1,159 research outputs found

    ASTRI SST-2M prototype and mini-array simulation chain, data reduction software, and archive in the framework of the Cherenkov Telescope Array

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    The Cherenkov Telescope Array (CTA) is a worldwide project aimed at building the next-generation ground-based gamma-ray observatory. Within the CTA project, the Italian National Institute for Astrophysics (INAF) is developing an end-to-end prototype of the CTA Small-Size Telescopes with a dual-mirror (SST-2M) Schwarzschild-Couder configuration. The prototype, named ASTRI SST-2M, is located at the INAF "M.C. Fracastoro" observing station in Serra La Nave (Mt. Etna, Sicily) and is currently in the scientific and performance validation phase. A mini-array of (at least) nine ASTRI telescopes has been then proposed to be deployed at the Southern CTA site, by means of a collaborative effort carried out by institutes from Italy, Brazil, and South-Africa. The CTA/ASTRI team is developing an end-to-end software package for the reduction of the raw data acquired with both ASTRI SST-2M prototype and mini-array, with the aim of actively contributing to the global ongoing activities for the official data handling system of the CTA observatory. The group is also undertaking a massive Monte Carlo simulation data production using the detector Monte Carlo software adopted by the CTA consortium. Simulated data are being used to validate the simulation chain and evaluate the ASTRI SST-2M prototype and mini-array performance. Both activities are also carried out in the framework of the European H2020-ASTERICS (Astronomy ESFRI and Research Infrastructure Cluster) project. A data archiving system, for both ASTRI SST-2M prototype and mini-array, has been also developed by the CTA/ASTRI team, as a testbed for the scientific archive of CTA. In this contribution, we present the main components of the ASTRI data handling systems and report the status of their development.Comment: Proceedings of the 35th International Cosmic Ray Conference (ICRC 2017), Bexco, Busan, Korea. All CTA contributions at arXiv:1709.0348

    Two pairs of proven monozygotic twins discordant for familial amyloid neuropathy (FAP) TTR Met 30.

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    J Med Genet. 1999 Aug;36(8):629-32. Two pairs of proven monozygotic twins discordant for familial amyloid neuropathy (FAP) TTR Met 30. Munar-Qués M, Pedrosa JL, Coelho T, Gusmão L, Seruca R, Amorim A, Sequeiros J. Grupo de Estudio de la PAF, Palma de Mallorca, Spain. Abstract Twin studies are an important tool in medical genetics for the evaluation of the relative roles of genetic and non-genetic factors in several diseases. Familial amyloidotic polyneuropathy type I (FAP-I), TTR Met 30, was present in two sets of proven monozygotic (MZ) twins, one from Majorca and the other from Portugal. Monozygosity was established by analysis of DNA polymorphisms. Both pairs were discordant for age at onset and some clinical manifestations of FAP-I. We reviewed the differences in age at onset and clinical features in both sets and in two other pairs of presumed MZ twins with FAP-I and compared them with those in MZ twin pairs with other Mendelian disorders, such as neurofibromatosis type 1, Huntington's disease, facioscapulohumeral muscular dystrophy, and myotonic dystrophy. We conclude that, in addition to the postulated modifying genes, there must be a significant contribution from non-genetic factors to the phenotypic variability of FAP-I (age at onset and clinical expression), either because of environmental differences or stochastic events during (or after) the twinning process. PMID: 10465115 [PubMed - indexed for MEDLINE]PMCID: PMC176297

    Morfogènesi i dinàmica de la platja des Codolar (Eivissa, Illes Balears)

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    S'ha analitzat la textura dels còdols de la platja des Codolar, Eivissa, a partir del mostreig de quatre seccions de la platja. A cada secció s’han pres mostres de la berma superior i de la inferior, totalitzant el mesurament de 400 còdols. S'han analitzat la distribució dels còdols, la seva mida i la seva classificació. La forma dels còdols s’ha parametritzat a partir del diagrama de Zingg, l'índex d’Arrodoniment de Wadell, la màxima projecció de Esfericitat i l'índex Oblat-Prolat. El resultat mostra una clara gradació de sud-est a nord-oest tant en la grandària com en el arrodoniment i la esfericitat dels còdols. Això en indica clarament que la seva font d'alimentació són els despreniments del cap Falcó, i que el seu transport es produeix per deriva litoral envers el nord-oest. El resultat és la formació d'una barra litoral que fins i tot presenta formes atribuïbles a ventalls d’overwash, que juntament amb ventalls al·luvials delimiten una zona humida, que a l'actualitat ocupen les Salines d'Eivissa.The texture of the Es Codolar gravel beach, South of Ibiza, was analyzed from samples in four sections of the beach. In each section two samples have been taken: one from the upper berm and another from the lower one. A total of 400 pebbles and cobbles were measured. The distribution of shingles, their grain size and sorting have been analyzed. Shingle shape has been parameterized trough the Zingg diagram, the Wadell roundness index, the maximum projection of sphericity and the Oblate-Prolate Index. The results show a clear gradient both in grain size, roundness and the shingles sphericity from Southeast to Northwest. This clearly indicates that the source of sediment supply are located at Cap Falcó detachments, Transport is produced by long shore drift towards the Northwest and he result is the formation of a shingle barrier that closes a wetland that nowadays currently occupy by the Salinas of Ibiza

    AGILE Observations of the Gravitational Wave Event GW150914

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    We report the results of an extensive search in the AGILE data for a gamma-ray counterpart of the LIGO gravitational wave event GW150914. Currently in spinning mode, AGILE has the potential of covering with its gamma-ray instrument 80 % of the sky more than 100 times a day. It turns out that AGILE came within a minute from the event time of observing the accessible GW150914 localization region. Interestingly, the gamma-ray detector exposed about 65 % of this region during the 100 s time intervals centered at -100 s and +300 s from the event time. We determine a 2-sigma flux upper limit in the band 50 MeV - 10 GeV, UL=1.9×108ergcm2s1UL = 1.9 \times 10^{-8} \rm \, erg \, cm^{-2} \, s^{-1} obtained about 300 s after the event. The timing of this measurement is the fastest ever obtained for GW150914, and significantly constrains the electromagnetic emission of a possible high-energy counterpart. We also carried out a search for a gamma-ray precursor and delayed emission over timescales ranging from minutes to days: in particular, we obtained an optimal exposure during the interval -150 / -30 s. In all these observations, we do not detect a significant signal associated with GW150914. We do not reveal the weak transient source reported by Fermi-GBM 0.4 s after the event time. However, even though a gamma-ray counterpart of the GW150914 event was not detected, the prospects for future AGILE observations of gravitational wave sources are decidedly promising.Comment: 20 pages, 6 figures. Submitted to the Astrophysical Journal Letters on April 1, 201

    Binaries with the eyes of CTA

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    The binary systems that have been detected in gamma rays have proven very useful to study high-energy processes, in particular particle acceleration, emission and radiation reprocessing, and the dynamics of the underlying magnetized flows. Binary systems, either detected or potential gamma-ray emitters, can be grouped in different subclasses depending on the nature of the binary components or the origin of the particle acceleration: the interaction of the winds of either a pulsar and a massive star or two massive stars; accretion onto a compact object and jet formation; and interaction of a relativistic outflow with the external medium. We evaluate the potentialities of an instrument like the Cherenkov telescope array (CTA) to study the non-thermal physics of gamma-ray binaries, which requires the observation of high-energy phenomena at different time and spatial scales. We analyze the capability of CTA, under different configurations, to probe the spectral, temporal and spatial behavior of gamma-ray binaries in the context of the known or expected physics of these sources. CTA will be able to probe with high spectral, temporal and spatial resolution the physical processes behind the gamma-ray emission in binaries, significantly increasing as well the number of known sources. This will allow the derivation of information on the particle acceleration and emission sites qualitatively better than what is currently available.Comment: 23 pages, 13 figures, accepted for publication in Astroparticle Physics, special issue on Physics with the Cherenkov Telescope Arra

    Multiwavelength variability and correlation studies of Mrk 421 during historically low X-ray and γ-ray activity in 2015-2016

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    Acciari, V. A., et al. (MAGIC Collaboration)We report a characterization of the multiband flux variability and correlations of the nearby (z = 0.031) blazar Markarian 421 (Mrk 421) using data from Metsähovi, Swift, Fermi-LAT, MAGIC, FACT, and other collaborations and instruments from 2014 November till 2016 June. Mrk 421 did not show any prominent flaring activity, but exhibited periods of historically low activity above 1 TeV (F>1 TeV 0.1 TeV) γ-rays, which, despite the low activity, show a significant positive correlation with no time lag. The HRkeV and HRTeV show the harder-when-brighter trend observed in many blazars, but the trend flattens at the highest fluxes, which suggests a change in the processes dominating the blazar variability. Enlarging our data set with data from years 2007 to 2014, we measured a positive correlation between the optical and the GeV emission over a range of about 60 d centred at time lag zero, and a positive correlation between the optical/GeV and the radio emission over a range of about 60 d centred at a time lag of 43+9-6 d. This observation is consistent with the radio-bright zone being located about 0.2 parsec downstream from the optical/GeV emission regions of the jet. The flux distributions are better described with a lognormal function in most of the energy bands probed, indicating that the variability in Mrk 421 is likely produced by a multiplicative process.The financial support of the German BMBF and MPG; the Italian INFN and INAF; the Swiss National Fund SNF; the ERDF under the Spanish MINECO (FPA2017-87859-P, FPA2017-85668-P, FPA2017-82729-C6-2-R, FPA2017-82729-C6-6-R, FPA2017-82729-C6-5-R, AYA2015-71042-P, AYA2016-76012-C3-1-P, ESP2017-87055-C2-2-P, FPA2017-90566-REDC); the Indian Department of Atomic Energy; the Japanese ICRR, the University of Tokyo, JSPS, and MEXT; the Bulgarian Ministry of Education and Science, National RI Roadmap Project DO1-268/16.12.2019 and the Academy of Finland grant nr. 320045 is gratefully acknowledged. This work was also supported by the Spanish Centro de Excelencia ‘Severo Ochoa’ SEV-2016-0588 and SEV-2015-0548, the Unidad de Excelencia ‘María de Maeztu’ MDM-2014-0369 and the ‘la Caixa’ Foundation (fellowship LCF/BQ/PI18/11630012), by the Croatian Science Foundation (HrZZ) Project IP-2016-06-9782 and the University of Rijeka Project 13.12.1.3.02, by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, the Polish National Research Centre grant UMO-2016/22/M/ST9/00382 and by the Brazilian MCTIC, CNPq, and FAPERJ

    The star forming region Monoceros R2 as a gamma-ray source

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    Context. After the release of the gamma-ray source catalog produced by the Fermi satellite during its first two years of operation, a significant fraction of sources still remain unassociated at lower energies. In addition to well-known high-energy emitters (pulsars, blazars, supernova remnants, etc.), theoretical expectations predict new classes of gamma-ray sources. In particular, gamma-ray emission could be associated with some of the early phases of stellar evolution, but this interesting possibility is still poorly understood. Aims. The aim of this paper is to assess the possibility of the Fermi gamma-ray source 2FGL J0607.5-0618c being associated with the massive star forming region Monoceros R2. Methods. A multi-wavelength analysis of the Monoceros R2 region is carried out using archival data at radio, infrared, X-ray, and gamma-ray wavelengths. The resulting observational properties are used to estimate the physical parameters needed to test the different physical scenarios. Results. We confirm the 2FGL J0607.5-0618c detection with improved confidence over the Fermi two-year catalog. We find that a combined effect of the multiple young stellar objects in Monoceros R2 is a viable picture for the nature of the source.Facultad de Ciencias Astronómicas y GeofísicasInstituto Argentino de Radioastronomí
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