J. L. Contreras
A5018588399- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Dark Matter and Cosmic Phenomena
- Particle physics theoretical and experimental studies
- Radio Astronomy Observations and Technology
- Quantum Chromodynamics and Particle Interactions
- High-Energy Particle Collisions Research
- Particle Detector Development and Performance
- Astrophysical Phenomena and Observations
- Neutrino Physics Research
- Pulsars and Gravitational Waves Research
- Astronomical Observations and Instrumentation
- Particle Accelerators and Free-Electron Lasers
- Radiation Detection and Scintillator Technologies
- Radiomics and Machine Learning in Medical Imaging
- Computational Physics and Python Applications
- Astronomy and Astrophysical Research
- Cosmology and Gravitation Theories
- Solar and Space Plasma Dynamics
- Galaxies: Formation, Evolution, Phenomena
- Astro and Planetary Science
- Radiation Therapy and Dosimetry
- Atomic and Subatomic Physics Research
- Nuclear Physics and Applications
- Stellar, planetary, and galactic studies
Universidad Complutense de Madrid
2015-2024
Universitat de Barcelona
2024
Institut d'Estudis Espacials de Catalunya
2024
Université Paris Cité
1994-2023
Centre National de la Recherche Scientifique
1993-2023
Max Planck Institute for Physics
2000-2023
University of Turku
2023
TU Dortmund University
2018-2023
University of Łódź
2007-2023
Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas
2023
The blazar Mrk 501 was observed at energies above 0.10 TeV with the MAGIC Telescope from 2005 May through July. high sensitivity of instrument enabled determination flux and spectrum source on a night-by-night basis. Throughout our observational campaign, found to vary by an order magnitude. Intranight variability flux-doubling times down 2 minutes during two most active nights, namely, June 30 July 9. These are fastest variations ever in 501. ~20 minute long flare 9 showed indication 4 ± 1...
The atmospheric Cherenkov gamma-ray telescope MAGIC, designed for a low-energy threshold, has detected very-high-energy gamma rays from giant flare of the distant Quasi-Stellar Radio Source (in short: radio quasar) 3C 279, at distance more than 5 billion light-years (a redshift 0.536). No quasar been observed previously in radiation, and this is also most object emitting above 50 gigaelectron volts. Because high-energy may be stopped by interacting with diffuse background light universe,...
Microquasars are binary star systems with relativistic radio-emitting jets. They potential sources of cosmic rays and can be used to elucidate the physics We report detection variable gamma-ray emission above 100 gigaelectron volts from microquasar LS I 61 + 303. Six orbital cycles were recorded. Several detections occur at a similar phase, which suggests that is periodic. The strongest not observed when two stars closest one another, implying strong modulation or absorption processes.
We present the first joint analysis of gamma-ray data from MAGIC Cherenkov telescopes and Fermi Large Area Telescope (LAT) to search for signals dark matter annihilation in dwarf satellite galaxies. combine 158 hours Segue 1 observations with 6-year 15 galaxies by -LAT. obtain limits on cross-section particle masses between 10 GeV 100 TeV—the widest mass range ever explored a single analysis. These improve previously published -LAT results up factor two at certain masses. Our new inclusive...
Very high energy (VHE) γ-ray emission from the flat spectrum radio quasar (FSRQ) PKS 1222+21 (4C 21.35, z = 0.432) was detected with MAGIC Cherenkov telescopes during a short observation (∼0.5 hr) performed on 2010 June 17. The detection coincides high-energy MeV/GeV activity measured by Large Area Telescope (LAT) board Fermi satellite. VHE extends about 70 GeV up to at least 400 and can be well described power-law dN/dE ∝ E−Γ photon index Γ 3.75 ± 0.27stat 0.2syst. averaged integral flux...
We report about very high energy (VHE) γ-ray observations of the Crab Nebula with MAGIC telescope. The flux from nebula was measured between 60 GeV and 9 TeV. spectrum can be described by a curved power law dF/dE = f0(E/300 GeV)[a+blog10(E/300 GeV)] normalization f0 (6.0 ± 0.2stat) × 10−10 cm−2 s−1 TeV−1, − 2.31 0.06stat, b 0.26 0.07stat. peak in spectral distribution is estimated at 77 35 GeV. Within observation time experimental resolution telescope, emission steady pointlike. emission's...
Abstract A neutrino with energy ∼290 TeV, IceCube-170922A, was detected in coincidence the BL Lac object TXS 0506+056 during enhanced gamma-ray activity, chance being rejected at ∼3 σ level. We monitored very-high-energy (VHE) band Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescopes for ∼41 hr from 1.3 to 40.4 days after detection. Day-timescale variability is clearly resolved. interpret quasi-simultaneous and broadband electromagnetic observations a novel one-zone...
We provide an updated assessment of the power Cherenkov Telescope Array (CTA) to search for thermally produced dark matter at TeV scale, via associated gamma-ray signal from pair-annihilating particles in region around Galactic centre. find that CTA will open a new window discovery potential, significantly extending range robustly testable models given standard cuspy profile density distribution. Importantly, even cored profile, projected sensitivity be sufficient probe various...
The Crab supernova remnant has been observed regularly with the stereoscopic system of five imaging air Cerenkov telescopes that was part High Energy Gamma Ray Astronomy (HEGRA) experiment. In total, close to 400 hr useful data have collected from 1997 2002. differential energy spectrum combined set can be approximated by a power law-type spectrum: dΦ/dE = Φ0 Γ, 10-11 photons cm-2 s-1 TeV-1, and Γ -2.62 ± 0.02stat 0.05sys. extends up energies 80 TeV is well matched model calculations in...
232 hours of data were accumulated from 1997 to 1999, using the HEGRA Stereoscopic Cherenkov Telescope System observe supernova remnant Cassiopeia A. TeV γ-ray emission was detected at level, and a flux above 1 derived. The spectral distribution is consistent with power law differential index between 10 TeV. As this first report detection source on "centi-Crab"scale, we present analysis in some detail. Implications for acceleration cosmic rays depend details modeling. We discuss important...
We analyze the timing of photons observed by MAGIC telescope during a flare active galactic nucleus Mkn 501 for possible correlation with energy, as suggested some models quantum gravity (QG), which predict vacuum refractive index ≃1+(E/MQGn)n, n=1,2. Parametrizing delay between γ-rays different energies Δt=±τlE or Δt=±τqE2, we find τl=(0.030±0.012) s/GeV at 2.5-σ level, and τq=(3.71±2.57)×10−6 s/GeV2, respectively. use these results to establish lower limits MQG1>0.21×1018 GeV...
We report on the results from observations in very high energy band (VHE; Eγ ≥ 100 GeV) of black hole X-ray binary (BHXB) Cygnus X-1. The were performed with MAGIC telescope, for a total 40 hr during 26 nights, spanning period between 2006 June and November. Searches steady γ-ray signals yielded no positive result, upper limits to integral flux ranging 1% 2% Crab Nebula flux, depending energy, have been established. also analyzed each observation night independently, obtaining evidence at...
One fundamental question about pulsars concerns the mechanism of their pulsed electromagnetic emission. Measuring high-end region a pulsar's spectrum would shed light on this question. By developing new electronic trigger, we lowered threshold Major Atmospheric gamma-ray Imaging Cherenkov (MAGIC) telescope to 25 GeV. In configuration, detected gamma-rays from Crab pulsar that were greater than GeV, revealing relatively high cutoff energy in phase-averaged spectrum. This indicates emission...
We report the detection of a new source very high energy (VHE; Eγ ≥ 100 GeV) γ-ray emission located close to Galactic plane, MAGIC J0616+225, which is spatially coincident with supernova remnant IC 443. The observations were carried out telescope in periods 2005 December-2006 January and 2006 December-2007 January. Here we present results from this source, leading VHE signal statistical significance 5.7 σ 2006/2007 data measured differential flux consistent power law, described as dNγ/(dA dt...
Recently, the Galactic center has been reported to be a source of very high energy (VHE) γ-rays by CANGAROO, VERITAS, and HESS experiments. The spectra as measured these experiments show substantial differences. In this Letter we present MAGIC observations center, resulting in detection differential γ-ray flux consistent with steady, hard-slope power law, described dNγ/(dA dt dE) = (2.9 ± 0.6) × 10-12(E/TeV)-2.2±0.2 cm-2 s-1 TeV-1. is centered at (R.A., decl.) (17h45m20s, -29°2'). This...
Supermassive black holes with masses of millions to billions solar are commonly found in the centers galaxies. Astronomers seek image jet formation using radio interferometry, but still suffer from insufficient angular resolution. An alternative method resolve small structures is measure time variability their emission. Here, we report on gamma-ray observations galaxy IC 310 obtained MAGIC telescopes revealing doubling scales faster than 4.8 min. Causality constrains size emission region be...
The Cherenkov Telescope Array (CTA) is a project for next-generation observatory very high energy (GeV-TeV) ground-based gamma-ray astronomy, currently in its design phase, and foreseen to be operative few years from now. Several tens of telescopes 2-3 different sizes, distributed over large area, will allow sensitivity about factor 10 better than current instruments such as H.E.S.S, MAGIC VERITAS, an coverage GeV several TeV, field view up deg. In the following study, we investigate...
The Perseus galaxy cluster was observed by the MAGIC Cherenkov telescope for a total effective time of 24.4 hr during 2008 November and December. resulting upper limits on gamma-ray emission above 100 GeV are in range 4.6 to 7.5 x 10^{-12} cm^{-2} s^{-1} spectral indices from -1.5 -2.5, thereby constraining produced cosmic rays, dark matter annihilations, central radio NGC1275. Results compatible with cosmological simulations cosmic-ray-induced emission, average ray-to-thermal pressure <4%...
We present the results of stereoscopic observations satellite galaxy Segue 1 with MAGIC Telescopes, carried out between 2011 and 2013. With almost 160 hours good-quality data, this is deepest observational campaign on any dwarf performed so far in very high energy range electromagnetic spectrum. search large data sample for signals dark matter particles mass 100 GeV 20 TeV. For we use full likelihood analysis method, which provides optimal sensitivity to characteristic gamma-ray spectral...