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  • richardmitnick 1:52 pm on March 12, 2021 Permalink | Reply
    Tags: "Giant gravitational wave detectors could hear murmurs from across universe", ASPERA Albert Einstein Telescope, , , European Space Agency(EU)/National Aeronautics and Space Administration (US) eLISA space based- the future of gravitational wave research., , KAGRA Large-scale Cryogenic Graviationai wave Telescope Project(JP), , ,   

    From Science Magazine: “Giant gravitational wave detectors could hear murmurs from across universe” 

    From Science Magazine

    Mar. 10, 2021
    Adrian Cho

    Just 5 years ago, physicists opened a new window on the universe when they first detected gravitational waves, ripples in space itself set off when massive black holes or neutron stars collide. Even as discoveries pour in, researchers are already planning bigger, more sensitive detectors. And a Ford versus Ferrari kind of rivalry has emerged, with scientists in the United States simply proposing bigger detectors, and researchers in Europe pursuing a more radical design.

    “Right now, we’re only catching the rarest, loudest events, but there’s a whole lot more, murmuring through the universe,” says Jocelyn Read, an astrophysicist at California State University, Fullerton(US), who’s working on the U.S. effort. Physicists hope to have the new detectors running in the 2030s, which means they have to start planning now, says David Reitze, a physicist at the California Institute of Technology(US). “Gravitational wave discoveries have captivated the world, so now is a great time to be thinking about what comes next.”

    Current detectors are all L-shaped instruments called interferometers. Laser light bounces between mirrors suspended at either end of each arm, and some of it leaks through to meet at the crook of the L. There, the light interferes in a way that depends on the arms’ relative lengths. By monitoring that interference, physicists can spot a passing gravitational wave, which will generally make the lengths of the arms waver by different amounts.

    Caltech/MIT Advanced aLigo

    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

    European Space Agency(EU)/National Aeronautics and Space Administration (US) eLISA space based, the future of gravitational wave research.

    To tamp down other vibrations, the interferometer must be housed in a vacuum chamber and the weighty mirrors hung from sophisticated suspension systems. And to detect the tiny stretching of space, the interferometer arms must be long. In the Laser Interferometer Gravitational-Wave Observatory (LIGO), twin instruments in Louisiana and Washington state that spotted the first gravitational wave from two black holes whirling into each other, the arms are 4 kilometers long. Europe’s Virgo detector in Italy has 3-kilometer-long arms.

    In spite of the detectors’ sizes, a gravitational wave changes the relative lengths of their arms by less than the width of a proton.

    The dozens of black hole mergers that LIGO and Virgo have spotted have shown that stellar-mass black holes, created when massive stars collapse to points, are more varied in mass than theorists expected.

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

    In 2017, LIGO and Virgo delivered another revelation, detecting two neutron stars spiraling together and alerting astronomers to the merger’s location on the sky. Within hours telescopes of all types had studied the aftermath of the resulting “kilonova,” observing how the explosion forged copious heavy elements.

    Researchers now want a detector 10 times more sensitive, which they say would have mind-boggling potential. It could spot all black hole mergers within the observable universe and even peer back to the time before the first stars to search for primordial black holes that formed in the big bang. It should also spot hundreds of kilonovae, laying bare the nature of the ultradense matter in neutron stars.

    The U.S. vision for such a dream machine is simple. “We’re just going to make it really, really big,” says Read, who is helping design Cosmic Explorer, an interferometer with arms 40 kilometers long—essentially, a LIGO detector scaled up 10-fold.

    The “cookie cutter design” might enable the United States to afford multiple, widely separated detectors, which would help pinpoint sources on the sky as LIGO and Virgo do now, says Barry Barish, a physicist at Caltech who directed the construction of LIGO.

    Siting such mammoth wave catchers may be tricky. The 40-kilometer arms have to be straight, but Earth is round. If the crook of the L sits on the ground, then the ends of the interferometers might have to rest on berms 30 meters high. So U.S. researchers hope to find bowl-like areas that might accommodate the structure more naturally.

    In contrast, European physicists envision a single subterranean gravitational wave observatory, called the Einstein Telescope [above], that would do it all. “We want to realize an infrastructure that is able to host all the evolutions [of detectors] for 50 years,” says Michele Punturo, a physicist with Italy’s National Institute for Nuclear Physics(IT) in Perugia and co-chair of the ET steering committee.

    The ET would comprise multiple V-shaped interferometers with arms 10 kilometers long, arranged in an equilateral triangle deep underground to help shield out vibrations. With interferometers pointed in three directions, the ET could determine the polarization of gravitational waves—the direction in which they stretch space—to help locate sources on the sky and probe the fundamental nature of the waves.

    The tunnels would actually house two sets of interferometers. The signals detected by LIGO and Virgo hum at frequencies that range from about 10 to 2000 cycles per second and rise as a pair of objects spirals together. But picking up lower frequencies of just a few cycles per second would open new realms. To detect them, a second interferometer that uses a lower power laser and mirrors cooled to near absolute zero would nestle in each corner of the ET. (Such mirrors are already in use at Japan’s KAGRA Large-scale Cryogenic Graviationai wave Telescope Project(JP) which has 3-kilometer arms and is striving to catch up with LIGO and Virgo.)

    By going to lower frequencies, the ET could detect the merger of black holes hundreds of times as massive as the Sun. It could also catch neutron-star pairs hours before they actually merge, giving astronomers advance warning of kilonova explosions, says Marica Branchesi, an astronomer at Italy’s Gran Sasso Science Institute. “The early emission [of light] is extremely important, because there is a lot of physics there,” she says.

    The ET should cost €1.7 billion, including €900 million for the tunneling and basic infrastructure, Punturo says. Researchers are considering two sites, one near where Belgium, Germany, and the Netherlands meet and another on the island of Sardinia. The plan is under review by the European Strategy Forum on Research Infrastructures, which could put the ET on its to-do list this summer. “This is an important political step,” Punturo says, but not final approval for construction.

    The U.S. proposal is less mature. Researchers want the National Science Foundation(US) to provide $65 million for design work so a decision on the billion-dollar machine can be made in the mid-2020s, Barish says. Physicists hope to have both Cosmic Explorer and the ET running in the mid-2030s, at the same time as the planned Laser Interferometer Space Antenna, a constellation of three spacecraft millions of kilometers apart that will sense gravitational waves of far lower frequencies from supermassive black holes in the centers of galaxies.

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

    European Space Agency(EU)/National Aeronautics and Space Administration (US) eLISA space based, the future of gravitational wave research.

    The push for new gravitational wave detectors isn’t necessarily a competition. “What we really want is to have ET and Cosmic Explorer and, ideally, even a third detector of similar sensitivity,” says Stefan Hild, a physicist at Maastricht University [Universiteit Maastricht](NL) who works on the ET. Reitze notes, however, that timing and cost could “push towards convergence and simplicity in designs.” Instead of a Ford and a Ferrari, perhaps physicists will end up building a few Audis.

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

  • richardmitnick 9:51 am on October 1, 2019 Permalink | Reply
    Tags: "Here's How Gravitational Wave Detectors Might Be Able to Detect Dark Matter Particles", ASPERA Albert Einstein Telescope, , ,   

    From Curiosity: “Here’s How Gravitational Wave Detectors Might Be Able to Detect Dark Matter Particles” 

    Curiosity Makes You Smarter

    From From Curiosity

    September 27, 2019
    Matt Williams

    The field of astronomy has been revolutionized thanks to the first-ever detection of gravitational waves (GWs). Since the initial detection was made in February of 2016 by scientists at the Laser Interferometer Gravitational-wave Observatory (LIGO), multiple events have been detected. These have provided insight into a phenomenon that was predicted over a century ago by Albert Einstein.

    MIT /Caltech Advanced aLigo

    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    As it turns out, the infrastructure that is used to detect GWs could also help crack another astronomical mystery: dark matter! According to a new study by a team of Japanese researchers, laser interferometers could be used to look for weakly interacting massive particles (WIMPs), a major candidate particle in the hunt for dark matter.

    To recap, WIMPS are a theoretical elementary particle that interacts with normal matter (baryonic) only through weak interaction. As with other elementary particles that are part of the Standard Model (of which WIMPS are not), they would have been created during the early universe when the cosmos was extremely hot.

    WIMPs are essentially the microscopic candidate particle, which puts them at the opposite end of the spectrum from the other major candidate — the macroscopic Massive Compact Halo Objects (MACHOs). So far, multiple experiments have been conducted to find these particles — ranging from particle collisions and indirect detections to more direct methods — but the results have been largely inconclusive.

    As Dr. Satoshi Tsuchida, a postdoctoral physics researcher at Osaka City University and the lead author of the study (which recently appeared online [above]), told Universe Today via email:

    “Most MACHOs are believed to consist of baryonic matter, but baryons account for only 5 percent of the universe. Thus, we cannot explain the structure of the present universe if all of dark matter consists of MACHOs. On the other hand, WIMPs are non-baryonic matter and we have no reason to exclude [them] from dark matter… Therefore, WIMPs can be promising dark matter candidates.”

    For the sake of their study, the research team (which includes members hail Osaka University’s Nambu Yoichiro Institute of Theoretical and Experimental Physics and Ritsumeikan University) propose a new search method that takes advantage of recent advances in gravity wave detection. Using the same method to detect ripples in spacetime, they argue that WIMPs could also be detected for the first time.

    This would constitute a “direct detection” approach using laser interferometers, a method that has been proposed in the past. However, this method has not yet been tested, in part because scientists have not yet calculated what kinds of signals will be caused by direct interactions between WIMPs and nucleons in a laser interferometer’s mirror.

    However, the research team argues that the motions of a pendulum and mirror in a GW detector will become excited due to a collision. The research team analyzed these motions and estimated how detectable they would be to a system of highly sophisticated sensors, like those used by LIGO and other GW detectors.

    From this, the team was able to provide a framework which could come in handy for future research. “Thus, our method might [provide] some new knowledge for dark matter [research],” said Dr. Satoshi. “The next-generation GW detectors have better sensitivity than current-generation ones, so the signal to noise ratio would be improved by some orders of magnitude.”

    “If we can establish a method to extract the dark matter signals on GW detector, the method could play [an] important role to elucidate the nature of WIMPs by [an] independent approach,” he added. “Thus, our study might help in revealing the structure of the universe not only at present, but also in the past and future.”

    These include the Kamioka Gravitational wave detector, Large-scale Cryogenic Gravitational wave Telescope (KAGRA) in Japan — which is currently being upgraded — and the Einstein Telescope (ET), a third-generation European detector that is still in the design phase.

    KAGRA gravitational wave detector, Kamioka mine in Kamioka-cho, Hida-city, Gifu-prefecture, Japan

    Depiction of the ASPERA Albert Einstein Telescope, Albert Einstein Institute Hannover and Max Planck Institute for Gravitational Physics and Leibniz Universitat Hannover

    When these come online and join LIGO and the Virgo observatory (in Italy), they will allow for an unprecedented rate of detection.

    This is not the first time that scientists have suggested other applications for GW research. For instance, an international team of scientists recently proposed that GWs could be used to study dwarf galaxies, in the hopes of seeing how they are dominated by dark matter. Another proposal is using GWs to measure the expansion rate of the universe — a method that could tell us a great deal about the nature and influence of dark energy!

    A mysterious astronomical force, one which was only recently confirmed, that could lead to a new understanding about two of the greatest cosmological mysteries! What a time to be alive!

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Curiosity Makes You Smarter

    Curiosity is on a mission to make learning easier and more fun than it has ever been. Our goal is to ignite curiosity and inspire people to learn. Each day, we create and curate engaging topics for millions of lifelong learners worldwide.

    Experience Curiosity on our website, through our apps and across social media. We designed Curiosity with your busy life in mind. Our editors find interesting and important topics that you’ll want to know more about, and introduce you to the best ways to keep learning.

    We hope you make Curiosity part of your daily digital diet. Never stop learning!

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