9,469 research outputs found

    Diffuse gamma-ray emission from galactic pulsars

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    Millisecond Pulsars are second most abundant source population discovered by the Fermi-LAT. They might contribute non-negligibly to the diffuse emission measured at high latitudes by Fermi-LAT, the IDGRB. Gamma-ray sources also contribute to the anisotropy of the IDGRB measured on small scales by Fermi-LAT. We aim to assess the contribution of the unresolved counterpart of the detected MSPs population to the IDGRB and the maximal fraction of the measured anisotropy produced by this source class. We model the MSPs spatial distribution in the Galaxy and the gamma-ray emission parameters by considering radio and gamma-ray observational constraints. By simulating a large number of MSPs populations, we compute the average diffuse emission and the anisotropy 1-sigma upper limit. The emission from unresolved MSPs at 2 GeV, where the peak of the spectrum is located, is at most 0.9% of the measured IDGRB above 10 degrees in latitude. The 1-sigma upper limit on the angular power for unresolved MSP sources turns out to be about a factor of 60 smaller than Fermi-LAT measurements above 30 degrees. Our results indicate that this galactic source class represents a negligible contributor to the high-latitude gamma-ray sky and confirm that most of the intensity and geometrical properties of the measured diffuse emission are imputable to other extragalactic source classes. Nevertheless, given the MSP distribution, we expect them to contribute significantly to the gamma-ray diffuse emission at low latitudes. Since, along the galactic disk, the population of young Pulsars overcomes in number the one of MSPs, we compute the gamma-ray emission from the whole population of unresolved Pulsars in two low-latitude regions: the inner Galaxy and the galactic center.Comment: 19 pages, 26 figures. It matches the published version, minor changes onl

    Interpretation of AMS-02 electrons and positrons data

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    We perform a combined analysis of the recent AMS-02 data on electrons, positrons, electrons plus positrons and positron fraction, in a self-consistent framework where we realize a theoretical modeling of all the astrophysical components that can contribute to the observed fluxes in the whole energy range. The primary electron contribution is modeled through the sum of an average flux from distant sources and the fluxes from the local supernova remnants in the Green catalog. The secondary electron and positron fluxes originate from interactions on the interstellar medium of primary cosmic rays, for which we derive a novel determination by using AMS-02 proton and helium data. Primary positrons and electrons from pulsar wind nebulae in the ATNF catalog are included and studied in terms of their most significant (while loosely known) properties and under different assumptions (average contribution from the whole catalog, single dominant pulsar, a few dominant pulsars). We obtain a remarkable agreement between our various modeling and the AMS-02 data for all types of analysis, demonstrating that the whole AMS-02 leptonic data admit a self-consistent interpretation in terms of astrophysical contributions.Comment: 33 pages, 26 figures and 4 tables, v2: accepted for publication in JCAP, minor changes relative to v

    Contribution of pulsars to cosmic-ray positrons in light of recent observation of inverse-Compton halos

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    The hypothesis that pulsar wind nebulae (PWNe) can significantly contribute to the excess of the positron (e+e^+) cosmic-ray flux has been consolidated after the observation of a γ\gamma-ray emission at TeV energies of a few degree size around Geminga and Monogem PWNe, and at GeV energies for Geminga at a much larger extension. The γ\gamma-ray halos around these PWNe are interpreted as due to electrons (e−e^-) and e+e^+ accelerated and escaped by their PWNe, and inverse Compton scattering low-energy photons of the interstellar radiation fields. The extension of these halos suggests that the diffusion around these PWNe is suppressed by two orders of magnitude with respect to the average in the Galaxy. We implement a two-zone diffusion model for the propagation of e+e^+ accelerated by the Galactic population of PWNe. We consider pulsars from the ATNF catalog and build up simulations of the PWN Galactic population. In both scenarios, we find that within a two-zone diffusion model, the total contribution from PWNe and secondary e+e^+ is at the level of AMS-02 data, for an efficiency of conversion of the pulsar spin down energy in e±e^\pm of η∼0.1\eta\sim0.1. For the simulated PWNe, a 1σ1\sigma uncertainty band is determined, which is of at least one order of magnitude from 10 GeV up to few TeV. The hint for a decreasing e+e^+ flux at TeV energies is found, even if it is strongly connected to the chosen value of the radius of the low diffusion bubble around each source.Comment: 10 pages, 7 figures. Figures 2, 3 and 5 updated. Results unchange

    Fertility preservation in ovarian tumours

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    A considerable number of patients with a cancer diagnosis are of childbearing age and have not satisfied their desire for a family. Despite ovarian cancer (OC) usually occurring in older patients, 3%–14% are diagnosed at a fertile age with the overall 5-year survival rate being 91.2% in women ≤44 years of age when it is found at 1A–B stage. In this scenario, testing the safety and the efficacy of fertility sparing strategies in OC patients is very important overall in terms of quality of life. Unfortunately, the lack of randomised trials to validate conservative approaches does not guarantee the safety of fertility preservation strategies. However, evidence-based data from descriptive series suggest that in selected cases, the preservation of the uterus and at least one part of the ovary does not lead to a high risk of relapse. This conservative surgery helps to maintain organ function, giving patients of childbearing age the possibility to preserve their fertility. We hereby analysed the main evidence from the international literature on this topic in order to highlight the selected criteria for conservative management of OC patients, including healthy BRCA mutations carriers

    Evaluating Risk to People and Property for Aircraft Emergency Landing Planning

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143122/1/1.I010513.pd

    Optimizing Steady Turns for Gliding Trajectories

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140649/1/1.g000319.pd
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