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  • richardmitnick 6:03 pm on December 17, 2018 Permalink | Reply
    Tags: , , , U Wisconsin IceCube and IceCube Gen-2   

    From U Wisconsin IceCube Collaboration: “IceCube and HAWC unite efforts to dissect the cosmic-ray anisotropy” 

    U Wisconsin ICECUBE neutrino detector at the South Pole

    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

    From From U Wisconsin IceCube Collaboration

    17 Dec 2018
    Sílvia Bravo

    HAWC High Altitude Cherenkov Experiment, located on the flanks of the Sierra Negra volcano in the Mexican state of Puebla at an altitude of 4100 meters(13,500ft), at WikiMiniAtlas 18°59′41″N 97°18′30.6″W. searches for cosmic rays

    It was only a few years ago that IceCube provided the first view of the arrival direction distribution of cosmic rays in the Southern Hemisphere. Observations in the Northern Hemisphere, including those from the HAWC gamma-ray observatory earlier this year, had already shown that the number of cosmic rays hitting the atmosphere varied depending on their direction and energy. The anisotropy patterns found in the Southern Hemisphere supported models that pointed to the local interstellar magnetic field as the origin of the dominant effects of this observation.

    In an attempt to better understand the anisotropy, the IceCube Neutrino Observatory and HAWC have united their efforts to study cosmic-ray arrival directions in both hemispheres at the same primary energy. The goal of this combined observation was to get a nearly full-sky coverage to study the propagation of cosmic rays with median energy of 10 TeV through our local interstellar medium as well as the interactions between interstellar and heliospheric magnetic fields. Results have just been accepted for publication in The Astrophysical Journal and include measurements on how the anisotropy modulations are distributed over different angular scales.

    1
    he all-sky distribution in relative intensity of 10 TeV cosmic rays (CR) obtained with the HAWC and IceCube observation. Blue means deficit with respect to the mean CR flux and red excess. On the left, the white arrow indicates the direction of motion of the solar system through the local interstellar medium; the black lines indicate the local interstellar magnetic field lines outside of the heliosphere. On the right, the view of the opposite side of the sky.

    Cosmic rays swirling through space constantly bombard Earth from every direction. Out of every 1,000 cosmic rays there is at most one cosmic ray with a preferred (nonrandom) arrival direction. We refer to this as anisotropy, and this tiny 0.1% effect is what scientists would like to decipher.

    The variations are small but significant and show two different amplitude scales, a large-scale anisotropy with variations of one per mille and a small-scale anisotropy with variations of one per ten thousand.

    The cosmic-ray anisotropy is associated with the distribution of the cosmic ray sources and with the properties of the magnetic fields through which the cosmic rays propagate. However, the limited field of view of any ground-based experiment prevents us from capturing the anisotropy features that are wider than the observable sky.

    The angular variations of this anisotropy support the contribution of two different mechanisms: the mean propagation along the turbulent interstellar magnetic field, which is expected to isotropically diffuse cosmic rays, and the deflection in nearby magnetic fields—the local interstellar magnetic field (LIMF) and the heliosphere—whose relative contribution depends on energy.

    Ground-based experiments typically require averaging the number of cosmic rays along each declination band, to estimate its response to a perfectly isotropic flux. This has the effect of washing out the vertical (north-south) component of the anisotropy. On the other hand, the heliospheric deflections induced on the cosmic-ray particle distribution by the long interstellar propagation are partially aligned along the LIMF and not significantly affected by the north-south blindness.

    In this study, IceCube and HAWC joined efforts to get a full-sky coverage that captures for the first time a full, unbiased picture of the cosmic-ray anisotropy. The work used five years of IceCube data, from May 2011 to May 2016, and two years of HAWC data, from May 2015 and May 2017.

    The fit of the IceCube-HAWC observed anisotropy at 10 TeV shows the expected alignment with the LIMF. Researchers then used this deviation to derive the north-south component of the dipole anisotropy.

    Previous studies of the anisotropy have shown that the dominant dipole variation starts to decrease around 10 TeV and then to abruptly increase again at energies around 100 TeV. This had been explained as a possible effect of the heliosphere, which has a much larger impact for lower energy cosmic rays.

    Deviations of the anisotropy from the LIMF could be due to the motion of the observer and/or to the effects of the heliosphere on the LIMF. However, only a full-sky study of the cosmic-ray anisotropy at different energies will make it possible to distinguish between these or other possible effects, thus enabling a deeper understanding of the properties of the LIMF and the heliosphere.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition
    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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  • richardmitnick 1:44 pm on November 10, 2018 Permalink | Reply
    Tags: A pair of inspiraling neutron stars, A possible scenario would be a neutrino created in the relativistic outflows of a merger of binary neutron stars or black holes or the core-collapse of a supernova all cataclysmic cosmic environments , , , , , , , , , , , The detection of gravitational waves and neutrinos from a single source would set a new milestone in multimessenger astronomy, The scrutiny of an astrophysical source with three different messengers would not only be the next breakthrough in the field but would also confirm that multimessenger astronomy is the only path to a , U Wisconsin IceCube and IceCube Gen-2   

    From U Wisconsin IceCube Collaboration: “Multimessenger searches for sources of gravitational waves and neutrinos” 

    U Wisconsin ICECUBE neutrino detector at the South Pole

    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

    From From U Wisconsin IceCube Collaboration

    09 Nov 2018
    Sílvia Bravo

    1
    Artist’s now iconic illustration of two merging neutron stars. The rippling space-time grid represents gravitational waves that travel out from the collision, while the narrow beams show the bursts of gamma rays and neutrinos that are shot out just seconds after the gravitational waves. Image: NSF/LIGO/Sonoma State University/A. Simonnet

    Last year was an extraordinary year for multimessenger astrophysics. In August 2017, a gravitational wave and its electromagnetic counterpart emission were detected from a pair of inspiraling neutron stars. Only a month later, a high-energy neutrino was detected at the South Pole and electromagnetic follow-up observations helped identify the first likely source of very high energy neutrinos and cosmic rays.

    Since then, the dream of astrophysicists has been to join neutrinos and gravitational waves in the detection of a multimessenger source. According to our understanding of the extreme universe, a possible scenario would be a neutrino created in the relativistic outflows of a merger of binary neutron stars or black holes or the core-collapse of a supernova, all cataclysmic cosmic environments that should also produce gravitational waves.

    The IceCube, LIGO, Virgo, and ANTARES collaborations have used data from the first observing period of Advanced LIGO and from the two neutrino detectors to search for coincident neutrino and gravitational wave emission from transient sources.

    The goal was to explore the discovery potential of a multimessenger observation, i.e., of a source detection that needs both messengers to confirm its astrophysical origin. Scientists did not find any significant coincidence. The results, recently submitted to The Astrophysical Journal, set a constraint on the density of these sources.

    The detection of gravitational waves and neutrinos from a single source would set a new milestone in multimessenger astronomy, allowing the simultaneous study of the inner and outer processes powering high-energy emission from astrophysical objects.

    A joint detection would also significantly improve the localization of the source and enable faster and more precise electromagnetic follow-up observations. The scrutiny of an astrophysical source with three different messengers would not only be the next breakthrough in the field but would also confirm that multimessenger astronomy is the only path to a profound understanding of the extreme universe.

    Even though the current search was very limited in time, researchers have set a strong constraint for joint emission from core-collapse supernovas, while binary mergers remain secure as potential multimessenger sources of gravitational waves and high-energy neutrinos.

    This study used datasets, spanning less than 2.5 months, that are also limited by LIGO’s sensitivity, which will soon improve by a factor of 2. The addition of new LIGO and Virgo data as well as from IceCube and ANTARES will greatly increase the sensitivity of joint searches. In the longer term, future next-generation neutrino and gravitational wave detectors will boost the potential of discovery for these searches.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    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 2:19 pm on November 8, 2018 Permalink | Reply
    Tags: , , , , During the daylight season at the South Pole as the Sun moves in circles above the horizon IceCube can track the Sun’s position by the decrease in the number of high-energy particles that reach the , , The Sun also casts a shadow on IceCube, U Wisconsin IceCube and IceCube Gen-2   

    From U Wisconsin IceCube Collaboration: “The Sun also casts a shadow on IceCube” 

    U Wisconsin ICECUBE neutrino detector at the South Pole

    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

    07 Nov 2018
    Sílvia Bravo

    From From U Wisconsin IceCube Collaboration

    During the daylight season at the South Pole, as the Sun moves in circles above the horizon, IceCube can track the Sun’s position by the decrease in the number of high-energy particles that reach the detector from its direction. This is what scientists call a cosmic-ray shadow, because the decline in particles is due to cosmic rays being stopped by the Sun on their way from their sources to Earth.

    The IceCube Collaboration has measured the Sun’s cosmic-ray shadow for the first time, from data covering a period of five years. The results, submitted today to The Astrophysical Journal, show a clear but different shadow pattern every year. When looking at the yearly variation, scientists have found that the shadow pattern follows changes in the solar activity, which we know are correlated with the strength of the Sun’s magnetic field. Thus, this study opens a new line of research for the Antarctic neutrino observatory: the study of the Sun’s magnetic field using IceCube cosmic-ray data.

    1
    Seasonal results for the 2-D binned maps of the Sun shadow. Each map uses data from November through February of each season. Image: IceCube Collaboration

    A few people get to spend a full year at the South Pole, accumulating countless stories that will be told over and over again after returning home. But only once during a year at the Pole does the Sun rise over the horizon, launching a dance of shadows that rotate each day around the clock.

    Deep in the ice, IceCube detects a relativistic particle about three thousand times per second. In most cases, a million to one, it is a muon created by cosmic ray interactions in the Earth’s atmosphere. When the Sun is up, some of these cosmic rays are stopped by the Sun on their way to the Earth’s atmosphere, which results in a small drop in the number of muons coming from that direction, creating a Sun shadow in the detector. In a similar way, IceCube can also track the passage of the Moon during the several days each month that it is visible at the South Pole.

    “With the data we analyzed—covering only about half of a solar cycle—we already see a clear variation of the Sun shadow. With more data, we will be able to prove in a statistically significant way that this variation actually correlates with solar activity,” explains Fabian Bos, who worked on this study as a PhD candidate at Ruhr Universität Bochum in Germany.

    As expected, IceCube data confirms that cosmic rays are stopped by both the Sun and the Moon. But while the Moon shadow remains steady year after year, the Sun casts a different shadow each year. The reason for this disparity is related to the magnetic field of the Sun, and physicists would like to gather more data to learn every detail about it.

    “The exciting news is that now we can compare our results to simulations of the Sun’s cosmic ray shadow,” says Frederik Tenholt, who is now also working on this topic for his PhD dissertation. “The solar magnetic field is a core ingredient of such simulations, which will enable the study of the solar magnetic field using IceCube data in a region where it is currently inaccessible to in situ measurements.“

    More massive than electrons, muons hit Earth from all directions and will travel a few kilometers through matter before they are absorbed. Thus, only those created in the southern sky will make it to IceCube, adding up to 100 billion muons detected every year.

    The reliability of the Moon shadow is proof that IceCube’s performance is very stable and that its angular resolution is well below one degree. Changes in the Sun shadow pattern are not yet well understood, but the shadow width seems to increase for years with increased solar activity, i.e., with a larger number of sunspots. In future analyses, and with data samples covering a longer period of time, IceCube plans to use these cosmic-ray muons to study in more detail the Sun’s magnetic field, which is known to change with a cycle of 22 years.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition
    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.

     
    • amjad 1:02 am on November 13, 2018 Permalink | Reply

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  • richardmitnick 5:35 pm on October 4, 2018 Permalink | Reply
    Tags: , IceCube Upgrade for precision neutrino physics and astrophysics kicks off, , , U Wisconsin IceCube and IceCube Gen-2   

    From U Wisconsin IceCube Collaboration: “IceCube Upgrade for precision neutrino physics and astrophysics kicks off” 

    U Wisconsin ICECUBE neutrino detector at the South Pole

    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

    From From U Wisconsin IceCube Collaboration

    04 Oct 2018
    Sílvia Bravo

    That IceCube has big plans for a larger and improved neutrino detector is not a secret. This week, the launch of the so-called IceCube Upgrade—which will deploy seven new strings at the bottom of the detector array—sets a milestone in what IceCubers have designed as an incremental extension of the Antarctic detector. The IceCube Neutrino Observatory currently consists of a cubic-kilometer of pristine ice at depths between 1.5 and 2.5 kilometers near the Amundsen-Scott South Pole Station, a U.S. research facility operated by the National Science Foundation (NSF).

    The IceCube Upgrade is a midscale NSF project with an estimated total award of $23M that will be managed through a cooperative agreement with the University of Wisconsin–Madison (UW–Madison)––home institution of the Wisconsin IceCube Particle Astrophysics Center, the team that led IceCube construction and currently operates the observatory. On October 1, 2018, a first increment of $1M has been released to allow IceCube headquarters to set in place the operational and management systems and prepare the final design review that will establish the baseline for the construction funding in early 2019.

    UW–Madison together with Michigan State University (MSU), Penn State University, the University of Alabama, and the University of Maryland colead this project with support from the IceCube Collaboration. Further contributions of more than $3M each from funding agencies in Germany and Japan as well as MSU in the U.S. will fund the production of the new optical modules, the light sensors that capture the interaction of neutrinos with the Antarctic ice. Almost eight years after construction was completed, the IceCube scientific program has resulted in outstanding breakthrough measurements in neutrino and multimessenger astronomy, including the discovery of very high energy astrophysical neutrinos, the identification of the first likely source of neutrinos and cosmic rays, and world-leading analyses in neutrino oscillations and searches for dark matter and other new physics.

    The new strings will increase the light collection in what is already a denser region of the gigaton neutrino detector, the DeepCore infill array. By decreasing the separation between IceCube strings from 125 to 75 meters and the distance between light sensors along a string from 17 to 7 meters, DeepCore reduced the energy threshold from the TeV-and-above scale suitable for neutrino astrophysics to the GeV scale required for measurements of neutrino properties at the highest energies. The seven new strings will be deployed with vertical and horizontal spacings that are three times smaller than DeepCore and will also include advanced calibration devices.

    1
    The sensors of the IceCube Upgrade will be deployed with vertical and horizontal spacings three times smaller than DeepCore. Credit: IceCube-Gen2 Collaboration.

    This state-of-the-art instrumentation will dramatically boost IceCube’s performance at the lowest energies, increasing the samples of atmospheric neutrinos by a factor of ten, and will enhance the pointing resolution of astrophysical neutrinos. As a result of this upgrade, IceCube will yield the world’s best measurements in neutrino oscillations as well as critical measurements that could provide evidence for new physics in the neutrino sector. The new calibration devices will advance our understanding of the response variability of the light sensors in both current and new strings, resulting in enhanced reconstruction of cascade events and better identification of tau neutrinos. Cascade signatures are the light patterns of more than 75% of astrophysical neutrinos and currently have a poorer pointing resolution than the so-called tracks––cascades allow reconstructing the direction of the incoming neutrino with a typical angular resolution of 5-10 degrees, while tracks point to the neutrino’s origin to within less than 1 degree. It was a track detected in September 2017 that triggered the multimessenger efforts that identified blazar TXS 056+56 as the first likely source of high-energy neutrinos and cosmic rays. The refined calibration of the existing sensors will also enable a reanalysis of more than ten years of archival data and increase the discovery potential of neutrino sources.

    The IceCube Upgrade will provide a superior overall instrument for a fraction of the investment made in the construction of the IceCube Neutrino Observatory, which was funded with an NSF Major Research Equipment and Facilities construction grant and supported with smaller contributions from international agencies in Belgium, Germany, Japan, and Sweden.

    This project is a first step in a long process developing IceCube-Gen2, a much larger extension of the IceCube Neutrino Observatory that will increase the in-ice instrumented volume by a factor of ten while integrating other techniques for neutrino and cosmic ray detection, such as radio antennas and surface scintillators.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition
    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 10:34 am on September 6, 2018 Permalink | Reply
    Tags: , , , , U Wisconsin IceCube and IceCube Gen-2   

    From Science Node: “Putting neutrinos on ice” 

    Science Node bloc
    From Science Node

    29 Aug, 2018
    Ken Chiacchia
    Jan Zverina

    1
    IceCube Collaboration/Google Earth: PGC/NASA U.S. Geological Survy Data SIO,NOAA, U.S. Navy, NGA, GEBCO Landsat/Copernicus.

    Identification of cosmic-ray source by IceCube Neutrino Observatory depends on global collaboration.

    Four billion years ago—before the first life had developed on Earth—a massive black hole shot out a proton at nearly the speed of light.

    Fast forward—way forward—to 45.5 million years ago. At that time, the Antarctic continent had started collecting an ice sheet. Eventually Antarctica would capture 61 percent of the fresh water on Earth.

    Thanks to XSEDE resources and help from XSEDE Extended Collaborative Support Service (ECSS) experts, scientists running the IceCube Neutrino Observatory in Antarctica and their international partners have taken advantage of those events to answer a hundred-year-old scientific mystery: Where do cosmic rays come from?

    U Wisconsin IceCube neutrino observatory

    U Wisconsin ICECUBE neutrino detector at the South Pole

    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

    Making straight the path

    First identified in 1912, cosmic rays have puzzled scientists. The higher in the atmosphere you go, the more of them you can measure. The Earth’s thin shell of air, scientists came to realize, was protecting us from potentially harmful radiation that filled space. Most cosmic ray particles consist of a single proton. That’s the smallest positively charged particle of normal matter.

    Cosmic ray particles are ridiculously powerful. Gonzalo Merino, computing facilities manager for the Wisconsin IceCube Particle Astrophysics Center at the University of Wisconsin-Madison (UW), compares the force of a proton accelerated by the LHC, the world’s largest atom-smasher, as similar to the force of a mosquito flying into a person.

    LHC

    CERN map


    CERN LHC Tunnel

    CERN LHC particles

    By comparison, the “Oh-My-God” cosmic ray particle detected by the University of Utah in 1991 hit with the force of a baseball flying at 58 miles per hour.

    Because cosmic-ray particles are electrically charged, they would be pushed and pulled by every magnetic field they encounter along the way. Cosmic rays would not travel in a straight line, particularly if they came from some powerful object far away in the Universe. You can’t figure out where they originated from by their direction when they hit Earth.

    Particle-physics theorists came to the rescue.

    “If cosmic rays hit any matter around them, the collision will generate secondary products,” Merino says. “A byproduct of any high-energy interaction with the protons that make up much of a cosmic ray will be neutrinos.”

    Neutrinos respond to gravity and to what’s known as the weak subatomic force, like most matter. But they aren’t affected by the electromagnetic forces that send cosmic rays on a drunkard’s walk. Scientists realized that the intense showers of protons at the source of cosmic rays had to be hitting matter nearby, producing neutrinos that can be tracked back to their source.

    The shape of water

    But if the matter that makes up your instrument can’t interact with an incoming neutrino, how are you going to detect it? The answer lay in making the detector big.

    “The probability that a neutrino will interact with matter is extremely low, but not zero,” Merino explains. “If you want to see neutrinos, you need to build a huge detector so that they collide with matter at a reasonable rate.”

    2
    Multimessenger astronomy combines information from different cosmic messenger—cosmic rays, neutrinos, gamma rays, and gravitational waves—to learn about the distant and extreme universe. Courtesy IceCube Collaboration.

    Enter the Antarctic ice shelf. The ice here is nearly pure water and could be used as a detector. From 2005 through 2010, a UW-led team created the IceCube Neutrino Observatory by drilling 86 holes deep in the ice, re-freezing detectors in the holes. Their new detector consisted of 5,160 detectors suspended in a huge ice cube six-tenths of a mile on each side.

    The IceCube scientists weren’t quite ready to detect cosmic-ray-associated neutrinos yet. While the IceCube observatory was nearly pure water, it wasn’t completely pure. As a natural formation, its transparency might differ a bit from spot to spot, which could affect detection.

    “Progress in understanding the precise optical properties of the ice leads to increasing complexity in simulating the propagation of photons in the instrument and to a better overall performance of the detector,” says Francis Halzen, a UW professor of physics and the lead scientist for the IceCube Neutrino Observatory.

    GPUs to the rescue

    The collaborators simulated the effects of neutrinos hitting the ice using traditional supercomputers containing standard central processing units (CPUs). They realized, though, that portions of their computations would instead work faster on graphics-processing units (GPUs), invented to improve video-game animation.

    “We realized that a part of the simulation is a very good match for GPUs,” Merino says. “These computations run 100 to 300 times faster on GPUs than on CPUs.”

    Madison’s own GPU cluster and collaborators’ campuses’ GPU systems helped, but it wasn’t enough.

    3

    Then Merino had a talk with XSEDE ECSS expert Sergiu Sanielevici from the Pittsburgh Supercomputing Center (PSC), lead of XSEDE’s Novel and Innovative Projects.

    Pittsburgh Supercomputing Center 3000 cores, 6 TFLOPS

    Sanielevici filled him in on the large GPU capability of XSEDE supercomputing systems. The IceCube team wound up using a number of XSEDE machines for GPU and CPU computations: Bridges at PSC, Comet at the San Diego Supercomputer Center (SDSC), XStream at Stanford University and the collection of clusters available through the Open Science Grid Consortium.

    3
    Bridges at PSC

    SDSC Dell Comet supercomputer at San Diego Supercomputer Center (SDSC)

    Stanford U Cray Xstream supercomputer

    The IceCube scientists could not assume that their computer code would run well in the XSEDE system. Their massive and complex flow of calculations could have slowed down considerably had the new machines conflicted with it. ECSS expertise was critical to making the join-up smooth.

    “XSEDE’s resources integrated seamlessly; that was very important for us,” Merino says. “XSEDE has been very collaborative, extremely open in facilitating that integration.”
    Paydirt

    Their detector built and simulated, the IceCube scientists had to wait for it to detect a cosmic neutrino. On Sept. 22, 2017, it happened. An automated system tuned to the signature of a cosmic-ray neutrino sent a message to the members of the IceCube Collaboration, an international team with more than 300 scientists in 12 countries.

    This was important. A single neutrino detection would not have been proof by itself. Scientists at observatories that detect other types of radiation expected from cosmic rays needed to look at the same spot in the sky.

    4
    Blazars are a type of active galaxy with one of its jets pointing toward us. It emits both neutrinos and gamma rays that could be detected by the IceCube Neutrino Observatory as well as by other telescopes on Earth and in space. Courtesy IceCube/NASA.

    They found multiple types of radiation coming from the same spot in the sky as the neutrino. At this spot was a “blazar” called TXS 0506+056, about 4 billion light years from Earth. A type of active galactic nucleus (AGN), a blazar is a huge black hole sitting in the center of a distant galaxy, flaring as it eats the galaxy’s matter. Blazars are AGNs that happen to be pointed straight at us.

    The scientists think that the vast forces surrounding the black hole are likely the catapult that shot cosmic-ray particles on their way toward Earth. After a journey of 4 billion years across the vastness of space, one of the neutrinos created by those particles blazed a path through IceCube’s detector.

    The IceCube scientists went back over nine and a half years of detector data, before they’d set up their automated warning. They found several earlier detections from TXS 0506+056, greatly raising their confidence.

    The findings led to papers in the prestigious journal Science and Science in July 2018. Future work will focus on confirming that blazars are the source—or at least a major source—of the high-energy particles that fill the Universe.

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Science Node is an international weekly online publication that covers distributed computing and the research it enables.

    “We report on all aspects of distributed computing technology, such as grids and clouds. We also regularly feature articles on distributed computing-enabled research in a large variety of disciplines, including physics, biology, sociology, earth sciences, archaeology, medicine, disaster management, crime, and art. (Note that we do not cover stories that are purely about commercial technology.)

    In its current incarnation, Science Node is also an online destination where you can host a profile and blog, and find and disseminate announcements and information about events, deadlines, and jobs. In the near future it will also be a place where you can network with colleagues.

    You can read Science Node via our homepage, RSS, or email. For the complete iSGTW experience, sign up for an account or log in with OpenID and manage your email subscription from your account preferences. If you do not wish to access the website’s features, you can just subscribe to the weekly email.”

     
  • richardmitnick 2:09 pm on August 31, 2018 Permalink | Reply
    Tags: , , , U Wisconsin IceCube and IceCube Gen-2   

    From U Wisconsin IceCube Collaboration: “Understanding inelasticity in high-energy neutrino interactions with IceCube” 

    U Wisconsin ICECUBE neutrino detector at the South Pole

    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

    From From U Wisconsin IceCube Collaboration

    31 Aug 2018
    Sílvia Bravo


    Once or twice per day, a muon neutrino interacts with a molecule of ice near one of the 5,000 sensors of the IceCube Neutrino Observatory. This weak interaction mediated by W boson is what scientists call a charged-current interaction, which produces a hadronic shower and a muon. The muon travels across the detector in a straight line, following almost the same direction as the original neutrino.

    This hadronic shower carries a fraction of the energy of the original neutrino, a parameter known as inelasticity. A better understanding of the inelasticity of neutrino interactions provides another way of deepening our knowledge of the unique physics hiding behind ghostly neutrinos.

    The IceCube Collaboration has recently presented its first measurements of the neutrino inelasticity, which are also the first-ever at very high energies—from 1 TeV up to nearly 800 TeV. The inelasticity distribution was found to be in good agreement with Standard Model prediction and was later used to perform other measurements, such as charm production in neutrino interactions or flavor composition of astrophysical neutrinos.

    These measurements are summarized in a paper recently submitted to Physical Review D and, together with previous measurements of the neutrino cross-section, show the potential of astrophysical and atmospheric neutrinos as a tool for particle and nuclear physics at high energies.

    2
    The mean inelasticity obtained from the fit in five bins of reconstructed energy. Vertical error bars indicate the 68% confidence interval for the mean inelasticity, and horizontal error bars indicate the expected central 68% of neutrino energies in each bin. The predicted mean inelasticity is shown in blue for neutrinos and in green for antineutrinos. A flux-averaged mean inelasticity is shown in red. Credit: IceCube Collaboration

    Scientists analyzed five years of IceCube data looking for starting multi-TeV neutrino interactions and found 2,650 tracks and 965 cascades. These tracks are mostly charged-current muon neutrino interactions for which the energy and inelasticity were measured.

    “The measurement of inelasticity was made possible with concepts from machine learning. Using thousands of simulated neutrino interactions, we were able to train a computer algorithm to learn the energy of the hadronic shower and the muon from the complicated pattern of light detected by IceCube’s sensors,” explains Gary Binder, who worked in this analysis during his PhD at the University of California, Berkeley.

    Neutrino inelasticity depends on the momentum distribution of quarks and antiquarks within nuclei. For example, the production of charm quarks is sensitive to the number of strange sea quarks in the nucleus. And a fit to IceCube data revealed charm quark production with more than 90% confidence.

    On the other hand, the inelasticity distributions for neutrinos and antineutrinos are somewhat different, and IceCube data allows to measure the ratio of antineutrinos to neutrinos produced in cosmic-ray air showers.

    “This analysis shows that IceCube can make significant contributions to the study of neutrino interactions, probing energies that are far beyond those accessible with terrestrial accelerators,” explains Spencer Klein, an IceCube researcher at Lawrence Berkeley National Laboratory and at University of California, Berkeley, and a coauthor of this work.

    This first measurement of the neutrino inelasticity at high energies also proved to be useful for studies of the astrophysical neutrino flux. The inclusion of inelasticity in an otherwise standard IceCube fit provides tighter constraints on the flavor composition of astrophysical neutrinos.

    This study developed a new approach to reconstructing starting tracks. It measured, separately, the energy of the cascade produced by the neutrino interaction and the muon that emerged from it. The sum gives the total energy, and the ratio of the cascade energy to the total energy is the inelasticity. The new technique produces a far more accurate energy estimate for starting tracks, which can be used to better probe the astrophysical neutrino energy spectrum¬¬––the current study found that starting tracks are consistent with other IceCube measurements.

    These results confirm that large-scale neutrino detectors can measure the inelasticity distribution of high-energy neutrinos, but the cubic-kilometer Antarctic detector has not yet reached the sensitivity that will enable precision tests of the neutrino sector and thus rigorous searches for new physics. Looking ahead, the inclusion of inelasticity in future IceCube starting event analyses will further tighten the constraints on the presence of tau neutrinos. More generally, inelasticity measurements are now known to be a robust tool for future, larger neutrino telescopes, such as the ten-cubic kilometer IceCube-Gen2 or the Mediterranean neutrino detector KM3NeT.

    3
    Artistic expression of KMNeT http://www.km3net.org

    5
    KM3NeT Digital Optical Module (DOM) in the laboratory. http://www.km3net.org

    See the full article here .

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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 5:03 am on August 15, 2018 Permalink | Reply
    Tags: , , , , U Wisconsin IceCube and IceCube Gen-2   

    From Nature via U Wisconsin IceCube: “Special relativity validated by neutrinos” 

    U Wisconsin ICECUBE neutrino detector at the South Pole

    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

    Nature Mag
    From Nature

    13 August 2018
    Matthew Mewes

    Neutrinos are tiny, ghost-like particles that habitually change identity. A measurement of the rate of change in high-energy neutrinos racing through Earth provides a record-breaking test of Einstein’s special theory of relativity.

    The existence of extremely light, electrically neutral particles called neutrinos was first postulated in 1930 to explain an apparent violation of energy conservation in the decays of certain unstable atomic nuclei. Writing in Nature Physics, the IceCube Collaboration1 now uses neutrinos seen in the world’s largest particle detector to scrutinize another cornerstone of physics: Lorentz invariance. This principle states that the laws of physics are independent of the speed and orientation of the experimenter’s frame of reference, and serves as the mathematical foundation for Albert Einstein’s special theory of relativity. Scouring their data for signs of broken Lorentz invariance, the authors carry out one of the most stringent tests of special relativity so far, and demonstrate how the peculiarities of neutrinos can be used to probe the foundations of modern physics.

    Physicists generally assume that Lorentz invariance holds exactly. However, in the late 1990s, the principle began to be systematically challenged2, largely because of the possibility that it was broken slightly in proposed theories of fundamental physics, such as string theory3. Over the past two decades, researchers have tested Lorentz invariance in objects ranging from photons to the Moon4.

    The IceCube Collaboration instead tested the principle using neutrinos. Neutrinos interact with matter through the weak force — one of the four fundamental forces of nature. The influence of the weak force is limited to minute distances. As a result, interactions between neutrinos and matter are extremely improbable, and a neutrino can easily traverse the entire Earth unimpeded. This poses a challenge for physicists trying to study these elusive particles, because almost every neutrino will simply pass through any detector completely unnoticed.

    The IceCube Neutrino Observatory, located at the South Pole, remedies this problem by monitoring an immense target volume to glimpse the exceedingly rare interactions. At the heart of the detector are more than 5,000 light sensors, which are focused on 1 cubic kilometre (1 billion tonnes) of ice. The sensors constantly look for the telltale flashes of light that are produced when a neutrino collides with a particle in the ice.

    The main goal of the IceCube Neutrino Observatory is to observe comparatively scarce neutrinos that are produced during some of the Universe’s most violent astrophysical events. However, in its test of Lorentz invariance, the collaboration studied more-abundant neutrinos that are generated when fast-moving charged particles from space collide with atoms in Earth’s atmosphere. There are three known types of neutrino: electron, muon and tau. Most of the neutrinos produced in the atmosphere are muon neutrinos.

    Atmospheric neutrinos generated around the globe travel freely to the South Pole, but can change type along the way. Such changes stem from the fact that electron, muon and tau neutrinos are not particles in the usual sense. They are actually quantum combinations of three ‘real’ particles — ν1, ν2 and ν3 — that have tiny but different masses.

    In a simple approximation relevant to the IceCube experiment, the birth of a muon neutrino in the atmosphere can be thought of as the simultaneous production of two quantum-mechanical waves: one for ν2 and one for ν3 (Fig. 1). These waves are observed as a muon neutrino only because they are in phase, which means the peaks of the two waves are seen at the same time. By contrast, a tau neutrino results from out-of-phase waves, whereby the peak of one wave arrives with the valley of the other.

    1
    Figure 1 | Propagation of neutrinos through Earth. There are three known types of neutrino: electron, muon and tau. a, A muon neutrino produced in Earth’s atmosphere can be thought of as the combination of two quantum-mechanical waves (red and blue) that are in phase — the peaks of the waves are observed at the same time. If a principle known as Lorentz invariance were violated, these waves could travel at different speeds through Earth’s interior and be detected in the out-of-phase tau-neutrino state. b, The IceCube Collaboration1 reports no evidence of such conversion, constraining the extent to which Lorentz invariance could be violated.

    If neutrinos were massless and Lorentz invariance held exactly, the two waves would simply travel in unison, always maintaining the in-phase muon-neutrino state. However, small differences in the masses of ν2 and ν3 or broken Lorentz invariance could cause the waves to travel at slightly different speeds, leading to a gradual shift from the muon-neutrino state to the out-of-phase tau-neutrino state. Such transitions are known as neutrino oscillations and enable the IceCube detector to pick out potential violations of Lorentz invariance. Oscillations resulting from mass differences are expected to be negligible at the neutrino energies considered in the authors’ analysis, so the observation of an oscillation would signal a possible breakdown of special relativity.

    The IceCube Collaboration is not the first group to seek Lorentz-invariance violation in neutrino oscillations [5–10]. However, two key factors allowed the authors to carry out the most precise search so far. First, atmospheric neutrinos that are produced on the opposite side of Earth to the detector travel a large distance (almost 13,000 km) before being observed, maximizing the probability that a potential oscillation will occur. Second, the large size of the detector allows neutrinos to be observed that have much higher energies than those that can be seen in other experiments.

    Such high energies imply that the quantum-mechanical waves have tiny wavelengths, down to less than one-billionth of the width of an atom. The IceCube Collaboration saw no sign of oscillations, and therefore inferred that the peaks of the waves associated with ν2 and ν3 are shifted by no more than this distance after travelling the diameter of Earth. Consequently, the speeds of the waves differ by no more than a few parts per 10^28 — a result that is one of the most precise speed comparisons in history.

    The authors’ analysis provides support for special relativity and places tight constraints on a number of different classes of Lorentz-invariance violation, many for the first time. Although already impressive, the IceCube experiment has yet to reach its full potential. Because of limited data, the authors restricted their attention to violations that are independent of the direction of neutrino propagation, neglecting possible direction-dependent violations that could arise more generally.

    With a greater number of neutrino detections, the experiment, or a larger future version [11], could search for direction-dependent violations. Eventually, similar studies involving more-energetic astrophysical neutrinos propagating over astronomical distances could test the foundations of physics at unprecedented levels.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Nature is a weekly international journal publishing the finest peer-reviewed research in all fields of science and technology on the basis of its originality, importance, interdisciplinary interest, timeliness, accessibility, elegance and surprising conclusions. Nature also provides rapid, authoritative, insightful and arresting news and interpretation of topical and coming trends affecting science, scientists and the wider public.

    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 5:42 pm on July 16, 2018 Permalink | Reply
    Tags: , Lorentz symmetry, , U Wisconsin IceCube and IceCube Gen-2   

    From U Wisconsin IceCube: “IceCube neutrinos pass a test of a fundamental symmetry in nature” 

    U Wisconsin ICECUBE neutrino detector at the South Pole

    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

    From From U Wisconsin IceCube

    6 Jul 2018
    Sílvia Bravo

    Science relies on the premise that nature’s laws are the same for anyone running an experiment. This may seem obvious to someone sitting on a couch at home, but for many of the objects we study—huge or tiny—that are fleeting through space and matter, it might not be the case.

    Scientists call this property Lorentz symmetry—that the laws of physics stay the same as long as observers move at constant speed, no matter the direction, with respect to each other—and many theories, including general relativity, rely on it. A well-known consequence of this symmetry is that the speed of light remains constant at 300 million meters per second.

    Several models trying to unify under one single theory both quantum theory and gravitation predict Lorentz violation at extremely, but significant, small scales. And, as one might guess, bizarre neutrinos could be the particles to reveal which theory is correct. However, for now, we don’t have an answer. A new measurement of the IceCube Collaboration has put Lorentz symmetry to the test and found—yet again—that neutrinos behave as expected. The results, published in Nature Physics, are the most stringent limits to date in the neutrino sector on the existence of a Lorentz violating field.

    1
    Muon neutrinos produced in the upper atmosphere are detected by IceCube in Antarctica. The potential signal is the anomalous disappearance of muon neutrinos, which might be caused by the presence of a hypothetical LV field that permeates space. The effect can be directional (arrows), but in this analysis we test the isotropic component. Credit: IceCube Collaboration.

    Since they were first postulated, neutrinos have been considered as tantalizing signatures of yet to be discovered new physics. The observation of neutrino oscillations––probably the most studied quantum phenomena––answered positively to whether these ghostly particles had mass while at the same time generating more puzzles to be solved.

    In a universe where the Lorentz symmetry can be breached, such as a universe where gravity can also be explained with quantum theories, the morphing of neutrinos from one type, or flavor, to another would deviate from standard neutrino oscillations. The effects of the interaction of neutrinos with a Lorentz violating field, or the aftermath of a small distortion of space-time, would be enhanced by the quantum interference of the different flavors and result in significant changes on the oscillation pattern.

    “Neutrino oscillations are a natural interferometer,” explains Teppei Katori, an assistant professor at Queen Mary University of London and one of the main analyzers of this work. And IceCube neutrinos are the ones with the highest energies ever the detected, produced by cosmic-ray protons colliding with atoms in the Earth’s atmosphere or coming directly from distant and powerful cosmic accelerators. “Neutrino oscillations observed with IceCube act as the biggest interferometer in the world to look for the tiniest effects in physics, such as a space-time deficit,” adds Katori.

    It was a legendary interferometer, the so-called Michelson and Morley experiment, that using a beam of light proved that space was not full of ether. A better theory to understand the nature of space was proposed by Einstein, and since then we understand space and time to be in a four-dimensional continuum.

    “We would love to be the direct descendants of Michelson and Morley, using interferometry to show that a beautiful field theory, in this case Einstein’s theory, is right, but not sufficient—that there is new physics out there that underlies our present model,” says Janet Conrad, a professor at MIT who also participated in this study.

    2
    The parameter ρ6 represents the Lorentz Violating field strength. The best-fit point is shown by the yellow cross and the blue (red) region is excluded at 99% (90%) C.L. Credit: IceCube Collaboration.

    IceCube researchers have looked for effects of an isotropic Lorentz violating field using two years of throughgoing atmospheric neutrinos with energies around and above one TeV. The results have not found variations in the typical neutrino oscillation patterns that could be pointing to new physics. “We have looked for missing muon neutrinos on the highest energy atmospheric events observed by IceCube and have found no significant deficit,” says Carlos Argüelles, a postdoctoral researcher at MIT and also a main analyzer of this work. “We’re getting closer to the Planck scale: an unexplored terrain where general relativity and quantum mechanics are both important. Exciting times lie ahead as we continue looking for strange flavor changes at higher and higher energies.”

    This nonobservation allowed setting the strongest limits to date on Lorentz violating fields in the neutrino sector. When looking at results from other types of experiments, these limits are also among the best in the world, showing the potential of neutrino experiments to study fundamental space-time properties.

    “IceCube’s access to the high-energy regime, along with its high statistics, makes it a powerful instrument to study physics beyond the standard model. This enabled us to probe for small distortions induced by Lorentz invariance violation in the atmospheric neutrino flux that are not accessible to other detectors,” says Ali Kheirandish, a postdoctoral researcher at UW–Madison and also an analyzer of this work.

    Improvements to these measurements are already in the works. The addition of astrophysical neutrinos will increase sensitivity to higher energies, where many searches for new physics could reach the precision to prove or rule out some theories.

    The IceCube analysis focused on an isotropic Lorentz violating field since its impact on neutrino oscillation signatures may be expected to be up to 1,000 larger than the impact from a directional field. However, as sensitivity increases, IceCube will also test directional fields, which are considered a smoking gun signature of Lorentz violation. Future extensions of IceCube as well as water-based neutrino detectors will provide larger samples of astrophysical neutrinos and will boost tests of the most fundamental symmetries in nature.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    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 2:40 pm on July 15, 2018 Permalink | Reply
    Tags: , , , , , , , , , U Wisconsin IceCube and IceCube Gen-2   

    From Spaceflight Insider: “Fermi Telescope discovers neutrino’s origin as supermassive black hole” 

    1

    From Spaceflight Insider

    NASA/Fermi LAT


    NASA/Fermi Gamma Ray Space Telescope

    A cosmic neutrino detected by NASA’s Fermi Gamma-ray Space Telescope was found to have originated in a gamma ray emitted by a supermassive black hole 3.7 billion light years away at the center of a galaxy in the constellation Orion.

    The discovery, made by an international team of scientists, marks the first time a high-energy neutrino from beyond the Milky Way has been traced to its place of origin as well as the furthest any neutrino has been known to travel.

    Neutrinos are high-energy, hard-to-catch particles likely produced in powerful cosmic events, such as supermassive black holes actively devouring matter and galaxy mergers. Because they travel at nearly the speed of light and do not interact with other matter, they are capable of traversing billions of light years.

    By studying neutrinos, scientists gain insight into the processes that drive powerful cosmic events, including supernovae and black holes.

    Gamma rays are the brightest and most energetic form of light, which is why scientists use them to trace the sources of neutrinos and cosmic rays.

    “The most extreme cosmic explosions produce gravitational waves, and the most extreme cosmic accelerators produce high-energy neutrinos and cosmic rays,” explained Regina Caputo of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and analysis coordinator for the Fermi Large Area Telescope Collaboration. “Through Fermi, gamma rays are providing a bridge to each of these new cosmic signals.”

    Scientists found this particular neutrino on September 22, 2017, using the National Science Foundation‘s (NSF) IceCube Neutrino Observatory at the Amundsen-Scott South Pole Station. They then traced the neutrino to its origin in a gamma ray blast within the distant supermassive black hole using Fermi.[ https://sciencesprings.wordpress.com/2018/07/13/the-great-neutrino-catch-a-bunch-of-articles/ ]

    “Again, Fermi has helped make another giant leap in a growing field we call multimessenger astronomy. Neutrinos and gravitational waves deliver new kinds of information about the most extreme environments in the universe. But to understand what they’re telling us, we need to connect them to the ‘messenger’ astronomers know best–light,” emphasized Paul Hertz, director of NASA’s Astrophysics Division in Washington, DC.

    IceCube tracked the neutrino, which hit Antarctica with 300 trillion electron volts. Its extremely high energy level meant it likely came from beyond our solar system. Its galaxy of origin, with which scientists are familiar, is a blazar, a galaxy with an extremely bright and active central supermassive black hole that blasts out jets of particles in opposite directions at nearly the speed of light.

    Blazars have several million to several billion times the mass of our Sun. Scientists find them when one of the jets they emit travels in the direction of Earth.

    Yasuyuki Tanaka of Japan’s Hiroshima University was the first scientist to link the neutrino to a specific blazar known as TXS 0506+056, which has recently shown increased activity. Fermi keeps track of approximately 2,000 blazars.

    Followup observations of TXS 0506 were conducted with the Major Atmospheric Gamma Imaging Cherenkov Telescopes (MAGIC) NASA’s Neil Gehrels Swift Observatory, and various other observatories.[See above link to previous post Bunch of Articles]

    Two papers on the discovery have been published here and here in the journal Science.

    See the full article here .

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    SpaceFlight Insider reports on events taking place within the aerospace industry. With our team of writers and photographers, we provide an “insider’s” view of all aspects of space exploration efforts. We go so far as to take their questions directly to those officials within NASA and other space-related organizations. At SpaceFlight Insider, the “insider” is not anyone on our team, but our readers.

    Our team has decades of experience covering the space program and we are focused on providing you with the absolute latest on all things space. SpaceFlight Insider is comprised of individuals located in the United States, Europe, South America and Canada. Most of them are volunteers, hard-working space enthusiasts who freely give their time to share the thrill of space exploration with the world.

     
  • richardmitnick 3:07 pm on July 12, 2018 Permalink | Reply
    Tags: Blazar, , , , , , , , U Wisconsin IceCube and IceCube Gen-2   

    From NRAO via newswise: “VLA Gives Tantalizing Clues About Source of Energetic Cosmic Neutrino” 

    NRAO Icon
    From National Radio Astronomy Observatory

    NRAO Banner

    via

    2

    newswise

    1
    Supermassive black hole at core of galaxy accelerates particles in jets moving outward at nearly the speed of light. In a Blazar, one of these jets is pointed nearly straight at Earth. Credit: Sophia Dagnello, NRAO/AUI/NSF

    A single, ghostly subatomic particle that traveled some 4 billion light-years before reaching Earth has helped astronomers pinpoint a likely source of high-energy cosmic rays for the first time. Subsequent observations with the National Science Foundation’s (NSF) Karl G. Jansky Very Large Array (VLA) [depicted below] have given the scientists some tantalizing clues about how such energetic cosmic rays may be formed at the cores of distant galaxies.

    On September 22, 2017, an observatory called IceCube, made up of sensors distributed through a square kilometer of ice under the South Pole, recorded the effects of a high-energy neutrino coming from far beyond our Milky Way Galaxy.

    U Wisconsin ICECUBE neutrino detector at the South Pole

    Lunar Icecube

    IceCube DeepCore annotated

    IceCube PINGU annotated


    DM-Ice II at IceCube annotated

    Neutrinos are subatomic particles with no electrical charge and very little mass. Since they interact only very rarely with ordinary matter, neutrinos can travel unimpeded for great distances through space.

    Follow-up observations with orbiting and ground-based telescopes from around the world soon showed that the neutrino likely was coming from the location of a known cosmic object — a blazar called TXS 0506+056, about 4 billion light-years from Earth.

    3

    Like most galaxies, blazars contain supermassive black holes at their cores. The powerful gravity of the black hole draws in material that forms a hot rotating disk. Jets of particles traveling at nearly the speed of light are ejected perpendicular to the disk. Blazars are a special class of galaxies, because in a blazar, one of the jets is pointed almost directly at Earth.

    Theorists had suggested that these powerful jets could greatly accelerate protons, electrons, or atomic nuclei, turning them into the most energetic particles known in the Universe, called ultra-high energy cosmic rays. The cosmic rays then could interact with material near the jet and produce high-energy photons and neutrinos, such as the neutrino detected by IceCube.

    Cosmic rays were discovered in 1912 by physicist Victor Hess, who carried instruments in a balloon flight. Subsequent research showed that cosmic rays are either protons, electrons, or atomic nuclei that have been accelerated to speeds approaching that of light, giving some of them energies much greater than those of even the most energetic electromagnetic waves. In addition to the active cores of galaxies, supernova explosions are probable sites where cosmic rays are formed. The galactic black-hole engines, however, have been the prime candidate for the source of the highest-energy cosmic rays, and thus of the high-energy neutrinos resulting from their interactions with other matter.

    “Tracking that high-energy neutrino detected by IceCube back to TXS 0506+056 makes this the first time we’ve been able to identify a specific object as the probable source of such a high-energy neutrino,” said Gregory Sivakoff, of the University of Alberta in Canada.

    Following the IceCube detection, astronomers looked at TXS 0506+056 with numerous telescopes and found that it had brightened at wavelengths including gamma rays, X-rays, and visible light. The blazar was observed with the VLA six times between October 5 and November 21, 2017.

    “The VLA data show that the radio emission from this blazar was varying greatly at the time of the neutrino detection and for two months afterward. The radio frequency with the brightest radio emission also was changing,” Sivakoff said.

    TXS 0506+056 has been monitored over a number of years with the NSF’s Very Long Baseline Array (VLBA), a continent-wide radio telescope system that produces extremely detailed images. The high-resolution VLBA images have shown bright knots of radio emission that travel outward within the jets at speeds nearly that of light. The knots presumably are caused by denser material ejected sporadically through the jet.

    “The behavior we saw with the VLA is consistent with the emission of at least one of these knots. It’s an intriguing possibility that such knots may be associated with generating high-energy cosmic rays and thus the kind of high-energy neutrino that IceCube found,” Sivakoff said.

    The scientists continue to study TXS 0506+056. “There are a lot of exciting phenomena going on in this object,” Sivakoff concluded.

    “The era of multi-messenger astrophysics is here,” said NSF Director France Córdova. “Each messenger — from electromagnetic radiation, gravitational waves and now neutrinos — gives us a more complete understanding of the Universe, and important new insights into the most powerful objects and events in the sky. Such breakthroughs are only possible through a long-term commitment to fundamental research and investment in superb research facilities.”

    Sivakoff and numerous colleagues from institutions around the world are reporting their findings in the journal Science.

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    NRAO/Karl V Jansky VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA

    The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), and the Very Long Baseline Array (VLBA)*.

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).

    NRAO VLBA

    NRAO VLBA

    *The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

    Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.

    And the future Expanded Very Large Array (EVLA).

     
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