ABSTRACT Supernova remnants (SNRs) are commonly believed to be the primary sources of Galactic cosmic rays. Despite intensive study of the non-thermal emission of many SNRs the identification of the ...accelerated particle type relies heavily on assumptions of ambient-medium parameters that are only loosely constrained. Compelling evidence of hadronic acceleration can be provided by detecting a strong roll-off in the secondary γ-ray spectrum below the production threshold energy of about 135 MeV, the so called "pion bump." Here we use five years of Fermi-Large Area Telescope data to study the spectrum above 60 MeV of the middle-aged SNR W51C. A clear break in the power-law γ-ray spectrum at is detected with significance and we show that this break is most likely associated with the energy production threshold of mesons. A high-energy break in the γ-ray spectrum at about 2.7 GeV is found with significance. The spectral index at energies beyond this second break is and closely matches the spectral index derived by the MAGIC Collaboration above 75 GeV. Therefore our analysis provides strong evidence to explain the γ-ray spectrum of W51C by a single particle population of protons with a momentum spectrum best described by a broken power law with break momentum W51C is the third middle-aged SNR that displays compelling evidence for cosmic-ray acceleration and thus strengthens the case of SNRs as the main source of Galactic cosmic rays.
We report a study of extended γ-ray emission with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope, which is likely to be the second case of a γ-ray detection from a ...star-forming region (SFR) in our Galaxy. The LAT source is located in the G25 region, 1 7 × 2 1 around (l, b) = (25 0, 0 0). The γ-ray emission is found to be composed of two extended sources and one pointlike source. The extended sources have similar sizes of about 1 4 × 0 6. An ∼0 4 diameter subregion of one has a photon index of Γ = 1.53 0.15, and is spatially coincident with HESS J1837−069, likely a pulsar wind nebula. The other parts of the extended sources have a photon index of Γ = 2.1 0.2 without significant spectral curvature. Given their spatial and spectral properties, they have no clear associations with sources at other wavelengths. Their γ-ray properties are similar to those of the Cygnus cocoon SFR, the only firmly established γ-ray detection of an SFR in the Galaxy. Indeed, we find bubble-like structures of atomic and molecular gas in G25, which may be created by a putative OB association/cluster. The γ-ray emitting regions appear confined in the bubble-like structure; similar properties are also found in the Cygnus cocoon. In addition, using observations with the XMM-Newton, we find a candidate young massive OB association/cluster G25.18+0.26 in the G25 region. We propose that the extended γ-ray emission in G25 is associated with an SFR driven by G25.18+0.26. Based on this scenario, we discuss possible acceleration processes in the SFR and compare them with the Cygnus cocoon.
Many diseases and injuries can impair joint mobility. Normal reference values are needed to determine extent of impairment to assess and monitor joint motion. There is very little published data ...describing normal joint range of motion (ROM) for healthy men and women across a wide span of ages. We enrolled male and female subjects aged between 2 and 69 years who were free from conditions that could potentially limit joint mobility for the study. Nine licensed physical therapists used universal goniometers to determine passive joint motion bilaterally of elbow flexion, extension, supination and pronation, shoulder flexion, hip flexion and extension, knee flexion and extension, and ankle dorsiflexion and plantarflexion. Descriptive statistics were calculated for male and female subjects in four age groups: 2–8, 9–19, 20–44 and 45–69 years. Joint ROM measurements were obtained on a total of 674 (53.6% female) healthy, normal subjects aged 2–69 years. Female subjects had greater joint mobility in all age groups in nearly all joints and the gender difference was most obvious in measures of ankle plantarflexion, elbow pronation and supination. Range of motion average values for all joints decreased with advancing age for both men and women and, in most cases, were significantly different than most commonly used normative values. Our study of ROM measurements taken by trained physical therapists on a large sample of healthy individuals revealed significant gender‐ and age‐related variation that may be an important consideration in patient assessment.
Dwarf spheroidal (dSph) galaxies are prime targets for present and future γ-ray telescopes hunting for indirect signals of particle dark matter. The interpretation of the data requires careful ...assessment of their dark matter content in order to derive robust constraints on candidate relic particles. Here, we use an optimized spherical Jeans analysis to reconstruct the ‘astrophysical factor’ for both annihilating and decaying dark matter in 21 known dSphs. Improvements with respect to previous works are: (i) the use of more flexible luminosity and anisotropy profiles to minimize biases, (ii) the use of weak priors tailored on extensive sets of contamination-free mock data to improve the confidence intervals, (iii) systematic cross-checks of binned and unbinned analyses on mock and real data, and (iv) the use of mock data including stellar contamination to test the impact on reconstructed signals. Our analysis provides updated values for the dark matter content of 8 ‘classical’ and 13 ‘ultrafaint’ dSphs, with the quoted uncertainties directly linked to the sample size; the more flexible parametrization we use results in changes compared to previous calculations. This translates into our ranking of potentially-brightest and most robust targets – namely Ursa Minor, Draco, Sculptor – and of the more promising, but uncertain targets – namely Ursa Major 2, Coma – for annihilating dark matter. Our analysis of Segue 1 is extremely sensitive to whether we include or exclude a few marginal member stars, making this target one of the most uncertain. Our analysis illustrates challenges that will need to be addressed when inferring the dark matter content of new ‘ultrafaint’ satellites that are beginning to be discovered in southern sky surveys.
We present the first Fermi Large Area Telescope (LAT) low energy catalog (1FLE) of sources detected in the energy range 30 – 100 MeV. The imaging Compton telescope (COMPTEL) onboard NASA’s Compton ...Gamma-Ray Observatory detected sources below 30 MeV, while catalogs of point sources released by the Fermi-LAT and EGRET collaborations use energies above 100 MeV. Because the Fermi-LAT detects gamma rays with energies as low as 20 MeV, we create a list of sources detected in the energy range between 30 and 100 MeV, which closes a gap of point source analysis between the COMPTEL catalog and the Fermi-LAT catalogs. One of the main challenges in the analysis of point sources is the construction of the background diffuse emission model. In our analysis, we use a background-independent method to search for point-like sources based on a wavelet transform implemented in the PGWave code. The 1FLE contains 198 sources detected above 3σ significance with eight years and nine months of the Fermi-LAT data. For 187 sources in the 1FLE catalog we have found an association in the Fermi-LAT 3FGL catalog: 148 are extragalactic, 22 are Galactic, and 17 are unclassified in the 3FGL. The ratio of the number of flat spectrum radio quasars (FSRQ) to BL Lacertae (BL Lacs) in 1FLE is three to one, which can be compared with an approximately 1:1 ratio for the 3FGL or a 1:6 ratio for 3FHL. The higher ratio of the FSRQs in the 1FLE is expected due to generally softer spectra of FSRQs relative to BL Lacs. Most BL Lacs in 1FLE are of low-synchrotron peaked blazar type (18 out of 31), which have softer spectra and higher redshifts than BL Lacs on average. Correspondingly, we find that the average redshift of the BL Lacs in 1FLE is higher than in 3FGL or 3FHL. There are 11 sources that do not have associations in the 3FGL. Most of the unassociated sources either come from regions of bright diffuse emission or have several known 3FGL sources in the vicinity, which can lead to source confusion. The remaining unassociated sources have significance less than 4σ.
Astrophysical collisionless shocks are among the most powerful particle accelerators in the Universe. Generated by violent interactions of supersonic plasma flows with the interstellar medium, ...supernova remnant shocks are observed to amplify magnetic fields1 and accelerate electrons and protons to highly relativistic speeds2–4. In the well-established model of diffusive shock acceleration5, relativistic particles are accelerated by repeated shock crossings. However, this requires a separate mechanism that pre-accelerates particles to enable shock crossing. This is known as the ‘injection problem’, which is particularly relevant for electrons, and remains one of the most important puzzles in shock acceleration6. In most astrophysical shocks, the details of the shock structure cannot be directly resolved, making it challenging to identify the injection mechanism. Here we report results from laser-driven plasma flow experiments, and related simulations, that probe the formation of turbulent collisionless shocks in conditions relevant to young supernova remnants. We show that electrons can be effectively accelerated in a first-order Fermi process by small-scale turbulence produced within the shock transition to relativistic non-thermal energies, helping overcome the injection problem. Our observations provide new insight into electron injection at shocks and open the way for controlled laboratory studies of the physics underlying cosmic accelerators.In laser–plasma experiments complemented by simulations, electron acceleration is observed in turbulent collisionless shocks. This work clarifies the pre-acceleration to relativistic energies required for the onset of diffusive shock acceleration.
Context.Ground based Cherenkov telescope systems measure astrophysical γ-ray emission against a background of cosmic-ray induced air showers. The subtraction of this background is a major challenge ...for the extraction of spectra and morphology of γ-ray sources. Aims.The unprecedented sensitivity of the new generation of ground based very-high-energy γ-ray experiments such as HESS has lead to the discovery of many previously unknown extended sources. The analysis of such sources requires a range of different background modelling techniques. Here we describe some of the techniques that have been applied to data from the HESS instrument and compare their performance. Methods.Each background model is introduced and discussed in terms of suitability for image generation or spectral analysis and possible caveats are mentioned. Results.We show that there is not a single multi-purpose model, different models are appropriate for different tasks. To keep systematic uncertainties under control it is important to apply several models to the same data set and compare the results.
We present an analysis of the optical spectra available in the Sloan Digital Sky Survey data release nine (SDSS DR9) for the blazars listed in the ROMA-BZCAT and for the gamma -ray blazar candidates ...selected according to their IR colors. First, we adopt a statistical approach based on Monte Carlo simulations to find the optical counterparts of the blazars listed in the ROMA-BZCAT catalog. Then, we crossmatched the SDSS spectroscopic catalog with our selected samples of blazars and gamma -ray blazar candidates, searching for those with optical spectra available to classify our blazar-like sources and, whenever possible, to confirm their redshifts. Our main objectives are to determine the classification of uncertain blazars listed in the ROMA-BZCAT and to discover new gamma-ray blazars. For the ROMA-BZCAT sources, we investigated a sample of 84 blazars, confirming the classification for 20 of them and obtaining 18 new redshift estimates. For the gamma -ray blazars, indicated as potential counterparts of unassociated Fermi sources or with uncertain nature, we established the blazar-like nature of 8 out of the 27 sources analyzed and confirmed 14 classifications.
In classical analyses of γ-ray data from imaging atmospheric Cherenkov telescopes (IACTs), such as the High Energy Stereoscopic System (H.E.S.S.), aperture photometry, or photon counting, is applied ...in a (typically circular) region of interest (RoI) encompassing the source. A key element in the analysis is to estimate the amount of background in the RoI due to residual cosmic ray-induced air showers in the data. Various standard background estimation techniques have been developed in the last decades, most of them rely on a measurement of the background from source-free regions within the observed field of view. However, in particular in the Galactic plane, source analysis and background estimation are hampered by the large number of, sometimes overlapping, γ-ray sources and large-scale diffuse γ-ray emission. For complicated fields of view, a three-dimensional (3D) likelihood analysis shows the potential to be superior to classical analysis. In this analysis technique, a spectromorphological model, consisting of one or multiple source components and a background component, is fitted to the data, resulting in a complete spectral and spatial description of the field of view. For the application to IACT data, the major challenge of such an approach is the construction of a robust background model. In this work, we apply the 3D likelihood analysis to various test data recently made public by the H.E.S.S. collaboration, using the open analysis frameworks ctools and Gammapy. First, we show that, when using these tools in a classical analysis approach and comparing to the proprietary H.E.S.S. analysis framework, virtually identical high-level analysis results, such as field-of-view maps and spectra, are obtained. We then describe the construction of a generic background model from data of H.E.S.S. observations, and demonstrate that a 3D likelihood analysis using this background model yields high-level analysis results that are highly compatible with those obtained from the classical analyses. This validation of the 3D likelihood analysis approach on experimental data is an important step towards using this method for IACT data analysis, and in particular for the analysis of data from the upcoming Cherenkov Telescope Array (CTA).
Essentials
High‐quality data are lacking on use of prophylaxis in adults with hemophilia and arthropathy.
SPINART was a 3‐year randomized clinical trial of late/tertiary prophylaxis vs on‐demand ...therapy.
Prophylaxis improved function, quality of life, activity and pain but not joint structure by MRI.
Prophylaxis improves function but must start before joint bleeding onset to prevent arthropathy.
Summary
Background
Limited data exist on the impact of prophylaxis on adults with severe hemophilia A and pre‐existing joint disease.
Objectives
To describe 3‐year bleeding, joint health and structure, health‐related quality‐of‐life (HRQoL) and other outcomes from the open‐label, randomized, multinational SPINART study.
Patients/Methods
Males aged 12–50 years with severe hemophilia A, ≥ 150 factor VIII exposure days, no inhibitors and no prophylaxis for > 12 consecutive months in the past 5 years were randomized to sucrose‐formulated recombinant FVIII prophylaxis or on‐demand therapy (OD). Data collected included total and joint bleeding events (BEs), joint structure (magnetic resonance imaging MRI), joint health (Colorado Adult Joint Assessment Scale CAJAS), HRQoL, pain, healthcare resource utilization (HRU), activity, and treatment satisfaction.
Results
Following 3 years of prophylaxis, adults maintained excellent adherence, with a 94% reduction in BEs despite severe pre‐existing arthropathy; 35.7% and 76.2% of prophylaxis participants were bleed‐free or had fewer than two BEs per year, respectively. As compared with OD, prophylaxis was associated with improved CAJAS scores (least squares LS mean, − 0.31 n = 42 versus + 0.63 n = 42) and HAEMO‐QoL‐A scores (LS mean, + 3.98 n = 41 versus − 6.00 n = 42), less chronic pain (50% decrease), and approximately two‐fold less HRU; activity, Euro QoL‐5D‐3L (EQ‐5D‐3L) scores and satisfaction scores also favored prophylaxis. However, MRI score changes were not different for prophylaxis versus OD (LS mean, + 0.79 n = 41 versus + 0.96 n = 38).
Conclusions
Over a period of 3 years, prophylaxis versus OD in adults with severe hemophilia A and arthropathy led to decreased bleeding, pain, and HRU, better joint health, activity, satisfaction, and HRQoL, but no reduction in structural arthropathy progression, suggesting that pre‐existing joint arthropathy may be irreversible.
PDF
