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  • richardmitnick 1:05 pm on March 9, 2022 Permalink | Reply
    Tags: "Black hole billiards in the centers of galaxies may explain black hole mergers", , Gravitational wave astrophysics, ,   

    From The University of Copenhagen [Københavns Universitet](DK) and The Niels Bohr Institute [Niels Bohr Institutet](DK) via phys.org: “Black hole billiards in the centers of galaxies may explain black hole mergers” 

    From The University of Copenhagen [Københavns Universitet](DK)


    Niels Bohr Institute bloc

    The Niels Bohr Institute [Niels Bohr Institutet](DK)



    Illustration of a swarm of smaller black holes in a gas disk rotating around a giant black hole. Credit: J. Samsing/Niels Bohr Institute

    Researchers have provided the first plausible explanation to why one of the most massive black hole pairs observed to date by gravitational waves also seemed to merge on a non-circular orbit. Their suggested solution, now published in Nature, involves a chaotic triple drama inside a giant disk of gas around a supermassive black hole in another galaxy.

    Black holes are one of the most fascinating objects in the universe, but our knowledge of them is still limited—especially because they do not emit any light. Up until a few years ago, light was our main source of knowledge about our universe and its black holes, until the Laser Interferometer Gravitational Wave Observatory (LIGO) in 2015 made its breakthrough observation of gravitational waves from the merger of two black holes.

    “But how and where in our universe do such black holes form and merge? Does it happen when nearby stars collapse and both turn into black holes, is it through close chance encounters in star clusters, or is it something else? These are some of the key questions in the new era of Gravitational Wave Astrophysics,” says assistant professor Johan Samsing from the Niels Bohr Institute at the University of Copenhagen, lead author of the paper.

    He and his collaborators may have now provided a new piece to the puzzle, which possibly solves the last part of a mystery that astrophysicists have struggled with for the past few years.

    Unexpected discovery in 2019

    The mystery dates back to 2019, when an unexpected discovery of gravitational waves was made by the LIGO and Virgo observatories. The event, named GW190521, is understood to be the merger of two black holes that were not only heavier than previously thought physically possible, but had also produced a flash of light.

    Possible explanations have since been provided for these two characteristics, but the gravitational waves also revealed a third astonishing feature of this event—namely that the black holes did not orbit each other along a circle in the moments before merging.

    “The gravitational wave event GW190521 is the most surprising discovery to date. The black holes’ masses and spins were already surprising, but even more surprising was that they appeared not to have a circular orbit leading up to the merger,” says co-author Imre Bartos, professor at the University of Florida.

    But why is a non-circular orbit so unusual and unexpected?

    “This is because of the fundamental nature of the gravitational waves emitted, which not only brings the pair of black holes closer for them to finally merge but also acts to circularize their orbit.” explains co-author Zoltan Haiman, a professor at Columbia University.

    This observation made many people around the world, including Johan Samsing in Copenhagen, wonder.

    “It made me start thinking about how such non-circular (known as ‘eccentric’) mergers can happen with the surprisingly high probability as the observation suggests,” says Samsing.

    It takes three to tango

    A possible answer would be found in the harsh environment in the centers of galaxies harboring a giant black hole millions of times the mass of the sun and surrounded by a flat, rotating disk of gas.

    “In these environments the typical velocity and density of black holes is so high that smaller black holes bounce around as in a giant game of billiards and wide circular binaries cannot exist,” points out co-author professor Bence Kocsis from the University of Oxford.

    But as the group further argued, a giant black hole is not enough.

    “New studies show that the gas disk plays an important role in capturing smaller black holes, which over time move closer to the center and also closer to one other. This not only implies they meet and form pairs, but also that such a pair might interact with another, third, black hole, often leading to a chaotic tango with three black holes flying around, ” explains astrophysicist Hiromichi Tagawa from Tohoku University, co-author of the study.

    However, all previous studies up to observation of GW190521 indicated that forming eccentric black hole mergers is relatively rare. This naturally brings up the question: Why did the already unusual gravitational wave source GW190521 also merge on an eccentric orbit?

    Two-dimensional black hole billiards

    Everything that has been calculated so far was based on the notion that the black hole interactions are taking place in three dimensions, as expected in the majority of stellar systems considered so far.

    “But then we started thinking about what would happen if the black hole interactions were instead to take place in a flat disk, which is closer to a two-dimensional environment. Surprisingly, we found in this limit that the probability of forming an eccentric merger increases by as much as a 100 times, which leads to about half of all black hole mergers in such disks possibly being eccentric,” says Johan Samsing and continues:

    “And that discovery fits incredibly well with the observation in 2019, which all in all now points in the direction that the otherwise spectacular properties of this source are not so strange again, if it was created in a flat gas disk surrounding a supermassive black hole in a galactic nucleus.”

    This possible solution also adds to a century-old problem in mechanics,

    “The interaction between three objects is one of the oldest problems in physics, which both Newton, myself, and others have intensely studied. That this now seems to play a crucial role in how black holes merge in some of the most extreme places of our universe is incredibly fascinating “, says co-author Nathan W. Leigh, professor at Universidad de Concepción, Chile.

    Black holes in gaseous disks

    The theory of the gas disk also fits with other researchers’ explanations of the other two puzzling properties of GW190521. The large masses of the black hole have been reached by successive mergers inside the disk, while the emission of light could originate from the ambient gas.

    “We have now shown that there can be a huge difference in the signals emitted from black holes that merge in flat, two-dimensional disks, versus those we often consider in three-dimensional stellar systems, which tells us that we now have an extra tool that we can use to learn about how black holes are created and merge in our universe,” says Samsing.

    But this study is only the beginning.

    “People have been working on understanding the structure of such gas disks for many years, but the problem is difficult. Our results are sensitive to how flat the disk is, and how the black holes move around in it. Time will tell whether we will learn more about these disks, once we have a larger population of black hole mergers, including more unusual cases similar to GW190521. To enable this, we must build on our now published discovery, and see where it leads us in this new and exciting field,” concludes co-author Zoltan Haiman.

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Niels Bohr Institute Campus

    The Niels Bohr Institute [Niels Bohr Institutet](DK) is a research institute of the The University of Copenhagen [Københavns Universitet][UCPH] (DK). The research of the institute spans astronomy, geophysics, nanotechnology, particle physics, quantum mechanics and biophysics.

    The Institute was founded in 1921, as the Institute for Theoretical Physics of the Københavns Universitet [UCPH](DK), by the Danish theoretical physicist Niels Bohr, who had been on the staff of the University of Copenhagen since 1914, and who had been lobbying for its creation since his appointment as professor in 1916. On the 80th anniversary of Niels Bohr’s birth – October 7, 1965 – the Institute officially became The Niels Bohr Institutet (DK). Much of its original funding came from the charitable foundation of the Carlsberg brewery, and later from the Rockefeller Foundation.

    During the 1920s, and 1930s, the Institute was the center of the developing disciplines of atomic physics and quantum physics. Physicists from across Europe (and sometimes further abroad) often visited the Institute to confer with Bohr on new theories and discoveries. The Copenhagen interpretation of quantum mechanics is named after work done at the Institute during this time.

    On January 1, 1993 the institute was fused with the Astronomic Observatory, the Ørsted Laboratory and the Geophysical Institute. The new resulting institute retained the name Niels Bohr Institutet (DK)).

    The University of Copenhagen [Københavns Universitet][UCPH] (DK) is the oldest university and research institution in Denmark. Founded in 1479 as a studium generale, it is the second oldest institution for higher education in Scandinavia after Uppsala University [Uppsala universitet](SE) (1477). The university has 23,473 undergraduate students, 17,398 postgraduate students, 2,968 doctoral students and over 9,000 employees. The university has four campuses located in and around Copenhagen, with the headquarters located in central Copenhagen. Most courses are taught in Danish; however, many courses are also offered in English and a few in German. The university has several thousands of foreign students, about half of whom come from Nordic countries.

    The university is a member of the International Alliance of Research Universities (IARU), along with University of Cambridge (UK), Yale University, The Australian National University (AU), and The University of California-Berkeley(US), amongst others. The 2016 Academic Ranking of World Universities ranks the University of Copenhagen as the best university in Scandinavia and 30th in the world, the 2016-2017 Times Higher Education World University Rankings as 120th in the world, and the 2016-2017 QS World University Rankings as 68th in the world. The university has had 9 alumni become Nobel laureates and has produced one Turing Award recipient.

    Its establishment sanctioned by Pope Sixtus IV, the University of Copenhagen was founded by Christian I of Denmark as a Catholic teaching institution with a predominantly theological focus. After 1537, it became a Lutheran seminary under King Christian III. Up until the 18th century, the university was primarily concerned with educating clergymen. Through various reforms in the 18th and 19th century, the University of Copenhagen was transformed into a modern, secular university, with science and the humanities replacing theology as the main subjects studied and taught.

    The University of Copenhagen consists of six different faculties, with teaching taking place in its four distinct campuses, all situated in Copenhagen. The university operates 36 different departments and 122 separate research centres in Copenhagen, as well as a number of museums and botanical gardens in and outside the Danish capital. The University of Copenhagen also owns and operates multiple research stations around Denmark, with two additional ones located in Greenland. Additionally, The Faculty of Health and Medical Sciences and the public hospitals of the Capital and Zealand Region of Denmark constitute the conglomerate Copenhagen University Hospital.

    A number of prominent scientific theories and schools of thought are namesakes of the University of Copenhagen. The famous Copenhagen Interpretation of quantum mechanics was conceived at the Niels Bohr Institute [Niels Bohr Institutet](DK), which is part of the university. The Department of Political Science birthed the Copenhagen School of Security Studies which is also named after the university. Others include the Copenhagen School of Theology and the Copenhagen School of Linguistics.

    As of October 2020, 39 Nobel laureates and 1 Turing Award laureate have been affiliated with the University of Copenhagen as students, alumni or faculty. Alumni include one president of the United Nations General Assembly and at least 24 prime ministers of Denmark. The University of Copenhagen fosters entrepreneurship, and between 5 and 6 start-ups are founded by students, alumni or faculty members each week.


    The University of Copenhagen was founded in 1479 and is the oldest university in Denmark. In 1474, Christian I of Denmark journeyed to Rome to visit Pope Sixtus IV, whom Christian I hoped to persuade into issuing a papal bull permitting the establishment of university in Denmark. Christian I failed to persuade the pope to issue the bull however and the king returned to Denmark the same year empty-handed. In 1475 Christian I’s wife Dorothea of Brandenburg Queen of Denmark made the same journey to Rome as her husband did a year before. Unlike Christian I Dorothea managed to persuade Pope Sixtus IV into issuing the papal bull. On the 19th of June, 1475 Pope Sixtus IV issued an official papal bull permitting the establishment of what was to become the University of Copenhagen.

    On the 4th of October, 1478 Christian I of Denmark issued a royal decree by which he officially established the University of Copenhagen. In this decree Christian I set down the rules and laws governing the university. The royal decree elected magistar Peder Albertsen as vice chancellor of the university and the task was his to employ various learned scholars at the new university and thereby establish its first four faculties: theology; law; medicine; and philosophy. The royal decree made the University of Copenhagen enjoy royal patronage from its very beginning. Furthermore, the university was explicitly established as an autonomous institution giving it a great degree of juridical freedom. As such the University of Copenhagen was to be administered without royal interference and it was not subject to the usual laws governing the Danish people.

    The University of Copenhagen was closed by the Church in 1531 to stop the spread of Protestantism and re-established in 1537 by King Christian III after the Lutheran Reformation and transformed into an evangelical-Lutheran seminary. Between 1675 and 1788 the university introduced the concept of degree examinations. An examination for theology was added in 1675 followed by law in 1736. By 1788 all faculties required an examination before they would issue a degree.

    In 1807 the British Bombardment of Copenhagen destroyed most of the university’s buildings. By 1836 however the new main building of the university was inaugurated amid extensive building that continued until the end of the century. The University Library (now a part of the Royal Library); the Zoological Museum; the Geological Museum; the Botanic Garden with greenhouses; and the Technical College were also established during this period.

    Between 1842 and 1850 the faculties at the university were restructured. Starting in 1842 the University Faculty of Medicine and the Academy of Surgeons merged to form the Faculty of Medical Science while in 1848 the Faculty of Law was reorganised and became the Faculty of Jurisprudence and Political Science. In 1850 the Faculty of Mathematics and Science was separated from the Faculty of Philosophy. In 1845 and 1862 Copenhagen co-hosted nordic student meetings with Lund University [Lunds universitet] (SE).

    The first female student was enrolled at the university in 1877. The university underwent explosive growth between 1960 and 1980. The number of students rose from around 6,000 in 1960 to about 26,000 in 1980 with a correspondingly large growth in the number of employees. Buildings built during this time period include the new Zoological Museum; the Hans Christian Ørsted and August Krogh Institutes; the campus centre on Amager Island; and the Panum Institute.

    The new university statute instituted in 1970 involved democratisation of the management of the university. It was modified in 1973 and subsequently applied to all higher education institutions in Denmark. The democratisation was later reversed with the 2003 university reforms. Further change in the structure of the university from 1990 to 1993 made a Bachelor’s degree programme mandatory in virtually all subjects.

    Also in 1993 the law departments broke off from the Faculty of Social Sciences to form a separate Faculty of Law. In 1994 the University of Copenhagen designated environmental studies; north–south relations; and biotechnology as areas of special priority according to its new long-term plan. Starting in 1996 and continuing to the present the university planned new buildings including for the University of Copenhagen Faculty of Humanities at Amager (Ørestaden) along with a Biotechnology Centre. By 1999 the student population had grown to exceed 35,000 resulting in the university appointing additional professors and other personnel.

    In 2003 the revised Danish university law removed faculty staff and students from the university decision process creating a top-down control structure that has been described as absolute monarchy since leaders are granted extensive powers while being appointed exclusively by higher levels in the organization.

    In 2005 the Center for Health and Society (Center for Sundhed og Samfund – CSS) opened in central Copenhagen housing the Faculty of Social Sciences and Institute of Public Health which until then had been located in various places throughout the city. In May 2006 the university announced further plans to leave many of its old buildings in the inner city of Copenhagen- an area that has been home to the university for more than 500 years. The purpose of this has been to gather the university’s many departments and faculties on three larger campuses in order to create a bigger more concentrated and modern student environment with better teaching facilities as well as to save money on rent and maintenance of the old buildings. The concentration of facilities on larger campuses also allows for more inter-disciplinary cooperation. For example the Departments of Political Science and Sociology are now located in the same facilities at CSS and can pool resources more easily.

    In January 2007 the University of Copenhagen merged with the Royal Veterinary and Agricultural University and the Danish University of Pharmaceutical Science. The two universities were converted into faculties under the University of Copenhagen and were renamed as the Faculty of Life Sciences and the Faculty of Pharmaceutical Sciences. In January 2012 the Faculty of Pharmaceutical Sciences and the veterinary third of the Faculty of Life Sciences merged with the Faculty of Health Sciences forming the Faculty of Health and Medical Sciences and the other two thirds of the Faculty of Life Sciences were merged into the Faculty of Science.

    Cooperative agreements with other universities

    The university cooperates with universities around the world. In January 2006, the University of Copenhagen entered into a partnership of ten top universities, along with the Australian National University (AU), Swiss Federal Institute of Technology in Zürich [ETH Zürich] [Eidgenössische Technische Hochschule Zürich](CH), The National University of Singapore [Universiti Nasional Singapura] (SG), Peking University [北京大学](CN), University of California Berkeley (US), University of Cambridge (UK), University of Oxford (UK), University of Tokyo {東京大学](JP) and Yale University (US). The partnership is referred to as the International Alliance of Research Universities (IARU).

    The Department of Scandinavian Studies and Linguistics at University of Copenhagen signed a cooperation agreement with the Danish Royal School of Library and Information Science in 2009.

  • richardmitnick 11:26 pm on February 10, 2022 Permalink | Reply
    Tags: "Future gravitational wave detector in space could uncover secrets of the Universe", , , , Gravitational wave astrophysics, , The University of Nottingham (UK)   

    From The University of Nottingham (UK): “Future gravitational wave detector in space could uncover secrets of the Universe” 


    From The University of Nottingham (UK)

    10 February 2022

    Professor Thomas Sotiriou

    Jane Icke
    Media Relations Manager Science
    Phone: 0115 7486462

    New research has shown that future gravitational wave detections from space will be capable of finding new fundamental fields and potentially shed new light on unexplained aspects of the Universe.

    Professor Thomas Sotiriou from the University of Nottingham’s Centre of Gravity and Andrea Maselli, researcher at INFN LNGS – Gran Sasso National Laboratory [Laboratori Nazionali del Gran Sasso](IT), together with researchers from The International School for Advanced Studies [Scuola Internazionale Superiore di Studi Avanzati] (IT), and La Sapienza University of Rome [Sapienza Università di Roma](IT), showed the unprecedented accuracy with which gravitational wave observations by the space interferometer LISA (Laser Interferometer Space Antenna), will be able to detect new fundamental fields.

    Gravity is talking. Lisa will listen. Dialogos of Eide.

    The European Space Agency [La Agencia Espacial Europea] [Agence spatiale européenne][Europäische Weltraumorganisation](EU)National Aeronautics and Space Administration (US) eLISA space based, the future of gravitational wave research, due to launch in 2037.

    The research has been published in Nature Astronomy.

    In this new study researchers suggest that eLISA, the space-based gravitational-wave (GW) detector which is expected to be launched by The European Space Agency [La Agencia Espacial Europea] [Agence spatiale européenne][Europäische Weltraumorganisation](EU) in 2037 will open up new possibilities for the exploration of the Universe.

    Professor Thomas Sotiriou, Director of the Nottingham Centre of Gravity explains: “New fundamental fields, and in particular scalars, have been suggested in a variety of scenarios: as explanations for Dark Matter, as the cause for the accelerated expansion of the Universe, or as low-energy manifestations of a consistent and complete description of gravity and elementary particles. We have now shown that eLISA will offer unprecedented capabilities in detecting scalar fields and this offers exciting opportunities for testing these scenarios.”

    Observations of astrophysical objects with weak gravitational fields and small spacetime curvature have provided no evidence of such fields so far. However, there is reason to expect that deviations from General Relativity, or interactions between gravity and new fields, will be more prominent at large curvatures. For this reason, the detection of GWs – which opened a novel window on the strong-field regime of gravity – represents an unique opportunity to detect these fields.

    Extreme Mass Ratio Inspirals (EMRI) in which a stellar-mass compact object, either a black hole or a neutron star, inspirals into black hole up to millions of times the mass of the Sun, are among the target sources of eLISA, and provide a golden arena to probe the strong-field regime of gravity. The smaller body performs tens of thousands of orbital cycles before it plunges into the supermassive black hole and this leads to long signals that can allow us to detect even the smallest deviations from the predictions of Einstein’s theory and the Standard Model of Particle Physics.

    The researchers have developed a new approach for modelling the signal and performed for the first time a rigorous estimate of eLISA’s capability to detect the existence of scalar fields coupled with the gravitational interaction, and to measure how much scalar field is carried by the small body of the EMRI. Remarkably, this approach is theory-agnostic, since it does not depend on the origin of the charge itself, or on the nature of the small body. The analysis also shows that such measurement can be mapped to strong bounds on the theoretical parameters that mark deviations from General Relativity or the Standard Model.

    LISA will be devoted to detect gravitational waves by astrophysical sources, will operate in a constellation of three satellites,orbiting around the Sun millions of kilometers far away each other. LISA will observe gravitational waves emitted at low frequency, within a band not available to terrestrial interferometers due to environmental noise. The visible spectrum for LISA will allow to study new families of astrophysical sources, different from those observed by Virgo and LIGO, as the EMRIs, opening a new window on the evolution of compact objects in a large variety of environments of our Universe.

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition


    The University of Nottingham (UK) is a public research university in Nottingham, United Kingdom. It was founded as University College Nottingham in 1881, and was granted a royal charter in 1948. The University of Nottingham belongs to the elite research intensive The Russell Group Association .

    Nottingham’s main campus (University Park) with Jubilee Campus and teaching hospital (Queen’s Medical Centre) are located within the City of Nottingham, with a number of smaller campuses and sites elsewhere in Nottinghamshire and Derbyshire. Outside the UK, the university has campuses in Semenyih, Malaysia, and Ningbo, China. Nottingham is organised into five constituent faculties, within which there are more than 50 schools, departments, institutes and research centres. Nottingham has about 45,500 students and 7,000 staff, and had an income of £703.6 million in 2019/20, of which £105.0 million was from research grants and contracts. The institution’s alumni have been awarded a variety of prestigious accolades, including 3 Nobel Prizes, a Fields Medal, a Turner Prize, and a Gabor Medal and Prize. The university is a member of the Association of Commonwealth Universities (UK), The European University Association, the The Russell Group Association, Universitas 21, Universities UK, The Virgo Consortium, and participates in the Sutton Trust Summer School programme as a member of the Sutton 30.

  • richardmitnick 3:13 pm on January 26, 2022 Permalink | Reply
    Tags: "International research network welcomes new partners", BRIdge the Disciplines related to the Galactic Chemical Evolution-or BRIDGCE, Chemical Elements as Tracers of the Evolution of the Cosmos- Infrastructures for Nuclear Astrophysics-ChETEC-INFRA, Gravitational wave astrophysics, , Michigan State University-led International Research Network for Nuclear Astrophysics expands to include three new partners in global quest to answer science’s most important questions., , The Canadian Nuclear Physics for Astrophysics Network-or CaNPAN,   

    From The Michigan State University (US): “International research network welcomes new partners” 

    Michigan State Bloc

    From The Michigan State University (US)

    Jan. 20, 2022
    Karen King

    The Michigan State University-led International Research Network for Nuclear Astrophysics has expanded to include three new partners in its global quest to answer science’s most important questions.
    Credit: FRIB at The Michigan State University (US)

    Michigan State University-led International Research Network for Nuclear Astrophysics expands to include three new partners in global quest to answer science’s most important questions.

    Science is a team sport. Searching for answers to science’s fundamental questions requires not only team effort, but the effort of multiple teams across multiple countries.

    In its quest to answer questions about the evolution and properties of cosmic matter and the origin of the world’s chemical elements, the International Research Network for Nuclear Astrophysics, or IReNA, supported by the National Science Foundation (US) and headquartered at Michigan State University, is expanding to include three new crucial research partners.

    IReNA’s new member networks are:

    BRIdge the Disciplines related to the Galactic Chemical Evolution-or BRIDGCE, is a United Kingdom-wide network supported by the Science and Technology Facilities Council, part of UK Research and Innovation. The goal of this network is to facilitate connections across the different disciplines involved in the study of the origin of the elements and using chemical elements as tracers of the universe’s evolution.

    The Canadian Nuclear Physics for Astrophysics Network-or CaNPAN, in Canada is a collaboration of astrophysicists and nuclear physicists. Its goal is to use Canadian nuclear physics facilities, expertise and equipment — in conjunction with Canadian computing resources — to provide education and advances in the understanding of the creation of the chemical elements and the role of stars in the universe.

    Chemical Elements as Tracers of the Evolution of the Cosmos- Infrastructures for Nuclear Astrophysics-ChETEC-INFRA, in Europe has partner institutions in 17 countries. It provides them access to the infrastructures necessary for nuclear astrophysics research: astronuclear laboratories, supercomputers and telescopes.

    They join six other networks that comprise IReNA: Joint Institute for Nuclear Astrophysics – Center for the Evolution of the Elements, or JINA-CEE; Chemical Elements as Tracers of the Evolution of the Cosmos, or ChETEC; ExtreMe Matter Institute, or EMMI; Nucleosynthesis Grid collaboration, or NuGRID; Collaborative Research Center “The Milky Way System,” or SFB 881; and Japan Forum of Nuclear Astrophysics/UKAKUREN.

    “We are very excited about the ‘bridge over the Atlantic Ocean’ joining the UK BRIDGCE research network and U.S.-based IReNA,” said Chiaki Kobayashi, chair of BRIDGCE’s steering committee and professor of astrophysics at The University of Hertfordshire (UK). “This bridge opens up excellent opportunities to exchange multidisciplinary knowledge and expertise, establish international connections and enhance training of the next generation of researchers. Our goal is to understand the origin of elements such as gold and platinum in the universe.”

    Since its founding in 2019, IReNA has improved communication across countries and disciplines to take advantage of developments in astronomy, nuclear experiments and theory. It is enabled by NSF’s AccelNet program dedicated to support strategic linkages among U.S. research networks and complementary networks abroad. IReNA employs a novel mechanism of connecting regional research networks across the world into a global network of networks.

    IReNA allows its new member networks to expand their access to laboratories and telescopes. IReNA benefits from the expanded pool of expertise and resources provided by the new member networks.

    “For CaNPAN to be able to join the IReNA network is a great opportunity to further collaboration between Canadian nuclear astrophysics researchers and their colleagues in the U.S. and around the world,” said Chris Ruiz, senior scientist at TRIUMF- Canada’s particle accelerator centre [Centre canadien d’accélération des particules](CA) and CaNPAN representative. “Also importantly, it connects students to their peers in the field and really fosters community among the future leaders of the field.”

    “We are excited to partner with IReNA to accelerate progress in our field,” said Daniel Bemmerer, ChETEC-INFRA representative and nuclear astrophysics group leader at The Helmholtz Center Dresden-Rossendorf [Helmholtz-Zentrum Dresden-Rossendorf](DE). “For example, we plan to offer complimentary access to ChETEC-INFRA infrastructures, partner in organizing meetings and improve the worldwide visibility of smaller European research institutions.”

    Nuclear astrophysics is a multidisciplinary field that addresses scientific questions at the intersection of nuclear physics and astrophysics. Research networks connecting nuclear physicists, astronomers and modelers are key to making progress.

    For example, when the observatories known as LIGO and Virgo announced the detection of gravitational waves from the collision of two neutron stars — neutron star merger GW170817 — in August 2017, the event was followed up by detection of electromagnetic emission by a coordinated network of ground and space-based telescopes.

    Caltech/MIT Advanced aLigo at Hanford, WA(US), Livingston, LA(US) and VIRGO Gravitational Wave interferometer, near Pisa(IT).

    This was the first cosmic event observed in both gravitational waves and light. Astronomy and nuclear astrophysics have since entered the multimessenger era. These multimessengers inform modelers about key nuclear physics input needed to understand how chemical elements are synthesized in such energetic cosmic events.

    More powerful accelerators and more sophisticated detectors at both radioactive and stable beam facilities allow for the measurements of short-lived nuclear species never before accessible. The Facility for Rare Isotope Beams, or FRIB, in the United States, for example, will soon produce some of these ephemeral rare isotopes.

    “There hasn’t been a more exciting time to be a researcher in this field,” said Hendrik Schatz, University Distinguished Professor with faculty appointments at FRIB and in MSU’s Department of Physics and Astronomy and director of IReNA and JINA-CEE. Schatz conducts nuclear research at FRIB. “We are at the crossroads of unprecedented scientific opportunities. By building networks of networks like IReNA, we are well-equipped to fully exploit these opportunities and to really accelerate science. We are also able to train the new generation of nuclear astrophysicists in a global and multidisciplinary environment.”

    IReNA is a National Science Foundation AccelNet Network of Networks. AccelNet is designed to accelerate the process of scientific discovery and prepare the next generation of U.S. researchers for multiteam international collaborations. The AccelNet program supports strategic linkages among U.S. research networks and complementary networks abroad that will leverage research and educational resources to tackle grand scientific challenges that require significant coordinated international efforts. Learn more at http://www.irenaweb.org.

    Michigan State University operates FRIB as a user facility for the Office of Nuclear Physics in the U.S. Department of Energy Office of Science.

    Hosting the most powerful heavy-ion accelerator, FRIB will enable scientists to make discoveries about the properties of rare isotopes in order to better understand the physics of nuclei, nuclear astrophysics, fundamental interactions and applications for society, including in medicine, homeland security and industry.

    The U.S. Department of Energy Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of today’s most pressing challenges. For more information, visit http://www.energy.gov/science.

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Michigan State Campus

    The Michigan State University (US) is a public research university located in East Lansing, Michigan, United States. Michigan State University (US) was founded in 1855 and became the nation’s first land-grant institution under the Morrill Act of 1862, serving as a model for future land-grant universities.

    The university was founded as the Agricultural College of the State of Michigan, one of the country’s first institutions of higher education to teach scientific agriculture. After the introduction of the Morrill Act, the college became coeducational and expanded its curriculum beyond agriculture. Today, Michigan State University (US) is one of the largest universities in the United States (in terms of enrollment) and has approximately 634,300 living alumni worldwide.

    U.S. News & World Report ranks its graduate programs the best in the U.S. in elementary teacher’s education, secondary teacher’s education, industrial and organizational psychology, rehabilitation counseling, African history (tied), supply chain logistics and nuclear physics in 2019. Michigan State University (US) pioneered the studies of packaging, hospitality business, supply chain management, and communication sciences. Michigan State University (US) is a member of the Association of American Universities and is classified among “R1: Doctoral Universities – Very high research activity”. The university’s campus houses the National Superconducting Cyclotron Laboratory, the W. J. Beal Botanical Garden, the Abrams Planetarium, the Wharton Center for Performing Arts, the Eli and Edythe Broad Art Museum, the Facility for Rare Isotope Beams, and the country’s largest residence hall system.


    The university has a long history of academic research and innovation. In 1877, botany professor William J. Beal performed the first documented genetic crosses to produce hybrid corn, which led to increased yields. Michigan State University (US) dairy professor G. Malcolm Trout improved the process for the homogenization of milk in the 1930s, making it more commercially viable. In the 1960s, Michigan State University (US) scientists developed cisplatin, a leading cancer fighting drug, and followed that work with the derivative, carboplatin. Albert Fert, an Adjunct professor at MSU, was awarded the 2007 Nobel Prize in Physics together with Peter Grünberg.

    Today Michigan State University (US) continues its research with facilities such as the Department of Energy (US)-sponsored Plant Research Laboratory and a particle accelerator called the National Superconducting Cyclotron Laboratory [below]. The Department of Energy (US) Office of Science named Michigan State University as the site for the Facility for Rare Isotope Beams (FRIB). The $730 million facility will attract top researchers from around the world to conduct experiments in basic nuclear science, astrophysics, and applications of isotopes to other fields.

    In 2004, scientists at the Cyclotron produced and observed a new isotope of the element germanium, called Ge-60 In that same year, Michigan State University (US), in consortium with the University of North Carolina at Chapel Hill (US) and the government of Brazil, broke ground on the 4.1-meter Southern Astrophysical Research Telescope (SOAR) in the Andes Mountains of Chile.

    NSF NOIRLab NOAO Southern Astrophysical Research [SOAR ] telescope situated on Cerro Pachón, just to the southeast of Cerro Tololo on the NOIRLab NOAO AURA site at an altitude of 2,700 meters (8,775 feet) above sea level.
    The consortium telescope will allow the Physics & Astronomy department to study galaxy formation and origins. Since 1999, MSU has been part of a consortium called the Michigan Life Sciences Corridor, which aims to develop biotechnology research in the State of Michigan. Finally, the College of Communication Arts and Sciences’ Quello Center researches issues of information and communication management.

    The Michigan State University (US) Spartans compete in the NCAA Division I Big Ten Conference. Michigan State Spartans football won the Rose Bowl Game in 1954, 1956, 1988 and 2014, and the university claims a total of six national football championships. Spartans men’s basketball won the NCAA National Championship in 1979 and 2000 and has attained the Final Four eight times since the 1998–1999 season. Spartans ice hockey won NCAA national titles in 1966, 1986 and 2007. The women’s cross country team was named Big Ten champions in 2019. In the fall of 2019, MSU student-athletes posted all-time highs for graduation success rates and federal graduation rates, according to NCAA statistics.

  • richardmitnick 1:05 pm on January 25, 2022 Permalink | Reply
    Tags: "The quantum squeeze", A new quantum sensor: the first practical superconducting transition-edge sensor., , , Gravitational wave astrophysics, In the 1960s researchers at the science lab of the Ford Motor Company developed the superconducting quantum interference device also known as a “SQUID.”, LIGO VIRGO KAGRA: Gravitational Wave Multimessenger Astrophysics Interferometry, , Quantum Squeezing: a way to circumvent quantum limitations that even quantum sensors have faced in the past., SQUIDs have played a key role in the development of ultrasensitive electric and magnetic measurement systems and are still in use., , , The Heisenberg Uncertainty Principle, The transition-edge sensor: It’s very much old-school quantum 1.0   

    From Symmetry: “The quantum squeeze” 

    Symmetry Mag

    From Symmetry

    Evelyn Lamb

    Illustration by Sandbox Studio, Chicago with Ana Kova.

    A technique from the newest generation of quantum sensors is helping scientists to use the limitations of the Heisenberg uncertainty principle to their advantage.

    In the 1960s researchers at the science lab of the Ford Motor Company developed the superconducting quantum interference device also known as a “SQUID.” It was the first usable sensor to take advantage of a quantum mechanical property—in this case, superconductivity.

    That made the SQUID one of the first generation of quantum sensors: devices that use a quantum system, quantum properties or quantum phenomena to make a physical measurement. Physicists took the idea and ran with it, coming up with new types of sensors they continue to use and improve today.

    SQUIDs have played a key role in the development of ultrasensitive electric and magnetic measurement systems and are still in use. For example, they amplify the detector signals for the Super Cryogenic Dark Matter Search. “As particle physicists, we’ve been using quantum sensing techniques for decades,” says SuperCDMS physicist Lauren Hsu of DOE’s Fermi National Accelerator Laboratory (US).

    Super Cryogenic Dark Matter Search from DOE’s SLAC National Accelerator Laboratory (US) at Stanford University (US) at SNOLAB (Vale Inco Mine, Sudbury, Canada).

    But SQUIDs are no longer the only quantum sensors around. One important recent development in quantum sensing is known as quantum squeezing—a way to circumvent quantum limitations that even quantum sensors have faced in the past.

    The first quantum sensors

    Ford’s SQUIDs, which needed to be cooled to a few degrees above absolute zero, used superconducting loops to measure minuscule magnetic fields.

    SQUIDs didn’t turn out to be of much use in an automobile. But not all Ford researchers were beholden to expectations that their creations would wind up in a car. “This shows you how different the world was back in the 1960s,” says Kent Irwin, a physicist at Stanford University (US) and DOE’s SLAC National Accelerator Laboratory (US). “These days Ford is not doing basic physics.”

    A few decades later, while in graduate school, Irwin built on the idea of the Ford Company’s SQUID to develop a new quantum sensor: the first practical superconducting transition-edge sensor.

    Irwin took advantage of the fact that superconducting material loses its superconductivity when it heats up, regaining its resistance at a precise temperature. By keeping a superconducting material as close as possible to this temperature limit, he could create a sensor that would undergo a significant change at the introduction of even a small amount of energy. Just a single photon hitting one of Irwin’s transition-edge sensors would cause it to shift to a different state.

    The transition-edge sensor is well-known and has been adopted widely in X-ray astronomy, dark matter detection, and measurements of the cosmic microwave background radiation. “It’s very much old-school quantum 1.0,” Irwin says.

    Quantum sensing for gravitational waves

    A new generation of quantum sensors goes beyond quantum 1.0. Some of today’s sensors make use of more than just superconductivity: They’ve managed to use the Heisenberg uncertainty principle—usually thought of as a limitation to how well physicists can make measurements—to their advantage.

    The Heisenberg uncertainty principle puts a cap on how accurately you can measure a pair of related properties. For example, the more you know about the position of a particle, the less you can know about its momentum.

    Quantum squeezing takes advantage of these relationships by purposefully tipping the balance: moving all the uncertainty of a measurement to one side or the other.

    Gravitational-wave detectors, such as LIGO in the US, and Virgo and GEO in Europe, have used quantum squeezing to great effect.

    Caltech /MIT Advanced aLigo.

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

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation.

    VIRGO Gravitational Wave interferometer, near Pisa, Italy.

    KAGRA Large-scale Cryogenic Gravitational Wave Telescope Project (JP).

    LIGO Virgo Kagra Masses in the Stellar Graveyard. Credit: Frank Elavsky and Aaron Geller at Northwestern University(US).

    In 2015, LIGO—the Laser-Interferometer Gravitational-wave Observatory—detected the first gravitational waves, undulations of spacetime first predicted by Albert Einstein. Once it got going, it was picking up new signs of gravitational-wave events every month.

    LIGO detects gravitational waves using an interferometer, an L-shaped device in which two beams of light are set up to bounce off identical mirrors and return [see above]. Under normal conditions, the beams will arrive at the same time and cancel one another out. No signal will hit the detector.

    But if a subtle outside force knocks them out of sync with one another, they won’t cancel each other out, and photons will hit the detector. If a gravitational wave passes through the two beams, it will hit one and then the other, interrupting their pattern.

    LIGO’s measurements are limited by the quantum properties of the photons that make up their beams of light. At the quantum level, photons are affected by fluctuations, virtual particles popping in and out of existence in the vacuum. Those fluctuations could cause a false signal in the detector. How could LIGO researchers tell the difference?

    “LIGO is using the most powerful lasers they can build, and the best mirrors they can build, and their back is against the wall,” Irwin says. “The only way to do better is to start beating quantum mechanics.”

    Scientists at LIGO and other gravitational-wave detectors looked to quantum squeezing to help them with their virtual photon problem.

    To generate squeezed light, researchers used a technology called an optical parametric oscillator, within which an input wave of laser light is converted to two output waves with smaller frequencies. This process entangles pairs of photons, and the resultant correlations of their properties serve to reduce uncertainty in one aspect of the arriving photons, allowing LIGO scientists to better measure another aspect, helping them sort the signal from the noise.

    Since April 2019, when LIGO began running with the quantum squeezers, the observatory has been able to detect new gravitational-wave signals—signs of collisions between massive objects such as black holes and neutron stars—more frequently, going from about one detection per month to about one per week.

    Quantum sensing for dark matter detection

    Quantum squeezing has also recently found an application in the search for Dark Matter.

    Dark Matter has never been observed directly, but clues in cosmology point to it making up approximately 85% of the matter in the universe. There are several different theories that describe what a Dark Matter particle could be.

    “The mass can be anywhere from a billionth the size of an electron up to a supermassive black hole,” Hsu says. “There are over 100 orders of magnitude that it can span.”

    The most promising small Dark Matter candidates are axions. In the presence of a strong magnetic field, axions occasionally convert into photons, which can then be detected by an experiment’s sensors.

    Like someone trying to find a radio station on a road trip in the middle of nowhere, they scan for a while at one frequency, to see if they detect a signal. If not, they turn the dial a little and try the next size up.

    It takes time to listen to each “station” once the detector is tuned to a particular possible axion signal; the more noise there is, the longer it takes to determine whether there might be a signal at all.

    The HAYSTAC experiment—for Haloscope at Yale Sensitive to Axion Cold Dark Matter—searches for axions by measuring two different components of electromagnetic field oscillations.

    Yale HAYSTAC axion dark matter experiment at Yale’s Wright Lab.

    Like LIGO, it is limited by the uncertainty principle; HAYSTAC researchers are unable to precisely measure both oscillations at once.

    But they didn’t need to. Like LIGO scientists, HAYSTAC scientists realized that if they could squeeze all the accuracy into just one side of the equation, it would improve the speed of their search. In early 2021, researchers announced that at HAYSTAC, they had also succeeded at using quantum squeezing to reduce noise levels in their experiment.

    Multiple groups have demonstrated promising new applications of superconducting circuit technology for axion detection.

    The “RF quantum upconverter” uses devices similar to Ford’s SQUIDs to evade the Heisenberg uncertainty principle in dark-matter searches at frequencies below HAYSTAC’s searches. Another uses a technology borrowed from quantum computing—qubits—as a sensor to evade Heisenberg’s limits at frequencies higher than HAYSTAC. Although neither technology has been used in dark matter searches yet, scientists believe that they could speed searches up by several orders of magnitude.

    At the current rate, it will still take axion experiments thousands of years to scan through every possible axion “station.” They may get lucky and find what they’re looking for early in the search, but it’s more likely that they’ll still need to find other ways to speed up their progress, perhaps with advances in quantum sensing, says Daniel Bowring, a Fermilab physicist who is involved in another axion search, the Axion Dark Matter Experiment.

    Inside the Axion Dark Matter eXperiment U Washington (US) Credit : Mark Stone U. of Washington. Axion Dark Matter Experiment.

    “It’s going to take a lot of people with really good imaginations,” Bowring says.

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.

  • richardmitnick 1:54 pm on January 18, 2022 Permalink | Reply
    Tags: "There are 40 billion billions of Black Holes in the Universe!", A remarkable amount-around 1% of the overall ordinary (baryonic) matter of the Universe-is locked up in stellar mass black holes., , , , , Gravitational wave astrophysics, How many black holes are out there in the Universe? This is one of the most relevant and pressing questions in modern astrophysics and cosmology., , , With a new computational approach SISSA researchers have been able to make the fascinating calculation.   

    From The International School for Advanced Studies [Scuola Internazionale Superiore di Studi Avanzati](IT): “There are 40 billion billions of Black Holes in the Universe!” 


    From The International School for Advanced Studies [Scuola Internazionale Superiore di Studi Avanzati](IT)


    Nico Pitrelli
    T +39 040 3787462
    M +39 339 1337950

    Donato Ramani
    T +39 040 3787513
    M +39 342 8022237

    There are 40 billion billions of Black Holes in the Universe!

    Image by PIxabay

    With a new computational approach SISSA researchers have been able to
    make the fascinating calculation. Moreover, according to their work, around
    1% of the overall ordinary (baryonic) matter is locked up in stellar mass
    black holes. Their results have just been published in the prestigious The
    Astrophysical Journal

    How many black holes are out there in the Universe? This is one of the most
    relevant and pressing questions in modern astrophysics and cosmology. The
    intriguing issue has recently been addressed by the SISSA Ph.D. student Alex
    Sicilia, supervised by Prof. Andrea Lapi and Dr. Lumen Boco, together with other
    collaborators from SISSA and from other national and international institutions. In
    a first paper of a series just published in The Astrophysical Journal, the authors have investigated the demographics of stellar mass black holes, which are black
    holes with masses between a few to some hundred solar masses, that originated
    at the end of the life of massive stars. According to the new research, a
    remarkable amount around 1% of the overall ordinary (baryonic) matter of
    the Universe is locked up in stellar mass black holes. Astonishingly, the
    researchers have found that the number of black holes within the
    observable Universe (a sphere of diameter around 90 billions light years) at
    present time is about 40 trillions, 40 billion billions (i.e., about 40 x 1018, i.e.
    4 followed by 19 zeros!).

    A new method to calculate the number of black holes

    As the authors of the research explain: “This important result has been obtained
    thanks to an original approach which combines the state-of-the-art stellar and
    binary evolution code SEVN developed by SISSA researcher Dr. Mario Spera to
    empirical prescriptions for relevant physical properties of galaxies, especially the
    rate of star formation, the amount of stellar mass and the metallicity of the
    interstellar medium (which are all important elements to define the number and
    the masses of stellar black holes). Exploiting these crucial ingredients in a self-
    consistent approach, thanks to their new computation approach, the researchers
    have then derived the number of stellar black holes and their mass distribution
    across the whole history of the Universe. Alex Sicilia, first author of the study,
    comments: “The innovative character of this work is in the coupling of a detailed
    model of stellar and binary evolution with advanced recipes for star formation and
    metal enrichment in individual galaxies. This is one of the first, and one of the
    most robust, ab initio computation of the stellar black hole mass function across
    cosmic history.”

    What’s the origin of most massive stellar black holes?

    The estimate of the number of black holes in the observable Universe is not the
    only issue investigated by the scientists in this piece of research. In collaboration
    with Dr. Ugo Di Carlo and Prof. Michela Mapelli from The University of Padua [Università degli Studi di Padova](IT),they
    have also explored the various formation channels for black holes of different
    masses, like isolated stars, binary systems and stellar clusters. According to their
    work, the most massive stellar black holes originate mainly from dynamical
    events in stellar clusters. Specifically, the researchers have shown that such
    events are required to explain the mass function of coalescing black holes as
    estimated from gravitational wave observations by the LIGO/Virgo collaboration.

    Caltech/MIT Advanced aLigo at Hanford, WA(US), Livingston, LA(US) and VIRGO Gravitational Wave interferometer, near Pisa(IT).

    Lumen Boco, co-author of the paper, comments: “Our work provides a robust
    theory for the generation of light seeds for (super)massive black holes at high
    redshift, and can constitute a starting point to investigate the origin of ‘heavy
    seeds’, that we will pursue in a forthcoming paper.

    A multidisciplinary work carried out in the context of “BiD4BESt – Big Data
    Application for Black Hole Evolution Studies”

    Prof. Andrea Lapi, Sicilia’s supervisor and coordinator of the Ph.D. in
    Astrophysics and Cosmology at SISSA, adds: “This research is really
    multidisciplinary, covering aspects of, and requiring expertise in stellar
    astrophysics, galaxy formation and evolution, gravitational wave and multi-messenger astrophysics; as such it needs collaborative efforts from various
    members of the SISSA Astrophysics and Cosmology group, and a strong
    networking with external collaborators.”

    Alex Sicilia’s work occurs in the context of a prestigious Innovative Training
    Network Project “BiD4BESt – Big Data Application for Black Hole Evolution
    Studies” co-PIed by Prof. Andrea Lapi from SISSA (H2020-MSCAITN-2019
    Project 860744), that has been funded by the European Union with about 3.5
    million Euros overall; it involves several academic and industrial partners, to
    provide Ph.D. training to 13 early stage researchers in the area of black hole
    formation and evolution, by exploiting advanced data science techniques.

    See the full article here.


    Please help promote STEM in your local schools.

    Stem Education Coalition

    International School for Advanced Studies, Trieste. Credit: Mike Peel (http://www.mikepeel.net)

    The International School for Advanced Studies [Scuola Internazionale Superiore di Studi Avanzati] (IT) (SISSA) is an international, state-supported, post-graduate-education and research institute, located in Trieste, Italy.

    SISSA is active in the fields of mathematics, physics, and neuroscience, offering both undergraduate and post-graduate courses. Each year, about 70 PhD students are admitted to SISSA based on their scientific qualifications. SISSA also runs master’s programs in the same areas, in collaboration with both Italian and other European universities.


    SISSA was founded in 1978, as a part of the reconstruction following the Friuli earthquake of 1976. Although the city of Trieste itself did not suffer any damage, physicist Paolo Budinich asked and obtained from the Italian government to include in the interventions the institution of a new, post-graduate teaching and research institute, modeled on the Scuola Normale Superiore di Pisa(IT). The school became operative with a PhD course in theoretical physics, and Budinich himself was appointed as general director. In 1986, Budinich left his position to Daniele Amati, who at the time was at the head of the theoretical division at The European Organization for Nuclear Research [Organisation européenne pour la recherche nucléaire](CH)[CERN]. Under his leadership, SISSA expanded its teaching and research activity towards the field of neuroscience, and instituted a new interdisciplinary laboratory aiming at connecting humanities and scientific studies. From 2001 to 2004, the director was the Italian geneticist Edoardo Boncinelli, who fostered the development of the existing research areas. Other directors were appointed in the following years, which saw the strengthening of SISSA collaboration with other Italian and European universities in offering master’s degree programs in the three areas of the School (mathematics, physics and neuroscience). The physicist Stefano Ruffo, the current director, was appointed in 2015. He signed a partnership with the International Centre for Genetic Engineering and Biotechnology to set up a new PhD program in Molecular Biology, with teaching activity organized by both institutions.


    SISSA houses the following research groups:

    Astroparticle Physics
    Condensed Matter
    Molecular and Statistical Biophysics
    Statistical Physics
    Theoretical Particle Physics
    Cognitive Neuroscience
    Molecular Biology
    Applied Mathematics
    Mathematical Analysis
    Mathematical Physics

    In addition, there is the Interdisciplinary Laboratory for Natural and Humanistic Sciences (now LISNU – Laboratorio Interdisciplinare Scienze Naturali e Umanistiche), which is endowed with the task of making connections between science, humanities, and the public. It currently offers a course in Scientific Communication and Scientific journalism.

    SISSA also enjoys special teaching and scientific links with the International Centre for Theoretical Physics, the International Centre for Genetic Engineering and Biotechnology and the Elettra Synchrotron Light Laboratory.

  • richardmitnick 1:35 pm on August 28, 2021 Permalink | Reply
    Tags: "Collaborations sets new constraints on cosmic strings", , , Gravitational wave astrophysics, KAGRA Collaboration, ,   

    From Caltech/MIT aLIGO, VIRGO and KAGRA via Phys.org: “Collaborations sets new constraints on cosmic strings” 

    From Caltech/MIT aLIGO, VIRGO Collaboration and KAGRA Collaboration



    From phys.org

    August 27, 2021

    Credit: Unsplash/CC0 Public Domain

    The LIGO/Virgo/KAGRA Collaboration, a large group of researchers at different institutes worldwide, has recently set the strongest constraints on cosmic strings to date, using the Advanced LIGO/Virgo full O3 dataset. This dataset contains the latest gravitational waves data detected by a network of three interferometers located in United States and in Italy.

    “We wanted to use the most current data of the third observing run (O3 dataset) to put constraints on cosmic strings,” Prof. Mairi Sakellariadou of King’s College London (UK), who is part of the LIGO-Virgo Collaboration, told Phys.org.

    Field theories predict that as the Universe expands and its temperature drops, it undergoes a series of phase transitions followed by spontaneously broken symmetries, which may leave behind topological defects, relics of the previous, more symmetrical phase of the Universe.

    “Just to give you an example, if you take water in its liquid form and you decrease the temperature below zero degrees Celcius, it will solidify,” Sakellariadou said. “Inside an ice cube, you can see filaments where the water is in the liquid form. This phenomenon may also happen in the Universe.” One-dimensional topological defects are referred to as cosmic strings. While particle physics models predict the existence of cosmic strings, there is currently no observational confirmation of their existence.

    “The heavier cosmic strings are, the stronger their gravitational effects will be,” Sakellariadou said. By analyzing observational data, we can put constraints on the parameter that tells us how heavy these objects are, in other words the epoch of cosmic string formation.”

    Setting constraints on cosmic strings also allows researchers to constraint particle physics models and cosmological scenarios. Using gravitational wave data, researchers are able to test particle physics models at energy scales that cannot be reached by accelerators like the Large Hadron Collider at CERN.

    “Constraints also depend on which model of cosmic strings we are using for the string loop distribution, which is dictated by involved numerical simulations” Sakellariadou said.

    So far, researchers have developed two possible numerical simulations. The first one was put forward several years ago by Bouchet, Lorenz, Ringeval and Sakellariadou, while the second was developed by Blanco-Pillado, Olum and Shlaer.

    Recently, Auclair, Ringeval, Sakellariadou and Steer developed a new analytic string loop model that interpolates between the two developed in the past with numerical simulations. This new model has been used for the first time in putting constraints on cosmic strings using gravitational wave data from the last observing run of the LIGO/Virgo/KAGRA collaboration.

    Remarkably, the recent constraints set by the LIGO/Virgo/KAGRA collaboration are stronger than the ones put by Big Bang nucleosynthesis, pulsar-timing array, or cosmic microwave background data. They have also improved on previous constraints set by LIGO/Virgo by 1 to 2 orders of magnitude.

    “As more data becomes available, we will be able to put even stronger constraints. From a theoretical point of view, however, it is also important to build and investigate new cosmic string models, and examine the implications of our work for particle physics beyond the Standard Model and cosmological scenarios”, Sakellariadou said.

    The research was published in Physical Review Letters.

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

  • richardmitnick 12:41 pm on August 21, 2021 Permalink | Reply
    Tags: "Addressing a Gap in Our Knowledge of Black Holes", , , , Gravitational wave astrophysics, ,   

    From AAS NOVA : “Addressing a Gap in Our Knowledge of Black Holes” 


    From AAS NOVA

    Artist’s by now iconic conception of two merging black holes similar to those detected by LIGO. Credit: Aurore Simonnet /Caltech MIT Advanced aLIGO(US)/Sonoma State University (US).

    One way for black holes to form is in supernovae, or the deaths of massive stars. However, our current knowledge of stellar evolution and supernovae suggests that black holes with masses between 55 and 120 solar masses can’t be produced via supernovae. Gravitational-wave signals from black hole mergers offer us an observational test of this “gap” in black hole masses.

    Black Hole Boundaries

    You need a massive star to go supernova to produce a black hole. Unfortunately, extremely massive stars explode so violently they leave nothing behind! This scenario can occur with pair-instability supernovae, which happens in stars with core masses between 40 and 135 solar masses. The “pair” in “pair-instability” refers to the electron–positron pairs that are produced by gamma rays interacting with nuclei in the star’s core. Energy is lost in this process, meaning that there’s less resistance to gravitational collapse.

    As the star collapses further, two things can happen. If the star is sufficiently massive, its core ignites in an explosion that tears the star apart, leaving no remnant. If the star is less massive, the core ignition causes the star to pulse and shed mass till it leaves the pair-production stage and its core collapses normally into black hole. The most massive black hole that can be produced in this scenario is roughly 55 solar masses, forming the lower end of the black hole mass gap.

    On the other side of the mass gap, it’s theoretically possible for certain massive stars to collapse normally without entering the pair-production state, thus evolving into black holes with masses greater than 120 solar masses. The unique thing about these massive stars is that they are low metallicity, containing practically no elements that are heavier than helium.

    So the bottom line is that we’re unlikely to observe any black holes with masses between 55 and 120 solar masses. But how can we test this prediction? Gravitational-wave signals are an option! Properties of merging black holes are coded into the gravitational waves produced by the merger, including the black hole masses. So, a recent study led by Bruce Edelman (University of Oregon (US)) looked at our current catalog of black hole merger signals to see if the mass gap would emerge from the data.

    Mind the Gap, If There Is a Gap

    Edelman and collaborators used two established model distributions of black hole masses to approach the problem. They also altered the models so the gap was explicitly allowed and so higher black hole masses could be explored without artificially inflating the rate of mergers above the gap. Edelman and collaborators then fit their models to data from 46 binary black hole mergers observed by the Laser Interferometer Gravitational-Wave Observatory and the Virgo interferometer.

    Masses in the Stellar Graveyard GWTC-2 plot v1.0 BY LIGO-Virgo. Credit: Frank Elavsky and Aaron Geller at Northwestern University(US)

    Caltech/MIT Advanced aLigo at Hanford, WA(US), Livingston, LA(US) and VIRGO Gravitational Wave interferometer, near Pisa(IT).

    Interestingly, the existence of the gap is rather ambiguous! One factor is the inclusion of the merger associated with the signal GW190521, which was likely a high mass merger whose component black holes straddle the mass gap. If the gap doesn’t exist, it’s possible that the unexpected black holes are formed by the merging of smaller black holes. On the whole, this result points to many avenues of study when it comes to pair-instability supernovae and black hole formation!


    “Poking Holes: Looking for Gaps in LIGO/Virgo’s Black Hole Population,” Bruce Edelman et al 2021 ApJL 913 L23.

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition


    AAS Mission and Vision Statement

    The mission of the American Astronomical Society is to enhance and share humanity’s scientific understanding of the Universe.

    The Society, through its publications, disseminates and archives the results of astronomical research. The Society also communicates and explains our understanding of the universe to the public.
    The Society facilitates and strengthens the interactions among members through professional meetings and other means. The Society supports member divisions representing specialized research and astronomical interests.
    The Society represents the goals of its community of members to the nation and the world. The Society also works with other scientific and educational societies to promote the advancement of science.
    The Society, through its members, trains, mentors and supports the next generation of astronomers. The Society supports and promotes increased participation of historically underrepresented groups in astronomy.
    The Society assists its members to develop their skills in the fields of education and public outreach at all levels. The Society promotes broad interest in astronomy, which enhances science literacy and leads many to careers in science and engineering.

    Adopted June 7, 2009

    The society was founded in 1899 through the efforts of George Ellery Hale. The constitution of the group was written by Hale, George Comstock, Edward Morley, Simon Newcomb and Edward Charles Pickering. These men, plus four others, were the first Executive Council of the society; Newcomb was the first president. The initial membership was 114. The AAS name of the society was not finally decided until 1915, previously it was the “Astronomical and Astrophysical Society of America”. One proposed name that preceded this interim name was “American Astrophysical Society”.

    The AAS today has over 7,000 members and six divisions – the Division for Planetary Sciences (1968); the Division on Dynamical Astronomy (1969); the High Energy Astrophysics Division (1969); the Solar Physics Division (1969); the Historical Astronomy Division (1980); and the Laboratory Astrophysics Division (2012). The membership includes physicists, mathematicians, geologists, engineers and others whose research interests lie within the broad spectrum of subjects now comprising contemporary astronomy.

    In 2019 three AAS members were selected into the tenth anniversary class of TED Fellows.

    The AAS established the AAS Fellows program in 2019 to “confer recognition upon AAS members for achievement and extraordinary service to the field of astronomy and the American Astronomical Society.” The inaugural class was designated by the AAS Board of Trustees and includes an initial group of 232 Legacy Fellows.

  • richardmitnick 10:01 am on August 13, 2021 Permalink | Reply
    Tags: "$3.4 million NSF grant aims to make LIGO multimessenger discoveries commonplace", Gravitational wave astrophysics, ,   

    From Pennsylvania State University (US) : “$3.4 million NSF grant aims to make LIGO multimessenger discoveries commonplace” 

    Penn State Bloc

    From Pennsylvania State University (US)

    August 12, 2021
    Matt Swayne

    A $3.4 million grant from the National Science Foundation (US) will help develop software and services to discover gravitational waves from black holes and neutron stars in real-time in order to facilitate the detection of prompt electromagnetic counterparts.

    The investment is aimed at the NSF-funded Laser Interferometer Gravitational-wave Observatory — or LIGO, a critical tool that has powered a flurry of recent scientific discoveries and enriched our knowledge of the universe through gravitational waves detected from merging neutron stars and black holes, according to Chad Hanna, an associate professor of physics & astronomy and astrophysics in Penn State’s Eberly College of Science and an Institute for Computational and Data Sciences co-hire.


    Specifically, the funds will be used to develop robust signal processing software and the creation of a suite of cyberinfrastructure services that will allow scientists to analyze LIGO data in real time. The goal is to allow scientists to make more discoveries, as well as be able to easily share those discoveries with the scientific community, which ultimately, will improve our understanding of the universe, Hanna added.

    “We hope that this grant will benefit the entire scientific community and that, with it, we’ll make robust detections of increasingly more gravitational waves from neutron star mergers, and other signals that might have electromagnetic or neutrino counterparts,” said Hanna.

    In 2017, LIGO kicked off a new era in astronomical observation, providing astronomers and astrophysicists with evidence of the first detection of gravitational waves from colliding neutron stars, as well as helping researchers settle the origin of mysterious gamma ray bursts, a phenomenon that has been debated by scientists for decades.

    However, Hanna said that these impressive discoveries may be just the initial set of breakthroughs that LIGO can enable.

    “We want more — we want to enable as many discoveries as possible because we learned so much from each one,” said Hanna. “And this grant is really trying to support the cyberinfrastructure that can help to make those discoveries more commonplace.”

    Hanna’s group leads efforts to detect gravitational waves in real-time to support multi-messenger astrophysics. The group is also involved with developing detection algorithms and software to identify the neutron star mergers in the gravitational wave data and using machine learning to cut through noisy data gathered during the gravitational wave observations. Both are integral to the real-time infrastructure and improvements will help facilitate future LIGO research, added Hanna.

    Hanna credited the support he receives from the ICDS team in both helping his own research, as well as the hardware and software that is helping a large part of the astronomical community involved in research boosted by LIGO.

    ICDS also provided initial funding through a seed grant for Hanna’s team to begin research on using machine learning to manage noise in data collected by LIGO.

    The LIGO era

    Astronomers have relied on LIGO, which has been termed a “marvel of precision engineering,” to peer into the universe in ways that were once impossible. LIGO is two detectors spread nearly 1,900 miles apart. One detector is in Hanford, Washington, and the other in Livingston, Louisiana [above].

    Scientists using LIGO have produced some of the biggest astronomical breakthroughs of the 21st century and, arguably, of all time. In 2016, astronomers used LIGO data, along with other scientific instruments and equipment, to identify evidence of gravitational waves, the ripples of spacetime predicted more than a century ago by Albert Einstein. These findings also led to the 2017 Nobel Prize for Physics.

    LIGO also detected the merger of two neutron stars that created a black hole and an explosion of light in 2017. Even more recently, researchers used LIGO to confirm the detection collisions between a black hole and a neutron star, not once but twice within 10 days.

    The award was part of NSF’s Physics at the Information Frontier program, which supports the enablement of advanced computational technologies to address important scientific goals.

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Penn State Campus

    The Pennsylvania State University (US) is a public state-related land-grant research university with campuses and facilities throughout Pennsylvania. Founded in 1855 as the Farmers’ High School of Pennsylvania, Penn State became the state’s only land-grant university in 1863. Today, Penn State is a major research university which conducts teaching, research, and public service. Its instructional mission includes undergraduate, graduate, professional and continuing education offered through resident instruction and online delivery. In addition to its land-grant designation, it also participates in the sea-grant, space-grant, and sun-grant research consortia; it is one of only four such universities (along with Cornell University(US), Oregon State University(US), and University of Hawaiʻi at Mānoa(US)). Its University Park campus, which is the largest and serves as the administrative hub, lies within the Borough of State College and College Township. It has two law schools: Penn State Law, on the school’s University Park campus, and Dickinson Law, in Carlisle. The College of Medicine is in Hershey. Penn State is one university that is geographically distributed throughout Pennsylvania. There are 19 commonwealth campuses and 5 special mission campuses located across the state. The University Park campus has been labeled one of the “Public Ivies,” a publicly funded university considered as providing a quality of education comparable to those of the Ivy League.

    Annual enrollment at the University Park campus totals more than 46,800 graduate and undergraduate students, making it one of the largest universities in the United States. It has the world’s largest dues-paying alumni association. The university offers more than 160 majors among all its campuses.

    Annually, the university hosts the Penn State IFC/Panhellenic Dance Marathon (THON), which is the world’s largest student-run philanthropy. This event is held at the Bryce Jordan Center on the University Park campus. The university’s athletics teams compete in Division I of the NCAA and are collectively known as the Penn State Nittany Lions, competing in the Big Ten Conference for most sports. Penn State students, alumni, faculty and coaches have received a total of 54 Olympic medals.

    Early years

    The school was sponsored by the Pennsylvania State Agricultural Society and founded as a degree-granting institution on February 22, 1855, by Pennsylvania’s state legislature as the Farmers’ High School of Pennsylvania. The use of “college” or “university” was avoided because of local prejudice against such institutions as being impractical in their courses of study. Centre County, Pennsylvania, became the home of the new school when James Irvin of Bellefonte, Pennsylvania, donated 200 acres (0.8 km2) of land – the first of 10,101 acres (41 km^2) the school would eventually acquire. In 1862, the school’s name was changed to the Agricultural College of Pennsylvania, and with the passage of the Morrill Land-Grant Acts, Pennsylvania selected the school in 1863 to be the state’s sole land-grant college. The school’s name changed to the Pennsylvania State College in 1874; enrollment fell to 64 undergraduates the following year as the school tried to balance purely agricultural studies with a more classic education.

    George W. Atherton became president of the school in 1882, and broadened the curriculum. Shortly after he introduced engineering studies, Penn State became one of the ten largest engineering schools in the nation. Atherton also expanded the liberal arts and agriculture programs, for which the school began receiving regular appropriations from the state in 1887. A major road in State College has been named in Atherton’s honor. Additionally, Penn State’s Atherton Hall, a well-furnished and centrally located residence hall, is named not after George Atherton himself, but after his wife, Frances Washburn Atherton. His grave is in front of Schwab Auditorium near Old Main, marked by an engraved marble block in front of his statue.

    Early 20th century

    In the years that followed, Penn State grew significantly, becoming the state’s largest grantor of baccalaureate degrees and reaching an enrollment of 5,000 in 1936. Around that time, a system of commonwealth campuses was started by President Ralph Dorn Hetzel to provide an alternative for Depression-era students who were economically unable to leave home to attend college.

    In 1953, President Milton S. Eisenhower, brother of then-U.S. President Dwight D. Eisenhower, sought and won permission to elevate the school to university status as The Pennsylvania State University. Under his successor Eric A. Walker (1956–1970), the university acquired hundreds of acres of surrounding land, and enrollment nearly tripled. In addition, in 1967, the Penn State Milton S. Hershey Medical Center, a college of medicine and hospital, was established in Hershey with a $50 million gift from the Hershey Trust Company.

    Modern era

    In the 1970s, the university became a state-related institution. As such, it now belongs to the Commonwealth System of Higher Education. In 1975, the lyrics in Penn State’s alma mater song were revised to be gender-neutral in honor of International Women’s Year; the revised lyrics were taken from the posthumously-published autobiography of the writer of the original lyrics, Fred Lewis Pattee, and Professor Patricia Farrell acted as a spokesperson for those who wanted the change.

    In 1989, the Pennsylvania College of Technology in Williamsport joined ranks with the university, and in 2000, so did the Dickinson School of Law. The university is now the largest in Pennsylvania. To offset the lack of funding due to the limited growth in state appropriations to Penn State, the university has concentrated its efforts on philanthropy.

  • richardmitnick 11:41 am on August 5, 2021 Permalink | Reply
    Tags: "A bounty of potential gravitational wave events hints at exciting possibilities", , Gravitational wave astrophysics,   

    From “Science News (US) : “A bounty of potential gravitational wave events hints at exciting possibilities” 

    From “Science News (US)

    August 4, 2021
    Emily Conover

    One way that gravitational waves (shown in this illustration) are stirred up is when two black holes spiral around one another and collide. Credit: MARK GARLICK/

    A new crew of potential ripples in spacetime has just debuted — emphasis on the word “potential.”

    By loosening the criteria for what qualifies as evidence for gravitational waves, physicists identified 1,201 possible tremors. Most are probably fakes, spurious jitters in the data that can mimic the cosmic vibrations, the team reports August 2 at arXiv.org. But by allowing in more false alarms, the new tally may also include some weak but genuine signals that would otherwise be missed, potentially revealing exciting new information about the sources of gravitational waves.

    Scientists can now look for signs that may corroborate some of the uncertain detections, such as flashes of light in the sky that flared from the cosmic smashups that set off the ripples. Gravitational waves are typically spawned by collisions of dense, massive objects, such as black holes or neutron stars, the remnants of dead stars (SN: 1/21/21).

    To come up with the new census, physicists reanalyzed six months of data from the Advanced Laser Interferometer Gravitational-Wave Observatory, or LIGO, and Virgo gravitational wave observatories. Scientists had already identified 39 of the events as likely gravitational waves in earlier analyses.

    Eight events that hadn’t been previously identified stand a solid chance of being legitimate — with greater than a 50 percent probability of coming from an actual collision.

    The physicists analyzed the data from those eight events to see how they might have occurred. In one, two black holes may have slammed together, melding into a whopper black hole with about 180 times the mass of the sun, which would make it the biggest black hole merger seen yet (SN: 9/2/20). Another event could be a rare sighting of a black hole swallowing a neutron star (SN: 6/29/21).

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

  • richardmitnick 4:12 pm on July 28, 2021 Permalink | Reply
    Tags: "On the hunt for 'hierarchical' black holes", Black holes-detected by their gravitational wave signal as they collide with other black holes-could be the product of much earlier parent collisions., , Gravitational wave astrophysics, , , ,   

    From University of Birmingham (UK) : “On the hunt for ‘hierarchical’ black holes” 

    From University of Birmingham (UK)

    27 July 2021

    Beck Lockwood,
    Press Office, University of Birmingham,
    Tel: +44 (0)781 3343348.

    Black holes-detected by their gravitational wave signal as they collide with other black holes-could be the product of much earlier parent collisions.

    Credit: Riccardo Buscicchio.

    Credit: CC0 Public Domain.

    Such an event has only been hinted at so far, but scientists at the University of Birmingham in the UK, and Northwestern University (US), believe we are getting close to tracking down the first of these so-called ‘hierarchical’ black holes.

    In a review paper, published in Nature Astronomy, Dr Davide Gerosa, of the University of Birmingham, and Dr Maya Fishbach of Northwestern University (US), suggest that recent theoretical findings together with astrophysical modelling and recorded gravitational wave data will enable scientists to accurately interpret gravitational wave signals from these events.

    Since the first gravitational wave was detected by the LIGO and Virgo detectors in September 2015, scientists have produced increasingly nuanced and sophisticated interpretations of these signals.

    There is now fervent activity to prove the existence of so-called ‘hierarchical mergers’ although the detection of GW190521 in 2019 – the most massive black hole merger yet detected – is thought to be the most promising candidate so far.

    “We believe that most of the gravitational waves so far detected are the result of first generation black holes colliding,” says Dr Gerosa. “But we think there’s a good chance that others will contain the remnants of previous mergers. These events will have distinctive gravitational wave signatures suggesting higher masses, and an unusual spin caused by the parent collision.”

    Understanding the characteristics of the environment in which such objects might be produced will also help narrow the search. This must be an environment with a large number of black holes, and one that is sufficiently dense to retain the black holes after they have merged, so they can go on and merge again.

    These could be, for example, nuclear star clusters, or accretion disks – containing a flow of gas, plasma and other particles – surrounding the compact regions at the centre of galaxies.

    “The LIGO and Virgo collaboration has already discovered more than 50 gravitational wave events,” says Dr Fishbach. “This will expand to thousands over the next few years, giving us so many more opportunities to discover and confirm unusual objects like hierarchical black holes in the universe.”

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    University of Birmingham (UK) has been challenging and developing great minds for more than a century. Characterised by a tradition of innovation, research at the University has broken new ground, pushed forward the boundaries of knowledge and made an impact on people’s lives. We continue this tradition today and have ambitions for a future that will embed our work and recognition of the Birmingham name on the international stage.

    The University of Birmingham is a public research university located in Edgbaston, Birmingham, United Kingdom. It received its royal charter in 1900 as a successor to Queen’s College, Birmingham (founded in 1825 as the Birmingham School of Medicine and Surgery), and Mason Science College (established in 1875 by Sir Josiah Mason), making it the first English civic or ‘red brick’ university to receive its own royal charter. It is a founding member of both the Russell Group (UK) of British research universities and the international network of research universities, Universitas 21.

    The student population includes 23,155 undergraduate and 12,605 postgraduate students, which is the 7th largest in the UK (out of 169). The annual income of the institution for 2019–20 was £737.3 million of which £140.4 million was from research grants and contracts, with an expenditure of £667.4 million.

    The university is home to the Barber Institute of Fine Arts, housing works by Van Gogh, Picasso and Monet; the Shakespeare Institute; the Cadbury Research Library, home to the Mingana Collection of Middle Eastern manuscripts; the Lapworth Museum of Geology; and the 100-metre Joseph Chamberlain Memorial Clock Tower, which is a prominent landmark visible from many parts of the city. Academics and alumni of the university include former British Prime Ministers Neville Chamberlain and Stanley Baldwin, the British composer Sir Edward Elgar and eleven Nobel laureates.

    Scientific discoveries and inventions

    The university has been involved in many scientific breakthroughs and inventions. From 1925 until 1948, Sir Norman Haworth was Professor and Director of the Department of Chemistry. He was appointed Dean of the Faculty of Science and acted as Vice-Principal from 1947 until 1948. His research focused predominantly on carbohydrate chemistry in which he confirmed a number of structures of optically active sugars. By 1928, he had deduced and confirmed the structures of maltose, cellobiose, lactose, gentiobiose, melibiose, gentianose, raffinose, as well as the glucoside ring tautomeric structure of aldose sugars. His research helped to define the basic features of the starch, cellulose, glycogen, inulin and xylan molecules. He also contributed towards solving the problems with bacterial polysaccharides. He was a recipient of the Nobel Prize in Chemistry in 1937.

    The cavity magnetron was developed in the Department of Physics by Sir John Randall, Harry Boot and James Sayers. This was vital to the Allied victory in World War II. In 1940, the Frisch–Peierls memorandum, a document which demonstrated that the atomic bomb was more than simply theoretically possible, was written in the Physics Department by Sir Rudolf Peierls and Otto Frisch. The university also hosted early work on gaseous diffusion in the Chemistry department when it was located in the Hills building.

    Physicist Sir Mark Oliphant made a proposal for the construction of a proton-synchrotron in 1943, however he made no assertion that the machine would work. In 1945, phase stability was discovered; consequently, the proposal was revived, and construction of a machine that could surpass proton energies of 1 GeV began at the university. However, because of lack of funds, the machine did not start until 1953. The DOE’s Brookhaven National Laboratory (US) managed to beat them; they started their Cosmotron in 1952, and had it entirely working in 1953, before the University of Birmingham.

    In 1947, Sir Peter Medawar was appointed Mason Professor of Zoology at the university. His work involved investigating the phenomenon of tolerance and transplantation immunity. He collaborated with Rupert E. Billingham and they did research on problems of pigmentation and skin grafting in cattle. They used skin grafting to differentiate between monozygotic and dizygotic twins in cattle. Taking the earlier research of R. D. Owen into consideration, they concluded that actively acquired tolerance of homografts could be artificially reproduced. For this research, Medawar was elected a Fellow of the Royal Society. He left Birmingham in 1951 and joined the faculty at University College London (UK), where he continued his research on transplantation immunity. He was a recipient of the Nobel Prize in Physiology or Medicine in 1960.

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