10,207 research outputs found
Diffuse gamma-ray emission from galactic pulsars
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
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
The hypothesis that pulsar wind nebulae (PWNe) can significantly contribute
to the excess of the positron () cosmic-ray flux has been consolidated
after the observation of a -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 -ray halos around these PWNe are
interpreted as due to electrons () and 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 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 is at the
level of AMS-02 data, for an efficiency of conversion of the pulsar spin down
energy in of . For the simulated PWNe, a
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 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
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
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143122/1/1.I010513.pd
Optimizing Steady Turns for Gliding Trajectories
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140649/1/1.g000319.pd
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