arXiv subjects

M. Gaug

Publications and source records attributed to M. Gaug.

169 records · Page 10Linked to original sources

arXiv2007

Tau neutrino search with the MAGIC telescope

The MAGIC telescope located on the Roque de los Muchachos on the Canary Island La Palma at a height of 2200 m a.s.l. is able to point to the sea. This permits a search for air shower signatures induced by particles coming out of the Earth. An analytical approximation results in tau neutrino effective areas from ~10^3 m^2 (at 100 TeV) to 10^5 m^2 (at 1 EeV) for an observation angle of about 1 degree below the horizon, rapidly diminishing with further inclination. Taking into account the huge effective area, this configuration was investigated for its suitability to search for ultra-high energy (UHE) tau-neutrino signatures. The outcome of simulations for tau-neutrino signatures will be presented, models for astrophysical neutrino sources reviewed, and estimated event rates in MAGIC are shown.

astro-ph↗

arXiv2007

MAGIC upper limits on the very high energy emission from GRBs

The fast repositioning system of the MAGIC Telescope has allowed during its first data cycle, between 2005 and the beginning of year 2006, observing nine different GRBs as possible sources of very high energy gammas. These observations were triggered by alerts from Swift, HETE-II, and Integral; they started as fast as possible after the alerts and lasted for several minutes, with an energy threshold varying between 80 and 200 GeV, depending upon the zenith angle of the burst. No evidence for gamma signals was found, and upper limits for the flux were derived for all events, using the standard analysis chain of MAGIC. For the bursts with measured redshift, the upper limits are compatible with a power law extrapolation, when the intrinsic fluxes are evaluated taking into account the attenuation due to the scattering in the Metagalactic Radiation Field (MRF).

astro-ph↗

arXiv2006

GRB 050713A: High Energy Observations of the GRB Prompt and Afterglow Emission

Swift discovered GRB 050713A and slewed promptly to begin observing with its narrow field instruments 72.6 seconds after the burst onset, while the prompt gamma-ray emission was still detectable in the BAT. Simultaneous emission from two flares is detected in the BAT and XRT. This burst marks just the second time that the BAT and XRT have simultaneously detected emission from a burst and the first time that both instruments have produced a well sampled, simultaneous dataset covering multiple X-ray flares. The temporal rise and decay parameters of the flares are consistent with the internal shock mechanism. In addition to the Swift coverage of GRB 050713A, we report on the Konus-Wind (K-W) detection of the prompt emission in the energy range 18-1150 keV, an upper limiting GeV measurement of the prompt emission made by the MAGIC imaging atmospheric Cherenkov telescope and XMM-Newton observations of the afterglow. Simultaneous observation between Swift XRT and XMM-Newton produce consistent results, showing a break in the lightcurve at T+~15ks. Together, these four observatories provide unusually broad spectral coverage of the prompt emission and detailed X-ray follow-up of the afterglow for two weeks after the burst trigger. Simultaneous spectral fits of K-W with BAT and BAT with XRT data indicate that an absorbed broken powerlaw is often a better fit to GRB flares than a simple absorbed powerlaw. These spectral results together with the rapid temporal rise and decay of the flares suggest that flares are produced in internal shocks due to late time central engine activity.

astro-ph↗

arXiv2006

Discovery of VHE gamma-ray emission from 1ES1218+30.4

The MAGIC collaboration has studied the high peaked BL-Lac object 1ES1218+30.4 at a redshift z = 0.182, using the MAGIC imaging air Cherenkov telescope located on the Canary island of La Palma. A gamma-ray signal was observed with 6.4sigma significance. The differential energy spectrum for an energy threshold of 120GeV can be fitted by a simple power law yielding F_E(E) = (8.1+-2.1)*10^-7 (E/250GeV)^(-3.0+-0.4) TeV^-1 m^-2 s^-1. During the six days of observation in January 2005 no time variability on time scales of days was found within the statistical errors. The observed integral flux above 350GeV is nearly a factor two below the the upper limit reported by the Whipple Collaboration in 2003.

astro-ph↗

arXiv2006

Flux upper limit of gamma-ray emission by GRB050713a from MAGIC Telescope observations

The long-duration GRB050713a was observed by the MAGIC Telescope, 40 seconds after the burst onset, and followed up for 37 minutes, until twilight. The observation, triggered by a SWIFT alert, covered energies above ~175 GeV. Using standard MAGIC analysis, no evidence for a gamma signal was found. As the redshift of the GRB was not measured directly, the flux upper limit, estimated by MAGIC, is still compatible with the assumption of an unbroken power-law spectrum extending from a few hundred keV to our energy range.

astro-ph↗

arXiv2005

FADC Pulse Reconstruction Using a Digital Filter for the MAGIC Telescope

Presently, the MAGIC telescope uses a 300 MHz FADC system to sample the transmitted and shaped signals from the captured Cherenkov light of air showers. We describe a method of Digital Filtering of the FADC samples to extract the charge and the arrival time of the signal: Since the pulse shape is dominated by the electronic pulse shaper, a numerical fit can be applied to the FADC samples taking the noise autocorrelation into account. The achievable performance of the digital filter is presented and compared to other signal reconstruction algorithms.

astro-ph↗

arXiv2005

The MAGIC Telescope and the Observation of Gamma Ray Bursts

The MAGIC Telescope, now taking data with an energy threshold well below 100 GeV, will soon be able to take full advantage of the fast slewing capability of its altazimuthal mount. Exploiting the link with the GCN network, the MAGIC Telescope could be one of the first ground-based experiments able to see the prompt emission of Gamma Ray Bursts in the few tens of GeV region.

astro-ph↗