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تسجيل مستخدم جديدThe population point of view on the evolution of TeV pulsar wind nebulae
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To investigate the nature and evolution of TeV pulsar wind nebulae, we examine the firmly identified PWNe in the H.E.S.S. Galactic Plane Survey, along with the few other known detections from the literature, as well as the upper limits extracted from the H.E.S.S survey. These data exhibit a correlation of TeV surface brightness with pulsar spin-down power. It appears to be caused by both an increase of TeV extension and a decrease of TeV luminosity with decreasing spin-down power. We also find that the offsets of pulsars with ages around 10 kyr with respect to the wind nebula centres are frequently larger than can be plausibly explained by pulsar proper motion and could be due to an asymmetric environment. These and other results will be presented and put to context with a basic modelling of TeV pulsar wind nebula evolution.
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The nine-year H.E.S.S. Galactic Plane Survey (HGPS) yielded the most uniform observation scan of the inner Milky Way in the TeV gamma-ray band to date. The sky maps and source catalogue of the HGPS allow for a systematic study of the population of Te
V pulsar wind nebulae found throughout the last decade. To investigate the nature and evolution of pulsar wind nebulae, for the first time we also present several upper limits for regions around pulsars without a detected TeV wind nebula. Our data exhibit a correlation of TeV surface brightness with pulsar spin-down power $dot{E}$. This seems to be caused both by an increase of extension with decreasing $dot{E}$, and hence with time, compatible with a power law $R_mathrm{PWN}(dot{E}) sim dot{E}^{-0.65 pm 0.20}$, and by a mild decrease of TeV gamma-ray luminosity with decreasing $dot{E}$, compatible with $L_{1-10,mathrm{TeV}} sim dot{E}^{0.59 pm 0.21}$. We also find that the offsets of pulsars with respect to the wind nebula centres with ages around 10 kyr are frequently larger than can be plausibly explained by pulsar proper motion and could be due to an asymmetric environment. In the present data, it seems that a large pulsar offset is correlated with a high apparent TeV efficiency $L_{1-10,mathrm{TeV}}/dot{E}$. In addition to 14 HGPS sources considered as firmly identified pulsar wind nebulae and 5 additional pulsar wind nebulae taken from literature, we find 10 HGPS sources that form likely TeV pulsar wind nebula candidates. Using a model that subsumes the present common understanding of the very high-energy radiative evolution of pulsar wind nebulae, we find that the trends and variations of the TeV observables and limits can be reproduced to a good level, drawing a consistent picture of present-day TeV data and theory.
Pulsar wind nebulae (PWNe) have been established as the most populous class of TeV gamma-ray emitters. Since launch, the Fermi Large Area Telescope (LAT)identified five high-energy (100MeV <E< 100 GeV) gamma-ray sources as PWNe, and detected a large
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During the search for counterparts of very-high-energy gamma-ray sources, we serendipitously discovered large, extended, low surface brightness emission from PWNe around pulsars with the ages up to ~100 kyrs, a discovery made possible by the low and
stable background of the Suzaku X-ray satellite. A systematic study of a sample of 8 of these PWNe, together with Chandra datasets, has revealed us that the nebulae keep expanding up to for ~100 kyrs, although time scale of the synchrotron X-ray emission is only ~60 yr for typical magnetic fields of 100 microG. Our result suggests that the accelerated electrons up to ~80 TeV can escape from the PWNe without losing most energies. Moreover, in order to explain the observed correlation between the X-ray size and the pulsar spindwon age, the magnetic field strength in the PWNe must decrease with time.
The discovery of extended TeV emission around the Geminga and PSR B0656+14 pulsars, with properties consistent with free particle propagation in the interstellar medium (ISM), has sparked considerable discussion on the possible presence of such halos
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The most numerous source class that emerged from the H.E.S.S. Galactic Plane Survey are Pulsar Wind Nebulae (PWNe). The 2013 reanalysis of this survey, undertaken after almost 10 years of observations, provides us with the most sensitive and most com
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