The MAGIC collaboration has recently reported the discovery of g-ray emission from the binary system LS I +61°303 in the TeV energy region. Here we present new observational results on this source in ...the energy range between 300 GeV and 3 TeV. In total, 112 hr of data were taken between 2006 September and December covering four orbital cycles of this object. This large amount of data allowed us to produce an integral flux light curve covering for the first time all orbital phases of LS I +61°303. In addition, we also obtained a differential energy spectrum for two orbital phase bins covering the phase range 0.5 < < 0.6 and 0.6 < < 0.7. The photon index in the two phase bins is consistent within the errors with an average index = 2.6 ± 0.2stat ± 0.2sys. LS I +61°303 was found to be variable at TeV energies on timescales of days. These new MAGIC measurements allowed us to search for intranight variability of the very high energy emission; however, no evidence for flux variability on timescales down to 30 min was found. To test for possible periodic structures in the light curve, we apply the formalism developed by Lomb and Scargle to the LS I +61°303 data taken in 2005 and 2006. We found the LS I +61°303 data set to be periodic with a period of (26.8 ± 0.2) days (with a post-trial chance probability of 10-7), close to the orbital period.
Based on MAGIC observations from 2007 June to July, we have obtained an integral upper limit to the VHE energy emission of the globular cluster M13 of F(E>200 GeV) < 5.1 X 10-12 cm-2 s-1, and ...differential upper limits for E > 140 GeV. Those limits allow us to constrain the population of millisecond pulsars within M13 and to test models for acceleration of leptons inside their magnetospheres and surrounding. We conclude that in M13 either millisecond pulsars are fewer than expected or they accelerate leptons less efficiently than predicted.
One fundamental question about pulsars concerns the mechanism of their pulsed electromagnetic emission. Measuring the high-end region of a pulsar's spectrum would shed light on this question. By ...developing a new electronic trigger, we lowered the threshold of the Major Atmospheric gamma-ray Imaging Cherenkov (MAGIC) telescope to 25 giga-electron volts. In this configuration, we detected pulsed gamma-rays from the Crab pulsar that were greater than 25 giga-electron volts, revealing a relatively high cutoff energy in the phase-averaged spectrum. This indicates that the emission occurs far out in the magnetosphere, hence excluding the polar-cap scenario as a possible explanation of our measurement. The high cutoff energy also challenges the slot-gap scenario. PUBLICATION ABSTRACT
The MAGIC telescope is the largest Cherenkov telescope worldwide, operating since late 2004. One of its main research topics is the discovery of extragalactic gamma-ray emitters at very high energies ...and high redshift, as active galactic nuclei. From the observations of such distant sources, it is also possible to study the nature of the extragalactic background light, and thanks to the time resolution achievable during high flaring emissions, to investigate on possible light propagation effects. The talk will present an overview of the most recent results concerning extragalactic sources.
Supermassive black holes with masses of millions to billions of solar masses are commonly found in the centers of galaxies. Astronomers seek to image jet formation using radio interferometry but ...still suffer from insufficient angular resolution. An alternative method to resolve small structures is to measure the time variability of their emission. Here we report on gamma-ray observations of the radio galaxy IC 310 obtained with the MAGIC (Major Atmospheric Gamma-ray Imaging Cherenkov) telescopes, revealing variability with doubling time scales faster than 4.8 min. Causality constrains the size of the emission region to be smaller than 20% of the gravitational radius of its central black hole. We suggest that the emission is associated with pulsar-like particle acceleration by the electric field across a magnetospheric gap at the base of the radio jet.
The MAGIC telescope reflecting surface Bigongiari, C.; Bastieri, D.; Galante, N. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2004, Letnik:
518, Številka:
1
Journal Article
Recenzirano
The Major Atmospheric Gamma Imaging Cherenkov telescope will achieve an energy threshold lower than any other present IACT
(E
Th
∼30
Gev)
thanks to the largest reflecting surface, a
17
m
diameter, ...f/1, tessellated parabolic reflector. The tiles are
50
cm×50
cm
all-aluminum spherical mirrors with different radii of curvature to best fit the paraboloid. The technology used to make these mirrors and the method used to measure their optical properties, as the focal length, the spot size and the reflectivity, are described. The results of these measurements are shown.
The nearby dwarf spheroidal galaxy Draco, with its high mass to light ratio, is one of the most auspicious targets for indirect dark matter (DM) searches. Annihilation of hypothetical DM particles ...can result in high-energy -rays, e.g., from neutralino annihilation in the supersymmetric framework. A search for a possible DM signal originating from Draco was performed with the MAGIC telescope during 2007. Analysis of the data results in a flux upper limit (2 capital sigma ) of image photons cm super(-2) s super(-1) for photon energies above 140 GeV, assuming a pointlike source. A comparison with predictions from supersymmetric models is also given. While our results do not constrain the mSUGRA phase parameter space, a very high flux enhancement can be ruled out.
Aims. We searched for very high energy (VHE) \gamma-ray emission from the supernova remnant Cassiopeia A Methods. The shell-type supernova remnant Cassiopeia A was observed with the 17 m MAGIC ...telescope between July 2006 and January 2007 for a total time of 47 h. Results. The source was detected above an energy of 250 GeV with a significance of 5.2\sigma and a photon flux above 1 TeV of (7.3 \pm 0.7_{\rm stat} \pm 2.2_{\rm sys}) \times 10 super(-13) cm super(-2) s super(-1). The photon spectrum is compatible with a power law d N /d E \propto E-\Gamma} with a photon index \Gamma = 2.3 \pm 0.2_{\rm stat} \pm 0.2_{\rm sys}. The source is point-like within the angular resolution of the telescope.
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