Discovery of VHE Gamma Radiation from IC443 with the MAGIC Telescope

We report the detection of a new source of very high energy (VHE, E_gamma >= 100GeV) gamma-ray emission located close to the Galactic Plane, MAGIC J0616+225, which is spatially coincident with SNR IC443. The observations were carried out with the MAGIC telescope in the periods December 2005 - January 2006 and December 2006 - January 2007. Here we present results from this source, leading to a VHE gamma-ray signal with a statistical significance of 5.7 sigma in the 2006/7 data and a measured differential gamma-ray flux consistent with a power law, described as dN_gamma/(dA dt dE) = (1.0 +/- 0.2)*10^(-11)(E/0.4 TeV)^(-3.1 +/- 0.3) cm^(-2)s^(-1)TeV^(-1). We briefly discuss the observational technique used and the procedure implemented for the data analysis. The results are put in the perspective of the multiwavelength emission and the molecular environment found in the region of IC443.Comment: Accepted by ApJ Letter

Seedling survival and dynamics of upper timberline in central Apennines

Despite several studies on the timberline dynamics in Europe were carried out in the last decades, very few papers refer to mountain areas where the timberline is composed of broadleaved trees, and no research was conducted on the dynamics of Apennine beech timberline in relation to seedling survival. The research aim was to analyse the beech wood timberline dynamics in the central Apennines, with reference to seedling survival. Furthermore, factors affecting seedling survival were identified. To assess the forest ecotone dynamics, vegetation layer cover, rock fragment cover and information about forest management and krummholz occurrence were collected in sampling plots placed over 1,600 m a.s.l., on north-facing slopes. The beech seedlings occurring in Brachypodium genuense-dominated stands above the timberline were counted and monitored along two growing seasons. Soil temperature, soil moisture, and photosynthetically active radiation available for seedlings (PHAR) in grasslands above timberline were measured. The research outputs indicate that timberline is not a natural boundary and that there is no evidence of its extension upwards. The greatest number of beech seedlings was recorded in late spring. The one-year mortality rate ranged from 71 to 100%. None of the seedlings still alive in the early autumn of the first year were recorded in the following spring. The competitive exclusion by Brachypodium genuense individuals, which limit the incident PHAR, and the low soil moisture during summer, were identified as the main factors that account for the high mortality of seedlings and affect beech regeneration above timberline. The effect of competition is probably intensified by the lack of pioneer shrubs which could otherwise serve as nurse plants for beech seedlings and protect them from browsing by wild ungulates. Thus, both the current and the past land use may be considered as driving forces in timberline dynamics. Probably, also the trend of global warming, that in the Mediterranean and sub-Mediterranean climatic context would determine the increase of summer drought stress, could worsen the effect of competitive exclusion of beech seedlings, so that it can be hypothesized that the expansion upwards of the upper timberline in the Apennines could be totally blocked

Discovery of Very High Energy gamma-rays from 1ES 1011+496 at z=0.212

We report on the discovery of Very High Energy (VHE) gamma-ray emission from the BL Lacertae object 1ES1011+496. The observation was triggered by an optical outburst in March 2007 and the source was observed with the MAGIC telescope from March to May 2007. Observing for 18.7 hr we find an excess of 6.2 sigma with an integrated flux above 200 GeV of (1.58$\pm0.32) 10^{-11}$ photons cm$^{-2}$ s$^{-1}$. The VHE gamma-ray flux is >40% higher than in March-April 2006 (reported elsewhere), indicating that the VHE emission state may be related to the optical emission state. We have also determined the redshift of 1ES1011+496 based on an optical spectrum that reveals the absorption lines of the host galaxy. The redshift of z=0.212 makes 1ES1011+496 the most distant source observed to emit VHE gamma-rays up to date.Comment: 4 pages, 6 figures, minor changes to fit the ApJ versio

Unfolding of differential energy spectra in the MAGIC experiment

The paper describes the different methods, used in the MAGIC experiment, to unfold experimental energy distributions of cosmic ray particles (gamma-rays). Questions and problems related to the unfolding are discussed. Various procedures are proposed which can help to make the unfolding robust and reliable. The different methods and procedures are implemented in the MAGIC software and are used in most of the analyses.Comment: Submitted to NIM

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).Comment: 25 pages, 9 figures, final version accepted by ApJ. Changet title to "MAGIC upped limits on the VERY high energy emission from GRBs", re-organized chapter with description of observation, removed non necessaries figures, added plot of effective area depending on zenith angle, added an appendix explaining the upper limit calculation, added some reference

Constraints on the steady and pulsed very high energy gamma-ray emission from observations of PSR B1951+32/CTB 80 with the MAGIC Telescope

We report on very high energy gamma-observations with the MAGIC Telescope of the pulsar PSR B1951+32 and its associated nebula, CTB 80. Our data constrain the cutoff energy of the pulsar to be less than 32 GeV, assuming the pulsed gamma-ray emission to be exponentially cut off. The upper limit on the flux of pulsed gamma-ray emission above 75 GeV is 4.3*10^-11 photons cm^-2 sec^-1, and the upper limit on the flux of steady emission above 140 GeV is 1.5*10^-11 photons cm^-2 sec^-1. We discuss our results in the framework of recent model predictions and other studies.Comment: 7 pages, 7 figures, replaced with published versio

Implementation of the Random Forest Method for the Imaging Atmospheric Cherenkov Telescope MAGIC

The paper describes an application of the tree classification method Random Forest (RF), as used in the analysis of data from the ground-based gamma telescope MAGIC. In such telescopes, cosmic gamma-rays are observed and have to be discriminated against a dominating background of hadronic cosmic-ray particles. We describe the application of RF for this gamma/hadron separation. The RF method often shows superior performance in comparison with traditional semi-empirical techniques. Critical issues of the method and its implementation are discussed. An application of the RF method for estimation of a continuous parameter from related variables, rather than discrete classes, is also discussed.Comment: 16 pages, 8 figure

First bounds on the very high energy gamma-ray emission from Arp 220

Using the Major Atmospheric Gamma Imaging Cherenkov Telescope (MAGIC), we have observed the nearest ultra-luminous infrared galaxy Arp 220 for about 15 hours. No significant signal was detected within the dedicated amount of observation time. The first upper limits to the very high energy $\gamma$-ray flux of Arp 220 are herein reported and compared with theoretical expectations.Comment: Accepted for publication in Ap

MAGIC observations of MWC 656, the only known Be/BH system

Context: MWC 656 has recently been established as the first observationally detected high-mass X-ray binary system containing a Be star and a black hole (BH). The system has been associated with a gamma-ray flaring event detected by the AGILE satellite in July 2010. Aims: Our aim is to evaluate if the MWC 656 gamma-ray emission extends to very high energy (VHE > 100 GeV) gamma rays. Methods. We have observed MWC 656 with the MAGIC telescopes for $\sim$23 hours during two observation periods: between May and June 2012 and June 2013. During the last period, observations were performed contemporaneously with X-ray (XMM-Newton) and optical (STELLA) instruments. Results: We have not detected the MWC 656 binary system at TeV energies with the MAGIC Telescopes in either of the two campaigns carried out. Upper limits (ULs) to the integral flux above 300 GeV have been set, as well as differential ULs at a level of $\sim$5% of the Crab Nebula flux. The results obtained from the MAGIC observations do not support persistent emission of very high energy gamma rays from this system at a level of 2.4% the Crab flux.Comment: Accepted for publication in A&A. 5 pages, 2 figures, 2 table