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  • richardmitnick 2:07 pm on January 21, 2020 Permalink | Reply
    Tags: , , , , , FRB 180916.J0158+65, FRB's Fast radio Bursts,   

    From Gemini Observatory: “Fast Radio Burst Observations Deepen Astronomical Mystery” 

    Gemini Observatory
    From Gemini Observatory

    January 6, 2020

    Peter Michaud
    NewsTeam Manager
    NSF’s National Optical-Infrared Astronomy Research Laboratory
    Gemini Observatory, Hilo HI
    Desk:: +1 808-974-2510
    Cell: +1 808-936-6643
    Email: pmichaud@gemini.edu

    Jason Hessels
    University of Amsterdam & ASTRON
    Email: j.w.t.hessels@uva.nl
    Phone: +31 610260062

    Shriharsh Tendulkar
    McGill University
    Email: shriharsh@physics.mcgill.ca

    Astronomers have pinpointed the origin of a repeating Fast Radio Burst to a nearby spiral galaxy, challenging theories on the unknown source of these pulses.

    Image of the host galaxy of FRB 180916 (center) acquired on Hawaii’s Maunakea with the 8-meter Gemini North telescope of the international Gemini Observatory (a program of the NSF’s OIR Lab). Images acquired in SDSS g’, r’, and z’ filters are used for the blue, green, and red colors, respectively. The position of the FRB in the spiral arm of the galaxy is marked by a green circle. Credit: Gemini Observatory/NSF’s Optical-Infrared Astronomy Research Laboratory/AURA

    Observations with the 8-meter Gemini North telescope [below], a program of the NSF’s National Optical-Infrared Astronomy Research Laboratory, have allowed astronomers to pinpoint the location of a Fast Radio Burst in a nearby galaxy — making it the closest known example to Earth and only the second repeating burst source to have its location pinpointed in the sky. The source of this burst of radio waves is located in an environment radically different from that seen in previous studies. This discovery challenges researchers’ assumptions on the origin of these already enigmatic extragalactic events.

    An unsolved mystery in astronomy has become even more puzzling. The source of Fast Radio Bursts (FRBs) — sudden bursts of radio waves lasting a few thousandths of a second — has remained unknown since their discovery in 2007. Research published today in the scientific journal Nature, and presented at the 235th meeting of the American Astronomical Society, has pinpointed the origin of an FRB to an unexpected environment in a nearby spiral galaxy. Observations with the Gemini North telescope of NSF’s Optical-Infrared Astronomy Research Laboratory (OIR Lab) on Maunakea in Hawai‘i, played a vital role in this discovery, which renders the nature of these extragalactic radio pulses even more enigmatic.

    The sources of FRBs and their nature are mysterious — many are one-off bursts but very few of them emit repeated flashes. The recently discovered FRB — identified by the unpoetic designation FRB 180916.J0158+65 — is one of only five sources with a precisely known location and only the second such source that shows repeated bursts. Such FRB’s are referred to as localized and can be associated with a particular distant galaxy, allowing astronomers to make additional observations that can provide insights into the origin of the radio pulse.

    “This object’s location is radically different from that of not only the previously located repeating FRB, but also all previously studied FRBs,” elaborates Kenzie Nimmo, PhD student at the University of Amsterdam and a fellow lead author of this paper. “This blurs the differences between repeating and non-repeating fast radio bursts. It may be that FRBs are produced in a large zoo of locations across the Universe and just require some specific conditions to be visible.”

    Pinpointing the location of FRB 180916.J0158+65 required observations at both radio and optical wavelengths. FRBs can only be detected with radio telescopes, so radio observations are fundamentally necessary to accurately determine the position of an FRB on the sky. This particular FRB was first discovered by the Canadian CHIME radio telescope array in 2018[1].

    CHIME Canadian Hydrogen Intensity Mapping Experiment -A partnership between the University of British Columbia, the University of Toronto, McGill University, Yale and the National Research Council in British Columbia, at the Dominion Radio Astrophysical Observatory in Penticton, British Columbia, CA Altitude 545 m (1,788 ft)

    The new research used the European VLBI Network (EVN)[2] to precisely localize the source, but measuring the precise distance and local environment of the radio source was only possible with follow-up optical observations with the Gemini North telescope.

    Global mm-VLBI Array

    The international Gemini Observatory comprises telescopes in both the northern and southern hemispheres, which together can access the entire night sky.

    “We used the cameras and spectrographs on the Gemini North telescope to image the faint structures of the host galaxy where the FRB resides, measure its distance, and analyze its chemical composition,” explains Shriharsh Tendulkar, a postdoctoral fellow at McGill University in Montreal, Canada who led the Gemini observations[3] and subsequent data analysis. “These observations showed that the FRB originates in a spiral arm of the galaxy, in a region which is rapidly forming stars.”

    However, the source of FRB 180916.J0158+65 — which lies roughly 500 million light-years from Earth — was unexpected and shows that FRB’s may not be linked to a particular type of galaxy or environment, deepening this astronomical mystery[4].

    “This is the closest FRB to Earth ever localised,” explains Benito Marcote, of the Joint Institute for VLBI European Research Infrastructure Consortium and a lead author of the Nature paper. “Surprisingly, it was found in an environment radically different from that of the previous four localised FRBs — an environment that challenges our ideas of what the source of these bursts could be.”

    The researchers hope that further studies will reveal the conditions that result in the production of these mysterious transient radio pulses, and address some of the many unanswered questions they pose. Corresponding author Jason Hessels of the Netherlands Institute for Radio Astronomy (ASTRON) and the University of Amsterdam states that “our aim is to precisely localize more FRBs and, ultimately, understand their origin.”

    “It’s a pleasure to see different observing facilities complement one another during challenging high-priority investigations such as this,” concludes Luc Simard, Gemini Board member and Director General of NRC-Herzberg, which hosts CHIME, as well as the Canadian Gemini Office. “We are particularly honored to have the opportunity to conduct astronomical observations on Maunakea in Hawai’i. This site’s exceptional observing conditions are vital to making astronomical discoveries such as this.”

    Chris Davis, National Science Foundation Program Officer for Gemini adds, “understanding the origin of FRBs will undoubtedly be an exciting challenge for astronomers in the 2020s; we’re confident that Gemini will play an important role, and it seems fitting that Gemini has made these important observations at the dawn of the new decade.”


    [1] The Canadian Hydrogen Intensity Mapping Experiment (CHIME) collaboration operates an innovative radio telescope at the Dominion Radio Astrophysical Observatory in Canada. The CHIME telescope’s novel construction makes it particularly adept at discovering FRBs such as FRB 180916.J0158+65.

    [2] Radio observations were made using eight radio telescopes of the European Very Long Baseline Interferometry Network (EVN) following the discovery of FRB 180916.J0158+65 by the CHIME/FRB Collaboration.

    [3] The Gemini observations were made between July and September of 2019 using the Gemini Multi-Object Spectrograph (GMOS) on the Gemini North telescope on Hawaii’s Maunakea.

    [4] Prior to the observations announced today, the evidence hinted at the possibility that repeating and non-repeating FRBs were formed in very different environments. The only repeating FRB apart from FRB 180916.J0158+65 with a precisely determined location was found to inhabit a region of massive star formation inside a dwarf galaxy. Conversely, the three localized non-repeating FRBs were all found in massive galaxies and appear not to be associated with star-forming regions, leading to speculation that there were two separate types of FRB.

    See the full article here .

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    NOAO Gemini North on MaunaKea, Hawaii, USA, Altitude 4,213 m (13,822 ft)

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

    Gemini’s mission is to advance our knowledge of the Universe by providing the international Gemini Community with forefront access to the entire sky.

    The Gemini Observatory is an international collaboration with two identical 8-meter telescopes. The Frederick C. Gillett Gemini Telescope is located on Mauna Kea, Hawai’i (Gemini North) and the other telescope on Cerro Pachón in central Chile (Gemini South); together the twin telescopes provide full coverage over both hemispheres of the sky. The telescopes incorporate technologies that allow large, relatively thin mirrors, under active control, to collect and focus both visible and infrared radiation from space.

    The Gemini Observatory provides the astronomical communities in six partner countries with state-of-the-art astronomical facilities that allocate observing time in proportion to each country’s contribution. In addition to financial support, each country also contributes significant scientific and technical resources. The national research agencies that form the Gemini partnership include: the US National Science Foundation (NSF), the Canadian National Research Council (NRC), the Chilean Comisión Nacional de Investigación Cientifica y Tecnológica (CONICYT), the Australian Research Council (ARC), the Argentinean Ministerio de Ciencia, Tecnología e Innovación Productiva, and the Brazilian Ministério da Ciência, Tecnologia e Inovação. The observatory is managed by the Association of Universities for Research in Astronomy, Inc. (AURA) under a cooperative agreement with the NSF. The NSF also serves as the executive agency for the international partnership.

  • richardmitnick 7:32 pm on January 6, 2020 Permalink | Reply
    Tags: "CHIME collaboration helps track down a fast radio burst to a nearby galaxy", (VLBI)-European Very Long Baseline Interferometry Network, , , , , , FRB's Fast radio Bursts, , The repeating radio source known as FRB 180916.J0158+65,   

    From Dunlap Institute for Astronomy and Astrophysics: “CHIME collaboration helps track down a fast radio burst to a nearby galaxy” 

    From Dunlap Institute for Astronomy and Astrophysics

    At U Toronto


    Fergus Grieve
    Faculty of Science, McGill University
    514-398-4400 x 09513

    CHIME Canadian Hydrogen Intensity Mapping Experiment -A partnership between the University of British Columbia, the University of Toronto, McGill University, Yale and the National Research Council in British Columbia, at the Dominion Radio Astrophysical Observatory in Penticton, British Columbia, CA Altitude 545 m (1,788 ft)


    Working with members of Canada’s CHIME Fast Radio Burst collaboration, including members at the Dunlap Institute and the University of Toronto, Astronomers in Europe have pinpointed the location of a repeating fast radio burst (FRB) first detected by the CHIME telescope in British Columbia in 2018. The breakthrough is only the second time that scientists have determined the precise location of a repeating source of these millisecond bursts of radio waves from space.

    In results published in the January 9 edition of Nature, the European VLBI Network (EVN) used eight telescopes spanning locations from the United Kingdom to China to simultaneously observe the repeating radio source known as FRB 180916.J0158+65.

    European VLBI

    Using a technique known as Very Long Baseline Interferometry (VLBI), the researchers achieved a level of resolution high enough to localize the FRB to a region approximately seven light years across – a feat comparable to an individual on Earth being able to distinguish a person on the Moon.

    A ‘very different’ location for an FRB

    With that level of precision, the research team was able to train an optical telescope onto the location to learn more about the environment from which the burst emanated. What they found has added a new chapter to the mystery surrounding the origins of FRBs.

    “We used the eight-metre Gemini North telescope in Hawaii to take sensitive images that showed the faint spiral arms of a Milky-Way-like galaxy and showed that the FRB source was in a star-forming region in one of those arms,” said co-author Shriharsh Tendulkar, a former McGill University postdoctoral researcher who co-led the optical imaging and spectroscopic analyses of the FRB’s location.

    NOAO Gemini North on MaunaKea, Hawaii, USA, Altitude 4,213 m (13,822 ft)

    This is a very different environment for a repeating FRB, compared to the dwarf galaxy in which the first repeating FRB 121102 was discovered to reside.”

    CHIME team’s hypotheses in line with observed data

    The discovery lined up with a number of ideas CHIME/FRB researchers had put forward following their initial detection of the burst in 2018.

    “The FRB is among the closest yet seen and we even speculated that it could be a more conventional object in the outskirts of our own galaxy,” said co-author Mohit Bhardwaj, a McGill University doctoral student and CHIME team member.

    “However the EVN observation proved that it’s in a relatively nearby galaxy, making it still a puzzling FRB, but close enough to now study using many other telescopes.”

    Zooming in on the radio sky

    Since it began operation in the summer of 2018, CHIME has detected dozens of fast radio bursts, greatly accelerating the rate of discovery of these transient astrophysical phenomena. With over 1,000 antennas, CHIME’s large field of view gives it a much greater chance of picking up fleeting bursts than conventional radio telescopes that are able to observe only a small area of the sky at a time.

    When it came to pinpointing FRB 180916, the CHIME/FRB team worked closely with their EVN colleagues to determine exactly where to point the VLBI telescopes.

    “By recording and processing the raw signal from each of the antenna elements that make up CHIME, we were able to refine the source position to a level close enough for EVN to successfully observe and localize multiple bursts from this FRB source,” said co-author Daniele Michilli, a McGill University postdoctoral researcher and CHIME/FRB team member.

    FRB’s proximity opens the way for further study

    At half-a-billion light years from Earth, the source of FRB 180916 is around seven times closer than the only other repeating burst to have been localized, and more than 10 times closer than any of the few non-repeating FRBs scientists have managed to pinpoint. That’s exciting for astronomers because it will enable more detailed study that may help narrow down the possible explanations for FRBs.

    “We have a new chance to perhaps detect emissions at other wavelengths – x-ray or visible light, for instance,” said McGill University astrophysicist Victoria Kaspi, a leading member of the CHIME/FRB collaboration. “And if we did, that would be hugely constraining of the models.”

    About the CHIME Fast Radio Burst Collaboration

    CHIME/FRB is a collaboration of over 50 scientists led by the University of British Columbia, McGill University, the University of Toronto, the Perimeter Institute for Theoretical Physics, and the National Research Council of Canada (NRC). The $16-million investment for CHIME was provided by the Canada Foundation for Innovation and the governments of British Columbia, Ontario and Quebec, with additional funding from the Dunlap Institute for Astronomy & Astrophysics, the Natural Sciences and Engineering Research Council and the Canadian Institute for Advanced Research. The telescope is located in the mountains of British Columbia’s Okanagan Valley at the NRC’s Dominion Radio Astrophysical Observatory near Penticton. CHIME is an official Square Kilometre Array (SKA) pathfinder facility.

    SKA Square Kilometer Array

    SKA South Africa

    For more information about the Dunlap Institute’s involvement in the CHIME collaboration, please contact:

    Meaghan MacSween
    Communications Officer, Dunlap Institute for Astronomy & Astrophysics, University of Toronto

    See the full article here .


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    Dunlap Institute campus

    The Dunlap Institute for Astronomy & Astrophysics at the University of Toronto is an endowed research institute with nearly 70 faculty, postdocs, students and staff, dedicated to innovative technology, ground-breaking research, world-class training, and public engagement. The research themes of its faculty and Dunlap Fellows span the Universe and include: optical, infrared and radio instrumentation; Dark Energy; large-scale structure; the Cosmic Microwave Background; the interstellar medium; galaxy evolution; cosmic magnetism; and time-domain science.
    The Dunlap Institute, Department of Astronomy & Astrophysics, Canadian Institute for Theoretical Astrophysics, and Centre for Planetary Sciences comprise the leading centre for astronomical research in Canada, at the leading research university in the country, the University of Toronto.
    The Dunlap Institute is committed to making its science, training and public outreach activities productive and enjoyable for everyone, regardless of gender, sexual orientation, disability, physical appearance, body size, race, nationality or religion.
    Our work is greatly enhanced through collaborations with the Department of Astronomy & Astrophysics, Canadian Institute for Theoretical Astrophysics, David Dunlap Observatory, Ontario Science Centre, Royal Astronomical Society of Canada, the Toronto Public Library, and many other partners.

  • richardmitnick 10:48 am on October 2, 2019 Permalink | Reply
    Tags: "Galaxy found to float in a tranquil sea of halo gas", , , , , , FRB's Fast radio Bursts,   

    From UC Santa Cruz: “Galaxy found to float in a tranquil sea of halo gas” 

    UC Santa Cruz

    From UC Santa Cruz

    September 26, 2019
    Tim Stephens

    Analysis of radio pulses that passed through a galactic halo reveals a surprisingly quiescent halo with very low density and weak magnetic field.

    This illustration shows the radio signal from the fast radio burst FRB 181112 passing through the halo of a foreground galaxy on its way toward the telescopes that detected it on Earth. (Illustration © J. Josephides, Centre for Astrophysics and Supercomputing, Swinburne University of Technology)

    Imaging with the Very Large Telescope (VLT) in Chile shows the host galaxy of the fast radio burst, with the position of the burst depicted by the red ellipses. The brighter galaxy located nearby is in the foreground, and the sight-line to the burst passes through the halo of this foreground galaxy. (Image credit: Prochaska et al., Science 2019)

    The ASKAP radio telescope array in outback Western Australia detected and localized the fast radio burst. (Image credit: CSIRO/Alex Cherney)

    Using one cosmic mystery to probe another, astronomers have analyzed the signal from a fast radio burst, an enigmatic blast of cosmic radio waves lasting less than a millisecond, to characterize the diffuse gas in the halo of a massive galaxy.

    A vast halo of low-density gas extends far beyond the luminous part of a galaxy where the stars are concentrated. Although this hot, diffuse gas makes up more of a galaxy’s mass than stars do, it is nearly impossible to see. In November 2018, astronomers detected a fast radio burst that passed through the halo of a massive galaxy on its way toward Earth, allowing them for the first time to get clues to the nature of the halo gas from an elusive radio signal.

    “The signal from the fast radio burst exposed the nature of the magnetic field around the galaxy and the structure of the halo gas. The study proves a new and transformative technique for exploring the nature of galaxy halos,” said J. Xavier Prochaska, professor of astronomy and astrophysics at UC Santa Cruz and lead author of a paper on the new findings published online September 26 in Science.

    Astronomers still don’t know what produces fast radio bursts, and only recently have they been able to trace some of these very short, very bright radio signals back to the galaxies in which they originated. The November 2018 burst (named FRB 181112) was detected and localized by the instrument that pioneered this technique, CSIRO’s Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope. Follow-up observations with other telescopes identified not only its host galaxy but also a bright galaxy in front of it.

    “When we overlaid the radio and optical images, we could see straight away that the fast radio burst pierced the halo of this coincident foreground galaxy and, for the first time, we had a direct way of investigating this otherwise invisible matter surrounding this galaxy,” said coauthor Cherie Day at Swinburne University of Technology, Australia.

    A galactic halo contains both dark matter and ordinary (“baryonic”) matter, which is expected to be mostly hot ionized gas. While the luminous part of a massive galaxy might be around 30,000 light-years across, its roughly spherical halo is ten times larger. Halo gas fuels star formation as it falls in toward the center of the galaxy, while other processes (such as supernova explosions) can eject material out of the star-forming regions and into the galactic halo. One reason astronomers want to study the halo gas is to better understand these ejection processes, which can shut down star formation.

    “The halo gas is a fossil record of these ejection processes, so our observations can inform theories about how matter is ejected and how magnetic fields are threaded through galaxies,” Prochaska said.

    Contrary to expectations, the results of the new study indicate a very low density and a feeble magnetic field in the halo of this intervening galaxy.

    “This galaxy’s halo is surprisingly tranquil,” Prochaska said. “The radio signal was largely unperturbed by the galaxy, which is in stark contrast to what previous models predict would have happened to the burst.”

    The signal of FRB 181112 consisted of several pulses, each lasting less than 40 microseconds (ten thousand times shorter than the blink of an eye). The short duration of the pulses puts an upper limit on the density of the halo gas, because passage through a denser medium would lengthen the radio signals. The researchers calculated that the density of the halo gas must be less than a tenth of an atom per cubic centimeter (equivalent to several hundred atoms in a volume the size of a child’s balloon).

    “Like the shimmering air on a hot summer’s day, the tenuous atmosphere in this massive galaxy should warp the signal of the fast radio burst. Instead we received a pulse so pristine and sharp that there is no signature of this gas at all,” said coauthor Jean-Pierre Macquart, an astronomer at the International Center for Radio Astronomy Research at Curtin University, Australia.

    The density constraints also limit the possibility of turbulence or clouds of cool gas within the halo (“cool” being a relative term, referring here to temperatures around 10,000 Kelvin, versus the hot halo gas at around 1 million Kelvin). “One favored model is that halos are pervaded by clouds of clumpy gas. We find no evidence for these clouds whatsoever,” Prochaska said.

    The FRB signal also yields information about the magnetic field in the halo, which affects the polarization of the radio waves. Analyzing the polarization as a function of frequency gives a “rotation measure” for the halo, which the researchers found to be very low. “The weak magnetic field in the halo is a billion times weaker than that of a refrigerator magnet,” Prochaska said.

    At this point, with results from only one galactic halo, the researchers cannot say whether the unexpectedly low density and magnetic field strength are unusual or if previous studies of galactic halos have overestimated these properties. ASKAP and other radio telescopes will use fast radio bursts to study many more galactic halos and resolve their properties.

    “This galaxy may be special,” Prochaska said. “We will need to use FRBs to study tens or hundreds of galaxies over a range of masses and ages to assess the full population.”

    In addition to Prochaska, Day, and Macquart, the coauthors of the paper include UCSC graduate student Sunil Simha and researchers at eight other institutions in Australia, the United States, South Korea, and Chile. This work was funded in part by the U.S. National Science Foundation and the Australian Research Council.

    See the full article here .


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    UCSC Lick Observatory, Mt Hamilton, in San Jose, California, Altitude 1,283 m (4,209 ft)


    UC Observatories Lick Autmated Planet Finder, fully robotic 2.4-meter optical telescope at Lick Observatory, situated on the summit of Mount Hamilton, east of San Jose, California, USA

    UCO Lick Shane Telescope
    UCO Lick Shane Telescope interior
    Shane Telescope at UCO Lick Observatory, UCSC

    UC Santa Cruz campus
    The University of California, Santa Cruz, opened in 1965 and grew, one college at a time, to its current (2008-09) enrollment of more than 16,000 students. Undergraduates pursue more than 60 majors supervised by divisional deans of humanities, physical & biological sciences, social sciences, and arts. Graduate students work toward graduate certificates, master’s degrees, or doctoral degrees in more than 30 academic fields under the supervision of the divisional and graduate deans. The dean of the Jack Baskin School of Engineering oversees the campus’s undergraduate and graduate engineering programs.

    UCSC is the home base for the Lick Observatory.

    Lick Observatory's Great Lick 91-centimeter (36-inch) telescope housed in the South (large) Dome of main building
    Lick Observatory’s Great Lick 91-centimeter (36-inch) telescope housed in the South (large) Dome of main building

  • richardmitnick 8:37 am on September 10, 2019 Permalink | Reply
    Tags: "Giant Radio Telescope in China Just Detected Repeating Signals From Across Space", , , , , FRB's Fast radio Bursts, , [FAST [Five-hundred-meter Aperture Spherical Telescope] radio telescope   

    From McGill University via Science Alert: “Giant Radio Telescope in China Just Detected Repeating Signals From Across Space” 

    McGill University

    From McGill University



    Science Alert

    10 SEP 2019

    Remember the spectacle of that gigantic telescope unveiled in a mountain-ringed valley in China just a few years ago? Well, the Five-hundred-meter Aperture Spherical Radio Telescope (FAST) has now picked up a mysterious space signal known as a fast radio burst.

    FAST [Five-hundred-meter Aperture Spherical Telescope] radio telescope, with phased arrays from CSIRO engineers Australia [located in the Dawodang depression in Pingtang County, Guizhou Province, south China

    Fast radio bursts or FRBs are brief but powerful pulses of energy from distant parts of the cosmos. The first one was spotted in 2007, and we’re finding more of them all the time.

    While astronomers have recently made some exciting progress in tracing FRBs, we just don’t know exactly what these signals are, or how they originate. They might be caused by black holes or neutron stars called magnetars, perhaps.

    What’s exciting about the detection by FAST is that this fast radio burst is a repeater. The burst is officially known as FRB 121102: first picked up in 2012 at the Arecibo Observatory in Puerto Rico, it’s appeared several times since.

    NAIC Arecibo Observatory operated by University of Central Florida, Yang Enterprises and UMET, Altitude 497 m (1,631 ft).

    Researchers note that the signal has travelled around 3 billion light-years across the Universe to reach us.

    FAST latched on to FRB 121102 on August 30, before recording dozens of later pulses (on one particular day, September 3, more than 20 pulses were detected). So, this looks like a particularly persistent FRB.

    The 19-beam receiver on FAST is especially sensitive to radio signals, covering the 1.05-1.45 GHz frequency range, and that makes it perfect for keeping an eye on FRB 121102.

    The more observations we can make of these FRBs, the better our chances of being able to work out exactly what they are. One idea is that FRBs are produced upon disintegration of the crusts of certain types of neutron stars.

    Another hypothesis posits that different FRBs actually have different causes [above, from Owens Valley Radio Observatory], which may explain why FRB 121102 repeats and others don’t appear to do so. We are at least getting better at pinpointing where these mysterious bursts of electromagnetic radiation come from.

    Now we can add the data gathered by FAST to our growing database of knowledge on these most intriguing of space phenomena. The team at the telescope has already been able to eliminate aircraft and satellite interference from their measurements.

    “I just think it is so amazing that nature produces something like that,” physicist Ziggy Pleunis of McGill University told ScienceAlert, after helping to detail eight new FRBs in a paper published last month.

    “Also, I think that there is some very important information in that structure that we just have to figure out how to encode and it has been a lot of fun to try to figure out what exactly that is.”

    See the full article here .


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    All about

    With some 300 buildings, more than 38,500 students and 250,000 living alumni, and a reputation for excellence that reaches around the globe, McGill has carved out a spot among the world’s greatest universities.
    Founded in Montreal, Quebec, in 1821, McGill is a leading Canadian post-secondary institution. It has two campuses, 11 faculties, 11 professional schools, 300 programs of study and some 39,000 students, including more than 9,300 graduate students. McGill attracts students from over 150 countries around the world, its 8,200 international students making up 21 per cent of the student body.

  • richardmitnick 9:13 am on August 23, 2019 Permalink | Reply
    Tags: , , , , FRB's Fast radio Bursts, , , XTE J1810-197   

    From Science Alert: “Analysis of a Strange Erupting Magnetar Hints Link With Mysterious Fast Radio Bursts” 


    From Science Alert

    23 AUG 2019

    Artist’s impression of a magnetar. (ESO/L. Calçada)

    A magnetar that recently erupted with a storm of activity may have given us a lead on the mystery of fast radio bursts (FRBs).

    According to a new analysis of the magnetar XTE J1810-197, millisecond bursts of low-frequency radio waves sputtered out by the dead star show an unusual similarity to FRB signals. It’s far from conclusive proof that the two phenomena are linked, but it’s one of the most tantalising hints yet.

    This claim is just one of several findings in a new paper, accepted into The Astrophysical Journal. The research team behind this work has analysed the magnetar’s low-frequency radio output using the second of just two outbursts we’ve ever caught from this source.

    Magnetars are a particularly strange type of neutron star. Their magnetic fields are somehow insanely strong – around a quadrillion times stronger than Earth’s own magnetic field. We don’t know what processes produce these magnetic fields, but they’re strong enough to make the space around them seriously screwy.

    We haven’t found many magnetars, as it’s thought that this life stage for a star lasts a very short time in cosmic terms: just 10,000 years. Of those we have found, XTE J1810-197 is among the strangest of them all.

    Located 10,000 light-years away in the constellation Sagittarius, it was the first of only four magnetars found to emit radio waves – but it only does so intermittently. It was crackling away in radio frequencies when it was discovered in 2003. Then, in 2008, it mysteriously went radio silent.

    But December of last year, it flared to radio life again, and astrophysicists at the National Centre for Radio Astrophysics in India turned the Giant Metrewave Radio Telescope (GMRT) in to listen.

    Giant Metrewave Radio Telescope, an array of thirty telecopes, located near Pune in India

    Their results, obtained mostly over four observation runs in the low-frequency 550 to 750 MHz range, revealed a rapid decrease in the radio flux density after the initial onset of the outburst. This was consistent with observations of the first outburst.

    “Similar to the previous outburst, the 650MHz flux density decreased by a factor of about 5 or more in the first 20 to 30 days,” the researchers write in their paper.

    What seemed to particularly intrigue them, however, is the possible link to fast radio bursts, mysterious spikes in radio data that last just a few milliseconds, but with as much energy as over 500 million Suns. Most FRBs have not been detected repeating (which the magnetar bursts did), but there were striking similarities.

    The team observed the magnetar emitting millisecond spikes of radio wave activity, with spectral structures that – just like FRBs – can’t be explained by effects caused by their passage through the interstellar medium, the gas and dust between the stars.

    “These structures might indicate a phenomenological link with the repeating fast radio bursts which also show interesting, more detailed frequency structures,” the researchers wrote.

    It’s only a “maybe” at this point. There are also a couple of features that would need to be looked into.

    Firstly, repeating FRBs often demonstrate a phenomenon known as frequency drift, where successive bursts drift downward in frequency like a sad trombone.

    Due to their resolution and scattering at the frequency range they were observing, the researchers were unable to resolve any frequency drift in their data. That doesn’t mean it wasn’t there, but it would require a different dataset to try and find it.

    Secondly, there’s the question of signal strength. The magnetar’s signal was an order of magnitude more powerful than the peak of repeating FRB 121102, but there’s a catch – the FRB travelled from much, much farther away.

    This implies the FRB’s source would have to be around 100 billion times more luminous than the peak of XTE J1810-197’s outburst as captured by the GMRT.

    “Nevertheless,” the researchers write, “the fact that the magnetar J1810−197 is only the third object after the repeating FRBs and the Crab pulsar which is found to exhibit frequency structures in its bursts, might provide a phenomenological link between the underlying emission mechanisms.”

    See the full article here .


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  • richardmitnick 9:14 am on August 15, 2019 Permalink | Reply
    Tags: , , , , , FRB's Fast radio Bursts,   

    From Science News: “Astronomers just quintupled the number of known repeating fast radio bursts” 

    From Science News

    August 14, 2019
    Lisa Grossman

    The find could help reveal what causes these cryptic flashes of radio waves from deep space.

    CONSTANT VIGILANCE A Canadian telescope called CHIME scans the sky each night for brief, bright bursts of cosmic radio waves. Now CHIME has spotted eight new bursts that flash over and over. Andre Renard/Dunlap Institute/University of Toronto/CHIME

    Astronomers have found eight new fast radio bursts that repeatedly flash on and off.

    That haul brings the total of known repeating fast radio bursts, or FRBs, to 10, compared with the 60 or so nonrepeating FRBs that have been spotted, researchers report August 9 at arXiv.org [Astrophysical Journal Letters]. Studying the cryptic bursts could reveal what phenomena cause these brief, brilliant flares of radio waves from deep space.

    The first nonrepeating burst was discovered only in 2007, so “FRBs are still quite new,” says astrophysicist Cherry Ng of the University of Toronto. But “the repeater population is larger than we might think. They’re not that unique,” she says.

    Ng and colleagues spotted the newly discovered repeating FRBs using the Canadian Hydrogen Intensity Mapping Experiment, or CHIME, in British Columbia. The telescope also found the second known repeating FRB in August 2018 (SN: 2/2/19, p. 12).

    The new batch of repeat bursts could help astronomers start to figure out the sources of these flashes of radio energy, as well as how they might be different from their nonrepeating kin.

    For instance, radio waves from the first known repeat FRB, reported in 2016, were scrambled and tossed around by electrons on the way to Earth. That suggests the repeating FRB’s source is in a dense, turbulent environment, such as a supernova remnant or a neutron star orbiting a black hole (SN: 2/3/18, p. 6). But the energy from some of the new bursts seems to have had a less tumultuous journey, suggesting that these repeating FRBs hail from a calmer environment.

    Each burst from a repeat FRB also seems to last longer than an individual FRB, about 10 milliseconds per repeat burst versus one millisecond for a nonrepeater. That finding could support the idea that the two types of radio blasts have entirely different sources, although Ng thinks it’s too soon to be sure (SN: 8/3/19, p. 10). “Maybe don’t bet too much money on it,” she says.

    CHIME also has found many more nonrepeating FRBs in the last year, Ng says. That research is yet to be published, but “it will be a game changer,” she says.

    See the full article here .


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  • richardmitnick 11:35 am on August 5, 2019 Permalink | Reply
    Tags: , , , , FRB's Fast radio Bursts, operated by the school of physics of U Sidney AU, , UTMOST-Molonglo Observatory Synthesis Telescope (MOST) a radio telescope operating at 843 mhz, Wael Farah developed the FRB detection system and is the first person to discover FRBs in real-time with a fully automated machine learning system.   

    From Swinburne University of Technology: “Swinburne uses AI to detect fast radio bursts in real-time” 

    Swinburne U bloc

    From Swinburne University of Technology

    5 August 2019
    Katherine Moody

    An artist’s impression of the fast radio burst detected on October 17 2018 at the Molonglo Radio Telescope near Canberra, Australia. Credit: James Josephides/Swinburne

    UTMOST-Molonglo Observatory Synthesis Telescope (MOST) a radio telescope operating at 843 mhz, operated by the school of physics of U Sidney, AU

    A Swinburne PhD student has built an automated system that uses artificial intelligence (AI) to revolutionise our ability to detect and capture fast radio bursts (FRBs) in real-time.

    FRBs are mysterious and powerful flashes of radio waves from space, thought to originate billions of light years from the Earth. They last for only a few milliseconds (a thousandth of a second) and their cause is one of astronomy’s biggest puzzles.

    Wael Farah developed the FRB detection system, and is the first person to discover FRBs in real-time with a fully automated, machine learning system. Mr Farah’s system has already identified five bursts – including one of the most energetic ever detected, as well as the broadest.

    His results have been published in the Monthly Notices of the Royal Astronomical Society.

    Capturing fast radio bursts in real-time

    Mr Farah trained the on-site computer at the Molonglo Radio Observatory near Canberra to recognise the signs and signatures of FRBs, and trigger an immediate capture of the finest details seen to date.

    The bursts were detected within seconds of their arrival at the Molonglo Radio Telescope, producing high quality data that allowed Swinburne researchers to study their structure accurately, and gather clues about their origin.

    Mr Farah says his interest in FRBs comes from the fact they can potentially be used to study matter around and between galaxies that is otherwise almost impossible to see.

    “It is fascinating to discover that a signal that travelled halfway through the universe, reaching our telescope after a journey of a few billion years, exhibits complex structure, like peaks separated by less than a millisecond,” he says.

    Molonglo project scientist, Dr Chris Flynn says: “Wael has used machine learning on our high-performance computing cluster to detect and save FRBs from amongst millions of other radio events, such as mobile phones, lightning storms, and signals from the Sun and from pulsars.”

    Australian Research Council Laureate Fellow and project leader, Professor Matthew Bailes says: “Molonglo’s real-time detection system allows us to fully exploit its high time and frequency resolution and probe FRB properties that were previously unobtainable.”

    One of the FRBs shows remarkable structure in time and radio frequency. The fine details seen here could only be captured because the computers had been trained to spot FRBs within seconds of their arrival at the Earth. Image credit: Wael Farah/Swinburne

    The five bursts were found as part of the UTMOST FRB search program – a joint collaboration between Swinburne and the University of Sydney. The Molonglo telescope is owned by the University of Sydney.

    World-first discoveries

    In June, Swinburne astrophysicists Dr Adam Deller and Dr Ryan Shannon, from the Centre for Astrophysics and Supercomputing, were part of a team that determined the precise location of a one-off FRB for the first time.

    Dr Shannon also led the discovery of 20 FRBS in 2018, nearly doubling the known number of bursts at that time.

    See the full article here .

    Please help promote STEM in your local schools.

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    Swinburne U Campus

    Swinburne University of Technology (often simply called Swinburne) is an Australian public university based in Melbourne, Victoria. It was founded in 1908 as the Eastern Suburbs Technical College by George Swinburne in order to serve those without access to further education in Melbourne’s eastern suburbs. Its main campus is located in Hawthorn, a suburb of Melbourne which is located 7.5 km from the Melbourne central business district.

    In addition to its main Hawthorn campus, Swinburne has campuses in the Melbourne metropolitan area at Wantirna and Croydon as well as a campus in Sarawak, Malaysia.
    In the 2016 QS World University Rankings, Swinburne was ranked 32nd for art and design, making it one of the top art and design schools in Australia and the world.

  • richardmitnick 11:29 am on July 21, 2019 Permalink | Reply
    Tags: , , , , , , FRB's Fast radio Bursts, Is anyone out there?, , , Shelley Wright of UCSD and Niroseti at UCSC Lick Observatory's Nickel Telescope,   

    From WIRED: “An Alien-Hunting Tech Mogul May Help Solve a Space Mystery” 

    Wired logo

    From WIRED

    Katia Moskvitch

    Yuri Milner. Billy H.C. Kwok/Getty Images

    In spring 2007, David Narkevic, a physics student at West Virginia University, was sifting through reams of data churned out by the Parkes telescope—a dish in Australia that had been tracking pulsars, the collapsed, rapidly spinning cores of once massive stars.

    CSIRO/Parkes Observatory, located 20 kilometres north of the town of Parkes, New South Wales, Australia

    His professor, astrophysicist Duncan Lorimer, had asked him to search for a recently discovered type of ultra-rapid pulsar dubbed RRAT. But buried among the mountain of data, Narkevic found an odd signal that seemed to come from the direction of our neighboring galaxy, the Small Magellanic Cloud.


    Small Magellanic Cloud. NASA/ESA Hubble and ESO/Digitized Sky Survey 2

    The signal was unlike anything Lorimer had encountered before. Although it flashed only briefly, for just five milliseconds, it was 10 billion times brighter than a typical pulsar in the Milky Way galaxy. It was emitting in a millisecond as much energy as the sun emits in a month.

    What Narkevic and Lorimer found was the first of many bizarre, ultra-powerful flashes detected by our telescopes. For years the flashes first seemed either improbable or at least vanishingly rare. But now researchers have observed more than 80 of these Fast Radio Bursts, or FRBs. While astronomers once thought that what would be later dubbed the “Lorimer Burst” was a one-off, they now agree that there’s probably one FRB happening somewhere in the universe nearly every second.

    And the reason for this sudden glut of discoveries? Aliens. Well, not aliens per se, but the search for them. Among the scores of astronomers and researchers working tirelessly to uncover these enigmatic signals is an eccentric Russian billionaire who, in his relentless hunt for extraterrestrial life, has ended up partly bankrolling one of the most complex and far-reaching scans of our universe ever attempted.

    Ever since Narkevic spotted the first burst, scientists have been wondering what could produce these mesmerizing flashes in deep space. The list of possible sources is long, ranging from the theoretical to the simply unfathomable: colliding black holes, white holes, merging neutron stars, exploding stars, dark matter, rapidly spinning magnetars, and malfunctioning microwaves have all been proposed as possible sources.

    While some theories can now be rejected, many live on. Finally though, after more than a decade of searching, a new generation of telescopes is coming online that could help researchers to understand the mechanism that is producing these ultra-powerful bursts. In two recent back-to-back papers, one published last week and one today, two different arrays of radio antennas—the Australian Square Kilometer Array Pathfinder (ASKAP) and Caltech’s Deep Synoptic Array 10 at the Owens Valley Radio Observatory (OVRO) in the US—have for the first time ever been able to precisely locate two different examples of these mysterious one-off FRBs.

    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.

    Caltech’s Deep Synoptic Array 10 dish array at Owens Valley Radio Observatory, near Big Pine, California USA, Altitude 1,222 m (4,009 ft

    Physicists are now expecting that two other new telescopes—Chime (the Canadian Hydrogen Intensity Mapping Experiment) in Canada and MeerKAT in South Africa—will finally tell us what produces these powerful radio bursts.

    CHIME Canadian Hydrogen Intensity Mapping Experiment -A partnership between the University of British Columbia, the University of Toronto, McGill University, Yale and the National Research Council in British Columbia, at the Dominion Radio Astrophysical Observatory in Penticton, British Columbia, CA Altitude 545 m (1,788 ft)

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

    But Narkevic’s and Lorimer’s discovery nearly got binned. For a few months after they first spotted the unusually bright burst, it looked like the findings wouldn’t make it any further than Lorimer’s office walls, just beyond the banks of the Monongahela River that slices through the city of Morgantown in West Virginia.

    Soon after detecting the burst, Lorimer asked his former graduate adviser Matthew Bailes, an astronomer at Swinburne University in Melbourne, to help him plot the signal—which to astronomers is now a famous and extremely bright energy peak, rising well above the power of any known pulsar. The burst seemed to come from much, much further away than where the Parkes telescope would usually find pulsars; in this case, probably from another galaxy, potentially billions of light-years away.

    “It just looked beautiful. I was like, ‘Whoa, that’s amazing.’ We nearly fell off our chairs,” recalls Bailes. “I had trouble sleeping that night because I thought if this thing is really that far away and that insanely bright, it’s an amazing discovery. But it better be right.”

    Within weeks, Lorimer and Bailes crafted a paper and sent it to Nature—and swiftly received a rejection. In a reply, a Nature editor raised concerns that there had been only one event, which appeared way brighter than seemed possible. Bailes was disappointed, but he had been in a worse situation before. Sixteen years earlier, he and fellow astronomer Andrew Lyne had submitted a paper claiming to have spotted the first ever planet orbiting another star—and not just any star but a pulsar. The scientific discovery turned out to be a fluke of their telescope. Months later, Lyne had to stand up in front of a large audience at an American Astronomical Society conference and announce their mistake. “It’s science. Anything can happen,” says Bailes. This time around, Bailes and Lorimer were certain that they had it right and decided to send their FRB paper to another journal, Science.

    After it was published, the paper immediately stirred interest; some scientists even wondered whether the mysterious flash was an alien communication. This wasn’t the first time that astronomers had reached for aliens as the answer for a seemingly inexplicable signal from space; in 1967, when researchers detected what turned out to be the first pulsar, they also wondered whether it could be a sign of intelligent life.

    Just like Narkevic decades later, Cambridge graduate student Jocelyn Bell had stumbled across a startling signal in the reams of data gathered by a radio array in rural Cambridgeshire.

    Women in STEM – Dame Susan Jocelyn Bell Burnell

    Dame Susan Jocelyn Bell Burnell, discovered pulsars with radio astronomy. Jocelyn Bell at the Mullard Radio Astronomy Observatory, Cambridge University, taken for the Daily Herald newspaper in 1968. Denied the Nobel.

    Dame Susan Jocelyn Bell Burnell at work on first plusar chart 1967 pictured working at the Four Acre Array in 1967. Image courtesy of Mullard Radio Astronomy Observatory.

    Dame Susan Jocelyn Bell Burnell 2009

    Dame Susan Jocelyn Bell Burnell (1943 – ), still working from http://www. famousirishscientists.weebly.com

    Not much of the array is left today; in the fields near the university where it once stood, there’s an overgrown hedge, hiding a collection of wonky, sad-looking wooden poles that were once covered in a web of copper wire designed to detect radio waves from faraway sources. The wire has long been stolen and sold on to scrap metal dealers.

    “We did seriously consider the possibility of aliens,” Bell says, now an emeritus professor at Oxford University. Tellingly, the first pulsar was half-jokingly dubbed LGM-1 —for little green men. With only half a year left until the defense of her PhD thesis, she was less than thrilled that “some silly lot of little green men” were using her telescope and her frequency to signal to planet Earth. Why would aliens “be using a daft technique signaling to what was probably still a rather inconspicuous planet?” she once wrote in an article for Cosmic Search Magazine.

    Just a few weeks later, however, Bell spotted a second pulsar, and then a third just as she got engaged, in January 1968. Then, as she was defending her thesis and days before her wedding, she discovered a fourth signal in yet another part of the sky. Proof that pulsars had to be a natural phenomenon of an astrophysical origin, not a signal from intelligent life. Each new signal made the prospect even more unlikely that groups of aliens, separated by the vastness of the space, were somehow coordinating their efforts to send a message to an uninteresting hunk of rock on the outskirts of the Milky Way.

    Lorimer wasn’t so lucky. After the first burst, six years would pass without another detection. Many scientists began to lose interest. The microwave explanation persisted for a while, says Lorimer, as skeptics sneered at the notion of finding a burst that was observed only once. It didn’t help that in 2010 Parkes detected 16 similar pulses, which were quickly proven to be indeed caused by the door of a nearby microwave oven that had been opened suddenly during its heating cycle.

    Yuri Milner on stage with Mark Zuckerberg at a Breakthrough Prize event in 2017. Kimberly White/Getty Images

    When Avi Loeb first read of Lorimer’s unusual discovery, he too wondered if it was nothing more than the result of some errant wiring or miscalibrated computer. The chair of the astronomy department at Harvard happened to be in Melbourne in November 2007, just as Lorimer’s and Bailes’ paper appeared in Science, so he had a chance to discuss the odd burst with Bailes. Loeb thought the radio flash was a compelling enigma—but not much more than that.

    Still, that same year Loeb wrote a theoretical paper arguing that radio telescopes built to detect very specific hydrogen emissions from the early universe would also be able to eavesdrop on radio signals from alien civilizations up to about 10 light-years away. “We have been broadcasting for a century—so another civilization with the same arrays can see us from a distance out to 50 light-years,” was Loeb’s reasoning. He followed up with another paper on the search for artificial lights in the solar system. There, Loeb showed that a city as bright as Tokyo could be detected with the Hubble Space Telescope even if it was located right at the edge of the solar system. In yet another paper he argued how to detect industrial pollution in planetary atmospheres.

    Ever since he was a little boy growing up in Israel, Loeb has been fascinated with life—on Earth and elsewhere in the universe. “Currently, the search for microbial life is part of the mainstream in astronomy—people are looking for the chemical fingerprints of primitive life in the atmosphere of exoplanets,” says Loeb, who first dabbled in philosophy before his degree in physics.

    But the search for intelligent life beyond Earth should also be part of the mainstream, he argues. “There is a taboo, it’s a psychological and sociological problem that people have. It’s because there is the baggage of science fiction and UFO reports, both of which have nothing to do with what actually goes on out there in space,” he adds. He’s frustrated with having to explain—and defend—his point of view. After all, he says, billions have been poured into the search for dark matter over decades with zero results. Should the search for extraterrestrial intelligence, more commonly known as SETI, be regarded as even more fringe than this fruitless search?

    Lorimer didn’t follow Loeb’s SETI papers closely. After six long and frustrating years, his luck turned in 2013, when a group of his colleagues—including Bailes—spotted four other bright radio flashes in Parkes’ data. Lorimer felt vindicated and relieved. More detections followed and the researchers were on a roll: At long last, FRBs had been confirmed as a real thing. After the first event was dubbed “Lorimer’s Burst,” it swiftly made it onto the physics and astronomy curricula of universities around the globe. In physics circles, Lorimer was elevated to the position of a minor celebrity.

    Keeping an eye on events from a distance was Loeb. One evening in February 2014, at a dinner in Boston, he started chatting to a charismatic Russian-Israeli called Yuri Milner, a billionaire technology investor with a background in physics and a well-known name in Silicon Valley. Ever since he could remember, Milner had been fascinated with life beyond Earth, a subject close to Loeb’s heart; the two instantly hit it off.

    Milner came to see Loeb again in May the following year, at Harvard, and asked the academic how long it would take to travel to Alpha Centauri, the star system closest to Earth.

    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker

    Loeb replied he would need half a year to identify the technology that would allow humans to get there in their lifetime. Milner then asked Loeb to lead Breakthrough Starshot, one of five Breakthrough Initiatives the Russian oligarch was about to announce in a few weeks—backed by $100 million of his own money and all designed to support SETI.

    Breakthrough Starshot Initiative

    Breakthrough Starshot

    ESO 3.6m telescope & HARPS at LaSilla, 600 km north of Santiago de Chile at an altitude of 2400 metres.

    SPACEOBS, the San Pedro de Atacama Celestial Explorations Observatory is located at 2450m above sea level, north of the Atacama Desert, in Chile, near to the village of San Pedro de Atacama and close to the border with Bolivia and Argentina

    SNO Sierra Nevada Observatory is a high elevation observatory 2900m above the sea level located in the Sierra Nevada mountain range in Granada Spain and operated maintained and supplied by IAC

    Teide Observatory in Tenerife Spain, home of two 40 cm LCO telescopes

    Observatori Astronòmic del Montsec (OAdM), located in the town of Sant Esteve de la Sarga (Pallars Jussà), 1,570 meters on the sea level

    Bayfordbury Observatory,approximately 6 miles from the main campus of the University of Hertfordshire

    Fast-forward six months, and at the end of December 2015 Loeb got a call asking him to prepare a presentation summarizing his recommended technology for the Alpha Centauri trip. Loeb was visiting Israel and about to head on a weekend trip to a goat farm in the southern part of the country. “The following morning, I was sitting next to the reception of the farm—the only location with internet connectivity—and typing the PowerPoint presentation that contemplated a lightsail technology for Yuri’s project,” says Loeb. He presented it at Milner’s home in Moscow two weeks later, and the Breakthrough Initiatives were announced with fanfare in July 2015.

    The initiatives were an adrenaline shot in the arm of the SETI movement—the largest ever private cash injection into the search for aliens. One of the five projects is Breakthrough Listen, which was championed, among others, by the famous astronomer Stephen Hawking (who has died since) and British astronomer royal Martin Rees.

    Breakthrough Listen Project


    UC Observatories Lick Autmated Planet Finder, fully robotic 2.4-meter optical telescope at Lick Observatory, situated on the summit of Mount Hamilton, east of San Jose, California, USA

    GBO radio telescope, Green Bank, West Virginia, USA

    CSIRO/Parkes Observatory, located 20 kilometres north of the town of Parkes, New South Wales, Australia

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

    Newly added

    CfA/VERITAS, a major ground-based gamma-ray observatory with an array of four 12m optical reflectors for gamma-ray astronomy in the GeV – TeV energy range. Located at Fred Lawrence Whipple Observatory, Mount Hopkins, Arizona, US in AZ, USA, Altitude 2,606 m (8,550 ft)

    Echoing the film Contact, with Jodie Foster playing an astronomer listening out for broadcasts from aliens (loosely based on real-life SETI astronomer Jill Tarter), the project uses radio telescopes around the world to look for any signals from extraterrestrial intelligence.

    Jill Tarter Image courtesy of Jill Tarter

    After the Breakthrough Initiatives were announced, Milner’s money quickly got invested into the deployment of cutting-edge technology—such as computer storage and new receivers—at existing radio telescopes, including Green Bank in West Virginia and Parkes in Australia; whether the astronomers using these observatories believed in alien life or not, they welcomed the investment with open arms. It didn’t take long to receive the first scientific returns.

    After the Breakthrough Initiatives were announced, Milner’s money quickly got invested into the deployment of cutting-edge technology—such as computer storage and new receivers—at existing radio telescopes, including Green Bank in West Virginia and Parkes in Australia; whether the astronomers using these observatories believed in alien life or not, they welcomed the investment with open arms. It didn’t take long to receive the first scientific returns.

    In August 2015 one of the previously spotted FRBs decided to make a repeat appearance, triggering headlines worldwide because it was so incredibly powerful, brighter than the Lorimer Burst and any other FRB. It was dubbed “the repeater” and is also known as the Spitler Burst, because it was first discovered by astronomer Laura Spitler of the Max Planck Institute for Radio Astronomy in Bonn, Germany.

    Max Planck Institute for Radio Astronomy

    Max Planck Institute for Radio Astronomy Bonn Germany

    Over the next few months, the burst flashed many more times, not regularly, but often enough to allow researchers to determine its host galaxy and consider its possible source—likely a highly magnetized, young, rapidly spinning neutron star (or magnetar).

    This localization was done with the Very Large Array (VLA), a group of 27 radio dishes in New Mexico that feature heavily in the film Contact. But the infrastructure at Green Bank Telescope upgraded by Breakthrough Listen caught the repeating flashes many more times, says Lorimer—allowing researchers to study its host galaxy more in detail. “It’s wonderful—they have a mission to find ET, but along the way they want to show that this is producing other useful results for the scientific community,” he adds. Detecting FRBs has quickly become one of the main objectives of Breakthrough Listen.

    Netting the repeater was both a boon and a hindrance—on the one hand, it eliminated models that cataclysmic events such as supernova explosions were causing FRBs; after all, these can happen only once. On the other hand, it deepened the mystery. The repeater lives in a small galaxy with a lot of star formation—the kind of environment where a neutron star could be born, hence the magnetar model. But what about all the other FRBs that don’t repeat?

    Researchers started to think that perhaps there were different types of these bursts, each with its own source. Scientific conferences still buzz with talks of mights and might-nots, with physicists eagerly debating possible sources of FRBs in corridors and at conference bars. In March 2017, Loeb caused a media frenzy by suggesting that FRBs could actually be of alien origin—solar-powered radio transmitters that might be interstellar light sails pushing huge spaceships across galaxies.

    That Parkes is part of the SETI project is obvious to any visitor. Walking up the flight of stairs to the circular operating tower below the dish, every button, every door, and every wall nostalgically screams 1960s, until you reach the control room full of modern screens where astronomers remotely control the antenna to observe pulsars.

    Up another flight of stairs is the data storage room, stacked with columns and columns of computer drives full of blinking lights. One thick column of hard drives is flashing neon blue, put there by Breakthrough Listen as part of a cutting-edge recording system designed to help astronomers search for every possible radio signal in 12 hours of data, much more than ever before. Bailes, who now splits his time between FRB search and Breakthrough Listen, takes a smiling selfie in front of Milner’s drives.

    While many early FRB discoveries were made with veteran telescopes—single mega dishes like Parkes and Green Bank—new telescopes, some with the financial backing of Breakthrough Listen, are now revolutionizing the FRB field.

    Deep in South African’s semi-desert region of the Karoo, eight hours by car from Cape Town, stands an array of 64 dishes, permanently tracking space. They are much smaller than their mega-dish cousins, and all work in unison. This is MeerKAT [above], another instrument in Breakthrough Listen’s growing worldwide network of giant telescopes. Together with a couple of other next-generation instruments, this observatory might hopefully tell us one day, probably in the next decade, what FRBs really are.

    The name MeerKAT means “More KAT,” a follow up to KAT 7, the Karoo Array Telescope of seven antennas—although real meerkats do lurk around the remote site, sharing the space with wild donkeys, horses, snakes, scorpions and kudus, moose-sized mammals with long, spiraling antlers. Visitors to MeerKAT are told to wear safety leather boots with steel toes as a precaution against snakes and scorpions. They’re also warned about the kudus, which are very protective of their calves and recently attacked the pickup truck of a security guard, turning him and his car over. Around MeerKAT there is total radio silence; all visitors have to switch off their phones and laptops. The only place with connectivity is an underground “bunker” shielded by 30-centimeter-thick walls and a heavy metal door to protect the sensitive antennas from any human-made interference.

    MeerKAT is one of the two precursors to a much bigger future radio observatory—the SKA, or Square Kilometer Array.

    SKA Square Kilometer Array

    SKA South Africa

    Once SKA is complete, scientists will have added another 131 antennas in the Karoo. The first SKA dish has just been shipped to the MeerKAT site from China. Each antenna will take several weeks to assemble, followed by a few more months of testing to see whether it actually works the way it should. If all goes well, more will be commissioned, built, and shipped to this faraway place, where during the day the dominant color is brown; as the sun sets, however, the MeerKAT dishes dance in an incredible palette of purples, reds, and pinks, as they welcome the Milky Way stretching its starry path just above. MeerKAT will soon be an incredible FRB machine, says Bailes.

    There is another SKA precursor—ASKAP in Australia.

    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.

    Back in 2007, when Lorimer was mulling over the Nature rejection, Ryan Shannon was finishing his PhD in physics at Cornell University in New York—sharing the office with Laura Spitler, who would later discover the Spitler Burst. Shannon had come to the US from Canada, growing up in a small town in British Columbia. About half an hour drive from his home is the Dominion and Radio Astronomical Observatory (DRAO)—a relatively small facility that was involved in building equipment for the VLA.


    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)

    Subconsciously, says Shannon, DRAO must have impacted his choice of career. And it was at DRAO that a few years later a totally new telescope—Chime [above]—would be built that would greatly impact the nascent field of FRB research. But in 2007 that was still to come. After graduating from Cornell in 2011, Shannon decided not to stay close to home—“something my mum would’ve wanted.” Instead, he moved to Australia and ultimately to Swinburne University on the outskirts of Melbourne.

    Shannon joined Bailes’ team in 2017—and by then astronomers had begun to understand why they weren’t detecting more FRBs, even though they were already estimating that these flashes were happening hundreds of times every day, if not more. “Our big radio telescopes don’t have wide fields of view, they can’t see the entire sky—that’s why we missed nearly all FRBs in the first decade of realizing these things exist,” says Shannon.

    When he, Bailes, and other FRB hunters saw the ultra-bright repeater, the Spitler Burst, they understood that there were fast radio bursts which could be found even without gigantic telescopes like Parkes, by using instruments that have a wider field of view. So they started building ASKAP [above]—a new observatory conceived in 2012 and recently completed in the remote Australian outback. It sports 36 dishes with a 12-meter diameter each, and just like with MeerKAT, they all work together.

    To get to ASKAP, in a very sparsely populated area in the Murchison Shire of Western Australia, one has to first fly to Perth, change for a smaller plane bound for Murchison, then squeeze into a really tiny single propeller plane, or drive for five hours across 150 kilometers of dirt roads. “When it rains, it turns to mud, and you can’t drive there,” says Shannon, who went to the ASKAP site twice, to introduce the local indigenous population to the new telescope constructed—with permission—on their land and see the remote, next-generation ultra-sensitive radio observatory for himself.

    MeerKAT and ASKAP bring two very different technological approaches to the hunt for FRBs. Both observatories look at the southern sky, which makes it possible to see the Milky Way’s bright core much better than in the northern hemisphere; they complement old but much upgraded observatories like Parkes and Arecibo in South America. But the MeerKAT dishes have highly sensitive receivers which are able to detect very distant objects, while ASKAP’s novel multi-pixel receivers on each dish offer a much wider field of view, enabling the telescope to find nearby FRBs more often.

    “ASKAP’s dishes are less sensitive, but we can observe a much larger portion of the sky,” says Shannon. “So ASKAP is going to be able to see things that are usually intrinsically brighter.” Together, the two precursors will be hunting for different parts of the FRB population—since “you want to understand the entire population to know the big picture.”

    MeerKAT only started taking data in February, but ASKAP has been busy scanning the universe for FRBs for a few years now. Not only has it already spotted about 30 new bursts, but in a new paper just released in Science, Shannon and colleagues have detailed a new way to localize them despite their short duration, which is a big and important step toward being able to determine what triggers this ultra-bright radiation. Think of ASKAP’s antennas as the eye of a fly; they can scan a wide patch of the sky to spot as many bursts as possible, but the antennas can all be made to point instantly in the same direction. This way, they make an image of the sky in real time, and spot a millisecond-long FRB as it washes over Earth. That’s what Shannon and his colleagues have done, and for the first time ever, managed to net one burst they named FRB 180924 and pinpoint its host galaxy, some 4 billion light-years away, all in real time.

    Another team, at Caltech’s Owens Valley Radio Observatory (OVRO) in the Sierra Nevada mountains in California, have also just caught a new burst and traced it back to its source, a galaxy 7.9 billion light years away.

    Caltech’s Deep Synoptic Array 10 dish array at Owens Valley Radio Observatory, near Big Pine, California USA, Altitude 1,222 m (4,009 ft

    And just like Shannon, they didn’t do it with a single dish telescope but a recently built array of 10 4.5-meter antennas called the Deep Synoptic Array-10. The antennas act together like a mile-wide dish to cover an area on the sky the size of 150 full moons. The telescope’s software then processes an amount of data equivalent to a DVD every second. The array is a precursor for the Deep Synoptic Array that, when built by 2021, will sport 110 radio dishes, and may be able to detect and locate more than 100 FRBs every year.

    What both ASKAP’s and OVRO’s teams found was that their presumably one-off bursts originated in galaxies very different from the home of the first FRB repeater. Both come from galaxies with very little star formation, similar to the Milky Way and very different from the home of the repeater, where stars are born at a rate of about a hundred times faster. The discoveries show that “every galaxy, even a run-of-the-mill galaxy like our Milky Way, can generate an FRB,” says Vikram Ravi, an astronomer at Caltech and part of the OVRO team.

    But the findings also mean that the magnetar model, accepted by many as the source of the repeating burst, does not really work for these one-off flashes. Perhaps, Shannon says, ASKAP’s burst could be the result of a merger of two neutron stars, similar to the one spotted two years ago by the gravitational wave detectors LIGO and Virgo in the US and Italy, because both host galaxies are very similar. “It’s a bit spooky that way,” says Shannon. One thing is clear though, he adds: The findings show that there is likely more than one type of FRBs.

    Back in Shannon’s hometown in Canada, the excitement has also been growing exponentially because of CHIME. Constructed at the same time as MeerKAT and ASKAP, this is a very different observatory; it has no dishes but antennas in the form of long buckets designed to capture light. In January, the CHIME team reported the detection of the second FRB repeater and 12 non-repeating FRBs. CHIME is expected to find many, many more bursts, and with ASKAP, MeerKAT and CHIME working together, astronomers hope to understand the true nature of the enigmatic radio flashes very soon.

    But will they fulfill Milner’s dream and successfully complete SETI, the search for extraterrestrial intelligence? Lorimer says that scientists hunting for FRBs and pulsars have for decades been working closely with colleagues involved in SETI projects.

    After all, Loeb’s models for different—alien—origins of FRBs are not fundamentally wrong. “The energetics when you consider what we know from the observations are consistent and there’s nothing wrong with that,” says Lorimer. “And as part of the scientific method, you definitely want to encourage those ideas.” He personally prefers to find the simplest natural explanation for the phenomena he observes in space—but until we manage to directly observe the source of these FRBs, all theoretical ideas should stand, as long as they are scientifically sound—whether they involve aliens or not.

    Any image repeats in this post were required for complete coverage.

    See the full article here .

    Totally missing from this article on SETI-

    SETI Institute

    SETI/Allen Telescope Array situated at the Hat Creek Radio Observatory, 290 miles (470 km) northeast of San Francisco, California, USA, Altitude 986 m (3,235 ft)

    UCSC alumna Shelley Wright, now an assistant professor of physics at UC San Diego, discusses the dichroic filter of the NIROSETI instrument. (Photo by Laurie Hatch).jpg

    Shelley Wright of UC San Diego, with NIROSETI, developed at U Toronto, at the 1-meter Nickel Telescope at Lick Observatory at UC Santa Cruz

    Laser SETI, the future of SETI Institute research

    SETI@home, a BOINC project originated in the Space Science Lab at UC Berkeley


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  • richardmitnick 10:16 am on July 6, 2019 Permalink | Reply
    Tags: , , Australian Square Kilometre Array Pathfinder (ASKAP), , Caltech Owens Valley Long Wavelength Array, , , FRB's Fast radio Bursts, FRBs are surprisingly common with perhaps 2000 of them pinpricking the sky every day, One of the big issues in astrophysics he adds is that most of the matter in the universe is invisible to us., , The vast majority are one-off events   

    From COSMOS Magazine: “A decade waiting (and working), then two FRBs nailed in a week” 

    Cosmos Magazine bloc

    From COSMOS Magazine

    06 July 2019
    Richard A Lovett

    But Australian and US astronomers took different approaches.

    An artist’s impression of Australia’s ASKAP radio telescope observing fast radio bursts.

    In less than a week as June became July, two teams of radio astronomers – one in Australia, the other in the US – announced they had independently accomplished a decade-long astronomical quest: identifying the sources of powerful blasts of intergalactic radiation known as fast radio bursts (FRBs).

    FRBs are enormous blazes of radio energy that in a few milliseconds can broadcast as much energy in radio waves as the monthly output of the sun in all forms combined.

    What causes them is unknown, but it can only be something dramatic, such as a collision between neutron stars, or even a neutron stars falling into a black hole. “For a long time, there were more theories than [known] bursts,” says Keith Bannister, an astronomer with CSIRO’s Australia Telescope National Facility (ATNF) and leader of the Australian team.

    FRBs are surprisingly common, with perhaps 2000 of them pinpricking the sky every day, Bannister says, but only a tiny fraction are detectable, “because traditional radio telescopes only see a small fraction of the sky”.

    Also, the vast majority are one-off events, making it incredibly difficult to figure out what galaxy they are coming from, once they are spotted.

    In an effort to solve this problem, Bannister’s team equipped 36 identical 12-metre radio telescopes that together form the Australian Square Kilometre Array Pathfinder (ASKAP) in Western Australia with a “phased array feed” that allowed each dish to see 36 distinct patches of the sky at once, each about 200 times larger than the full moon.

    They also upgraded their software to rapidly triangulate on an FRB via 0.1 nanosecond differences in the time it takes the signal to reach the various telescopes in the array: a method, Bannister says, that allowed them to pinpoint its origin to a precision of 1/50,000th of a degree – the width of a human hair, 200 metres away.

    The US team took a different approach. Rather than retrofitting an existing telescope array, it built a new one from the ground up.

    Due to the extreme brightness of FRBs, “Keith Bannister and I both realised that we can utilise relatively insensitive but wide field-of view telescopes to try to localise them,” says its leader, Vikram Ravi, a radio astronomer at California Institute of Technology, Pasadena.

    His team therefore purchased 10 broad-field-of-view 4.5-meter radio antennas – instruments not much larger than the best satellite TV dishes – and laid them out in the Owens Valley of eastern California, at a total cost of under $US500,000.

    Caltech Owens Valley Long Wavelength Array-currently hosts LEDA, the largest correlator ever built, Owens Valley, California, Altitude 1,222 m (4,009 ft)

    “It was a shoestring experiment,” Ravi says. “I literally moved them in place and focused them by hand.” The ultimate goal, he adds, is to expand the project to include 110 such dishes.

    Finding the sources of FRBs is important for two reasons. One is simply that it helps us figure out what causes them. The FRB located by Bannister’s team, for example, came not from the centre of its galaxy, but from its outskirts – “or at least its suburbs”, Bannister says. “This means our FRB wasn’t produced by a gigantic black hole at the galaxy’s centre.”

    Ravi adds that both the FRBs come from mature, Milky Way style galaxies. That’s interesting because the only other FRB whose source has ever been identified – a repeating burster whose repeated bursts made it easier to localise – came from a very different type of galaxy. That one had 1000 times less mass but was in a “starburst” stage, in which it was forming new stars at an extremely rapid pace.

    Based on that, one theory had been that FRBs came from the deaths of such galaxies’ most giant youthful stars, which live fast and die in blazes of glory known as superluminous supernovae.

    But such gigantic explosions are uncommon in more mature galaxies, suggesting that in the case of the two FRBs identified by Bannister’s team and Ravi’s, superluminous supernovae probably didn’t play a role.

    Localising the sources of FRBs is also important, Ravi says, because FRBs can be used as probes of the distribution of matter in the universe.

    One of the big issues in astrophysics, he adds, is that most of the matter in the universe is invisible to us.

    Much of that is dark matter, an enigmatic substance to date is detected only by its gravity, but the vast bulk of normal matter is also invisible, Ravi says. All that’s known is that it’s very hot – on the order of a million degrees or more – and very diffuse, partly contained in tenuous halos around galaxies, but possibly also dispersed throughout the intergalactic medium.

    FRBs, Ravi says, offer a way to figure out where this unseen matter lies, and how it is distributed.

    That’s because as the radio burst travels through this diffuse medium, different frequencies travel at slightly different speeds. It’s not a big difference, but it’s enough that an FRB signal can become stretched as it travels, with higher frequencies travelling faster, and lower frequencies travelling slower.

    “We observe the burst arriving first at the high frequencies, then later at the low frequencies,” Ravi says, an effect that can stretch a millisecond FRB to nearly a second.

    Different parts of the signal can also reach us by different paths, in which they start out travelling in a slightly different direction than the main part of the signal, then are refracted back into our own line of sight.

    “It’s sort of like why stars twinkle,” Ravi says.

    The effect is small, but it’s a sign that the medium through which the FRB signal propagated might have been “clumpy”, rather than uniformly distributed.

    To figure all of this out, Ravi says, it’s really useful to know how far an FRB signal has been travelling before it reaches us (and to know how many other galaxies it has passed close to. That’s another reason why it’s useful to locate the source galaxies of as many such signals as possible.

    Shami Chatterjee, a radio astronomer at Cornell University, Ithaca, New York, and leader of the team that located the source of the repeating FRB, agrees.

    Bannister’s find (and by extension, Ravi’s), he says, is “a magnificent technical achievement” that should, among other things, open the floodgates to more such findings, allowing FRBs to live up to their promise as probes of the intergalactic medium.

    “Once we have a few dozen,” he says, “FRBs will be one of the only viable probes of the intergalactic medium.”

    See the full article here .

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  • richardmitnick 2:10 pm on March 10, 2019 Permalink | Reply
    Tags: , , , , , FRB's Fast radio Bursts,   

    From Columbia University via WIRED: “Astronomers Think They Can Explain Mysterious Cosmic Bursts” 

    Columbia U bloc

    From Columbia University


    Wired logo


    Joshua Sokol

    CHIME Canadian Hydrogen Intensity Mapping Experiment -A partnership between the University of British Columbia, Dunlap Institute/CHIME Collaboration at University of Toronto, McGill University, Yale and the National Research Council in British Columbia, at the Dominion Radio Astrophysical Observatory in Penticton, British Columbia, CA

    Between this past Christmas and New Year’s Day, Brian Metzger realized he had his home to himself—no emails coming in, no classes to teach—and maybe, just maybe, the glimmer of an answer to one of astronomy’s most stubborn mysteries.

    Brian Metzger and his wife, Stacey Thomas, at the 2019 Breakthrough Prize awards ceremony, where he was recognized with the New Horizons in Physics Prize. Breakthrough Prize.

    He chased hard after the lead, worried a little error could unravel everything or that someone else would put together the same pieces first. “You’re racing a little bit against the clock, because other people probably see this as well,” said Metzger, an astrophysicist at Columbia University. “It can kind of become all-consuming.”

    Along with scores of other researchers around the world, Metzger has spent the last few years brainstorming ways to understand fast radio bursts (FRBs). These are millisecond-long blips of intense and unexplained radio signals that pop up all over the sky, temporarily outshining radio pulsars in our galaxy despite being perhaps a million times farther away. Before 2013, many astrophysicists doubted that they even existed. In the years since, researchers have invented dozens of possible explanations for what might be causing them. One catalog counts 48 separate theories, a tally that until recently outnumbered the events themselves.

    An FRB theory needs two parts, roughly akin to a suspect and a weapon in a cosmic game of Clue. The suspect is an astrophysical beast that can unleash vast sums of energy. The weapon is something that will transform that energy into a bright, head-scratchingly unusual radio signal.

    Now Metzger and his colleagues think they have reconstructed the crime scene. Earlier this month they released a paper that sketched out a way for FRBs to arise from explosions in regions of space cluttered with dense clouds of particles and magnetic fields.

    The model favors, but doesn’t require, a magnetar as the source of the explosions. A magnetar is a young neutron star that sometimes burps out charged particles in a supersize version of the coronal mass ejections that erupt on the sun. Each new blast plows into the surrounding clutter. When it does, it creates a shock wave, which in turn beams a short, laserlike flash of radio waves halfway across the universe.

    “In just very general terms, this makes a ton of sense,” said James Cordes, an astrophysicist at Cornell University, adding that while further details still need to be worked out, “I would say it’s a good horse to bet on.”

    What the astronomers really like, though, is that Metzger’s theory generates very specific predictions for what future FRBs should look like, predictions that will soon be put to make-or-break tests. A new Canadian radio telescope called CHIME is expected to find between one and 10 FRBs each day after it becomes fully operational later this year. During initial testing last summer it detected a baker’s dozen of the bursts, results that were published in January. “I think that over the next year or so we’ll be able to test this very well,” said Shriharsh Tendulkar, an astrophysicist at McGill University and a member of CHIME’s FRB team.

    At Shock Wave Speed

    The theory developed by Metzger and his colleagues Ben Margalit and Lorenzo Sironi builds on the biggest break in the FRB case so far. In 2016, a team led by Laura Spitler at the Max Planck Institute for Radio Astronomy in Bonn, Germany, published their results on the first-ever FRB known to repeat. Previously, each event had been a one-off. As a consequence, astronomers were unable to track down where they were in the sky, so while they suspected FRBs came from far beyond our galaxy, they knew nothing about where. But this one blared out burst after enigmatic burst at unpredictable intervals.

    Radio astronomers soon pinpointed its origin to a small, misshapen dwarf galaxy. Trying to squeeze out every clue from these radio signals, they found that it came from a dense region of plasma gripped by extreme magnetic fields. They also found that the burst was surrounded by a fainter, constant radio glow. And last November, the astronomer Jason Hessels (with Spitler and others) noticed something else strange: Each split-second burst actually contains a few sub-bursts that, without fail, shift downward from higher to lower radio frequencies.

    To Metzger’s team, this last clue seemed oddly familiar. In the 1950s, physicists studied the blast waves of nuclear weapons to estimate their yields. In these models, the shock fronts from nuclear explosions sweep up more gas as they expand outward. That extra weight slows down the shock, and because it slows, radiation released from the shock front shifts downward in frequency thanks to the Doppler effect.

    Metzger had been thinking this blast wave effect might hint at the true nature of FRBs when suddenly, in early January, the haul from the CHIME telescope included another repeating event. This one’s repeating radio signals showed the same downward frequency drift. “The idea was there with the first repeater,” Metzger said, “but seeing that feature of FRBs reinforced sort of put me on overdrive.”

    Now Metzger, Margalit and Sironi have released their full model, based mostly on explaining the ins and outs of the first repeater. Imagine a magnetar, a city-sized neutron star forged in a supernova only a few years or decades earlier, its surface roiling and churning. Like the sun on a bad day, this young magnetar releases occasional flares that blast out electrons, positrons and maybe heavier ions at near the speed of light.

    When this material launches, it runs into older particles vomited out during previous flares. Where the new ejecta meets the older debris, it piles up into a shock, inside which magnetic fields soar. As the shock presses outward, the electrons inside gyrate around along magnetic field lines, and that motion produces a burst of radio waves. That signal then shifts from higher to lower frequencies as the shock slows. (And presumably, far away and eons later, Earth’s astronomers get a very exciting email alert from radio telescopes.)

    Lucy Reading-Ikkanda/Quanta Magazine

    All this is still tenuous, but the idea is ready to pass or flunk based on what happens next in the FRB story. It’s the most quantitative, deeply thought-out scenario yet. “They’ve done the most-detailed calculations, and they’ve been able to make the most-specific observational predictions,” Spitler said.

    Metzger’s model predicts a number of specific features that future FRBs should share. For one: All future FRBs should follow the same downward shift in frequency. They might show gamma-ray or X-ray emission, which astronomers such as Spitler have already started to hunt for. They should live in galaxies that are forming lots of new stars and producing fresh magnetars. And when they do repeat, they should take breaks from bursting after astronomers observe a major flare. At that point, the system is so choked with material that subsequent flashes can’t make it out.

    Metzger’s model now faces a crowded bracket of other, still-viable theories. FRBs could be a consequence of merging neutron stars, which lit up both telescopes and gravitational-wave detectors for the first time in 2017.


    Neutron stars might also make FRBs when they crash into other objects like black holes or white dwarfs, when they themselves collapse into black holes, or when their magnetic field lines are plucked by fierce winds of plasma.

    And it’s not even clear if FRBs all come from a single kind of event. While Metzger’s model has a “stranglehold” on observations of the first repeater, said the astrophysicist Victoria Kaspi, also at McGill, “I personally am always a little nervous when something is so tailored to one source.” Compared with the repeaters, perhaps one-off bursts come from entirely different sources. Or, as Spitler and others pointed out last November, all FRBs might turn out to repeat if astronomers only waited around for long enough.

    The data are about to pour in, ready to narrow the field. During the past five months, while CHIME has been in a commissioning phase, researchers have found more bursts that they haven’t publicly released. Team members hope to start the official observing run in April. The Australian Square Kilometer Array, a network of 36 radio dishes in western Australia, is also trawling for more examples and working to pinpoint their exact homes. And within a few years, so will HIRAX: an array of dishes in South Africa, Botswana and Rwanda that will hunt FRBs in an environment free from ambient radio signals.

    After years of sparse data and theoretical daydreaming, a solution finally seems within reach. In mid-February, FRB-curious astronomers met in Amsterdam to share new, please-don’t-post-this-on-Twitter discoveries and discuss the idea that neutron stars are in some way responsible. “That is what is so nice about his theory coming out just recently,” wrote Amanda Weltman, a theoretical astrophysicist at the University of Cape Town, in an email. “It is a perfect time.” The researchers debated Metzger’s model, presented at the meeting by his coauthor Margalit, but wouldn’t yet commit to it. “We are on the verge of convergence,” Tendulkar said. “Let’s just put it that way.”

    See the full article here .


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    Columbia U Campus

    Columbia University was founded in 1754 as King’s College by royal charter of King George II of England. It is the oldest institution of higher learning in the state of New York and the fifth oldest in the United States.

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