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  • richardmitnick 1:12 pm on September 10, 2021 Permalink | Reply
    Tags: "Caltech Astronomers Win New Horizons Breakthrough Prize", , , First-ever observations of the cosmic event to be witnessed in both gravitational waves and electromagnetic-or light-waves., multi-messenger astronomy, The event called GW170817 began when two dense stellar remnants-called neutron stars-spiraled together and collided.   

    From California Institute of Technology (US) : “Caltech Astronomers Win New Horizons Breakthrough Prize” 

    Caltech Logo

    From California Institute of Technology (US)

    September 09, 2021

    Professor of Astronomy Mansi Kasliwal (MS ’07, PhD ’11) and Professor of Astronomy Gregg Hallinan have been named winners of a 2022 New Horizons Prize in Physics, one of several Breakthrough Prizes announced today.

    Mansi Kasliwal Credit: Lance Hayashida/Caltech.

    Gregg Hallinan

    Together with former Caltech postdoctoral scholar Alessandra Corsi, now at The Texas Tech University (US), and Raffaella Margutti of The University of California-Berkeley (US), the scientists are being honored “for leadership in laying foundations for electromagnetic observations of sources of gravitational waves, and leadership in extracting rich information from the first observed collision of two neutron stars,” according to the award citation.

    In 2017, Kasliwal, Hallinan, Corsi, and Margutti helped make history with their observations of the first-ever cosmic event to be witnessed in both gravitational waves and electromagnetic-or light-waves. The event called GW170817 began when two dense stellar remnants-called neutron stars-spiraled together and collided, creating a storm of ripples in space and time, or gravitational waves, that traveled outward in all directions. Some of those waves ultimately reached Earth, where the Laser Interferometer Gravitational-wave Observatory(LIGO) detected their signatures.

    Just seconds after the gravitational waves were produced, the neutron star collision resulted in an explosion of matter, as well as light spanning the electromagnetic spectrum, ranging from high-energy gamma rays to low-energy radio waves. Kasliwal’s team was one of the first to observe the collision in visible and infrared light, using the National Science Foundation (NSF)-funded Global Relay of Observatories Watching Transients Happen (GROWTH) project, a worldwide network of telescopes that specializes in catching short-lived energetic events such as this. The GROWTH team put together a picture of a cocoon breaking out to explain the rich multi-wavelength dataset.

    Around two weeks later, as predicted by models, Gregg Hallinan, who is also director of the Owens Valley Radio Observatory (OVRO), together with Alessandra Corsi and collaborators, began seeing the radio waves created by the event using the Very Large Array, a collection of 27 radio telescopes in New Mexico.

    These radio observations later confirmed the presence of the cocoon, as well as providing the first direct confirmation that a relativistic jet, consistent with an energetic short gamma-ray burst, was produced by the merger. The collision was also seen by X-ray detecting telescopes.

    The observation of celestial events through multiple channels (gravitational waves, visible light, X-rays and radio waves, in this case is known as multi-messenger astronomy, and is a growing field of study.

    “It is truly an honor to be awarded the New Horizons Prize in Physics, and to share it with valued colleagues,” Hallinan says. “Multi-messenger astronomy is an exciting field undergoing exponential growth, and I am grateful to those who have worked closely with me on this journey, particularly Kunal Mooley, Mansi Kasliwal, Udi Nakar, Samaya Nissanke, Kenta Hotokezaka, Alessandra Corsi, Shri Kulkarni, and Dale Frail.”

    Kasliwal also highlighted the team-based nature of the work.

    “Collaborating with a worldwide network of astronomers—the GROWTH collaboration—and working closely with observatory staff and engineers is inspiring. Mentoring students and postdocs is the biggest perk of my job,” Kasliwal says. “Pursuing astrophysics to unlock mysteries of our universe is truly a dream job for me—a passion converted into a profession in a dynamic field where the book is actively being written. Discovering where and how the elements in our periodic table are synthesized is exhilarating.”

    Each New Horizons Prize, which is intended to honor early-career scientists showing leadership in their field, is accompanied by a $100,000 award. The awards ceremony, televised live, has been postponed until 2022 due to the ongoing COVID-19 pandemic.

    See the full article here .

    Please help promote STEM in your local schools.

    Stem Education Coalition

    The California Institute of Technology (US) is a private research university in Pasadena, California. The university is known for its strength in science and engineering, and is one among a small group of institutes of technology in the United States which is primarily devoted to the instruction of pure and applied sciences.

    Caltech was founded as a preparatory and vocational school by Amos G. Throop in 1891 and began attracting influential scientists such as George Ellery Hale, Arthur Amos Noyes, and Robert Andrews Millikan in the early 20th century. The vocational and preparatory schools were disbanded and spun off in 1910 and the college assumed its present name in 1920. In 1934, Caltech was elected to the Association of American Universities, and the antecedents of National Aeronautics and Space Administration (US)’s Jet Propulsion Laboratory, which Caltech continues to manage and operate, were established between 1936 and 1943 under Theodore von Kármán.

    Caltech has six academic divisions with strong emphasis on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. First-year students are required to live on campus, and 95% of undergraduates remain in the on-campus House System at Caltech. Although Caltech has a strong tradition of practical jokes and pranks, student life is governed by an honor code which allows faculty to assign take-home examinations. The Caltech Beavers compete in 13 intercollegiate sports in the NCAA Division III’s Southern California Intercollegiate Athletic Conference (SCIAC).

    As of October 2020, there are 76 Nobel laureates who have been affiliated with Caltech, including 40 alumni and faculty members (41 prizes, with chemist Linus Pauling being the only individual in history to win two unshared prizes). In addition, 4 Fields Medalists and 6 Turing Award winners have been affiliated with Caltech. There are 8 Crafoord Laureates and 56 non-emeritus faculty members (as well as many emeritus faculty members) who have been elected to one of the United States National Academies. Four Chief Scientists of the U.S. Air Force and 71 have won the United States National Medal of Science or Technology. Numerous faculty members are associated with the Howard Hughes Medical Institute(US) as well as National Aeronautics and Space Administration(US). According to a 2015 Pomona College(US) study, Caltech ranked number one in the U.S. for the percentage of its graduates who go on to earn a PhD.


    Caltech is classified among “R1: Doctoral Universities – Very High Research Activity”. Caltech was elected to the Association of American Universities in 1934 and remains a research university with “very high” research activity, primarily in STEM fields. The largest federal agencies contributing to research are National Aeronautics and Space Administration(US); National Science Foundation(US); Department of Health and Human Services(US); Department of Defense(US), and Department of Energy(US).

    In 2005, Caltech had 739,000 square feet (68,700 m^2) dedicated to research: 330,000 square feet (30,700 m^2) to physical sciences, 163,000 square feet (15,100 m^2) to engineering, and 160,000 square feet (14,900 m^2) to biological sciences.

    In addition to managing JPL, Caltech also operates the Caltech Palomar Observatory(US); the Owens Valley Radio Observatory(US);the Caltech Submillimeter Observatory(US); the W. M. Keck Observatory at the Mauna Kea Observatory(US); the Laser Interferometer Gravitational-Wave Observatory at Livingston, Louisiana and Richland, Washington; and Kerckhoff Marine Laboratory(US) in Corona del Mar, California. The Institute launched the Kavli Nanoscience Institute at Caltech in 2006; the Keck Institute for Space Studies in 2008; and is also the current home for the Einstein Papers Project. The Spitzer Science Center(US), part of the Infrared Processing and Analysis Center(US) located on the Caltech campus, is the data analysis and community support center for NASA’s Spitzer Infrared Space Telescope [no longer in service].

    Caltech partnered with University of California at Los Angeles(US) to establish a Joint Center for Translational Medicine (UCLA-Caltech JCTM), which conducts experimental research into clinical applications, including the diagnosis and treatment of diseases such as cancer.

    Caltech operates several Total Carbon Column Observing Network(US) stations as part of an international collaborative effort of measuring greenhouse gases globally. One station is on campus.

  • richardmitnick 7:31 am on January 30, 2020 Permalink | Reply
    Tags: (MOU)-Memorandum of Understanding, , , , , CTA will comprise two arrays on different continents observing gamma rays: one in Chile at ESO’s Cerro Paranal and one in Spain on La Palma in the Canary Islands., multi-messenger astronomy, , , SKA will have radio telescopes in Australia and South Africa.,   

    From SKA: “SKA signs cooperation agreement with Čerenkov Telescope Array” 

    SKA South Africa

    From SKA

    29 January 2020

    The SKA Organisation (SKAO) [all telescope images below] will engage in closer collaboration with the Čerenkov Telescope Array Observatory (CTAO) under a new agreement signed by the two research infrastructures.


    The Memorandum of Understanding (MOU) will facilitate greater sharing of knowledge and expertise in areas including engineering, science, technology and administration.

    SKAO and CTAO are both large international collaborations and have several member countries in common, including many European countries but also astronomy organisations in Australia and South Africa. Like the SKA, which will have radio telescopes in Australia and South Africa, CTA will also comprise two arrays on different continents observing gamma rays: one in Chile at ESO’s Cerro Paranal and one in Spain on La Palma in the Canary Islands.

    The two observatories are due to begin delivering science within just a few years of each other.

    Both have also begun transitions on the governance front; the SKA is becoming an intergovernmental organisation or IGO, while CTAO is becoming a European Research Infrastructure Consortium (ERIC).

    “Both the SKA and CTA are pushing the boundaries of what’s possible technically, scientifically and logistically, and some of the challenges that brings are common to both projects,” says Simon Berry, Director of Strategy for the SKA. “This MOU formalises our relationship, so we can keep learning from each other’s experiences and share expertise for the benefit of both observatories.”

    “In this age of multi-messenger astronomy, building alliances with observatories across the spectrum are critical to achieving our common missions to expand our view and understanding of the Universe,” says Federico Ferrini, CTAO Managing Director. “The CTAO-SKAO partnership was an obvious fit due to our vast similarities, and we are looking forward to the collaboration.”

    While the respective telescopes will observe opposite ends of the spectrum, there are exciting areas of scientific synergy between them. Both radio and gamma rays are a probe of the violent and variable universe, including the study of active galactic nuclei, transient events such as gamma-ray bursts and fast radio bursts, accretion into compact objects and gravitational wave counterparts.

    As the flagship very high-energy gamma-ray observatory for the coming decades, CTA is one of several next-generation facilities targeting other wavelengths or cosmic messengers (detections that do not use photons, such as neutrinos or gravitational waves) which will be complementary to the SKA. Coordinated observations between such facilities can give a more complete picture of astronomical sources and phenomena, resulting in greatly enhanced scientific discoveries.

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Australian Square Kilometre Array Pathfinder (ASKAP) is a radio telescope array located at Murchison Radio-astronomy Observatory (MRO) in the Australian Mid West. ASKAP consists of 36 identical parabolic antennas, each 12 metres in diameter, working together as a single instrument with a total collecting area of approximately 4,000 square metres.

    SKA Meerkat telescope, 90 km outside the small Northern Cape town of Carnarvon, SA

    Murchison Widefield Array,SKA Murchison Widefield Array, Boolardy station in outback Western Australia, at the Murchison Radio-astronomy Observatory (MRO)

    SKA Hera at SKA South Africa

    SKA Pathfinder – LOFAR location at Potsdam via Google Images

    About SKA

    The Square Kilometre Arraywill be the world’s largest and most sensitive radio telescope. The total collecting area will be approximately one square kilometre giving 50 times the sensitivity, and 10 000 times the survey speed, of the best current-day telescopes. The SKA will be built in Southern Africa and in Australia. Thousands of receptors will extend to distances of 3 000 km from the central regions. The SKA will address fundamental unanswered questions about our Universe including how the first stars and galaxies formed after the Big Bang, how dark energy is accelerating the expansion of the Universe, the role of magnetism in the cosmos, the nature of gravity, and the search for life beyond Earth. Construction of phase one of the SKA is scheduled to start in 2016. The SKA Organisation, with its headquarters at Jodrell Bank Observatory, near Manchester, UK, was established in December 2011 as a not-for-profit company in order to formalise relationships between the international partners and centralise the leadership of the project.

    The Square Kilometre Array (SKA) project is an international effort to build the world’s largest radio telescope, led by SKA Organisation. The SKA will conduct transformational science to improve our understanding of the Universe and the laws of fundamental physics, monitoring the sky in unprecedented detail and mapping it hundreds of times faster than any current facility.

    Already supported by 10 member countries – Australia, Canada, China, India, Italy, New Zealand, South Africa, Sweden, The Netherlands and the United Kingdom – SKA Organisation has brought together some of the world’s finest scientists, engineers and policy makers and more than 100 companies and research institutions across 20 countries in the design and development of the telescope. Construction of the SKA is set to start in 2018, with early science observations in 2020.

  • richardmitnick 1:03 pm on September 5, 2018 Permalink | Reply
    Tags: , , , , , , , multi-messenger astronomy,   

    From Caltech: “Superfast Jet Observed Streaming Away from Stellar Collision” 

    Caltech Logo

    From Caltech

    Elise Cutts

    An artist’s impression of the jet (pictured as a ball of fire), produced in the neutron star merger first detected on August 17, 2017 by telescopes around the world, as well as LIGO, which detects gravitational waves (green ripples). Credit: James Josephides (Swinburne University of Technology, Australia)

    Using a collection of National Science Foundation radio telescopes, researchers have confirmed that a narrow jet of material was ejected at near light speeds from a neutron star collision. The collision, which was observed August 17, 2017 and occurred 130 million miles from Earth, initially produced gravitational waves that were observed by the Laser Interferometry Gravitational-wave Observatory (LIGO), alongside a flood of light in the form of gamma rays, X-rays, visible light, and radio waves. It was the first cosmic event to be observed in both gravitational waves and light waves.

    Confirmation that a superfast jet had been produced by the neutron star collision came after radio astronomers discovered that a region of radio emission created by the merger had moved in a seemingly impossible way that only a jet could explain. The radio observations were made using the Very Long Baseline Array (VLBA), the Robert C. Byrd Green Bank Telescope (GBT), and the Very Large Array (VLA). The VLA is operated by the National Radio Astronomy Observatory (NRAO), which is closely associated with the other two telescopes involved in the discovery.


    GBO radio telescope, Green Bank, West Virginia, USA

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

    “We measured an apparent motion that is four times faster than light. That illusion, called superluminal motion, results when the jet is pointed nearly toward Earth and the material in the jet is moving close to the speed of light,” says Kunal Mooley, a Caltech postdoctoral scholar with a joint appointment at the NRAO and lead author of a new study about the jet appearing online September 5 in the journal Nature. Mooley and Assistant Professor of Astronomy Gregg Hallinan were part of an international collaboration that observed and interpreted the movement of the radio emission.

    “We were lucky to be able to observe this event, because if the jet had been pointed too much farther away from Earth, the radio emission would have been too faint for us to detect,” says Hallinan.

    Superfast jets are known to give rise to intense, short-duration gamma-ray bursts or sGRBs, predicted by theorists to be associated with neutron star collisions. The observation of a jet associated with this collision is therefore an important confirmation of theoretical expectations.

    Superfast jets are known to give rise to intense, short-duration gamma-ray bursts or sGRBs, predicted by theorists to be associated with neutron star collisions. The observation of a jet associated with this collision is therefore an important confirmation of theoretical expectations.

    The aftermath of the merger is now also better understood: the jet likely interacted with surrounding debris, forming a broad “cocoon” of material that expanded outward and accounted for the majority of the radio signal observed soon after the collision. Later on, the observed radio emission came mainly from the jet.

    Read the full story from NRAO at https://public.nrao.edu/news/superfast-jet-neutron-star-merger/.

    See the full article here .
    See also https://sciencesprings.wordpress.com/2017/10/16/from-ucsc-a-uc-santa-cruz-special-report-neutron-stars-gravitational-waves-and-all-the-gold-in-the-universe/

    Please help promote STEM in your local schools.

    Stem Education Coalition

    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

    Caltech campus

  • richardmitnick 3:05 pm on August 17, 2018 Permalink | Reply
    Tags: , , , , , , , multi-messenger astronomy   

    From Discover Magazine: “Astronomers Find New Way to Supersize Baby Black Holes” 


    From Discover Magazine

    August 16, 2018
    Jake Parks

    This artist’s concept depicts a supermassive black hole surrounded by a dense disk of gas and dust in the center of a galaxy. (Credit: NASA/JPL-Caltech)

    Just last year, three American physicists shared the Nobel Prize in Physics for their role in the historic detection of gravitational waves. The signals came from cosmic ripples in space-time created by some of the most violent events in the universe: colliding black holes.

    Scientists have now detected six gravitational-wave signals — five from merging pairs of stellar-mass black holes, and one from a merging pair of neutron stars. But strangely, most of the stellar-mass black holes involved were more than 20 times as massive as the Sun. The find perplexed astronomers. Stellar-mass black holes, which form when massive stars collapse, typically top out at about 10 to 15 times the mass of the Sun.

    Bulking Up Black Holes

    So, how did these relatively small black holes bulk up before merging?

    In the past, scientists suspected these black holes grew larger because they started their lives as giant stars with very few metals — or elements besides hydrogen and helium. Since low-metallicity stars produce weak solar winds, they keep most of their mass before collapsing into black holes.

    But according to a new study published in The Astrophysical Journal Letters, there may be more than one way to make a black hole balloon in size — and it doesn’t involve a low-metal diet.

    Instead, the authors outline a way that average stellar-mass black hole can grow by gobbling up the material circling a galaxy’s supermassive black hole. Furthermore, this new mechanism also may predict a fresh source of gravitational waves.

    Gravitational waves are produced by the inspiral and eventual merger of two extremely dense objects, such as black holes or neutron stars. This creates ripples in the fabric of space-time that propagate outward at the speed of light. (Credit: R. Hurt/Caltech-JPL)

    Spiraling Disks

    Astronomers know that the majority of large galaxies house supermassive black holes in their cores. Many of these black holes lie dormant for most of their lives, accreting little matter and producing little light.

    However, some supermassive black holes are surrounded by a dense disk of gas and dust that harshly grinds together as it spins inward toward the supermassive black hole itself. This spinning disk generates incredible amounts of friction, which causes the material inside it to glow brightly. If these radiant disks are especially bright, astronomers refer to them as active galactic nuclei, or AGN.

    Just outside these chaotic disks, however, are numerous stars — many of which will eventually evolve into stellar-mass black holes.

    According to the new study, a pair of these nearby stellar-mass black holes can easily become trapped within the AGN’s disk. And when this happens, the black holes feed on the available matter as they spiral ever closer, growing from around seven solar masses to more than 20 solar masses before they eventually merge.

    The gravitational-wave signal generated by such a merger would indicate that the two black holes involved were around 20 solar masses, even though they both initially started much smaller.

    Multi-Messenger Astronomy

    One interesting offshoot of this newly proposed method for forming supersized stellar-mass black holes is that their environment can often cause them to synchronize their spin axes, like two tops spinning in tandem. According to the study, such systems release about 10 percent of their energy as gravitational waves when they do finally merge. That’s as much as three times more gravitational-wave energy than would be released if the black holes were randomly oriented, which means these mergers are likely detectable with current technology, such as the Laser Interferometer Gravitational-wave Observatory (LIGO).

    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation

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

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

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

    ESA/eLISA the future of gravitational wave research

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

    See also https://sciencesprings.wordpress.com/2017/10/20/from-ucsc-neutron-stars-gravitational-waves-and-all-the-gold-in-the-universe/

    The authors also say these black holes would likely emit large amounts of X-rays, gamma rays, or even radio waves. Those wavelengths could provide an electromagnetic counterpart to a gravitational-wave signal, revealing important details that would otherwise remain hidden.

    Last year, astronomers managed to do just this when they observed both gravitational waves and gamma rays from the merger of two neutron stars. At the time, astronomer Josh Simon of Carnegie Observatories said of the neutron star detection, “There are things you can discover with gravitational waves that you could never see with electromagnetic light, and vice versa. Having that combination should provide us with insights into these extreme objects.”

    What’s Next?

    So, is this newly proposed method for forming supersized stellar-mass black holes the explanation for LIGO’s extra-large detections, or are low-metal stars responsible? Or maybe it’s a combination of both. At this point, we just don’t know for sure.

    However, LIGO and its sister detector Virgo are currently undergoing planned upgrades, and should start observing again in early 2019. And when they kick back on, astronomers will no doubt be hunting for gravitational-wave signals that can be paired with electromagnetic observations. Such multi-messenger detections will likely be key to the future of astronomy, so make sure to stay tuned.

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

  • richardmitnick 8:11 am on August 11, 2018 Permalink | Reply
    Tags: , , , , , multi-messenger astronomy   

    From Ethan Siegel: “What Happens When Planets, Stars And Black Holes Collide?” 

    From Ethan Siegel
    Aug 10, 2018

    Two neutron stars colliding, which is the primary source of many of the heaviest periodic table elements in the Universe. About 3-5% of the mass gets expelled in such a collision; the rest becomes a single black hole.Dana Berry, SkyWorks Digital, Inc.

    The Universe as we know it has been around for nearly 14 billion years: plenty of time for gravity to pull matter into clusters, clumps, and collapsed objects. By the present day, the Universe is filled with planets, stars, galaxies, and even larger structures, all bound together against the backdrop of the expanding Universe.

    But things aren’t so clean and neat. As large as space is, there are literally trillions of objects in our galaxy, moving on timescales of billions of years. Some of the systems that form will have multiple objects in them, and collisions between them aren’t just likely, they’re inevitable. Whenever a collision or merger occurs, it forever changes what we’re left with. Here’s the cosmic story of what happens.

    When an object collides with a planet, it can kick up debris and lead to the formation of nearby moons. This is where Earth’s Moon came from, and also where it’s thought that Mars’ and Pluto’s moons arose from as well.NASA/JPL-Caltech.

    Planet-planet collisions. Early on in the Solar System, there were likely more than eight planets. There may have been a fifth gas giant out between Jupiter and Neptune; our best simulations indicate that it got ejected. But in the inner Solar System, we believe there was a Mars-sized world that collided with a young Earth, giving rise to an enormous cloud of debris that coalesced to create our Moon. The giant impact hypothesis has been thoroughly validated by a number of lines of evidence, including by the lunar samples we brought back to Earth from the Apollo missions.

    Rather than the two Moons we see today, a collision followed by a circumplanetary disk may have given rise to three moons of Mars, where only two survive today.Labex UnivEarths / Université Paris Diderot

    Beyond that, we also have some pretty good evidence that Mars’ moons were created, along with a third, larger one that’s since fallen back down onto the red planet, by a large proto-planetary collision, too.

    From all the simulations we’ve performed and the evidence we’ve accumulated, rocky planets of comparable sizes collide quite frequently in the early stages of a solar system’s creation. When they smash together, they create a single, larger planet, but with a cloud of debris that coalesces to form one nearby, large satellite and up to several smaller, more distant satellites. The Pluto-Charon system is a spectacular example of this, with four additional, outer, tumbling moons.

    The inspiral and merger scenario for brown dwarfs as well-separated as these two are would take a very long time due to gravitational waves. But collisions are quite likely. Just as red stars colliding produce blue straggler stars, brown dwarf collisions can make red dwarf stars. Over long enough timescales, these ‘blips’ of light may become the only sources illuminating the Universe.Melvyn B. Davies, Nature 462, 991-992 (2009)

    Brown dwarf collisions. Want to make a star, but you didn’t accumulate enough mass to get there when the gas cloud that created you first collapsed? There’s a second chance available to you! Brown dwarfs are like very massive gas giants, more than a dozen times as massive as Jupiter, that experience strong enough temperatures (about 1,000,000 K) and pressures at their centers to ignite deuterium fusion, but not hydrogen fusion. They produce their own light, they remain relatively cool, and they aren’t quite true stars. Ranging in mass from about 1% to 7.5% of the Sun’s mass, they are the failed stars of the Universe.

    But if you have two in a binary system, or two in disparate systems that collide by chance, all of that can change in a flash.

    These are the two brown dwarfs that make up Luhman 16, and they may eventually merge together to create a star.NASA/JPL/Gemini Observatory/AURA/NSF

    The reason for that is that very little about the compositions of these failed stars changes over time. They’re still made of 70-75% hydrogen each, and when they merge together, they still have all of that unburned fuel. If the total mass of the merged object now exceeds that critical threshold of 0.075 solar masses, the Universe will have created a new star! With this much mass in a single object, temperatures will rise past that critical 4,000,000 K to ignite hydrogen fusion. Instead of two brown dwarfs, we’ll have created a red dwarf: a bona fide M-class star. The nearby binary brown dwarf system Luhman 16, just 6.5 light years away, is tantalizingly close to having the exact parameters necessary to eventually become a red dwarf star.

    A selection of the globular cluster Terzan 5, a unique link to the Milky Way’s past. Incredibly old stars can be found within globular clusters, relics of some of the first ‘bursts’ of star formation to occur in our vicinity of the Universe. The occasional blue star seen within, however, tells us that there’s more to the story.NASA/ESA/Hubble/F. Ferraro

    Two stars colliding. Stars come in a wide variety of masses, with the lower-mass ones appearing redder, cooler, and burning through their fuel more slowly, while the higher-mass ones are bluer, hotter, and live for shorter amounts of time. When we look at star clusters, we can get an idea of how old they are by viewing the highest-mass stars that are left, since the most massive ones die the fastest.

    Yet when we look at some of the oldest star clusters of all, we find a population of stars that are bluer and hotter than ought to be present. They simply don’t match up with the rest of the stars that are around. These blue straggler stars are real, though, and they have a fantastic explanation: stellar collisions.

    Blue straggler stars, circled in the inset image, are formed when older stars or even stellar remnants merge together. After the last stars have burned out, the same process could bring light to the Universe, albeit briefly, once again.NASA, ESA, W. Clarkson (Indiana University and UCLA), and K. Sahu (STScl)

    Take any two (or more) stars and merge them together, and they’ll make a single, more massive star. Even when all that remain are the redder stars, say one of 0.7 solar masses and one of 0.8 solar masses, if they merge together, they can create a bluer (1.5 solar mass) star, even if the star cluster they exist in is too old to have a 1.5 solar mass star remaining.

    Blue stragglers are common in the dense environments of globular clusters, and demonstrate that even long after all the stars as massive as the Sun have burned out, we will still create new ones simply by gravitational mergers.

    The ultimate event for multi-messenger astronomy would be a merger of two white dwarfs that were close enough to Earth to detect neutrinos, light, and gravitational waves all at once. These objects are known to produce Type Ia supernovae.NASA, ESA, and A. Feild (STScI)

    White dwarf collisions. So, your normal, main-sequence star lived through its life, burning through all the fuel it will ever burn. As a remnant, its core became a white dwarf star: the future fate of our Sun. And then, floating out there in the depths of interstellar space, it collided with another white dwarf star.


    White dwarf-white dwarf collisions lead to Type Ia supernovae, and may yet be the most common way these cataclysms originate. When such an event occurs, the stars undergo a runaway fusion reaction, giving off a tremendous amount of light and energy, and utterly destroy both white dwarfs that gave rise to the event. This is the one type of collision that completely destroys both the colliding objects.

    See https://sciencesprings.wordpress.com/2017/10/20/from-ucsc-neutron-stars-gravitational-waves-and-all-the-gold-in-the-universe/

    Artist’s illustration of two merging neutron stars. Binary neutron star systems inspiral and merge as well, but the closest orbiting pair we’ve found won’t merge until nearly 100 million years have passed. LIGO will likely find many others before that.NSF / LIGO / Sonoma State University / A. Simonnet

    Neutron star collisions. Arising from even more massive stars than those that give rise to white dwarfs, neutron stars can often exist in multi-star systems. Recently, we’ve observed two neutron stars in a binary system inspiraling and merging: a kilonova event. When this occurs, a large burst of energy is given off, and a substantial fraction of mass is ejected. The critical 2017 event that occurred marked the first time that the same object was observed in both gravitational waves and electromagnetic radiation.

    The masses of stellar remnants are measured in many different ways. This graphic shows the masses for black holes detected through electromagnetic observations (purple); the black holes measured by gravitational-wave observations (blue); neutron stars measured with electromagnetic observations (yellow); and the masses of the neutron stars that merged in an event called GW170817, which were detected in gravitational waves (orange). The result of the merger was a neutron star, briefly, that swiftly became a black hole. LIGO-Virgo/Frank Elavsky/Northwestern

    If the two neutron stars merge together to create a single one, they either:

    become a more massive neutron star (if their total is less than ~2.5 solar masses),
    become a neutron star that spins and then collapses to a black hole (if the total is under 2.75 solar masses),
    or collapses directly to a black hole (if the total mass is over 2.75 solar masses).

    Over the coming years and decades, we hope to observe many of these events to refine the accuracy of these statements even further.

    Black hole collisions. Merge a black hole with a black hole, and you get an even more massive black hole. But there’s a catch: up to around 5% of that mass gets lost! The first merging black hole pair we ever saw was a 36 solar mass black hole merging with a 29 solar mass black hole. But it created a black hole whose final mass was just 62 solar masses! A total of three suns worth of mass was simply lost.

    Where did it go? It was emitted in the form of gravitational radiation: the gravitational waves that LIGO detected from over a billion light years away. For a brief moment lasting less than a second, two merging black holes can emit more energy into the observable Universe than all the stars within it combined.

    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation

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

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

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

    ESA/eLISA the future of gravitational wave research

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

    Other collisions are expected, such as black hole-neutron star, neutron star-white dwarf, neutron star-normal star, or even black hole-normal star. Objects like active galaxies or microquasars may be triggered by a black hole devouring stars or gas clouds. We have yet to observe any of these collisions as they happen, however, although we have discovered a candidate for a Thorne-Zytkow object: a neutron star at the core of a red giant star. Space may be a very big place, but it’s far from empty. Particularly within galaxies and star/globular clusters, the density of planets, stars, and stellar remnants are tremendous, and collisions such as these are inevitable. Whatever the consequences may be, it’s up to us to find out!

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    “Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan

  • richardmitnick 7:17 am on August 11, 2018 Permalink | Reply
    Tags: , , , , , , multi-messenger astronomy   

    From Center For Astrophysics: “Spitzer Infrared Observations of a Gravitational Wave Source – a Binary Neutron Star Merger” 

    Harvard Smithsonian Center for Astrophysics

    From Center For Astrophysics

    GW170817 is the name given to a gravitational wave signal seen by the LIGO and Virgo detectors on 17 August 2017.

    See https://sciencesprings.wordpress.com/2017/10/20/from-ucsc-neutron-stars-gravitational-waves-and-all-the-gold-in-the-universe/

    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation

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

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

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

    ESA/eLISA the future of gravitational wave research

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

    Lasting for about 100 seconds, the signal was produced by the merger of two neutron stars. The observation was then confirmed – the first time this has happened for gravitational waves – by observations with light waves: the preceding five detections of merging black holes did not have (and were not expected to have) any detectable electromagnetic signals. The light from the neutron star merger is produced by the radioactive decay of atomic nuclei created in the event. (Neutron star mergers do more than just produce optical light, by the way: they are also responsible for making most of the gold in the universe.) Numerous ground-based optical observations of the merger concluded that the decaying atomic nuclei fall into at least two groups, a rapidly evolving and fast moving one composed of elements less massive than Lanthanide Series elements, and one that is more slowly evolving and dominated by heavier elements.

    Ten days after the merger, the continuum emission peaked at infrared wavelengths with a temperature of approximately 1300 kelvin, and continued to cool and dim. The Infrared Array Camera (IRAC) on the Spitzer Space Telescope observed the region around GW170817 for 3.9 hours in three epochs 43, 74 and 264 days after the event (SAO is the home of IRAC PI Fazio and his team). The shape and evolution of the emission reflect the physical processes at work, for example, the fraction of heavy elements in the ejecta or the possible role of carbon dust. Tracking the flux over time enables the astronomers to refine their models and understanding of what happens when neutron stars merge.

    A team of CfA astronomers, Victoria Villar, Philip Cowperthwaite, Edo Berger, Peter Blanchard, Sebastian Gomez, Kate Alexander, Tarraneh Eftekhari, Giovanni Fazio, James Guillochon, Joe Hora, Matthew Nicholl, and Peter Williams and two colleagues participated in an effort to measure and interpret the infrared observations. The source was extremely faint and moreover lies close to a very bright point source. Using a novel algorithm to prepare and subtract the IRAC images to eliminate the constant-brightness objects, the team was able to spot the merger source clearly in the first two epochs, although it was fainter than was predicted by the models by more than about a factor of two. It had dimmed beyond detection by the third epoch. However the rate of dimming and the infrared colors are consistent with models; at these epochs the material had cooled down to about 1200 kelvin. The team suggests several possible reasons for the surprising faintness, including possible transformation of the ejecta into a nebulous phase and notes that the new dataset will help refine the models.

    The scientists conclude by emphasizing that future binary star merger detections (an improved LISA will begin observing again in 2019) will similarly benefit from infrared observations, and that characterization of the infrared will enable more accurate determination of the nuclear decay processes underway. Their current paper, moreover, shows that Spitzer should be able to spot binary mergers as far away as four hundred million light-years, about the distance that the improved LISA should be able to probe.

    Spitzer Space Telescope Infrared Observations of the Binary Neutron Star Merger GW170817
    The Astrophysical Journal Letters

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    The Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy.

  • richardmitnick 11:42 am on January 3, 2018 Permalink | Reply
    Tags: Celebrating Innovation, Celebrating Women in Physics, Continue the Journey, , multi-messenger astronomy, , Recent Perimeter News, The Centre for the Universe   

    From PI: “Recent Perimeter News” 

    Perimeter Institute

    Perimeter Institute

    A Stellar Year

    From the dawn of multi-messenger astronomy to the discovery of more Earth-sized exoplanets and a solar eclipse that captivated millions, 2017 was a year in which humanity turned its gaze skyward.

    Many believe we have entered a new “golden age” of physics. Researchers at Perimeter continue to probe for answers about dark matter, quantum gravity, black holes, and the birth of the universe.

    The Centre for the Universe

    In November 2017, Perimeter announced the creation of the Centre for the Universe – a new hub for cutting-edge cosmology research. Centre patrons include world-renowned cosmologist Stephen Hawking and Nobel Prize winner Art MacDonald. The Centre will bring together international scientists, bridging fundamental theory and experiment, to tackle questions about the origin, evolution, and fate of the universe.

    Read more here.

    On the Horizon

    The Event Horizon Telescope (EHT) project turned its incredibly precise gaze toward a black hole earlier this year, and the scientific world awaits the resulting imagery.

    Event Horizon Telescope Array

    Arizona Radio Observatory
    Arizona Radio Observatory/Submillimeter-wave Astronomy (ARO/SMT)

    Atacama Pathfinder EXperiment

    CARMA Array no longer in service
    Combined Array for Research in Millimeter-wave Astronomy (CARMA)

    Atacama Submillimeter Telescope Experiment (ASTE)
    Atacama Submillimeter Telescope Experiment (ASTE)

    Caltech Submillimeter Observatory
    Caltech Submillimeter Observatory (CSO)

    IRAM NOEMA interferometer
    Institut de Radioastronomie Millimetrique (IRAM) 30m

    James Clerk Maxwell Telescope interior, Mauna Kea, Hawaii, USA
    James Clerk Maxwell Telescope interior, Mauna Kea, Hawaii, USA

    Large Millimeter Telescope Alfonso Serrano
    Large Millimeter Telescope Alfonso Serrano

    CfA Submillimeter Array Hawaii SAO
    Submillimeter Array Hawaii SAO

    ESO/NRAO/NAOJ ALMA Array, Chile

    South Pole Telescope SPTPOL
    South Pole Telescope SPTPOL

    Future Array/Telescopes

    Plateau de Bure interferometer
    Plateau de Bure interferometer

    NSF CfA Greenland telescope

    Greenland Telescope

    A process called Very Long Baseline Interferometry (VLBI) is used by this network of eight large radio telescopes to capture history’s first picture of a black hole’s event horizon. Avery Broderick leads Perimeter’s Event Horizon Initiative, which will help analyze and interpret the data collected by the telescope array. The EHT team is waiting for the last remaining data to arrive from the South Pole and expects to have results early in the new year.

    Read more here

    A Year of Celebration

    Celebrating Innovation

    Innovation150 – a part of Canada 150 celebrations – was led by Perimeter, with the Power of Ideas Tour visiting cities and towns across the country. More than 100,000 people attended tour events and many more attended talks, festivals, and other Innovation150 experiences.

    Read more here

    Celebrating Women in Physics

    Perimeter’s Emmy Noether Initiatives continued to celebrate and support women scientists throughout the year. A free, downloadable poster series also shone the spotlight on some women pioneers in physics.

    Read more here.

    Continue the Journey

    Advances in creating quantum light, determining what dark matter isn’t, sharing the wonders of science – Perimeter was a bustling hub of research, education, and outreach in 2017. Read more at http://www.insidetheperimeter.ca.

    Thank you for joining us on this journey. We look forward to sharing more exciting news with you throughout 2018.

    With appreciation,


    Jacqueline Watty
    Senior Advancement Officer
    Perimeter Institute for Theoretical Physics
    519-569-7600 ext. 4472

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    About Perimeter

    Perimeter Institute is the world’s largest research hub devoted to theoretical physics. The independent Institute was founded in 1999 to foster breakthroughs in the fundamental understanding of our universe, from the smallest particles to the entire cosmos. Research at Perimeter is motivated by the understanding that fundamental science advances human knowledge and catalyzes innovation, and that today’s theoretical physics is tomorrow’s technology. Located in the Region of Waterloo, the not-for-profit Institute is a unique public-private endeavour, including the Governments of Ontario and Canada, that enables cutting-edge research, trains the next generation of scientific pioneers, and shares the power of physics through award-winning educational outreach and public engagement.

  • richardmitnick 12:16 pm on December 25, 2017 Permalink | Reply
    Tags: , , , , , , multi-messenger astronomy, Waves of joy: why astronomers are ecstatic about colliding neutron stars   

    From COSMOS: “Waves of joy: why astronomers are ecstatic about colliding neutron stars” 

    Cosmos Magazine bloc

    COSMOS Magazine

    22 December 2017
    Lauren Fuge

    An artist’s impression of colliding neutron stars. MARK GARLICK/UNIVERSITY OF WARWICK.

    Every few years, a discovery is announced that makes scientists so excited they could explode – consider the rockstar coverage that greeted the discovery of the Higgs boson in 2012, or the triumphant global cheer when Curiosity landed safely on Mars in the same year.

    CERN CMS Higgs Event

    CERN ATLAS Higgs Event

    NASA/Mars Curiosity Rover

    On 16 October 2017 the announcement of another science spectacle swept the world: for the first time, astronomers had been treated to the cosmic fireworks of colliding neutron stars. They could both listen – thanks to gravitational waves – and watch – thanks to electromagnetic waves. Astronomers the world over were catapulted into a frenzy.

    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation

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

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

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

    ESA/eLISA the future of gravitational wave research

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

    Here are five reasons why.

    1. Their life’s work was just validated.

    The reality of science – and especially physics and astronomy – is that, sometimes, scientists end up studying phenomena that they’re not 100% sure actually exist. For some researchers, this discovery confirmed that they haven’t wasted their careers.

    Anna Heffernan, Marie Curie Fellow at the University of Florida and the University College Dublin, summed up the sentiment: “I’ve spent my life looking at gravitational waves – at least, the last 11 or 12 years – and to actually find that they really do exist and I haven’t dedicated 12 years to nonsense was a very good feeling.”

    David Blair, from the University of Western Australia, spent even longer in the dark. “I started working on the first high sensitivity gravitational wave detectors in the USA in 1973,” he said. “I expected to spend a year or two detecting Einstein’s waves and then move on to something else … Forty-four years later we have found the holy grail!”

    Image: CSIRO

    2. Astronomers have reached a goal they have chased for decades.

    This discovery not only validated many scientists’ entire careers but also marked the triumphant achievement of a long-held and dearly desired goal: “That is,” said National Science Foundation director France Córdova, “to simultaneously observe rare cosmic events using both traditional as well as gravitational-wave observatories.”

    Cataclysmic Collision Artist’s illustration of two merging neutron stars. The rippling space-time grid represents gravitational waves that travel out from the collision, while the narrow beams show the bursts of gamma rays that are shot out just seconds after the gravitational waves. Swirling clouds of material ejected from the merging stars are also depicted. The clouds glow with visible and other wavelengths of light. Image credit: NSF/LIGO/Sonoma State University/A. Simonnet

    It is “very, very exciting” that it worked out in the end, said Rainer Weiss, LIGO co-founder and winner of the 2017 Nobel Prize in Physics: “For as long as 40 years, people have been thinking about this, trying to make a detection, sometimes failing in the early days, and then slowly but surely getting the technology together to be able to do it.”

    Scientists persisted for so long, explained Tamara Davis from the ARC Centre of Excellence for All-Sky Astrophysics (CAASTRO) and the University of Queensland, because hearing this faint sound and momentary burst of light confirmed a suite of predictions – “such as how the heavy elements were created, what happens when neutron stars collide, and how fast is the universe expanding.”

    Ju Li, of the University of Western Australia, agreed: “It is extraordinary that with one faint sound, the faintest sound ever detected, we have created one giant leap in our understanding of the universe.”

    Blair adds: “This is the most amazing vindication of all of Einstein’s theories.”

    3. The discovery involved a massive, unprecedented global collaboration.

    After the initial gravitational waves alert on August 17, hundreds of astronomers around the world leapt into action to try and spot electromagnetic radiation from the source.

    Stefano Covino, at INAF–Osservatorio Astronomico di Brera in Italy, says the effort was frankly impressive. “The days were filled with frenetic and exciting activity,” he remembers. “You had the precise feeling that something historic was happening.”

    According to Dave Reitze, executive director of LIGO, these mass-scale follow-up observations allowed astronomers to obtain “a full picture of one of the most violent, cataclysmic events in the universe. This is the most intense observational campaign there has ever been.”

    Matthew Bailes, the Director of the ARC Centre of Excellence for Gravitational Wave Discovery, agrees that the “avalanche of science was virtually unparalleled in modern astrophysics.”

    As a result, dozens of research papers went online on October 16, the day of the official announcement. One paper in particular [The Astrophysical Journal] demonstrates the mind-blowing scale of the collaboration – it’s co-authored by almost 4000 astronomers from more than 900 institutions: about a third of all astronomers in the world.

    4. It marks the beginning of a new era of multi-messenger astronomy.

    “Probably the most exciting thing of all is really that it’s the beginning,” says Richard O’Shaughnessy at the Rochester Institute of Technology’s Center for Computational Relativity and Gravitation. “This is a transformation in the way that we’re going to do astronomy.”

    His sentiment was echoed by almost every astronomers who spoke about the event. If there’s one thing scientists get universally excited about, it’s doing more science.

    Jeff Cooke from Swinburne University is among the enthusiastic horde: “Before this event, it was like we were sitting in an IMAX theatre with blindfolds on. The gravitational wave detectors let us ‘hear’ the movies of black hole collisions, but we couldn’t see anything. This event lifted the blindfolds and, wow, what an amazing show!”

    Neil Tanvir from Leicester University explains further: “This discovery has opened up a new approach to astronomical research, where we combine information from both electromagnetic light and from gravitational waves. We call this multi-messenger astronomy – but until now it has just been a dream.”

    Some astronomers, like Edward van den Heuvel from the University of Amsterdam, are already getting pumped for what the next few decades hold.

    “Within 20 years or so, gravitational-wave measurements may be just as routine as X-ray observations have become over the past 40 years,” he says. “It’s really beyond my wildest dreams.”

    5. It’s just plain cool.

    There’s just no getting around the fact that measuring miniscule fluctuations in the fabric of spacetime from a titanic clash of ultra-dense stars 130 million years ago – and in the process, finding that our predictions were spot on – is just amazingly cool.

    Covino is particularly excited because the data coming in so far “are an amazingly close match to theory. It is a triumph for the theorists, a confirmation that the LIGO–VIRGO events are absolutely real.”

    Stephen Smartt of Queen’s University Belfast agrees wholeheartedly: “It’s quite amazing that these physical models predated the discovery by years, but ended up being very similar to the data that we actually saw!”

    According to David Coward from the University of Western Australia, he and his team “knew on day one, when the event happened, that this was something big. This is like gold for scientists.”

    For some astronomers, the discovery is so awesome that words just aren’t enough.

    “Superlatives fail,” says O’Shaughnessy.

    See the full article here .

    See further from UCSC, https://sciencesprings.wordpress.com/2017/10/20/from-ucsc-neutron-stars-gravitational-waves-and-all-the-gold-in-the-universe/ for the full story including the optical astronomy involved in this event.

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