252 research outputs found
Modulation Mechanism of TeV, GeV, and X-ray Emission in LS5039
The emission mechanism of the gamma-ray binary LS5039 in energy bands of TeV,
GeV, and X-ray is investigated. Observed light curves in LS5039 show that TeV
and GeV fluxes anticorrelate and TeV and X-ray fluxes correlate. However, such
correlated variations have not been explained yet reasonably at this stage.
Assuming that relativistic electrons are injected constantly at the location of
the compact object as a point source, and that they lose energy only by the
inverse Compton (IC) process, we calculate gamma-ray spectra and light curves
by the Monte Carlo method, including the full electromagnetic cascade process.
Moreover, we calculated X-ray spectra and light curves by using the resultant
electron distribution. As a result, we are able to reproduce qualitatively
spectra and light curves observed by HESS, Fermi, and Suzaku for the
inclination angle i = 30 dig and the index of injected electron distribution p
= 2.5. We conclude that TeV-GeV anticorrelation is due to anisotropic IC
scattering and anisotropic gamma-gamma absorption, and that TeV-X correlation
is due to the dependence of IC cooling time on orbital phases. In addition, the
constraint on the inclination angle implies that the compact object in LS5039
is a black hole.Comment: 27 pages, 7 figures, published in The Astrophysical Journa
Pulsar model of the high energy phenomenology of LS 5039
Under the assumption that LS 5039 is a system composed by a pulsar rotating
around an O6.5V star in a day orbit, we present the results of a
theoretical modeling of the high energy phenomenology observed by the High
Energy Stereoscopy Array (H.E.S.S.). This model (including detailed account of
the system geometry, Klein-Nishina inverse Compton, -
absorption, and cascading) is able to describe well the rich observed
phenomenology found in the system at all timescales, both flux and
spectrum-wise.Comment: Figures and results are unchanged. Some new text and new reference
Electrical and dielectric characterization of trabecular bone quality (Hohkaluun laadun karakterisointi sähköisellä impedanssispektroskopialla)
Optical depths for gamma-rays in the radiation field of a star heated by external X-ray source in LMXBs: Application to Her X-1 and Sco X-1
The surface of a low mass star inside a compact low mass X-ray binary system
(LMXB) can be heated by the external X-ray source which may appear due to the
accretion process onto a companion compact object (a neutron star or a black
hole). As a result, the surface temperature of the star can become
significantly higher than it is in the normal state resulting from
thermonuclear burning. We wonder whether high energy electrons and gamma-rays,
injected within the binary system, can efficiently interact with this enhanced
radiation field. To decide this, we calculate the optical depths for the
gamma-ray photons in the radiation field of such irradiated star as a function
of the phase of the binary system. Based on these calculations, we conclude
that compact low mass X-ray binary systems may also become sources of high
energy gamma-rays since conditions for interaction of electrons and gamma-rays
are quite similar to these ones observed within the high mass TeV gamma-ray
binaries such as LS 5039 and LSI 303 +61. However, due to differences in the
soft radiation field, the expected gamma-ray light curves can significantly
differ between low mass and high mass X-ray binaries. As an example, we apply
such calculations to two well known LMXBs: Her X-1 and Sco X-1. It is concluded
that electrons accelerated to high energies inside these binaries should find
enough soft photon target from the companion star for efficient gamma-ray
production.Comment: 10 pages, 8 figures, accepted to A&
O znaczeniu alimentów w systemie pomocy społecznej
Maintenance is a form of fulfilment of the maintenance duty whose purpose is to provide means of subsistence to a family member who cannot meet his or her reasonable needs independently. In public law, maintenance is also given other meanings, in particular its precedence over social benefits is emphasised. Poland’s Social Assistance Act treats maintenance as the personal income of a child entitled to it and, on the part of the person named as the debtor, as an expense deductible from income. Past failure to fulfil the maintenance duty by a resident of a social welfare home is considered as a premise for the exemption of his/her descendants from the fee for staying in the facility. The function of maintenance is recognised in the fact that heads of social welfare centres have the right to bring legal action for maintenance claims on behalf of citizens. Maintenance appears as a tool to protect the social order and axiological order of the social welfare system.
Alimenty są formą realizacji obowiązku alimentacyjnego, ich celem jest dostarczanie środków utrzymania członkowi rodziny, który nie może samodzielnie zaspokoić swoich usprawiedliwionych potrzeby. W prawie publicznym alimentom przypisuje się również inne znaczenia, przede wszystkim podkreśla się pierwszeństwo ich dochodzenia przed świadczeniami socjalnymi. W ustawie o pomocy społecznej alimenty traktuje się jako dochód osobisty dziecka uprawnionego do alimentacji, a po stronie dłużnika alimentacyjnego jako wydatek odliczany od przychodu. Zaniedbanie w przeszłości obowiązku alimentacyjnego przez mieszkańca domu pomocy społecznej uznawane jest za przesłankę zwolnienia jego zstępnych z opłaty za pobyt w placówce. Wyrazem uznania funkcji tych świadczeń jest przyznanie kierownikom ośrodków pomocy społecznej prawa do wytaczania przed sądem powództw o roszczenia alimentacyjne na rzecz obywateli. Alimenty jawią się jako narzędzie ochrony ładu społecznego i porządku aksjologicznego systemu pomocy społecznej
One-dimensional pair cascade emission in gamma-ray binaries
In gamma-ray binaries such as LS 5039 a large number of electron-positron
pairs are created by the annihilation of primary very high energy (VHE)
gamma-rays with photons from the massive star. The radiation from these
particles contributes to the total high energy gamma-ray flux and can initiate
a cascade, decreasing the effective gamma-ray opacity in the system. The aim of
this paper is to model the cascade emission and investigate if it can account
for the VHE gamma-ray flux detected by HESS from LS 5039 at superior
conjunction, where the primary gamma-rays are expected to be fully absorbed. A
one-dimensional cascade develops along the line-of-sight if the deflections of
pairs induced by the surrounding magnetic field can be neglected. A
semi-analytical approach can then be adopted, including the effects of the
anisotropic seed radiation field from the companion star. Cascade equations are
numerically solved, yielding the density of pairs and photons. In LS 5039, the
cascade contribution to the total flux is large and anti-correlated with the
orbital modulation of the primary VHE gamma-rays. The cascade emission
dominates close to superior conjunction but is too strong to be compatible with
HESS measurements. Positron annihilation does not produce detectable 511 keV
emission. This study provides an upper limit to cascade emission in gamma-ray
binaries at orbital phases where absorption is strong. The pairs are likely to
be deflected or isotropized by the ambient magnetic field, which will reduce
the resulting emission seen by the observer. Cascade emission remains a viable
explanation for the detected gamma-rays at superior conjunction in LS 5039.Comment: 8 pages, 7 figures, 1 table, accepted for publication in Astronomy
and Astrophysic
GLAST testing of a pulsar model matching H.E.S.S. observations of LS 5039
LS 5039 is one of a handful of X-ray binaries that have been recently
detected at high-energy -rays, in this case, by the High-Energy
Stereoscopy Array (H.E.S.S.). The nature of this system is unknown: both a
black hole and a pulsar have been invoked as possible compact object
companions. Here we work with a model of the high energy phenomenology of the
system in which it is assumed that the companion object is a pulsar rotating
around an O6.5V star in the days orbit. The model assumes two
different sets of power-law spectral parameters of the interacting primary
leptons corresponding to the two orbital phase intervals defined by H.E.S.S. as
having different gamma-ray spectra and very-high-energy (VHE) cutoffs. We show
the H.E.S.S. phenomenology is completely explained by this model. We present
predictions for photons with lower energies (for GeV), subject to test
in the forthcoming months with the GLAST satellite. We find that GLAST is able
to judge on this model within one year.Comment: Accepted for publication in The Astrophysical Journal Letter
Probing the Pulsar Wind in the gamma-ray Binary System PSR B1259-63/SS 2883
The spectral energy distribution from the X-ray to the very high energy
regime ( GeV) has been investigated for the -ray binary system
PSR B1259-63/SS2883 as a function of orbital phase within the framework of a
simple model of a pulsar wind nebula. The emission model is based on the
synchrotron radiation process for the X-ray regime and the inverse Compton
scattering process boosting stellar photons from the Be star companion to the
very high energy (100GeV-TeV) regime. With this model, the observed temporal
behavior can, in principle, be used to probe the pulsar wind properties at the
shock as a function of the orbital phase. Due to theoretical uncertainties in
the detailed microphysics of the acceleration process and the conversion of
magnetic energy into particle kinetic energy, the observed X-ray data for the
entire orbit are fit using two different methods.Comment: 46 pages, 16 figures, accepted for publication in Ap
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