A5105878493- Astrophysics and Cosmic Phenomena
- Dark Matter and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Particle Detector Development and Performance
- Cosmology and Gravitation Theories
- Pulsars and Gravitational Waves Research
- Radio Astronomy Observations and Technology
- Particle physics theoretical and experimental studies
- Neutrino Physics Research
- Atomic and Subatomic Physics Research
- Galaxies: Formation, Evolution, Phenomena
- Astronomical Observations and Instrumentation
- Radiation Detection and Scintillator Technologies
- Scientific Research and Discoveries
- Astronomy and Astrophysical Research
- Particle Accelerators and Free-Electron Lasers
- Stellar, planetary, and galactic studies
- History and Developments in Astronomy
- Astrophysics and Star Formation Studies
- CCD and CMOS Imaging Sensors
- Astro and Planetary Science
- Nuclear Physics and Applications
- Computational Physics and Python Applications
- Noncommutative and Quantum Gravity Theories
Institut de Recherche sur les Lois Fondamentales de l'Univers
2016-2025
CEA Paris-Saclay
2016-2025
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2016-2025
Université Paris-Saclay
2013-2025
Astrophysique, Instrumentation et Modélisation
2023-2024
Université Paris Cité
2008-2024
Laboratoire AstroParticule et Cosmologie
2008-2024
University of Tübingen
2021-2024
University of Würzburg
2023
Max Planck Institute for Physics
2023
The high-frequency peaked BL Lac PKS 2155-304 at redshift z = 0.116 is a well-known VHE (>100 GeV) γ-ray emitter. Since 2002 its flux has been monitored using the H.E.S.S. stereoscopic array of imaging atmospheric Cerenkov telescopes in Namibia. During 2006 July dark period, average was measured to be more than 10 times typical values observed from object. This article focuses solely on an extreme outburst detected early hours 28 (MJD 53,944). during this I(>200 (1.72 ± 0.05stat 0.34syst) ×...
The very large collection area of ground-based gamma-ray telescopes gives them a substantial advantage over balloon or satellite based instruments in the detection very-high-energy (>600 GeV) cosmic-ray electrons. Here we present electron spectrum derived from data taken with High Energy Stereoscopic System (H.E.S.S.) imaging atmospheric Cherenkov telescopes. In this measurement, first type, are able to extend measurement beyond range accessible direct measurements. We find evidence for...
The measurement of an excess in the cosmic-ray electron spectrum between 300 and 800 GeV by ATIC experiment has - together with PAMELA detection a rise positron fraction up to 100 motivated many interpretations terms dark matter scenarios; alternative explanations assume nearby source like pulsar or supernova remnant. Here we present H.E.S.S. starting at 340 GeV. While overall flux measured is consistent data within statistical systematic errors, exclude pronounced peak as suggested for...
SS 433 is a microquasar, stellar binary system that launches collimated relativistic jets. We observed in gamma rays using the High Energy Stereoscopic System (H.E.S.S.) and found an energy-dependent shift apparent position of gamma-ray emission from parsec-scale These observations trace energetic electron population indicate inverse Compton scattering mechanism rays. Our modeling morphology constrains location particle acceleration requires abrupt deceleration jet flow. infer presence...
The detection of fast variations the tera-electron volt (TeV) (10(12) eV) gamma-ray flux, on time scales days, from nearby radio galaxy M87 is reported. These are about 10 times as those observed in any other wave band and imply a very compact emission region with dimension similar to Schwarzschild radius central black hole. We thus can exclude several sites processes production. observations confirm that TeV gamma rays emitted by extragalactic sources than blazars, where jets not...
We present deep H.E.S.S. observations of the supernova remnant (SNR) RX J1713.7-3946. Combining data three years - from 2003 to 2005 we obtain significantly increased statistics and energy coverage as compared earlier & 2004 results. The are analysed separately for different years. Very good agreement gamma-ray morphology differential spectra is found when comparing combined image reveals J1713.7-3946 with unprecedented precision. An angular resolution 0.06 deg achieved, revealing...
We observed the W28 field (for ~40 h) at Very High Energy (VHE) gamma-ray energies (E>0.1 TeV) with H.E.S.S. Cherenkov telescopes. A reanalysis of EGRET E>100 MeV data was also undertaken. Results from NANTEN 4m telescope Galactic plane survey and other CO observations have been used to study molecular clouds. discovered VHE emission (HESSJ1801-233) coincident northeastern boundary W28, a complex sources (HESSJ1800-240A, B C) ~0.5 deg south in disc. The differential photon spectra are well...
Aims. LS 5039 is a High Mass X-ray Binary (HMXRB) comprising compact object in an eccentric 3.9 day orbit around massive O6.5V star. Observations at energies above 0.1 TeV (1011 eV) by the Energy Stereoscopic System (HESS) 2004 revealed that source of Very (VHE) γ-rays and hence, able to accelerate particles multi-TeV energies. Deeper observations HESS were carried out 2005 effort probe further high energy astrophysics taking place. In particular, we have searched for orbital modulation VHE...
Aims.To investigate the very high energy (VHE: >100 GeV) γ-ray emission from high-frequency peaked BL Lac 1ES 0229+200.
We report the discovery of faint very high energy (VHE; E > 100 GeV) γ-ray emission from radio galaxy Centaurus A in observations performed with High Energy Stereoscopic System (H.E.S.S.) experiment, an imaging atmospheric Cherenkov telescope array consisting four telescopes located Namibia. has been observed for more than 120 hr. signal a statistical significance 5.0σ is detected region including core and inner kpc jets. The integral flux above threshold ∼250 GeV measured to be 0.8% Crab...
Context.The detection of gamma rays in the very-high-energy (VHE) energy range (100 GeV–100 TeV) provides a direct view parent population ultra-relativistic particles found astrophysical sources. For this reason, VHE are useful for understanding underlying processes non-thermal
Aims.We present results from deep γ-ray observations of the Galactic pulsar wind nebula HESS J1825–137 performed with array.
We report on the first simultaneous observations that cover optical, X-ray, and high-energy gamma-ray bands of BL Lac object PKS 2155−304. The were observed for 11 days, between 2008 August 25 September 6 (MJD 54704−54715), jointly with Fermi Gamma-ray Space Telescope HESS atmospheric Cherenkov array, providing MeV–TeV spectral energy distribution (SED) new generation γ-ray telescopes. ATOM telescope RXTE Swift observatories provided optical X-ray coverage low-energy component over same time...
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...
We derive new bounds on decaying Dark Matter from the gamma ray measurements of (i) isotropic residual (extragalactic) background by Fermi and (ii) Fornax galaxy cluster HESS. find that those are among most stringent constraints currently available, for a large range DM masses variety decay modes, excluding half-lives up to ~10^26 few 10^27 seconds. In particular, they rule out interpretation in terms e^\pm spectral features Pamela, HESS, unless very conservative choices adopted. also...
The central region of the Milky Way is one foremost locations to look for dark matter (DM) signatures. We report first results on a search DM particle annihilation signals using new observations from an unprecedented gamma-ray survey Galactic Center (GC) region, ${\it i.e.}$, Inner Galaxy Survey, at very high energies ($\gtrsim$ 100 GeV) performed with H.E.S.S. array five ground-based Cherenkov telescopes. No significant excess found in 2014-2020 dataset and profile likelihood ratio analysis...
TeV-scale particles that couple to the standard model through weak force represent a compelling class of dark matter candidates. The search for such Weakly Interacting Massive Particles (WIMPs) has already spanned multiple decades, and whilst it yet provide any definitive evidence their existence, viable parameter space remains. In this paper, we show upcoming Cherenkov Telescope Array (CTA) significant sensitivity uncharted at TeV mass scale. To do so, focus on two prototypical candidates,...
Recurrent Novae are repeating thermonuclear explosions in the outer layers of white dwarfs, due to accretion fresh material from a binary companion. The shock generated by ejected slamming into companion star's wind, accelerates particles very-high-energies. We report very-high-energy (VHE, $\gtrsim100$\,GeV) gamma rays recurrent nova RS\,Ophiuchi up month after its 2021 outburst, using High Energy Stereoscopic System. VHE emission has similar temporal profile lower-energy GeV emission,...
Magnetic fields in galaxies and galaxy clusters are believed to be the result of amplification intergalactic seed during formation large-scale structures universe. However, origin, strength, morphology this magnetic field (IGMF) remain unknown. Lower limits on (or indirect detection of) IGMF can obtained from observations high-energy gamma rays distant blazars. Gamma interact with extragalactic background light produce electron-positron pairs, which subsequently initiate electromagnetic...
GRB221009A is the brightest gamma-ray burst ever detected. To probe very-high-energy (VHE, $>$\!100 GeV) emission, High Energy Stereoscopic System (H.E.S.S.) began observations 53 hours after triggering event, when brightness of moonlight no longer precluded observations. We derive differential and integral upper limits using H.E.S.S. data from third, fourth, ninth nights initial GRB detection, applying atmospheric corrections. The combined yield an energy flux limit $\Phi_\mathrm{UL}^{95\%}...
Context.The blazar 1ES 1101-232 was observed with the High Energy Stereoscopic System (HESS) of Atmospheric Cherenkov Telescopes (ACT) in 2004 and 2005, for a live time 43 h. VHE (E > 1011 eV) γ-rays were detected first from this object.
<i>Aims. <i/>A detailed study of the spectrum and variability source HESS J1745-290 in Galactic Center (GC) region using new data from H.E.S.S. array Cherenkov telescopes is presented. Flaring activity quasi periodic oscillations (QPO) are investigated.<i>Methods. <i/>The image analysis performed with a combination semi-analytical shower model statistical moment-based Hillas technique. The lightcurves derived likelihood method based on spectral shape hypothesis. Rayleigh tests Fourier GC...
In the past few decades, several models have predicted an energy dependence of speed light in context quantum gravity. For cosmological sources such as active galaxies, this minuscule effect can add up to measurable photon-energy dependent time lags. Letter a search for lags during High Energy Stereoscopic System observations exceptional very high flare galaxy PKS 2155-304 on 28 July 2006 is presented. Since no significant lag found, lower limits scale modifications are derived.
<i>Aims.<i/>Our aim is to study the production mechanism for very-high-energy (VHE; >100 GeV) <i>γ<i/>-rays in distant active galactic nuclei (AGN) and use observed VHE spectrum derive limits on Extragalactic Background Light (EBL). We also want determine physical quantities through modeling of object's broad-band spectral energy distribution (SED).<i>Methods.<i/>VHE observations (~25 h live time) BL Lac 1ES 0347-121 (redshift ) were conducted with High Energy Stereoscopic System (HESS)...
Aims.The complex Monoceros Loop SNR/Rosette Nebula region contains several potential sources of very-high-energy (VHE) γ-ray emission and two as yet unidentified high-energy EGRET sources. Sensitive VHE observations are required to probe acceleration processes in this region.