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Jul 12, 2018

Discovery of neutrino and gamma rays from the same blazar source by IceCube and Fermi with contribution of MAGIC and AGILE


Neutrinos, electrically uncharged and traveling at nearly the speed of light, are able to escape the densest astrophysical environments and point back to their source of origin, therefore they represent unique tracers of cosmic-ray particles acceleration. Such extreme environments can be found in blazars, that are active galactic nuclei characterized by accreting supermassive black holes developing immense relativistic jets of plasma pointing close to our line of sight. Blazars are among the most powerful objects in the universe speculated to be sources of high-energy cosmic rays. 

The discovery of an association of a very high-energy neutrino with a flaring photon gamma-ray blazar object by the IceCube experiment and the Fermi space satellite,  announced on July 12, 2018 with a press conference by NSF  and a cover and paper in the Science journal, highlights for the first time mechanisms and conditions for highest-energy cosmic rays acceleration and the existence of extragalactic sources producing high-energy neutrinos and gamma rays. The detection of an about 290 TeV energy neutrino (namely the event IC-170922A) on 22 September 2017 by the IceCube experiment at the Amundsen-Scott South Pole Station, in Antarctica, was found to be consistent with the location of a Fermi Gamma-ray Space Telescope catalogued gamma-ray source (3FGL J0509.4+0541, i.e. the blazar TXS 0506+056). The Fermi Large Area Telescope (LAT) first reported the positional coincidence (within 0.1 degrees) of the very high-energy neutrino event with a gamma-ray source detected at E>100 MeV, the blazar TXS 0506+056 (also known as MG1 J050927+0541, RX J0509.3+054, ZS 0506+056 and other), in a flaring state, issuing one Astronomer's Telegram (ATel) on September, 28, 2017. 

This triggered many observations and results with the corresponding multi-wavelength follow-up measurements, for example by MAGIC, AGILE, Swift and NuSTAR. All these are missions and experiments see the participation of the ASI Space Science Data Center (SSDC), and Fermi, MAGIC and AGILE are built with a fundamental contribution of INFN and INAF. Notably AGILE confirmed soon after the association of IC-170922A with the E>100 MeV gamma-ray activity of TXS 0506+056 with another ATel, while the MAGIC Cherenkov telescope also detected it and revealed periods where the gamma-ray flux from the blazar reached energies of up to 400 GeV. Subsequent measurements of the source have been completed at X-ray, optical, and radio wavelengths. Formerly AGILE suggested also a possible association of gamma rays with an IceCube neutrino event in July 2016, after the detection of a gamma-ray transient found to be consistent with the position and time of IC-160731. 

Based on the redshift of TXS 0506+056, with value z=0.3365 corresponding to a luminosity distance of 5.5 billion light years, accurately measured and published in February 2018 (only upper/lower limits were available before), constraints are derived for the muon neutrino luminosity for this source, found to be similar to the luminosity observed in gamma rays. The energies of the gamma rays and the neutrino indicate that blazar jets may accelerate cosmic rays to at least several PeV. Chance correlation of this neutrino with the flare of TXS 0506+056 is statistically disfavored at the level of 3 sigma in any of the evaluated models associating neutrino and gamma-ray production. This important result for the newborn multi-messenger astro-particle physics confirms the close relations among the different cosmic messengers. The most extreme cosmic explosions producing transient gamma rays (GRBs) also produce gravitational waves, and the most extreme cosmic accelerators producing intense, persisting and variable flux of gamma-rays (blazars) produce high-energy neutrinos and cosmic rays. 

Through the Fermi and AGILE satellites and the large ground based astro-particle experiments for neutrinos, UHE cosmic rays and gravitational waves, gamma rays are providing a bridge to each of these new cosmic signals, opening the multi-messenger astronomy era. Many interpretations and works, published or in preparation, are following up the discovery, shedding light on a truly multi-messenger scenario for the flaring GeV gamma-ray blazar TXS 0506+056 and the implications for very high-energy neutrino emission and cosmic ray acceleration. The ASI SSDC is contributing and supporting archive, data, software and science operations and data analysis tasks for the Fermi, AGILE, Swift, and NuSTAR missions.

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Figure collage credits: SCIENCE magazine/American Association for the Advancement of Science (AAAS), SCIENCE Communication Lab, IceCube Collaboration, NSF U.S. National Science Foundation-Office of Polar Programs, NSF U.S. National Science Foundation-Physics Division, University of Wisconsin-Madison, National Aeronautics and Space Administration (NASA), NASA's Goddard Space Flight Center/CI Lab, NASA/DOE/Fermi Large Area Telescope Collaboration, Sonoma State University, MAGIC Collaboration, AGILE Collaboration, PGC/NASA U.S. Geological Survy Data SIO,NOAA, U.S. Navy, NGA, GEBCO Landsat/Copernicus, Jamie Yang, Savannah Guthrie, Nicolle R. Fuller, Aurore Simonnet.

 

May 03, 2018

SSDC contribution to Gaia second data release

On april 25th the Gaia collaboration has released the richest star catalogue to date, including high-precision measurements of nearly 2 billion stars and revealing previously unseen details of our Galaxy.
The previous and first data release, based on just over one year of observations, was published in 2016; it contained distances and motions of two million stars.
This new data release, which covers the observations carried on between 25 July 2014 and 23 May 2016, pins down the positions of 1.7 billion stars, and with a much greater precision. Among the contributors to this huge success is SSDC, one of the partner data centers hosting a copy of Gaia catalogue, which are in charge of developing and maintaining access and data extraction to enable the astronomical community to handle and fully exploit the scientific potential of this enormous archive. In addition, SSDC is responsible for the calculation of the official cross-match of the Gaia catalogue with the largest public available optical and near-IR catalogues ensuring an all-sky, panchromatic vision of the universe.

At this link a video report on Gaia team at SSDC.

Feb 02, 2018

The High energy Particle Detector (HEPD) is now on orbit!

CSES (China Seismo-Electro-magnetic Satellite), which hosts the HEPD payload was launched on February 2, 2018 at 08:51 (CET, Rome time) from the  Jiuquan Satellite  Launch  Center.
HEPD, one of the nine instruments on board of CSES,  was built by Italian research groups (ASI, INFN and some universities) and is a space detector for charged high energy particles (electrons up to 200MeV, protons up to 300MeV and light nuclei up to few hundreds of MeV/n).
HEPD will perform the precision measurements of the electron, proton and nuclei fluxes, and of their time behavior. These measurements will allow one to investigate the emission of Solar Energetic Particles (SEPs), the precision study of charged particles, which are trapped within the Geo-magnetic field, and the search for correlation between particle fluxes variations in the Earth's Van Allen Belts and intense seismic events.
 
The HEPD Team at SSDC, composed of M. Mergé and V.Vitale with P. Picozza as senior scientist, contributed to the detector development, test and calibration.
Currently the SSDC Team is deeply involved in the data processing, handling and storage, as also to the development of science analysis software.

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Jan 17, 2018

Fermi GBM wins the 2018 "Bruno Rossi Prize"

We are pleased to report that the 2018 Bruno Rossi Prize of the High Energy Astrophysics Division (HEAD) of the American Astronomical Society has been awarded to Dr. Colleen Wilson-Hodge and the Fermi Gamma-Ray Burst Monitor (GBM) instrument Team for their masterpiece discovery of soft gamma rays coincident with a gravitational wave burst event GW170817 = GRB 170817A in the galaxy NGC 4993  (see also the Oct. 16, 2017 press conference video at NSF, Fermi after minute 21:40) and the confirmation that short gamma-ray bursts are produced by binary neutron-star mergers. This is the sixth time that a space mission supported by SSDC has been directly awarded a Rossi Prize, after BeppoSAX in 1998, Swift in 2007, Fermi (Large Area Telescope, LAT) in 2011, AGILE in 2012 and NuSTAR in 2015. This is also the fourth time that the Fermi mission is awarded with a direct prize to teams of the Fermi instruments (2001 and 2018) or to scientists that have obtained important results thanks to Fermi data (2013 for Fermi LAT gamma-ray pulsar studies, 2014 for the Fermi LAT discovery of the gamma-ray bubbles of our Milky Way galaxy). 
The Italian INFN is an important member of the LAT Collaboration having built the tracker in cooperation with Italian industries, and providing a continuous support to operations and to data calibration, analysis and scientific exploitation. The INFN Fermi team at the SSDC, composed of S. Ciprini and D. Gasparrini, is contributing by establishing and maintaining a mirror archive of the LAT high level data products, by developing quick-look interactive tools and gamma-ray source catalogs and lists, by performing LAT instrument services, shifts, responsibilities, and by participating to gamma-ray data validation, data analysis and scientific exploitation of the LAT archive, this also in the important frame of multi-frequency/multi-messenger astro-particle physics and astronomy.

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Dec 06, 2017

DAMPE direct detection of a TeV-energy break in cosmic-ray spectrum of electrons and positrons

The Chinese Dark Matter Particle Explorer (DAMPE, also known as Sun Wukong) space mission published its first relevant scientific results in Nature scientific journal, presenting the precise measurement of high energy cosmic ray electrons plus positrons (CREs), and highlighting a solid break (i.e. a sharp variation) in the spectral energy distribution at about 0.9 TeV.

High energy CREs provide an ideal probe of sources in our neighbourhood since they loose quickly their energy during their propagation in the interstellar medium: precision measurement of their flux by DAMPE can considerably narrow down the parameter space of different models - such as nearby pulsars, supernova remnants and/or candidates of particle dark matter - needed in order to explain the 'positron excess' observed by AMS up to about 500 GeV. Evidence for a spectral break in the TeV energy range has been previously provided by indirect measurements of H.E.S.S., although the results were qualified by sizeable systematic uncertainties. DAMPE CREs spectrum data are instead characterized by unprecedentedly energy resolution and low background. A smoothly broken power-law model rather than a single power-law model can properly fit the majority of the spectrum.

The DAMPE mission is funded by the strategic priority science and technology projects in space science of the Chinese Academy of Sciences (CAS). DAMPE, China's first astroparticle physics satellite, was launched from Jiuquan Satellite Launch Center into sun-synchronous orbit on Dec. 17th, 2015. At an altitude of about 500 km, DAMPE has been collecting data since a week after its launch. In its first 530 days of science operation through June 8 of this year, DAMPE has detected 1.5 million cosmic ray electrons and positrons above 25 GeV. DAMPE, with its 1900Kg of total weight (1400Kg for the scientific experiment), is expected to record more than 10 billion cosmic ray events over its useful life-projected to exceed five years given the current state of its instruments.
DAMPE is a collaboration of more than a hundred scientists, technicians and students at nine institutes in China, Switzerland and Italy, under the leadership of the Purple Mountain Observatory (PMO) of the CAS. Italy is involved with a group of about twenty scientists from the INFN sections of Perugia, Bari and Lecce and the Universities of Perugia, Bari and Salento. A key component of DAMPE is the silicon tracker, developed with the coordination of INFN-Perugia, based on the experience and skills acquired in the work done for other space experiments such as AMS-02 and Fermi-LAT. After the publication of the results about CREs, the Italian scientific group is working to measure the flux of protons and ions, and to study the detected high energy gamma-ray photons.

DAMPE is among the projects developed in the SSDC center: not only DAMPE data have been immediately available for download from the Cosmic Rays Data Base, but SSDC appears among the institutes in the Nature publication thanks to the contribute of D.D'Urso to the data handling in the Europe.

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