Exploratory Research in Astrophysics (CIERA).

    Astronomers have hypothesized that cosmic magnetic fields might flow through the jets, helping them form and providing structural support. The physical extent of these magnetic fields, which have implications for the jet launching mechanism, however, had never before been measured.

    To obtain these measurements, the international team employed a novel trick. They observed the jets in linearly polarized light, which is sensitive to the size of magnetic field patches. Larger magnetic field patches, for example, produce more polarized light.

    On January 14, 2019, a flash of gamma rays triggered NASA’s Swift satellite, which alerted astronomers of the burst’s location in the direction of the constellation Fornax. The astronomers then used the Atacama Large Millimeter/Submillimeter Array (ALMA) telescope in Chile to search for radio waves from the explosion, which occurred more than 4.5 billion years ago in a galaxy 7 billion light-years away.

    NASA Neil Gehrels Swift Observatory

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    “Magnetic fields are ubiquitous but notoriously difficult to constrain in our universe,” said Fong, an assistant professor of astrophysics. “The fact that we have been able to detect their presence — let alone in the fastest jets we know of — is an incredible and storied feat of observation.”

    The team detected a subtle, but revealing, polarization signal of 0.8%, implying magnetic field patches about the size of our solar system. Next, the researchers will combine this new information with data from X-ray and visible light telescopes.

    “The lower frequency data from the Very Large Array (VLA) in New Mexico helped confirm that we were seeing the light from the jet itself rather than from the interaction of the jet with its environment,” said Alexander, a NASA Einstein Fellow who led the VLA observations.

    NRAO/Karl V Jansky Expanded Very Large Array, on the Plains of San Agustin fifty miles west of Socorro, NM, USA, at an elevation of 6970 ft (2124 m)

    “This is a truly remarkable measurement,” said Margutti, “both from the technical side and for its deep scientific implications on the nature of magnetic fields in the most relativistic sources known in our universe.”

    The research, ALMA detection of linearly polarized reverse shock in GRB 190114C, was supported by NASA. The research team comprised astronomers from the University of Bath, Northwestern, Open University of Israel, Harvard University, California State University, Max Planck Institute and Liverpool John Moores University.

    See the full article here.

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Northwestern South Campus
    South Campus

    On May 31, 1850, nine men gathered to begin planning a university that would serve the Northwest Territory.

    Given that they had little money, no land and limited higher education experience, their vision was ambitious. But through a combination of creative financing, shrewd politicking, religious inspiration and an abundance of hard work, the founders of https://www.northwestern.edu/were able to make that dream a reality.

    In 1853, the founders purchased a 379-acre tract of land on the shore of Lake Michigan 12 miles north of Chicago. They established a campus and developed the land near it, naming the surrounding town Evanston in honor of one of the University’s founders, John Evans. After completing its first building in 1855, Northwestern began classes that fall with two faculty members and 10 students.
    Twenty-one presidents have presided over Northwestern in the years since. The University has grown to include 12 schools and colleges, with additional campuses in Chicago and Doha, Qatar.

    Northwestern is recognized nationally and internationally for its educational programs.

     
  • richardmitnick 4:04 pm on June 7, 2019 Permalink | Reply
    Tags: , , , Black hole accretion disks, , , Northwestern University,   

    From Northwestern University: “Most-detailed-ever simulations of black hole solve longstanding mystery” 

    Northwestern U bloc
    From Northwestern University

    June 06, 2019
    Amanda Morris

    An international team has constructed the most detailed, highest resolution simulation of a black hole to date. The simulation proves theoretical predictions about the nature of accretion disks — the matter that orbits and eventually falls into a black hole — that have never before been seen.

    The research published on June 5 in the MNRAS.

    Among the findings, the team of computational astrophysicists from Northwestern University, the University of Amsterdam and the University of Oxford found that the inner-most region of an accretion disk aligns with its black hole’s equator.

    This discovery solves a longstanding mystery, originally presented by physicists Jim Bardeen and Jacobus Petterson in 1975. At the time, Bardeen and Petterson argued that a spinning black hole would cause the inner region of a tilted accretion disk to align with its black hole’s equatorial plane.

    After a decades-long, global race to find the so-called Bardeen-Petterson effect, the team’s simulation found that, whereas the outer region of an accretion disk remains tilted, the disk’s inner region aligns with the black hole. A smooth warp connects the inner and outer regions. The team solved the mystery by thinning the accretion disk to an unprecedented degree and including the magnetized turbulence that causes the disk to accrete. Previous simulations made a substantial simplification by merely approximating the effects of the turbulence.

    “This groundbreaking discovery of Bardeen-Petterson alignment brings closure to a problem that has haunted the astrophysics community for more than four decades,” said Northwestern’s Alexander Tchekhovskoy, who co-led the research. “These details around the black hole may seem small, but they enormously impact what happens in the galaxy as a whole. They control how fast the black holes spin and, as a result, what effect black holes have on their entire galaxies.”

    Tchekhovskoy is an assistant professor of physics and astronomy in Northwestern’s Weinberg College of Arts and Sciences and a member of CIERA (Center for Interdisciplinary Exploration and Research in Astrophysics), an endowed research center at Northwestern focused on advancing astrophysics studies with an emphasis on interdisciplinary connections. Matthew Liska, a researcher at the University of Amsterdam’s Anton Pannenkoek Institute for Astronomy, is the paper’s first author.

    “These simulations not only solve a 40-year-old problem, but they have demonstrated that, contrary to typical thinking, it is possible to simulate the most luminous accretion disks in full general relativity,” Liska said. “This paves the way for a next generation of simulations, which I hope will solve even more important problems surrounding luminous accretion disks.”

    Elusive alignment

    Nearly everything researchers know about black holes has been learned by studying accretion disks. Without the intensely bright ring of gas, dust and other stellar debris that swirls around black holes, astronomers would not be able to spot a black hole in order to study it. Accretion disks also control a black hole’s growth and rotation speed, so understanding the nature of accretion disks is key to understanding how black holes evolve and function.

    “Alignment affects how accretion disks torque their black holes,” Tchekhovskoy said. “So it affects how a black hole’s spin evolves over time and launches outflows that impact the evolution of their host galaxies.”

    From Bardeen and Petterson until present day, simulations have been too simplified to find the storied alignment. Two main issues have acted as a barrier for computational astrophysicists. For one, accretion disks come so close to the black hole that they move through warped space-time, which rushes into the black hole at immense speed. Complicating matters further, the black hole’s rotation forces space-time to spin around it. Properly accounting for both of these crucial effects requires general relativity, Albert Einstein’s theory that predicts how objects affect the geometry of space-time around them.

    Second, astrophysicists have not had computing power to account for magnetic turbulence, or the stirring inside of the accretion disk. This stirring is what causes the disk’s particles to hold together in a circular shape and what causes gas eventually to fall into the black hole.

    “Imagine you have this thin disk. Then, on top of that, you have to resolve the turbulent motions inside the disk,” Tchekhovskoy said. “It becomes a really difficult problem.”

    Without being able to resolve these features, computational scientists were unable to simulate realistic black holes.

    Cracking the code

    To develop a code capable of carrying out simulations of titled accretion disks around black holes, Liska and Tchekhovskoy used graphical processing units (GPUs) instead of central processing units (CPUs). Extremely efficient at manipulating computer graphics and image processing, GPUs accelerate the creation of images on a display. They are much more efficient than CPUs for computing algorithms that process large swaths of data.

    Tchekhovskoy likens GPUs to 1,000 horses and CPUs to a 1,000-horsepower Ferrari.

    “Let’s say you need to move into a new apartment,” he explained. “You will have to make a lot of trips with this powerful Ferrari because it won’t fit many boxes. But if you could put one box on each horse, you could move everything in one go. That’s the GPU. It has a lot of elements, each of which is slower than those in the CPU, but there are so many of them.”

    Liska also added a method called adaptive mesh refinement, which uses a dynamic mesh, or grid, that changes and adapts to the flow of movement throughout the simulation. It saves energy and computer power by focusing only on specific blocks in the grid where movement occurs.

    The GPUs substantially accelerated the simulation, and the adaptive mesh increased resolution. These improvements allowed the team to simulate the thinnest accretion disk to date, with a height-to-radius ratio of 0.03. When the disk was simulated this thin, the researchers could see alignment occur right next to the black hole.

    “The thinnest disks simulated before had a height-to-radius ratio of 0.05, and it turns out that all of the interesting things happen at 0.03,” Tchekhovskoy said.

    In a surprise finding, even with these incredibly thin accretion disks, the black hole still emitted powerful jets of particles and radiation.

    “Nobody expected jets to be produced by these disks at such slight thicknesses,” Tchekhovskoy said. “People expected that the magnetic fields that produce these jets would just rip through these really thin disks. But there they are. And that actually helps us resolve observational mysteries.”

    The study, “Bardeen-Petterson alignment, jets and magnetic truncation in GRMHD simulations of tilted thin accretion discs,” was supported by the National Science Foundation (award numbers 1615281, OAC-1811605 and PHY-1125915), the Netherlands Organisation for Scientific Research, The Royal Society and NASA.

    The simulation used in the work was performed on the Blue Waters supercomputers at the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign.

    NCSA U Illinois Urbana-Champaign Blue Waters Cray Linux XE/XK hybrid machine supercomputer

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Northwestern South Campus
    South Campus

    On May 31, 1850, nine men gathered to begin planning a university that would serve the Northwest Territory.

    Given that they had little money, no land and limited higher education experience, their vision was ambitious. But through a combination of creative financing, shrewd politicking, religious inspiration and an abundance of hard work, the founders of Northwestern University were able to make that dream a reality.

    In 1853, the founders purchased a 379-acre tract of land on the shore of Lake Michigan 12 miles north of Chicago. They established a campus and developed the land near it, naming the surrounding town Evanston in honor of one of the University’s founders, John Evans. After completing its first building in 1855, Northwestern began classes that fall with two faculty members and 10 students.
    Twenty-one presidents have presided over Northwestern in the years since. The University has grown to include 12 schools and colleges, with additional campuses in Chicago and Doha, Qatar.

    Northwestern is recognized nationally and internationally for its educational programs.

     
  • richardmitnick 10:44 am on October 18, 2018 Permalink | Reply
    Tags: , Northwestern University, ,   

    From Northwestern University: “Unprecedented look at electron brings us closer to understanding the universe” 

    Northwestern U bloc
    From Northwestern University

    October 17, 2018
    Amanda Morris

    Study supports Standard Model of particle physics, excludes alternative models.

    1
    An artist’s representation of an electron orbiting an atom’s nucleus, spinning about its axis as a cloud of other subatomic particles pop in and out of existence.
    No image caption or credit.

    The scientific community can relax. The electron is still round.

    At least for now.

    In a new study, researchers at Northwestern, Harvard and Yale universities examined the shape of an electron’s charge with unprecedented precision to confirm that it is perfectly spherical. A slightly squashed charge could have indicated unknown, hard-to-detect heavy particles in the electron’s presence, a discovery that could have upended the global physics community.

    “If we had discovered that the shape wasn’t round, that would be the biggest headline in physics for the past several decades,” said Gerald Gabrielse, who led the research at Northwestern. “But our finding is still just as scientifically significant because it strengthens the Standard Model of particle physics and excludes alternative models.”

    The study will be published Oct. 18 in the journal Nature. In addition to Gabrielse, the research was led by John Doyle, the Henry B. Silsbee Professor of Physics at Harvard, and David DeMille, professor of physics at Yale. The trio leads the National Science Foundation (NSF)-funded Advanced Cold Molecule Electron (ACME) Electric Dipole Moment Search.

    The sub-standard Standard Model

    A longstanding theory, the Standard Model of particle physics describes most of the fundamental forces and particles in the universe.

    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.


    Standard Model of Particle Physics from Symmetry Magazine

    The model is a mathematical picture of reality, and no laboratory experiments yet performed have contradicted it.

    This lack of contradiction has been puzzling physicists for decades.

    “The Standard Model as it stands cannot possibly be right because it cannot predict why the universe exists,” said Gabrielse, the Board of Trustees Professor of Physics in Northwestern’s Weinberg College of Arts and Sciences. “That’s a pretty big loophole.”

    Gabrielse and his ACME colleagues have spent their careers trying to close this loophole by examining the Standard Model’s predictions and then trying to confirm them through table-top experiments in the lab.

    Attempting to “fix” the Standard Model, many alternative models predict that an electron’s seemingly uniform sphere is actually asymmetrically squished. One such model, called the Supersymmetric Model, posits that unknown, heavy subatomic particles influence the electron to alter its perfectly spherical shape — an unproven phenomenon called the “electric dipole moment.”

    Standard model of Supersymmetry DESY

    These undiscovered, heavier particles could be responsible for some of the universe’s most glaring mysteries and could possibly explain why the universe is made from matter instead of antimatter.

    “Almost all of the alternative models say the electron charge may well be squished, but we just haven’t looked sensitively enough,” said Gabrielse, the founding director of Northwestern’s new Center for Fundamental Physics. “That’s why we decided to look there with a higher precision than ever realized before.”

    Squashing the alternative theories

    The ACME team probed this question by firing a beam of cold thorium-oxide molecules into a chamber the size of a large desk. Researchers then studied the light emitted from the molecules. Twisting light would indicate an electric dipole moment. When the light did not twist, the research team concluded that the electron’s shape was, in fact, round, confirming the Standard Model’s prediction. No evidence of an electric dipole moment means no evidence of those hypothetical heavier particles. If these particles do exist at all, their properties differ from those predicted by theorists.

    “Our result tells the scientific community that we need to seriously rethink some of the alternative theories,” DeMille said.

    In 2014, the ACME team performed the same measurement with a simpler apparatus. By using improved laser methods and different laser frequencies, the current experiment was an order of magnitude more sensitive than its predecessor.

    “If an electron were the size of Earth, we could detect if the Earth’s center was off by a distance a million times smaller than a human hair,” Gabrielse explained. “That’s how sensitive our apparatus is.”

    Gabrielse, DeMille, Doyle and their teams plan to keep tuning their instrument to make more and more precise measurements. Until researchers find evidence to the contrary, the electron’s round shape — and the universe’s mysteries — will remain.

    “We know the Standard Model is wrong, but we can’t seem to find where it’s wrong. It’s like a huge mystery novel,” Gabrielse said. “We should be very careful about making assumptions that we’re getting closer to solving the mystery, but I do have considerable hope that we’re getting closer at this level of precision.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Northwestern South Campus
    South Campus

    On May 31, 1850, nine men gathered to begin planning a university that would serve the Northwest Territory.

    Given that they had little money, no land and limited higher education experience, their vision was ambitious. But through a combination of creative financing, shrewd politicking, religious inspiration and an abundance of hard work, the founders of Northwestern University were able to make that dream a reality.

    In 1853, the founders purchased a 379-acre tract of land on the shore of Lake Michigan 12 miles north of Chicago. They established a campus and developed the land near it, naming the surrounding town Evanston in honor of one of the University’s founders, John Evans. After completing its first building in 1855, Northwestern began classes that fall with two faculty members and 10 students.
    Twenty-one presidents have presided over Northwestern in the years since. The University has grown to include 12 schools and colleges, with additional campuses in Chicago and Doha, Qatar.

    Northwestern is recognized nationally and internationally for its educational programs.

     
  • richardmitnick 8:58 pm on May 13, 2018 Permalink | Reply
    Tags: , , , , , , Northwestern University,   

    From Northwestern University: “Dozens of binaries from Milky Way’s globular clusters could be detectable by LISA” 

    Northwestern U bloc
    From Northwestern University

    May 11, 2018
    Megan Fellman

    Next-generation gravitational wave detector in space will complement LIGO on Earth.

    ESA/eLISA space based the future of gravitational wave research

    The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A string of detections — four more binary black holes and a pair of neutron stars — soon followed the Sept. 14, 2015, observation.

    UC Santa Cruz

    UC Santa Cruz

    14

    A UC Santa Cruz special report

    Tim Stephens

    Astronomer Ryan Foley says “observing the explosion of two colliding neutron stars” [see https://sciencesprings.wordpress.com/2017/10/17/from-ucsc-first-observations-of-merging-neutron-stars-mark-a-new-era-in-astronomy ]–the first visible event ever linked to gravitational waves–is probably the biggest discovery he’ll make in his lifetime. That’s saying a lot for a young assistant professor who presumably has a long career still ahead of him.

    2
    The first optical image of a gravitational wave source was taken by a team led by Ryan Foley of UC Santa Cruz using the Swope Telescope at the Carnegie Institution’s Las Campanas Observatory in Chile. This image of Swope Supernova Survey 2017a (SSS17a, indicated by arrow) shows the light emitted from the cataclysmic merger of two neutron stars. (Image credit: 1M2H Team/UC Santa Cruz & Carnegie Observatories/Ryan Foley)

    Carnegie Institution Swope telescope at Las Campanas, Chile, 100 kilometres (62 mi) northeast of the city of La Serena. near the north end of a 7 km (4.3 mi) long mountain ridge. Cerro Las Campanas, near the southern end and over 2,500 m (8,200 ft) high, at Las Campanas, Chile

    A neutron star forms when a massive star runs out of fuel and explodes as a supernova, throwing off its outer layers and leaving behind a collapsed core composed almost entirely of neutrons. Neutrons are the uncharged particles in the nucleus of an atom, where they are bound together with positively charged protons. In a neutron star, they are packed together just as densely as in the nucleus of an atom, resulting in an object with one to three times the mass of our sun but only about 12 miles wide.

    “Basically, a neutron star is a gigantic atom with the mass of the sun and the size of a city like San Francisco or Manhattan,” said Foley, an assistant professor of astronomy and astrophysics at UC Santa Cruz.

    These objects are so dense, a cup of neutron star material would weigh as much as Mount Everest, and a teaspoon would weigh a billion tons. It’s as dense as matter can get without collapsing into a black hole.

    THE MERGER

    Like other stars, neutron stars sometimes occur in pairs, orbiting each other and gradually spiraling inward. Eventually, they come together in a catastrophic merger that distorts space and time (creating gravitational waves) and emits a brilliant flare of electromagnetic radiation, including visible, infrared, and ultraviolet light, x-rays, gamma rays, and radio waves. Merging black holes also create gravitational waves, but there’s nothing to be seen because no light can escape from a black hole.

    Foley’s team was the first to observe the light from a neutron star merger that took place on August 17, 2017, and was detected by the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO).


    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    ESA/eLISA the future of gravitational wave research

    1
    Skymap showing how adding Virgo to LIGO helps in reducing the size of the source-likely region in the sky. (Credit: Giuseppe Greco (Virgo Urbino group)

    Now, for the first time, scientists can study both the gravitational waves (ripples in the fabric of space-time), and the radiation emitted from the violent merger of the densest objects in the universe.

    3
    The UC Santa Cruz team found SSS17a by comparing a new image of the galaxy N4993 (right) with images taken four months earlier by the Hubble Space Telescope (left). The arrows indicate where SSS17a was absent from the Hubble image and visible in the new image from the Swope Telescope. (Image credits: Left, Hubble/STScI; Right, 1M2H Team/UC Santa Cruz & Carnegie Observatories/Ryan Foley)

    It’s that combination of data, and all that can be learned from it, that has astronomers and physicists so excited. The observations of this one event are keeping hundreds of scientists busy exploring its implications for everything from fundamental physics and cosmology to the origins of gold and other heavy elements.


    A small team of UC Santa Cruz astronomers were the first team to observe light from two neutron stars merging in August. The implications are huge.

    ALL THE GOLD IN THE UNIVERSE

    It turns out that the origins of the heaviest elements, such as gold, platinum, uranium—pretty much everything heavier than iron—has been an enduring conundrum. All the lighter elements have well-explained origins in the nuclear fusion reactions that make stars shine or in the explosions of stars (supernovae). Initially, astrophysicists thought supernovae could account for the heavy elements, too, but there have always been problems with that theory, says Enrico Ramirez-Ruiz, professor and chair of astronomy and astrophysics at UC Santa Cruz.

    4
    The violent merger of two neutron stars is thought to involve three main energy-transfer processes, shown in this diagram, that give rise to the different types of radiation seen by astronomers, including a gamma-ray burst and a kilonova explosion seen in visible light. (Image credit: Murguia-Berthier et al., Science)

    A theoretical astrophysicist, Ramirez-Ruiz has been a leading proponent of the idea that neutron star mergers are the source of the heavy elements. Building a heavy atomic nucleus means adding a lot of neutrons to it. This process is called rapid neutron capture, or the r-process, and it requires some of the most extreme conditions in the universe: extreme temperatures, extreme densities, and a massive flow of neutrons. A neutron star merger fits the bill.

    Ramirez-Ruiz and other theoretical astrophysicists use supercomputers to simulate the physics of extreme events like supernovae and neutron star mergers. This work always goes hand in hand with observational astronomy. Theoretical predictions tell observers what signatures to look for to identify these events, and observations tell theorists if they got the physics right or if they need to tweak their models. The observations by Foley and others of the neutron star merger now known as SSS17a are giving theorists, for the first time, a full set of observational data to compare with their theoretical models.

    According to Ramirez-Ruiz, the observations support the theory that neutron star mergers can account for all the gold in the universe, as well as about half of all the other elements heavier than iron.

    RIPPLES IN THE FABRIC OF SPACE-TIME

    Einstein predicted the existence of gravitational waves in 1916 in his general theory of relativity, but until recently they were impossible to observe. LIGO’s extraordinarily sensitive detectors achieved the first direct detection of gravitational waves, from the collision of two black holes, in 2015. Gravitational waves are created by any massive accelerating object, but the strongest waves (and the only ones we have any chance of detecting) are produced by the most extreme phenomena.

    Two massive compact objects—such as black holes, neutron stars, or white dwarfs—orbiting around each other faster and faster as they draw closer together are just the kind of system that should radiate strong gravitational waves. Like ripples spreading in a pond, the waves get smaller as they spread outward from the source. By the time they reached Earth, the ripples detected by LIGO caused distortions of space-time thousands of times smaller than the nucleus of an atom.

    The rarefied signals recorded by LIGO’s detectors not only prove the existence of gravitational waves, they also provide crucial information about the events that produced them. Combined with the telescope observations of the neutron star merger, it’s an incredibly rich set of data.

    LIGO can tell scientists the masses of the merging objects and the mass of the new object created in the merger, which reveals whether the merger produced another neutron star or a more massive object that collapsed into a black hole. To calculate how much mass was ejected in the explosion, and how much mass was converted to energy, scientists also need the optical observations from telescopes. That’s especially important for quantifying the nucleosynthesis of heavy elements during the merger.

    LIGO can also provide a measure of the distance to the merging neutron stars, which can now be compared with the distance measurement based on the light from the merger. That’s important to cosmologists studying the expansion of the universe, because the two measurements are based on different fundamental forces (gravity and electromagnetism), giving completely independent results.

    “This is a huge step forward in astronomy,” Foley said. “Having done it once, we now know we can do it again, and it opens up a whole new world of what we call ‘multi-messenger’ astronomy, viewing the universe through different fundamental forces.”

    IN THIS REPORT

    Neutron stars
    A team from UC Santa Cruz was the first to observe the light from a neutron star merger that took place on August 17, 2017 and was detected by the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO)

    5
    Graduate students and post-doctoral scholars at UC Santa Cruz played key roles in the dramatic discovery and analysis of colliding neutron stars.Astronomer Ryan Foley leads a team of young graduate students and postdoctoral scholars who have pulled off an extraordinary coup. Following up on the detection of gravitational waves from the violent merger of two neutron stars, Foley’s team was the first to find the source with a telescope and take images of the light from this cataclysmic event. In so doing, they beat much larger and more senior teams with much more powerful telescopes at their disposal.

    “We’re sort of the scrappy young upstarts who worked hard and got the job done,” said Foley, an untenured assistant professor of astronomy and astrophysics at UC Santa Cruz.

    7
    David Coulter, graduate student

    The discovery on August 17, 2017, has been a scientific bonanza, yielding over 100 scientific papers from numerous teams investigating the new observations. Foley’s team is publishing seven papers, each of which has a graduate student or postdoc as the first author.

    “I think it speaks to Ryan’s generosity and how seriously he takes his role as a mentor that he is not putting himself front and center, but has gone out of his way to highlight the roles played by his students and postdocs,” said Enrico Ramirez-Ruiz, professor and chair of astronomy and astrophysics at UC Santa Cruz and the most senior member of Foley’s team.

    “Our team is by far the youngest and most diverse of all of the teams involved in the follow-up observations of this neutron star merger,” Ramirez-Ruiz added.

    8
    Charles Kilpatrick, postdoctoral scholar

    Charles Kilpatrick, a 29-year-old postdoctoral scholar, was the first person in the world to see an image of the light from colliding neutron stars. He was sitting in an office at UC Santa Cruz, working with first-year graduate student Cesar Rojas-Bravo to process image data as it came in from the Swope Telescope in Chile. To see if the Swope images showed anything new, he had also downloaded “template” images taken in the past of the same galaxies the team was searching.

    9
    Ariadna Murguia-Berthier, graduate student

    “In one image I saw something there that was not in the template image,” Kilpatrick said. “It took me a while to realize the ramifications of what I was seeing. This opens up so much new science, it really marks the beginning of something that will continue to be studied for years down the road.”

    At the time, Foley and most of the others in his team were at a meeting in Copenhagen. When they found out about the gravitational wave detection, they quickly got together to plan their search strategy. From Copenhagen, the team sent instructions to the telescope operators in Chile telling them where to point the telescope. Graduate student David Coulter played a key role in prioritizing the galaxies they would search to find the source, and he is the first author of the discovery paper published in Science.

    10
    Matthew Siebert, graduate student

    “It’s still a little unreal when I think about what we’ve accomplished,” Coulter said. “For me, despite the euphoria of recognizing what we were seeing at the moment, we were all incredibly focused on the task at hand. Only afterward did the significance really sink in.”

    Just as Coulter finished writing his paper about the discovery, his wife went into labor, giving birth to a baby girl on September 30. “I was doing revisions to the paper at the hospital,” he said.

    It’s been a wild ride for the whole team, first in the rush to find the source, and then under pressure to quickly analyze the data and write up their findings for publication. “It was really an all-hands-on-deck moment when we all had to pull together and work quickly to exploit this opportunity,” said Kilpatrick, who is first author of a paper comparing the observations with theoretical models.

    11
    César Rojas Bravo, graduate student

    Graduate student Matthew Siebert led a paper analyzing the unusual properties of the light emitted by the merger. Astronomers have observed thousands of supernovae (exploding stars) and other “transients” that appear suddenly in the sky and then fade away, but never before have they observed anything that looks like this neutron star merger. Siebert’s paper concluded that there is only a one in 100,000 chance that the transient they observed is not related to the gravitational waves.

    Ariadna Murguia-Berthier, a graduate student working with Ramirez-Ruiz, is first author of a paper synthesizing data from a range of sources to provide a coherent theoretical framework for understanding the observations.

    Another aspect of the discovery of great interest to astronomers is the nature of the galaxy and the galactic environment in which the merger occurred. Postdoctoral scholar Yen-Chen Pan led a paper analyzing the properties of the host galaxy. Enia Xhakaj, a new graduate student who had just joined the group in August, got the opportunity to help with the analysis and be a coauthor on the paper.

    12
    Yen-Chen Pan, postdoctoral scholar

    “There are so many interesting things to learn from this,” Foley said. “It’s a great experience for all of us to be part of such an important discovery.”

    13
    Enia Xhakaj, graduate student

    IN THIS REPORT

    Scientific Papers from the 1M2H Collaboration

    Coulter et al., Science, Swope Supernova Survey 2017a (SSS17a), the Optical Counterpart to a Gravitational Wave Source

    Drout et al., Science, Light Curves of the Neutron Star Merger GW170817/SSS17a: Implications for R-Process Nucleosynthesis

    Shappee et al., Science, Early Spectra of the Gravitational Wave Source GW170817: Evolution of a Neutron Star Merger

    Kilpatrick et al., Science, Electromagnetic Evidence that SSS17a is the Result of a Binary Neutron Star Merger

    Siebert et al., ApJL, The Unprecedented Properties of the First Electromagnetic Counterpart to a Gravitational-wave Source

    Pan et al., ApJL, The Old Host-galaxy Environment of SSS17a, the First Electromagnetic Counterpart to a Gravitational-wave Source

    Murguia-Berthier et al., ApJL, A Neutron Star Binary Merger Model for GW170817/GRB170817a/SSS17a

    Kasen et al., Nature, Origin of the heavy elements in binary neutron star mergers from a gravitational wave event

    Abbott et al., Nature, A gravitational-wave standard siren measurement of the Hubble constant (The LIGO Scientific Collaboration and The Virgo Collaboration, The 1M2H Collaboration, The Dark Energy Camera GW-EM Collaboration and the DES Collaboration, The DLT40 Collaboration, The Las Cumbres Observatory Collaboration, The VINROUGE Collaboration & The MASTER Collaboration)

    Abbott et al., ApJL, Multi-messenger Observations of a Binary Neutron Star Merger

    PRESS RELEASES AND MEDIA COVERAGE


    Watch Ryan Foley tell the story of how his team found the neutron star merger in the video below. 2.5 HOURS.

    Press releases:

    UC Santa Cruz Press Release

    UC Berkeley Press Release

    Carnegie Institution of Science Press Release

    LIGO Collaboration Press Release

    National Science Foundation Press Release

    Media coverage:

    The Atlantic – The Slack Chat That Changed Astronomy

    Washington Post – Scientists detect gravitational waves from a new kind of nova, sparking a new era in astronomy

    New York Times – LIGO Detects Fierce Collision of Neutron Stars for the First Time

    Science – Merging neutron stars generate gravitational waves and a celestial light show

    CBS News – Gravitational waves – and light – seen in neutron star collision

    CBC News – Astronomers see source of gravitational waves for 1st time

    San Jose Mercury News – A bright light seen across the universe, proving Einstein right

    Popular Science – Gravitational waves just showed us something even cooler than black holes

    Scientific American – Gravitational Wave Astronomers Hit Mother Lode

    Nature – Colliding stars spark rush to solve cosmic mysteries

    National Geographic – In a First, Gravitational Waves Linked to Neutron Star Crash

    Associated Press – Astronomers witness huge cosmic crash, find origins of gold

    Science News – Neutron star collision showers the universe with a wealth of discoveries

    UCSC press release
    First observations of merging neutron stars mark a new era in astronomy

    Credits

    Writing: Tim Stephens
    Video: Nick Gonzales
    Photos: Carolyn Lagattuta
    Header image: Illustration by Robin Dienel courtesy of the Carnegie Institution for Science
    Design and development: Rob Knight
    Project managers: Sherry Main, Scott Hernandez-Jason, Tim Stephens

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

    Gemini South telescope, Cerro Tololo Inter-American Observatory (CTIO) campus near La Serena, Chile, at an altitude of 7200 feet

    Noted in the vdeo but not in te article:

    NASA/Chandra Telescope

    NASA/SWIFT Telescope

    NRAO/Karl V Jansky VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA

    Prompt telescope CTIO Chile

    NASA NuSTAR X-ray telescope

    Now, another detector is being built to crack this window wider open. This next-generation observatory, called LISA, is expected to be in space in 2034, and it will be sensitive to gravitational waves of a lower frequency than those detected by the Earth-bound Laser Interferometer Gravitational-Wave Observatory (LIGO).

    A new Northwestern University study predicts dozens of binaries (pairs of orbiting compact objects) in the globular clusters of the Milky Way will be detectable by LISA (Laser Interferometer Space Antenna). These binary sources would contain all combinations of black hole, neutron star and white dwarf components. Binaries formed from these star-dense clusters will have many different features from those binaries that formed in isolation, far from other stars.

    The study is the first to use realistic globular cluster models to make detailed predictions of LISA sources. “LISA Sources in Milky-Way Globular Clusters” was published today, May 11, by the journal Physical Review Letters.

    “LISA is sensitive to Milky Way systems and will expand the breadth of the gravitational wave spectrum, allowing us to explore different types of objects that aren’t observable with LIGO,” said Kyle Kremer, the paper’s first author, a Ph.D. student in physics and astronomy in Northwestern’s Weinberg College of Arts and Sciences and a member of a computational astrophysics research collaboration based in Northwestern’s Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA).

    In the Milky Way, 150 globular clusters have been observed so far. The Northwestern research team predicts one out of every three clusters will produce a LISA source. The study also predicts that approximately eight black hole binaries will be detectable by LISA in our neighboring galaxy of Andromeda and another 80 in nearby Virgo.

    Before the first detection of gravitational waves by LIGO, as the twin detectors were being built in the United States, astrophysicists around the world worked for decades on theoretical predictions of what astrophysical phenomena LIGO would observe. That is what the Northwestern theoretical astrophysicists are doing in this new study, but this time for LISA, which is being built by the European Space Agency with contributions from NASA.

    “We do our computer simulations and analysis at the same time our colleagues are bending metal and building spaceships, so that when LISA finally flies, we’re all ready at the same time,” said Shane L. Larson, associate director of CIERA and an author of the study. “This study is helping us understand what science is going to be contained in the LISA data.”

    A globular cluster is a spherical structure of hundreds of thousands to millions of stars, gravitationally bound together. The clusters are some of the oldest populations of stars in the galaxy and are efficient factories of compact object binaries.

    The Northwestern research team had numerous advantages in conducting this study. Over the past two decades, Frederic A. Rasio and his group have developed a powerful computational tool — one of the best in the world — to realistically model globular clusters. Rasio, the Joseph Cummings Professor in Northwestern’s department of physics and astronomy, is the senior author of the study.

    The researchers used more than a hundred fully evolved globular cluster models with properties similar to those of the observed globular clusters in the Milky Way. The models, which were all created at CIERA, were run on Quest, Northwestern’s supercomputer cluster. This powerful resource can evolve the full 12 billion years of a globular cluster’s life in a matter of days.

    NASA (ATP grant NNX14AP92G) and the National Science Foundation (grant AST-1716762) supported the research.

    Other authors of the paper include Sourav Chatterjee and Katelyn Breivik, both of Northwestern and CIERA, and Carl L. Rodriguez, of the MIT-Kavli Institute for Astrophysics and Space Research.

    See the full article here

    See the full article here .

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Northwestern South Campus
    South Campus

    On May 31, 1850, nine men gathered to begin planning a university that would serve the Northwest Territory.

    Given that they had little money, no land and limited higher education experience, their vision was ambitious. But through a combination of creative financing, shrewd politicking, religious inspiration and an abundance of hard work, the founders of Northwestern University were able to make that dream a reality.

    In 1853, the founders purchased a 379-acre tract of land on the shore of Lake Michigan 12 miles north of Chicago. They established a campus and developed the land near it, naming the surrounding town Evanston in honor of one of the University’s founders, John Evans. After completing its first building in 1855, Northwestern began classes that fall with two faculty members and 10 students.
    Twenty-one presidents have presided over Northwestern in the years since. The University has grown to include 12 schools and colleges, with additional campuses in Chicago and Doha, Qatar.

    Northwestern is recognized nationally and internationally for its educational programs.

     
  • richardmitnick 11:58 am on May 8, 2018 Permalink | Reply
    Tags: , , Drug May Reverse Imbalance Linked to Autism Symptoms, , Northwestern University   

    From Northwestern University: “Drug May Reverse Imbalance Linked to Autism Symptoms” 

    Northwestern U bloc
    From Northwestern University

    May 7, 2018
    Will Doss

    1
    Anis Contractor, PhD, professor of Physiology and senior author of a study published in Molecular Psychiatry.

    An FDA-approved drug can reverse an ionic imbalance in neurons that leads to hyper-excitability in mice modeling an autism-related genetic disorder, according to a Northwestern Medicine study published in Molecular Psychiatry.

    These findings suggest that the sensory hypersensitivity experienced by patients with Fragile X syndrome, a syndromic autism, may be caused by elevated intracellular chloride in neurons during early development, according to Anis Contractor, PhD, professor of Physiology and senior author of the study.

    “Some children with Fragile X syndrome or autism have changes in sensory processing, similar to the mouse model,” Contractor said. “The mouse models give us a window into the human disorder. Although mouse brain development is not a completely faithful model of humans, there certainly are parallels.”

    While most genetic mutations that cause autism are very rare — and most cases of autism spectrum disorder are not linked to a genetic cause — children with Fragile X syndrome have a well-defined mutation in a gene on the X chromosome, so Fragile X syndrome is used as a laboratory model for certain aspects of autism, including sensory hypersensitivity.

    “A lot of patients don’t like loud sounds or don’t like to be touched,” Contractor said. “When I talk to parents of children with Fragile X, some tell me these sensory issues lead to many other problems, because the kids are withdrawn or socially isolated.”

    Prior studies in Contractor’s lab established the role of intracellular chloride in certain symptoms of Fragile X syndrome: While it is important for neurotransmitter signaling, high chloride concentration in neural cells can also cause abnormal excitation, shifting the timing of important developmental critical periods.

    These critical periods are phases of early brain development where essential neural circuitry is formed; shifting them earlier or later affects how the brain is wired, as can be seen in the sensory cortex of mouse models. In normal mice, activity in a single whisker activates a single cluster of cells, relaying information about the force and direction in which the whisker was moved.

    However, in mice with Fragile X syndrome, activity from a single whisker activates multiple clusters of cells, creating hyper-excitability.

    “The activity bleeds to other clusters of cells, activating more cells than it normally would,” he said.

    To investigate if this hyper-excitability could be reversed, Contractor and his colleagues treated mice for two weeks after birth with bumetanide, a drug originally used for hypertension.

    “It’s actually not used very much anymore, because there are better drugs on the market now. But in addition to its effect on blood pressure it can affect neuronal chloride transporters and the influx of chloride into the cell,” Contractor said.

    In mice with the Fragile X mutation, Contractor found it returned the concentration of intracellular chloride back to normal in neurons, shifting the critical periods back to their correct timing and leading to more typical synapse development.

    “We found that if we gave this drug early in development, it not only corrected the development of synapses during the early critical period, it also corrected the sensory problems we saw in adult mice,” Contractor said. “It is possible that correcting chloride or correcting neurotransmitter signaling in humans could also have the same effect.”

    In fact, a high concentration of intracellular chloride could be associated with a variety of developmental disorders, not just Fragile X syndrome and autism, according to Contractor.

    “We think it actually might be a more general mechanism, it’s been shown to play a role in Down syndrome and childhood epilepsies as well,” Contractor said. “People are interested in this chloride mechanism in a whole host of neurodevelopmental disorders.”

    Contractor is also a professor in the Department of Neurobiology in the Weinberg College of Arts and Sciences. Qionger He, PhD, a former postdoctoral fellow in Contractor’s laboratory, was first author of the study. Feinberg co-authors include Jeffrey Savas, PhD, assistant professor in the Ken & Ruth Davee Department of Neurology and of Medicine and Pharmacology, Sam Smukowski, staff member in the Savas Laboratory and Jian Xu, PhD, research assistant professor of Physiology.

    The authors also collaborated with Carlos Portera-Cailliau, MD, PhD, associate professor of Neurology at the University of Southern California-Los Angeles, and other members of his research group.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Northwestern South Campus
    South Campus

    On May 31, 1850, nine men gathered to begin planning a university that would serve the Northwest Territory.

    Given that they had little money, no land and limited higher education experience, their vision was ambitious. But through a combination of creative financing, shrewd politicking, religious inspiration and an abundance of hard work, the founders of Northwestern University were able to make that dream a reality.

    In 1853, the founders purchased a 379-acre tract of land on the shore of Lake Michigan 12 miles north of Chicago. They established a campus and developed the land near it, naming the surrounding town Evanston in honor of one of the University’s founders, John Evans. After completing its first building in 1855, Northwestern began classes that fall with two faculty members and 10 students.
    Twenty-one presidents have presided over Northwestern in the years since. The University has grown to include 12 schools and colleges, with additional campuses in Chicago and Doha, Qatar.

    Northwestern is recognized nationally and internationally for its educational programs.

     
  • richardmitnick 2:21 pm on February 5, 2018 Permalink | Reply
    Tags: , Controlling Quantum Interactions in a Single Material, Northwestern University,   

    From Northwestern University: “Controlling Quantum Interactions in a Single Material” 

    Northwestern U bloc
    Northwestern University

    Feb 5, 2018
    No writer credit

    1
    Structural and electronic properties of Ag2BiO3. Crystal structure of a the ferroelectric Pnn2 and b the hypothetical paraelectric Pnna phase. Red, gray, green, blue, and purple spheres are O2−, Ag+, Bi4+, Bi3+, and Bi5+ ions, respectively. c and d are the band structures of the Pnn2 and Pnna phases, respectively. The Fermi level is shifted to 0 eV. High symmetry points in the first Brillouin zone are defined in Supplementary Figure 1. e and f are the spin textures of the inner and outer branches of conduction bands at the R point in the polar Pnn2 phase. The color code indicates the energy level with respect to the bottom of conduction band. Credit: Nature Communications (2018). DOI: 10.1038/s41467-017-02814-4

    The search and manipulation of novel properties emerging from the quantum nature of matter could lead to next-generation electronics and quantum computers. But finding or designing materials that can host such quantum interactions is a difficult task.

    “Harmonizing multiple quantum mechanical properties, which often do not coexist together, and trying to do it by design is a highly complex challenge,” said Northwestern Engineering’s James Rondinelli.

    But Rondinelli and an international team of theoretical and computational researchers have done just that. Not only have they demonstrated that multiple quantum interactions can coexist in a single material, the team also discovered how an electric field can be used to control these interactions to tune the material’s properties.

    This breakthrough could enable ultrafast, low-power electronics and quantum computers that operate incredibly faster than current models in the areas of data acquisition, processing, and exchange.

    Supported by the US Army Research Office, National Science Foundation of China, German Research Foundation, and China’s National Science Fund for Distinguished Young Scholars, the research was published online today in the journal Nature Communications. James Rondinelli, the Morris E. Fine Junior Professor in Materials and Manufacturing in Northwestern’s McCormick School of Engineering, and Cesare Franchini, professor of quantum materials modeling at the University of Vienna, are the paper’s co-corresponding authors. Jiangang He, a postdoctoral fellow at Northwestern, and Franchini served as the paper’s co-first authors.

    Quantum mechanical interactions govern the capability of and speed with which electrons can move through a material. This determines whether a material is a conductor or insulator. It also controls whether or not the material exhibits ferroelectricity, or shows an electrical polarization.

    “The possibility of accessing multiple order phases, which rely on different quantum-mechanical interactions in the same material, is a challenging fundamental issue and imperative for delivering on the promises that quantum information sciences can offer,” Franchini said.

    Using computational simulations performed at the Vienna Scientific Cluster, the team discovered coexisting quantum-mechanical interactions in the compound silver-bismuth-oxide.

    2
    Vienna Scientific Cluster

    Bismuth, a post-transition metal, enables the spin of the electron to interact with its own motion — a feature that has no analogy in classical physics. It also does not exhibit inversion symmetry, suggesting that ferroelectricity should exist when the material is an electrical insulator. By applying an electric field to the material, researchers were able to control whether the electron spins were coupled in pairs (exhibiting Weyl-fermions) or separated (exhibiting Rashba-splitting) as well as whether the system is electrically conductive or not.

    “This is the first real case of a topological quantum transition from a ferroelectric insulator to a non-ferroelectric semi-metal,” Franchini said. “This is like awakening a different kind of quantum interactions that are quietly sleeping in the same house without knowing each other.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Northwestern South Campus
    South Campus

    On May 31, 1850, nine men gathered to begin planning a university that would serve the Northwest Territory.

    Given that they had little money, no land and limited higher education experience, their vision was ambitious. But through a combination of creative financing, shrewd politicking, religious inspiration and an abundance of hard work, the founders of Northwestern University were able to make that dream a reality.

    In 1853, the founders purchased a 379-acre tract of land on the shore of Lake Michigan 12 miles north of Chicago. They established a campus and developed the land near it, naming the surrounding town Evanston in honor of one of the University’s founders, John Evans. After completing its first building in 1855, Northwestern began classes that fall with two faculty members and 10 students.
    Twenty-one presidents have presided over Northwestern in the years since. The University has grown to include 12 schools and colleges, with additional campuses in Chicago and Doha, Qatar.

    Northwestern is recognized nationally and internationally for its educational programs.

     
  • richardmitnick 3:57 pm on January 30, 2018 Permalink | Reply
    Tags: , , , , Newborns or survivors? The unexpected matter found in hostile black hole winds, Northwestern University   

    From Northwestern: “Newborns or survivors? The unexpected matter found in hostile black hole winds” 

    Northwestern U bloc
    Northwestern University

    January 30, 2018
    Kayla Stoner

    1
    No image caption or credit

    The existence of large numbers of molecules in winds powered by supermassive black holes at the centers of galaxies has puzzled astronomers since they were discovered more than a decade ago. Molecules trace the coldest parts of space, and black holes are the most energetic phenomena in the universe, so finding molecules in black hole winds was like discovering ice in a furnace.

    Astronomers questioned how anything could survive the heat of the energetic outflows, but a new theory from researchers in Northwestern University’s Center for Interdisciplinary Research and Exploration in Astrophysics (CIERA) predicts that these molecules are not survivors at all, but brand-new molecules, born in the winds with unique properties that enable them to adapt to and thrive in the hostile environment.

    The theory, published in the Monthly Notices of the Royal Astronomical Society, is the work of Lindheimer post-doctoral fellow Alexander Richings, who developed the computer code that, for the first time, modeled the detailed chemical processes that occur in interstellar gas accelerated by radiation emitted during the growth of supermassive black holes. Claude-André Faucher-Giguère, who studies galaxy formation and evolution as an assistant professor in Northwestern’s Weinberg College of Arts and Sciences, is a co-author.

    2
    Galaxy-scale outflow driven by the central black hole/ ESA

    “When a black hole wind sweeps up gas from its host galaxy, the gas is heated to high temperatures, which destroy any existing molecules,” Richings said. “By modeling the molecular chemistry in computer simulations of black hole winds, we found that this swept-up gas can subsequently cool and form new molecules.

    This theory answers questions raised by previous observations made with several cutting-edge astronomical observatories including the Herschel Space Observatory and the Atacama Large Millimeter Array, a powerful radio telescope located in Chile.

    In 2015, astronomers confirmed the existence of energetic outflows from supermassive black holes found at the center of most galaxies [Nature]. These outflows kill everything in their path, expelling the food – or molecules – that fuel star formation. These winds are also presumed to be responsible for the existence of “red and dead” elliptical galaxies, in which no new stars can form.

    Then, in 2017, astronomers observed rapidly moving new stars forming in the winds [Nature] – a phenomenon they thought would be impossible given the extreme conditions in black hole-powered outflows.

    New stars form from molecular gas, so Richings and Faucher-Giguère’s new theory of molecule formation helps explain the formation of new stars in winds. It upholds previous predictions that black hole winds destroy molecules upon first collision but also predicts that new molecules – including hydrogen, carbon monoxide and water – can form in the winds themselves.

    4
    Zoomed-in view of the black hole wind at the center of a galaxy/ ESA

    “This is the first time that the molecule formation process has been simulated in full detail, and in our view, it is a very compelling explanation for the observation that molecules are ubiquitous in supermassive black hole winds, which has been one of the major outstanding problems in the field,” Faucher-Giguère said.

    Richings and Faucher-Giguère predict that the new molecules formed in the winds are warmer and brighter in infrared radiation compared to pre-existing molecules. That theory will be put to the test when NASA launches the James Webb Space Telescope in spring 2019. If the theory is correct, the telescope will be able to map black hole outflows in detail using infrared radiation.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Northwestern South Campus
    South Campus

    On May 31, 1850, nine men gathered to begin planning a university that would serve the Northwest Territory.

    Given that they had little money, no land and limited higher education experience, their vision was ambitious. But through a combination of creative financing, shrewd politicking, religious inspiration and an abundance of hard work, the founders of Northwestern University were able to make that dream a reality.

    In 1853, the founders purchased a 379-acre tract of land on the shore of Lake Michigan 12 miles north of Chicago. They established a campus and developed the land near it, naming the surrounding town Evanston in honor of one of the University’s founders, John Evans. After completing its first building in 1855, Northwestern began classes that fall with two faculty members and 10 students.
    Twenty-one presidents have presided over Northwestern in the years since. The University has grown to include 12 schools and colleges, with additional campuses in Chicago and Doha, Qatar.

    Northwestern is recognized nationally and internationally for its educational programs.

     
  • richardmitnick 10:32 am on January 10, 2018 Permalink | Reply
    Tags: , , Northwestern University, Relativistic jets’ behavior   

    From Northwestern University: “Black hole breakthrough: new insight into mysterious jets” 

    Northwestern U bloc
    Northwestern University

    January 09, 2018
    Kayla Stoner

    Supercomputer power enables advanced simulations of relativistic jets’ behavior.

    Through first-of-their-kind supercomputer simulations, researchers, including a Northwestern University professor, have gained new insight into one of the most mysterious phenomena in modern astronomy: the behavior of relativistic jets that shoot from black holes, extending outward across millions of light years.

    Advanced simulations created with one of the world’s most powerful supercomputers show the jets’ streams gradually change direction in the sky, or precess, as a result of space-time being dragged into the rotation of the black hole. This behavior aligns with Albert Einstein’s predictions about extreme gravity near rotating black holes, published in his famous theory of general relativity.


    This simulation produced using the Blue Waters supercomputer is the first simulation ever to demonstrate that relativistic jets follow along with the precession of the tilted accretion disk around the black hole. At close to a billion computational cells, it is the highest resolution simulation of an accreting black hole ever achieved.

    “Understanding how rotating black holes drag the space-time around them and how this process affects what we see through the telescopes remains a crucial, difficult-to-crack puzzle,” said Alexander Tchekhovskoy, assistant professor of physics and astronomy at Northwestern’s Weinberg College of Arts and Sciences. “Fortunately, the breakthroughs in code development and leaps in supercomputer architecture are bringing us ever closer to finding the answers.”

    The study, published in the Monthly Notices of the Royal Astronomical Society, is a collaboration between Tchekhovskoy, Matthew Liska and Casper Hesp. Liska and Hesp are the study’s lead authors and graduate students at The University of Amsterdam, Netherlands.

    Rapidly spinning black holes not only engulf matter but also emit energy in the form of relativistic jets. Similar to how water in a bathtub forms a whirlpool as it goes down a drain, the gas and magnetic fields that feed a supermassive black hole swirl to form a rotating disk — a tangled spaghetti of magnetic field lines mixed into a broth of hot gas. As the black hole consumes this astrophysical soup, it gobbles up the broth but leaves the magnetic spaghetti dangling out of its mouth. This makes the black hole into a kind of launching pad from which energy, in the form of relativistic jets, shoots from the web of twisted magnetic spaghetti.

    The jets emitted by black holes are easier to study than the black holes themselves because the jets are so large. This study enables astronomers to understand how quickly the jet direction is changing, which reveals information about the black hole spin as well as the orientation and size of the rotating disk and other difficult-to-measure properties of black hole accretion.

    Whereas nearly all previous simulations considered aligned disks, in reality, most galaxies’ central supermassive black holes are thought to harbor tilted disks — meaning the disk rotates around a separate axis than the black hole itself. This study confirms that if tilted, disks change direction relative to the black hole, precessing around like a spinning top. For the first time, the simulations showed that such tilted disks lead to precessing jets that periodically change their direction in the sky.

    An important reason precessing jets were not discovered earlier is that 3-D simulations of the region surrounding a rapidly spinning black hole require an enormous amount of computational power. To address this issue, the researchers constructed the first black hole simulation code accelerated by graphical processing units (GPUs). A National Science Foundation grant enabled them to carry out the simulations on Blue Waters, one of the largest supercomputers in the world, located at the University of Illinois.

    U Illinois Urbana-Champaign Blue Waters Cray Linux XE/XK hybrid machine supercomputer


    Comparing a low resolution simulation (left) to the high-resolution simulation produced using Blue Waters (right) show the effect of resolution on tilted accretion models. The high resolution model shows that precession and alignment slow down as a result of disk expansion due to magnetic turbulence.

    The confluence of the fast code, which efficiently uses a cutting-edge GPU architecture, and the Blue Waters supercomputer allowed the team to carry out simulations with the highest resolution ever achieved – up to a billion computational cells.

    “The high resolution allowed us, for the first time, to ensure that small-scale turbulent disk motions are accurately captured in our models,” Tchekhovskoy said. “To our surprise, these motions turned out to be so strong that they caused the disk to fatten up and the disk precession to stop. This suggests that precession can come about in bursts.”

    Because accretion onto black holes is a highly complex system akin to a hurricane, but located so far away we cannot discern many details, simulations offer a powerful way of making sense of telescope observations and understanding the behavior of black holes.

    The simulation results are important for further studies involving rotating black holes, which are currently being conducted all over the world. Through these efforts, astronomers are attempting to understand recently discovered phenomena such as the first detections of gravitational waves from neutron star collisions and the accompanying electromagnetic fireworks as well as regular stars being engulfed by supermassive black holes.

    The calculations also are being applied to interpreting the observations of the Event Horizon Telescope (EHT), which captured the first recordings of the supermassive black hole shadow in the center of the Milky Way.

    Additionally, the jets’ precession could explain fluctuations in the intensity of light coming from around black holes, called quasi-periodic oscillations (QPOs). Such oscillations can occur similarly to the way in which the rotating beam of a lighthouse increases in intensity as it passes by an observer. QPOs were first discovered near black holes (as X-rays) in 1985 by Michiel van der Klis (University of Amsterdam), who is a co-author of the new article.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Northwestern South Campus
    South Campus

    On May 31, 1850, nine men gathered to begin planning a university that would serve the Northwest Territory.

    Given that they had little money, no land and limited higher education experience, their vision was ambitious. But through a combination of creative financing, shrewd politicking, religious inspiration and an abundance of hard work, the founders of Northwestern University were able to make that dream a reality.

    In 1853, the founders purchased a 379-acre tract of land on the shore of Lake Michigan 12 miles north of Chicago. They established a campus and developed the land near it, naming the surrounding town Evanston in honor of one of the University’s founders, John Evans. After completing its first building in 1855, Northwestern began classes that fall with two faculty members and 10 students.
    Twenty-one presidents have presided over Northwestern in the years since. The University has grown to include 12 schools and colleges, with additional campuses in Chicago and Doha, Qatar.

    Northwestern is recognized nationally and internationally for its educational programs.

     
  • richardmitnick 8:05 pm on October 15, 2017 Permalink | Reply
    Tags: , , , , , , Nanotechnology is a multidisciplinary field where chemistry medicine and engineering all intersect, Northwestern University, , Spherical nucleic acid (SNA) technology, Studying and manipulating molecules and materials with dimensions on the 1 to 100 nanometer length scale (1 nm = one billionth of a meter)   

    From Northwestern University- “Titans of nanotechnology: The next big thing is very small” 

    Northwestern U bloc
    Northwestern University

    October 09, 2017

    1
    Teri Odom and Chad Mirkin of the International Institute for Nanotechnology.

    World-renowned nanoscientists and chemists Chad Mirkin, the Director of the International Institute for Nanotechnology (IIN) at Northwestern University, and Teri Odom, the IIN’s Associate Director, sit down to discuss the golden age of miniaturization and how the “science of small things” is fostering major advances.

    The IIN, founded in 2000, is making major strides in nanotechnology and thriving in a big way. Nanoscience and technology — a field focused on studying and manipulating molecules and materials with dimensions on the 1 to 100 nanometer length scale (1 nm = one billionth of a meter) — was anticipated in 1959 by physicist Richard Feynman and made possible with the advent of the electron and scanning tunneling microscopes in the 1980s. It is engaging scientists from all over the world across many disciplines. They are using such tools to explore, and ultimately solve, some of the world’s most pressing issues in medicine, engineering, energy, and defense.

    We [interviewer is not named] sit in on a conversation between Mirkin and Odom to see where this exciting field is headed.

    Q: Your team discovered spherical nucleic acid (SNA) technology, where tiny particles can be decorated with short snippets of DNA or RNA. With the creation of SNAs, you’ve basically taken known molecules, reorganized them at the nanoscale into ball-like forms, and changed their properties. What is the potential of such a discovery, and what exciting breakthroughs are on the near horizon?

    Mirkin: Two really promising areas in which we are applying SNA technology are biomedicine and gene regulation — the idea that one can create ways of using DNA- and RNA-based SNAs as potent new drugs. For example, we can put SNAs into commercially available creams, like Aquaphor®, and apply them topically to treat diseases of the skin. There are more than 200 skin diseases with a known genetic basis, making the DNA- and RNA-based SNAs a general strategy for treating skin diseases. Conventional DNA and RNA constructs based on linear nucleic acids cannot be delivered in this way – they do not penetrate the skin. But, SNAs can because of their unique architecture that changes the way they interact with biological structures and in particular, receptors on skin cells that recognize them, but not linear DNA or RNA. SNAs can also be used to treat diseases of the bladder, colon, lung, and eye — organs and tissues that also are hard to treat using traditional means.

    Q: Nanotechnology is a multidisciplinary field where chemistry, medicine and engineering all intersect to create innovative solutions for a whole range of issues. One area is photonics, where advances at the nanoscale are changing how we communicate. How?

    Odom: We’re trying to reduce the size of lasers, which are typically macroscopic devices, down to the nanometer scale. The ability to design nanomaterials that can control the production and guiding of light — which is composed of individual particles called photons — can transform a range of different technologies. For example, communication based on photons (like in optical fibers) vs. electrons (like in copper wires) is faster and much more efficient. Applications that exploit light can readily be transformed by nanotechnology.

    Q: Nanotechnology has revolutionized the basic sciences, fast-tracking their translational impact. For example, your colleague Samuel Stupp, director of the Simpson Querrey Institute for BioNanotechnology at Northwestern, is on the verge of conducting clinical trials in spinal regeneration through “soft” nanotechnology breakthroughs. Has nanotechnology also revolutionized the traditional scientific method, too?

    Mirkin: The desire to come up with a solution to a given problem often leads scientists to develop new capabilities. That’s the thrilling thing about science in general, but about nanotechnology in particular: we often have goals, which are driven by engineering needs, but along the way we discover fundamentally interesting principles that we didn’t anticipate and that inform our view of the world around us. These discoveries take us down new paths — ones that might be even more interesting than the original ones we were on. This is the nature and importance of basic science research.

    Odom: Nano provides the fundamentals. But then, we adapt, based on these unanticipated properties, while still keeping our long-range goals in mind. That’s pretty neat. You can adjust in ways that keep discovery and creativity at the forefront. Without that, we all would be bored.

    Q: Nobel Prize winner Sir Fraser Stoddart, John Rogers, William Dichtel, Milan Mrksich and the aforementioned Stupp are just a few of the many big names in the Northwestern nanotechnology community. What is Northwestern doing right and what’s the global impact?

    Mirkin: These are heavy hitters, people who can go anywhere in the world, but they chose to come to Northwestern because they recognized that this is a very special time in our history. We are on an incredible trajectory here, and they want to be a part of it.

    Odom: We have a holistic way of training new faculty and graduate students because we want them to have a complete picture of everything that’s going on here. This is how we do science at Northwestern, and we really apply it to nanotechnology. Part of our success as a chemistry department has come from our ability to make things, to measure them, and to model them — I like to think of this integration as the “3Ms” principle. Our achievements in nanotechnology have been built on these three synergistic areas of expertise.

    Mirkin: It really starts with world-class talent, and then collaboration. You can collaborate all you want, but if you don’t have world-class talent, it doesn’t matter. Since we’re going all-in on the medical side, in 15 years I went from having zero collaborations with the medical school, to now having 17. There is a natural interaction here between clinicians, scientists, and engineers that make everyone’s work so much stronger. Within the next five years, I anticipate that there will be cancer treatments based upon nanotechnology that greatly improve outcomes and, in some subsets of diseases, actually leads to cures.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Northwestern South Campus
    South Campus

    On May 31, 1850, nine men gathered to begin planning a university that would serve the Northwest Territory.

    Given that they had little money, no land and limited higher education experience, their vision was ambitious. But through a combination of creative financing, shrewd politicking, religious inspiration and an abundance of hard work, the founders of Northwestern University were able to make that dream a reality.

    In 1853, the founders purchased a 379-acre tract of land on the shore of Lake Michigan 12 miles north of Chicago. They established a campus and developed the land near it, naming the surrounding town Evanston in honor of one of the University’s founders, John Evans. After completing its first building in 1855, Northwestern began classes that fall with two faculty members and 10 students.
    Twenty-one presidents have presided over Northwestern in the years since. The University has grown to include 12 schools and colleges, with additional campuses in Chicago and Doha, Qatar.

    Northwestern is recognized nationally and internationally for its educational programs.

     
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