6,355 research outputs found

    Bayesian Analysis for Extracting Properties of the Nuclear Equation of State from Observational Data including Tidal Deformability from GW170817

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    We develop a Bayesian analysis method for selecting the most probable equation of state under a set of constraints from compact star physics, which now include the tidal deformability from GW170817. We apply this method for the first time to a two-parameter family of hybrid equations of state that is based on realistic models for the hadronic phase (KVORcut02) and the quark matter phase (SFMα\alpha) which produce a third family of hybrid stars in the mass-radius diagram. One parameter (α\alpha) characterizes the screening of the string tension in the string-flip model of quark matter while the other (ΔP\Delta_P) belongs to the mixed phase construction that mimics the thermodynamics of pasta phases and includes the Maxwell construction as a limiting case for ΔP=0\Delta_P=0. We present the corresponding results for compact star properties like mass, radius and tidal deformabilities and use empirical data for them in the newly developed Bayesian analysis method to obtain the probabilities for the model parameters within their considered range.Comment: 8 pages, 4 figures, version accepted for publication in univers

    Calibration of the logarithmic-periodic dipole antenna (LPDA) radio stations at the Pierre Auger Observatory using an octocopter

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    An in-situ calibration of a logarithmic periodic dipole antenna with a frequency coverage of 30 MHz to 80 MHz is performed. Such antennas are part of a radio station system used for detection of cosmic ray induced air showers at the Engineering Radio Array of the Pierre Auger Observatory, the so-called Auger Engineering Radio Array (AERA). The directional and frequency characteristics of the broadband antenna are investigated using a remotely piloted aircraft carrying a small transmitting antenna. The antenna sensitivity is described by the vector effective length relating the measured voltage with the electric-field components perpendicular to the incoming signal direction. The horizontal and meridional components are determined with an overall uncertainty of 7.4(-0.3)(+0.9)%and 10.3(-1.7)(+2.8)% respectively. The measurement is used to correct a simulated response of the frequency and directional response of the antenna. In addition, the influence of the ground conductivity and permittivity on the antenna response is simulated. Both have a negligible influence given the ground conditions measured at the detector site. The overall uncertainties of the vector effective length components result in an uncertainty of 8.8(-1.3)(+2.1)% in the square root of the energy fluence for incoming signal directions with zenith angles smaller than 60 degrees

    Tratamiento de fracturas toracolumbares: nuestra experiencia en el periodo 2000-2003. Protocolo de actuación

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    Presentamos una revisión de los resultados obtenidos en pacientes intervenidos de fracturas tóraco-lumbares durante los años 2000 a 2003, en ambos inclusive, por el servicio de Traumatología y Cirugía Ortopédica del Hospital Universitario Virgen de las Nieves de Granada; así como el protocolo seguido en el manejo diagnóstico-terapéutico de este tipo de pacientes. Las fracturas más frecuentes fueron en L1 y del tipo A3 de la clasificación AO. La vía de abordaje más utilizada fue la posterior (138 casos). En 132 casos se instrumentó la vértebra fracturada y en 39 casos fue necesaria la descompresión. El índice sagital medio preoperatorio fue de 17,5º y el postoperatorio de 3,5º. La pérdida de altura vertebral preoperatoria fue del 52% y del 14% al final del tratamiento. En 39 pacientes con déficit neurológico se realizó descompresión. En el 79% de los casos los resultados fueron excelentes y en el resto regulares o malos.We present the results of surgical treatment in patients with thoraco-lumbar fractures operated on between the years 2000 and 2003 at the Orthopedic and Traumatology Department of the hospital Virgen de las Nieves Hospital of Granada, Spain. The diagnosis and therapeutic protocol of this type of patients is also evaluated. A3 type from AO classification fracture of L1, was the most frequent injury. Posterior surgical approach of the spine was mainly used (138 cases), in 132 cases the fracture was stabilized by means of internal fixation and 39 cases required decompression of the lumbar canal. The average sagital index was 17,5º preoperative and 3,5º after surgery. The average loss of height was 52% preoperative and 14% at the end of treatment. In 39 surgical decompression was indicated for neurological impairment. Excellent results were obtained in 79% of the cases, the rest were fair and poor

    Globalisation, forced migration and public health: getting the big picture into focus

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    The 2HWC HAWC Observatory Gamma Ray Catalog

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    We present the first catalog of TeV gamma-ray sources realized with the recently completed High Altitude Water Cherenkov Observatory (HAWC). It is the most sensitive wide field-of-view TeV telescope currently in operation, with a 1-year survey sensitivity of ~5-10% of the flux of the Crab Nebula. With an instantaneous field of view >1.5 sr and >90% duty cycle, it continuously surveys and monitors the sky for gamma ray energies between hundreds GeV and tens of TeV. HAWC is located in Mexico at a latitude of 19 degree North and was completed in March 2015. Here, we present the 2HWC catalog, which is the result of the first source search realized with the complete HAWC detector. Realized with 507 days of data and represents the most sensitive TeV survey to date for such a large fraction of the sky. A total of 39 sources were detected, with an expected contamination of 0.5 due to background fluctuation. Out of these sources, 16 are more than one degree away from any previously reported TeV source. The source list, including the position measurement, spectrum measurement, and uncertainties, is reported. Seven of the detected sources may be associated with pulsar wind nebulae, two with supernova remnants, two with blazars, and the remaining 23 have no firm identification yet.Comment: Submitted 2017/02/09 to the Astrophysical Journa

    Phase diagrams in nonlocal PNJL models constrained by Lattice QCD results

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    Based on lattice QCD-adjusted SU(2) nonlocal Polyakov--Nambu--Jona-Lasinio (PNJL) models, we investigate how the location of the critical endpoint in the QCD phase diagram depends on the strenght of the vector meson coupling, as well as the Polyakov-loop (PL) potential and the form factors of the covariant model. The latter are constrained by lattice QCD data for the quark propagator. The strength of the vector coupling is adjusted such as to reproduce the slope of the pseudocritical temperature for the chiral phase transition at low chemical potential extracted recently from lattice QCD simulations. Our study supports the existence of a critical endpoint in the QCD phase diagram albeit the constraint for the vector coupling shifts its location to lower temperatures and higher baryochemical potentials than in the case without it.Comment: 23 pages, 10 figures. Version accepted in Phys. Part. Nucl. Lett. (to appear), references adde

    The Sensitivity of HAWC to High-Mass Dark Matter Annihilations

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    The High Altitude Water Cherenkov (HAWC) observatory is a wide field-of-view detector sensitive to gamma rays of 100 GeV to a few hundred TeV. Located in central Mexico at 19 degrees North latitude and 4100 m above sea level, HAWC will observe gamma rays and cosmic rays with an array of water Cherenkov detectors. The full HAWC array is scheduled to be operational in Spring 2015. In this paper, we study the HAWC sensitivity to the gamma-ray signatures of high-mass (multi- TeV) dark matter annihilation. The HAWC observatory will be sensitive to diverse searches for dark matter annihilation, including annihilation from extended dark matter sources, the diffuse gamma-ray emission from dark matter annihilation, and gamma-ray emission from non-luminous dark matter subhalos. Here we consider the HAWC sensitivity to a subset of these sources, including dwarf galaxies, the M31 galaxy, the Virgo cluster, and the Galactic center. We simulate the HAWC response to gamma rays from these sources in several well-motivated dark matter annihilation channels. If no gamma-ray excess is observed, we show the limits HAWC can place on the dark matter cross-section from these sources. In particular, in the case of dark matter annihilation into gauge bosons, HAWC will be able to detect a narrow range of dark matter masses to cross-sections below thermal. HAWC should also be sensitive to non-thermal cross-sections for masses up to nearly 1000 TeV. The constraints placed by HAWC on the dark matter cross-section from known sources should be competitive with current limits in the mass range where HAWC has similar sensitivity. HAWC can additionally explore higher dark matter masses than are currently constrained.Comment: 15 pages, 4 figures, version to be published in PR

    Daily monitoring of TeV gamma-ray emission from Mrk 421, Mrk 501, and the Crab Nebula with HAWC

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    We present results from daily monitoring of gamma rays in the energy range 0.5\sim0.5 to 100\sim100 TeV with the first 17 months of data from the High Altitude Water Cherenkov (HAWC) Observatory. Its wide field of view of 2 steradians and duty cycle of >95>95% are unique features compared to other TeV observatories that allow us to observe every source that transits over HAWC for up to 6\sim6 hours each sidereal day. This regular sampling yields unprecedented light curves from unbiased measurements that are independent of seasons or weather conditions. For the Crab Nebula as a reference source we find no variability in the TeV band. Our main focus is the study of the TeV blazars Markarian (Mrk) 421 and Mrk 501. A spectral fit for Mrk 421 yields a power law index Γ=2.21±0.14stat±0.20sys\Gamma=2.21 \pm0.14_{\mathrm{stat}}\pm0.20_{\mathrm{sys}} and an exponential cut-off E0=5.4±1.1stat±1.0sysE_0=5.4 \pm 1.1_{\mathrm{stat}}\pm 1.0_{\mathrm{sys}} TeV. For Mrk 501, we find an index Γ=1.60±0.30stat±0.20sys\Gamma=1.60\pm 0.30_{\mathrm{stat}} \pm 0.20_{\mathrm{sys}} and exponential cut-off E0=5.7±1.6stat±1.0sysE_0=5.7\pm 1.6_{\mathrm{stat}} \pm 1.0_{\mathrm{sys}} TeV. The light curves for both sources show clear variability and a Bayesian analysis is applied to identify changes between flux states. The highest per-transit fluxes observed from Mrk 421 exceed the Crab Nebula flux by a factor of approximately five. For Mrk 501, several transits show fluxes in excess of three times the Crab Nebula flux. In a comparison to lower energy gamma-ray and X-ray monitoring data with comparable sampling we cannot identify clear counterparts for the most significant flaring features observed by HAWC.Comment: 18 pages, 10 figures, accepted for publication in The Astrophysical Journa
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