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  • richardmitnick 4:19 pm on February 4, 2019 Permalink | Reply
    Tags: High energy neutrinos, In a recent multimessenger partnership IceCube researchers have joined efforts with Pan-STARRS1 astronomers to follow up high-energy neutrino alerts, ,   

    From U Wisconsin IceCube Collaboration: “Pan-STARRS1 far vision at the service of neutrino sources” 

    U Wisconsin ICECUBE neutrino detector at the South Pole

    From From U Wisconsin IceCube Collaboration

    04 Feb 2019
    Sílvia Bravo

    Pan-STARSS1, a 1.8-meter-diameter optical telescope on the island of Maui is the world’s leading near-Earth object discovery telescope. However, its large digital camera, with almost 1.4 billion pixels, can also detect galactic and extragalactic transient phenomena and has a great potential for the discovery of supernovas, some of which could be sources of high-energy neutrinos.

    Pann-STARS 1 Telescope, U Hawaii, situated at Haleakala Observatories near the summit of Haleakala in Hawaii, USA, altitude 3,052 m (10,013 ft)

    In a recent publication submitted to Astronomy and Astrophysics, the IceCube Collaboration and Pan-STARRS1 scientists have searched for counterpart transient optical emission associated with IceCube high-energy neutrino alerts. When following five alerts sent during 2016-17, researchers found one supernova worth studying, SN PS16cgx. However, a more detailed analysis showed that it is most likely a Type Ia supernova, i.e., the result of a white dwarf explosion, which is not expected to produce neutrinos.

    1
    Pan-STARRS1 riz-band false-colour 1′ × 1′subsection of the field of PS16cgx. North is up, east is left.

    Neutrino emission is expected in large amounts from supernovas, but in many cases these neutrinos have typical energies in the MeV range and are not associated with high-energy cosmic rays.

    Very high energy neutrinos, which point to cosmic-ray sources, can be produced in some types of supernovas and usually only during a very short time. Astronomers have detected more than ten thousand extragalactic supernovas, and a few more in the Milky Way––if we take into account early observations by the naked eye or with the first telescopes––but to date none of them has proven to be a source of astrophysical TeV-and-above neutrinos.

    In a recent multimessenger partnership, IceCube researchers have joined efforts with Pan-STARRS1 astronomers to follow up high-energy neutrino alerts, looking for counterpart electromagnetic emission. For small flares of neutrinos, such as the case of individual IceCube alerts, the associated electromagnetic emission can be the only way to single out a potential neutrino source. This was the case, for example, in the identification of the first likely source of high-energy neutrinos and cosmic rays following a 290-TeV neutrino detected in IceCube in September 2017.

    Moreover, only a detailed understanding of mulimessenger and multiwavelength emission can reveal the processes that power the most extreme environments in the universe.

    In fact, IceCube’s high-energy realtime alerts program was launched in 2016 to boost these types of follow-ups, trying to catch transient phenomena that would otherwise be only serendipitously observed by several telescopes at the same time.

    Pan-STARRS1 followed five of the IceCube alerts sent during the first two years of operation of the realtime program. The first alert was sent on April 27, 2016, and turned out to be the only one with a prospective counterpart emission from Pan-STARRS1 observations.

    Transient PS16cgx showed a rising light curve over two days, which is a typical signature of a young supernova, possibly undergoing a potential explosion epoch where very high energy neutrinos could be produced.

    Initial spectral observations were not able to clarify whether this was a Type Ia supernova, which is not expected to emit high-energy neutrinos, or a Type Ic supernova, a stripped core-collapse supernova that could be a cosmic-ray generator and, thus, an emitter of high-energy neutrinos.

    After further inspection, looking for more detailed features of the electromagnetic emission spectrum, researchers concluded that the observations are in reasonable agreement with emission expected from a Type Ia supernova and that, at the same time, there is no specific argument to support a classification as a Type Ic supernova. Therefore, scientists think that the IceCube neutrino and PS16cgx are not related.

    Looking at the rate of high-energy alerts with good pointing resolution in IceCube––currently, fewer than ten per year––researchers estimate that one could expect a true association of a supernova and a high-energy neutrino once every two years, assuming that all IceCube alerts can be followed up. These results also support expanding the redshift range, i.e., the distance of the transient sources, of these joint searches, which would increase the number of transient phenomena observed and, thus, the discovery potential of neutrino and cosmic-ray sources.

    IceCube employs more than 5000 detectors lowered on 86 strings into almost 100 holes in the Antarctic ice NSF B. Gudbjartsson, IceCube Collaboration

    Lunar Icecube

    IceCube DeepCore annotated

    IceCube PINGU annotated


    DM-Ice II at IceCube annotated

    See the full article here .

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    Please help promote STEM in your local schools.

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    IceCube is a particle detector at the South Pole that records the interactions of a nearly massless sub-atomic particle called the neutrino. IceCube searches for neutrinos from the most violent astrophysical sources: events like exploding stars, gamma ray bursts, and cataclysmic phenomena involving black holes and neutron stars. The IceCube telescope is a powerful tool to search for dark matter, and could reveal the new physical processes associated with the enigmatic origin of the highest energy particles in nature. In addition, exploring the background of neutrinos produced in the atmosphere, IceCube studies the neutrinos themselves; their energies far exceed those produced by accelerator beams. IceCube is the world’s largest neutrino detector, encompassing a cubic kilometer of ice.

     
  • richardmitnick 11:53 am on July 12, 2018 Permalink | Reply
    Tags: A cosmic particle spewed from a distant galaxy strikes Earth, , , , , , , High energy neutrinos, , , ,   

    From Astronomy Magazine: “A cosmic particle spewed from a distant galaxy strikes Earth” 

    Astronomy magazine

    From Astronomy Magazine

    July 12, 2018
    Michelle Hampson

    The rare detection of a high-energy neutrino hints at how these strange particles are created.

    U Wisconsin ICECUBE neutrino detector at the South Pole



    IceCube Gen-2 DeepCore PINGU annotated

    Four billion years ago, an immense galaxy with a black hole at its heart spewed forth a jet of particles at nearly the speed of light. One of those particles, a neutrino that is just a fraction of the size of a regular atom, traversed across the universe on a collision course for Earth, finally striking the ice sheet of Antarctica last September. Coincidentally, a neutrino detector planted by scientists within the ice recorded the neutrino’s charged interaction with the ice, which resulted in a blue flash of light lasting just a moment. The results are published today in the journal Science.

    This detection marks the second time in history that scientists have pinpointed the origins of a neutrino from outside of our solar system. And it’s the first time they’ve confirmed that neutrinos are created in the supermassive black holes at the centers of galaxies — a somewhat unexpected source.

    Neutrinos are highly energetic particles that rarely ever interact with matter, passing through it as though it weren’t even there. Determining the type of cosmological events that create these particles is critical for understanding the nature of the universe. But the only confirmed source of neutrinos, other than our Sun, is a supernova that was recorded in 1987.

    2
    The most recent Hubble image of SN 1987A, taken in January 2017, captures the glow of hydrogen gas around the supernova remnant.
    NASA, ESA, and R. Kirshner (Harvard-Smithsonian Center for Astrophysics and Gordon and Betty Moore Foundation) and P. Challis (Harvard-Smithsonian Center for Astrophysics)

    Physicists have a number of theories about what sort of astronomical events may create neutrinos, with some suggesting that blazars could be a source. Blazars are massive galaxies with black holes at their center, trying to suck in too much matter at once, causing jets of particles to be ejected outward at incredible speeds. Acting like the giant counterparts to terrestrial particle accelerators, blazar jets are believed to produce cosmic rays that can in turn create neutrinos.

    “This [detection] in particular is a chance of nature,” says Darren Grant, a lead scientist of the team that first discovered the high-energy neutrino, as part of the neutrino detection project IceCube. “There’s a blazar there that just happened to turn on at the right time and we happened to capture it. It’s one of those eureka moments. You hope to experience those a few times in your career and this was one of them, where everything aligned.”

    A cosmic messenger

    On September 22, 2017, the neutrino reached the Antarctica ice sheet, passing by an ice crystal at just the right angle to cause a subatomic particle (called a muon) to be created from the interaction. The resulting blue flash was recorded by one of IceCube’s 5,160 detectors, embedded within the ice. Grant was in the office when the detection occurred. This neutrino was about 300 million times more energetic than those that are emitted by the Sun.

    Grant and his colleague briefly admired the excellent image depicting the trajectory of the muon, which provides basic information necessary to begin tracing back the neutrino’s origin. However, they weren’t overly excited quite yet. His team observes about 10 to 20 high-energy neutrinos each year, but the right combination of events — in space, time and energy, for example — is required to precisely pinpoint the source of the neutrino. Such an alignment had eluded scientists so far. As Grant’s team began their analysis, though, they began to narrow in on a region: an exceptionally bright blazar called TXS 0506+056.

    3
    IceCube employs more than 5,000 detectors lowered on 86 strings into almost 100 holes in the Antarctic ice.
    NSF / B. Gudbjartsson, IceCube Collaboration

    Upon the detection, an automatic alert was sent to other astronomy teams around the world, which monitor various incoming cosmic signals, such as radio and gamma rays. A few days later a team of scientists using the MAGIC telescope in the Canary Islands responded with some exciting news: the arrival of the neutrino had coincided with a burst of gamma rays – which are extremely energetic photons – also coming from the direction of TXS 0506+056.

    MAGIC Cherenkov gamma ray telescope on the Canary island of La Palma, Spain, Altitude 2,200 m (7,200 ft)

    Other teams analyzing the region following the initial detection observed changes in X-ray emissions and radio signals too. Collectively, the data is a huge step forward for physicists in understanding blazars, and high-energy cosmological events in general.

    John Learned of University of Hawaii, Manoa, who was not involved in the study, says that the data linking the blazar as the source is “overwhelmingly convincing” and he emphasizes the importance of this finding. “This is the realization of many long-standing scientific dreams. Neutrinos at high energies can tell us about the guts of these extremely luminous objects … The implications of the finding are that we are now finally … [able] to see inside the most dense and luminous objects, and to further our grasp of the ‘deus ex machina’ which drives them and powers these awesome phenomena.”

    For example, this detection also provides the first evidence that a blazar can produce the high-energy protons needed to generate neutrinos such as the one IceCube saw.

    4
    Blazars are active supermassive black holes sucking in immense amounts of material, which form swirling accretion disks and generate high-powered particle jets that churn out particles that astronomers have believed eventually result in neutrinos. DESY, Science Communication Lab

    Sources of high-energy protons also remain largely a mystery, so the identification of one such source is another big step forward for astronomers. “It’s really quite convincing that we’ve unlocked one piece of that puzzle,” says Grant.

    Gems from the past

    And it gets even better. “We looked back at [archival] data [that had been collected since 2010], in the direction of this particular blazar source, and what we discovered was really quite remarkable,” Grant says. A barrage of high-energy neutrinos and gamma rays from TXS 0506+056 reached Earth in late 2014 and early 2015. At the time, IceCube’s real-time alert system was not fully functioning, so other scientific teams were not aware of the detection. But now these previous neutrinos are on scientists’ radar, providing a more long-term glimpse into the life of a blazar.

    “That was really icing on the cake, because what [the archived data indicated] was that the source had been active in neutrinos in the past, and then again, with this very high-energy neutrino in September — those are the pieces that really start to come together, to make a picture of what’s happening there,” explains Grant.

    6
    The alert IceCube sent once the neutrino’s interaction with the ice was detected resulted in follow-up observations from about 20 Earth- and space-based observatories. This immense effort resulted in the clear identification of a distant blazar as the source of the neutrino — as well as gamma rays, X-rays, radio emission, and optical light.
    Nicolle R. Fuller/NSF/IceCube

    The data also reveal that radio emissions from TXS 0506+056 gradually increased in the 18 months leading up to the September neutrino detection. Greg Sivakoff, an associate professor at the University of Alberta who helped analyze the data, says one possibility is that the black hole began to consume surrounding matter much faster during this time, causing the jet of particles being emitted to speed up. He says, “If the jet gets too fast too quickly, it might run into some of its own material, creating what astronomers call a shock. Shocks have long been used in astronomy to explain how particles are accelerated to high energies. We are not sure that this is the answer yet, but this may be part of the story.”

    Scientists are continuing to monitor TXS 0506+056, hoping to learn more about this colossal event. One team conducted a detailed analysis to determine how far away the blazar is from us, astounded to discover that it is a whopping four billion light years away. While TXS 0506+056 was always considered a bright object in the sky, this luminosity at such a distance makes it one of the brightest objects in the universe. No doubt future studies of this powerful blazar will yield valuable insights into the most energetic events to occur in our universe.

    Learned says, “We are just opening a new door and I would love to be able to say what we shall find beyond. But I guarantee that initiating this new means of observing the universe will bring surprises and new insights. In an extreme analogy it is like asking Galileo what his new astronomical telescope will reveal.”

    See the full article here .
    See also From CfA: VERITAS Supplies Critical Piece to Neutrino Discovery Puzzle


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    Please help promote STEM in your local schools.

    Stem Education Coalition

     
  • richardmitnick 9:07 am on October 8, 2016 Permalink | Reply
    Tags: , , , , High energy neutrinos, , ,   

    From IceCube: “Neutrinos and gamma rays, a partnership to explore the extreme universe” 

    icecube
    IceCube South Pole Neutrino Observatory

    07 Oct 2016
    Sílvia Bravo

    Solving the mystery of the origin of cosmic rays will not happen with a “one-experiment show.” High-energy neutrinos might be produced by galactic supernova remnants or by active galactic nuclei as well as other potential sources that are being sought. And, if our models are right, gamma rays at lower energies could also help identify neutrino sources and, thus, cosmic-ray sources. It’s sort of a “catch one, get them all” opportunity.

    IceCube’s collaborative efforts with gamma-ray, X-ray, and optical telescopes started long ago. Now, the IceCube, MAGIC and VERITAS collaborations present updates to their follow-up programs that will allow the gamma-ray community to collect data from specific sources during periods when IceCube detects a higher number of neutrinos.

    MAGIC Cherenkov gamma ray telescope  on the Canary island of La Palma, Spain
    MAGIC Cherenkov gamma ray telescope on the Canary island of La Palma, Spain

    CfA/VERITAS, AZ, USA
    “CfA/VERITAS, AZ, USA

    Details of the very high energy gamma-ray follow-up program have been submitted to the Journal of Instrumentation.

    1
    Image: Juan Antonio Aguilar and Jamie Yang. IceCube/WIPAC

    From efforts begun by its predecessor AMANDA, IceCube initiated a gamma-ray follow-up program with MAGIC for sources of electromagnetic radiation emissions with large time variations. If we can identify periods of increased neutrino emission, then we can look for gamma-ray emission later on from the same direction.

    For short transient sources, such as gamma-ray bursts and core-collapse supernovas, X-ray and optical wavelength telescopes might also detect the associated electromagnetic radiation. In this case, follow-up observations are much more time sensitive, with electromagnetic radiation expected only a few hours after neutrino emission from a GRB or a few weeks after a core-collapse supernova.

    Updates to this transient follow-up system will use a multistep high-energy neutrino selection to send alerts to gamma-ray telescopes, such as MAGIC and VERITAS, if clusters of neutrinos are observed from a predefined list of potential sources. The combined observation of an increased neutrino and gamma-ray flux could point us to the first source of astrophysical neutrinos. Also, the information provided by both cosmic messengers will improve our understanding of the physical processes that power those sources.

    The initial selection used simple cuts on a number of variables to discriminate between neutrinos and the atmospheric muon background. IceCube, MAGIC, and VERITAS are currently testing a new event selection that uses learning machines and other sophisticated discrimination algorithms to take into account the geometry and time evolution of the hit pattern in IceCube events. Preliminary studies show that this advanced event selection has a sensitivity comparable to offline point-source samples, with a 30-40% sensitivity increase in the Northern Hemisphere with respect to the old selection. The new technique does not rely only on catalogues of sources and allows observing neutrino flares in the Southern Hemisphere. Thus, those alerts will also be forwarded to the H.E.S.S. collaboration, expanding the gamma-ray follow-up program to the entire sky.

    HESS Cherenko Array, located on the Cranz family farm, Göllschau, in Namibia, near the Gamsberg
    HESS Cherenko Array, located on the Cranz family farm, Göllschau, in Namibia, near the Gamsberg

    During the last few years, IceCube has sent several alerts to VERITAS and MAGIC that have not yet resulted in any significant correlation between neutrino and gamma-ray emission. For some of those, however, the source was not in the reach of the gamma-ray telescopes, either because it was out of the field of view or due to poor weather conditions. Follow-up studies have allowed setting new limits on high-energy gamma-ray emission.

    With the increased sensitivity in the Northern Hemisphere and new alerts to telescopes in the Southern Hemisphere, the discovery potential of these joint searches for neutrino and gamma-ray sources is greatly enhanced. Stay tuned for new results!

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    ICECUBE neutrino detector

    IceCube neutrino detector interior

    IceCube is a particle detector at the South Pole that records the interactions of a nearly massless sub-atomic particle called the neutrino. IceCube searches for neutrinos from the most violent astrophysical sources: events like exploding stars, gamma ray bursts, and cataclysmic phenomena involving black holes and neutron stars. The IceCube telescope is a powerful tool to search for dark matter, and could reveal the new physical processes associated with the enigmatic origin of the highest energy particles in nature. In addition, exploring the background of neutrinos produced in the atmosphere, IceCube studies the neutrinos themselves; their energies far exceed those produced by accelerator beams. IceCube is the world’s largest neutrino detector, encompassing a cubic kilometer of ice.

     
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