arXiv subjects

J. Rico

Publications and source records attributed to J. Rico.

28 records · Page 2Linked to original sources

arXiv2011

The search for galactic dark matter clump candidates with Fermi and MAGIC

We present a systematic search for potential dark matter clumps in our Galaxy among the 630 unassociated sources included in the LAT 1-year Point Source Catalog. Assuming a dark matter particle that generates observable gamma-ray photons beyond the Fermi energy range through self-annihilation, we compile a list of reasonable targets for the MAGIC Imaging Atmospheric Cherenkov Telescopes. In order to narrow down the origin of these enigmatic sources, we summarize ongoing multiwavelength studies including X-ray, radio, and optical spectroscopy. We report on observations of two of these candidates using the MAGIC Telescopes. We find that the synergy between Fermi and Cherenkov telescopes, along with multiwavelength observations, could play a key role in indirect searches for dark matter.

astro-ph.HE↗

arXiv2011

A Multi-APD readout for EL detectors

Detectors with an electroluminesence readout show an excellence performance in respect of energy resolution making them interesting for various applications as X-ray detection, double beta and dark matter experiments, Compton and gamma cameras, etc. In the following the study of a readout based on avalanche photo diodes to detect directly the VUV photons is presented. Results of measurements with 5 APDs in xenon at pressures between 1 and 1.65 bar are shown indicating that such a readout can provide excellent energy and a moderate position resolution.

physics.ins-det↗

arXiv2009

NEXT, a HPGXe TPC for neutrinoless double beta decay searches

We propose a novel detection concept for neutrinoless double-beta decay searches. This concept is based on a Time Projection Chamber (TPC) filled with high-pressure gaseous xenon, and with separated-function capabilities for calorimetry and tracking. Thanks to its excellent energy resolution, together with its powerful background rejection provided by the distinct double-beta decay topological signature, the design discussed in this Letter Of Intent promises to be competitive and possibly out-perform existing proposals for next-generation neutrinoless double-beta decay experiments. We discuss the detection principles, design specifications, physics potential and R&D plans to construct a detector with 100 kg fiducial mass in the double-beta decay emitting isotope Xe(136), to be installed in the Canfranc Underground Laboratory.

hep-ex↗

arXiv2009

Microquasar observations with the MAGIC telescope

Microquasars, X-ray binaries displaying relativistic jets driven by accretion onto a compact object, are some of the most efficient accelerators in the Galaxy. Theoretical models predict Very High Energy (VHE) emission at the base of the jet where particles are accelerated to multi-TeV energies. This emission could be detected by present IACTs. %Moreover, gamma-ray fluxes should increase during flaring events when accretion rates are enhanced. The MAGIC telescope observed the microquasars GRS 1915+105, Cyg X-3, Cyg X-1 and SS433 for ~ 150 hours in total from 2005 to 2008. We triggered our observations by using multi wavelength information through radio flaring alerts with the RATAN telescope as well as by ensuring the low/hard state of the source through RXTE/ASM and Swift/BAT monitoring data. We report on the upper limits on steady and variable emission from these sources over this long period.

astro-ph.HE↗

arXiv2009

The MAGIC highlights of the gamma ray binary LS I +61 303

The discovery of emission of TeV gamma rays from X-ray binaries has triggered an intense effort to better understand the particle acceleration, absorption, and emission mechanisms in compact binary systems. Here we present the pioneering effort of the MAGIC collaboration to understand the very high energy emission of the prototype system LS I +61 303. We report on the variable nature of the emission from LS I +61 303 and show that this emission is indeed periodic. The system shows regular outburst at TeV energies in phase phi=0.6-0.7 and detect no signal at periastron (phi~ 0.275). Furthermore we find no indication of spectral variation along the orbit of the compact object and the spectral energy distribution is compatible with a simple power law with index Gamma=2.6+-0.2_(stat)+-0.2_(sys). To answer some of the open questions concerning the emission process of the TeV radiation we conducted a multiwavelength campaign with the MAGIC telescope, XMM-Newton, and Swift in September 2007. We detect a simultaneous outburst at X-ray and TeV energies, with the peak at phase 0.62 and a similar shape at both wavelengths. A linear fit to the strictly simultaneous X-ray/TeV flux pairs provides r=0.81 -0.21 +0.06. Here we present the observations and discuss the implications of the obtained results to the emission processes in the system.

astro-ph.HE↗

arXiv2009

Search for Dark Matter signatures with MAGIC-I and prospects for MAGIC Phase-II

In many Dark Matter (DM) scenarios, the annihilation of DM particles can produce gamma rays with a continuum spectrum that extends up to very high energies of the order of the electroweak symmetry breaking scale (hundreds of GeV). Astrophysical structures supposed to be dynamically dominated by DM, such as dwarf Spheroidal Galaxies, Galaxy Clusters (the largest ones in the local Universe being mostly observable from the northern hemisphere) and Intermediate Mass Black Holes, can be considered as interesting targets to look for DM annihilation with Imaging Atmospheric Cherenkov Telescopes (IACTs). Instead, the center of our Galaxy seems to be strongly contaminated with astrophysical sources. The 17m Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC-I) Telescope, situated in the Canary island of La Palma (2200 m a.s.l.), is best suited for DM searches, due to its unique combination of high sensitivity and low energy threshold among current IACTs which can potentially allow to provide clues on the high energy end, and possibly peak, of the gamma-ray DM-induced spectrum constrained at lower energies with the Fermi Space Telescope. The recent results achieved by MAGIC-I for some of the best candidates, as well as the DM detection prospects for the MAGIC Phase II, are reported.

astro-ph.HE↗

arXiv2007

Observations of Very High Energy Gamma-Rays during Moonlight and Twilight with the MAGIC Telescope

We study the capability of the MAGIC telescope to observe under moderate moonlight. TeV gamma-ray signals from the Crab nebula were detected with the MAGIC telescope during periods when the Moon was above the horizon and during twilight. This was accomplished by increasing the trigger discriminator thresholds. No change is necessary in the high voltage settings since the camera PMTs were especially designed to avoid high currents. We characterize the telescope performance by studying the effect of the moonlight on the gamma-ray detection efficiency and sensitivity, as well as on the energy threshold.

astro-ph↗

arXiv2007

Observations of microquasars with the MAGIC telescope

We report on the results from the observations in very high energy band (VHE, E_gamma > 100GeV) of the black hole X-ray binary (BHXB) Cygnus X-1. The observations were performed with the MAGIC telescope, for a total of 40 hours during 26 nights, spanning the period between June and November 2006. We report on the results of the searches for steady and variable gamma-ray signals, including the first experimental evidence for an intense flare, of duration between 1.5 and 24 hours.

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↗

arXiv2000

The flavor of neutrinos in muon decays at a neutrino factory and the LSND puzzle

The accurate prediction of the neutrino beam produced in muon decays and the absence of opposite helicity contamination for a particular neutrino flavor make a future neutrino factory the ideal place to look for the lepton flavor violating (LFV) decays of the kind $μ^+\ra e^+\nuebar\numu$ and lepton number violating (LNV) processes like $μ^-\ra e^-\nue\numu$. Excellent sensitivities can be achieved using a detector capable of muon and/or electron identification with charge discrimination. This would allow to set experimental limits that improve current ones by more than two orders of magnitude and test the hypothesis that the LSND excess is due to such anomalous decays, rather than neutrino flavor oscillations in vacuum.

hep-ph↗