463 research outputs found
Very high energy gamma-ray follow-up observations of novae and dwarf novae with the MAGIC telescopes
In the last few years the Fermi-LAT instrument has detected GeV gamma-ray
emission from several novae. Such GeV emission can be interpreted in terms of
inverse Compton emission from electrons accelerated in the shock or in terms of
emission from hadrons accelerated in the same conditions. The latter might
reach much higher energies and could produce a second component in the
gamma-ray spectrum at TeV energies. We perform follow-up observations of
selected novae and dwarf novae in search of the second component in TeV energy
gamma rays. This can shed light on the acceleration process of leptons and
hadrons in nova explosions. We have performed observations with the MAGIC
telescopes of 3 sources, a symbiotic nova YY Her, a dwarf nova ASASSN-13ax and
a classical nova V339 Del, shortly after their outbursts. We did not detect TeV
gamma-ray emission from any of the objects observed. The TeV upper limits from
MAGIC observations and the GeV detection by Fermi constrain the acceleration
parameters for electrons and hadrons.Comment: Proceedings of the 34th International Cosmic Ray Conference, 30 July-
6 August, 2015, The Hague, The Netherlands. The content of this submission is
similar to our paper in the Fermi Symposium of novae observations with MAGIC,
which appeared as arXiv:1502.05853. arXiv admin note: substantial text
overlap with arXiv:1502.0585
A Template-based gamma-ray Reconstruction Method for Air Shower Arrays
We introduce a new Monte Carlo template-based reconstruction method for air shower arrays, with a focus on shower core and energy reconstruction of -ray induced air showers. The algorithm fits an observed lateral amplitude distribution of an extensive air shower against an expected probability distribution using a likelihood approach. A full Monte Carlo air shower simulation in combination with the detector simulation is used to generate the expected probability distributions. The goodness of fit can be used to discriminate between -ray and hadron induced air showers. As an example, we apply this method to the High Altitude Water Cherenkov -ray Observatory and its recently installed high-energy upgrade. The performance of this method and the applicability to air shower arrays with mixed detector types makes it a promising reconstruction approach for current and future instruments
Prospects for the Observation of Primordial Black Hole evaporation with the Southern Wide Field of View Gamma-ray Observatory
Primordial Black Holes (PBHs) are remnants of objects formed in the early
Universe. Their lifetime is an increasing function of their mass, so PBHs in
the right mass range can end their lives in an evaporation event that is
potentially detectable by our instruments now. This evaporation may result in a
-ray flash that can be detected by the current generation of
Very-High-Energy -ray detectors. The Southern Wide field of view
Gamma-ray Observatory (SWGO) will be part of the next generation of these
instruments. It will be able to establish limits on PBH evaporations for
integration windows between 0.5 and 5 s, in a radius of 0.25 pc around the
Earth, being sensitive to a rate of the order of 50 pc yr,
more than one order of magnitude more constraining than the currently
established best limits.Comment: Accepted by JCA
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