A5106480757- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Dark Matter and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Radio Astronomy Observations and Technology
- Neutrino Physics Research
- Radiomics and Machine Learning in Medical Imaging
- Particle Detector Development and Performance
- Particle Accelerators and Free-Electron Lasers
- Astronomy and Astrophysical Research
- Cosmology and Gravitation Theories
- Astronomical Observations and Instrumentation
- Stellar, planetary, and galactic studies
- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Image and Signal Denoising Methods
- Geophysics and Gravity Measurements
- Particle physics theoretical and experimental studies
- Blind Source Separation Techniques
- Nuclear Physics and Applications
- Advanced Image Fusion Techniques
- X-ray Spectroscopy and Fluorescence Analysis
- Atomic and Subatomic Physics Research
- Medical Imaging Techniques and Applications
Astrophysique, Instrumentation et Modélisation
2016-2025
CEA Paris-Saclay
2016-2025
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2016-2025
Centre National de la Recherche Scientifique
2015-2024
Université Paris-Saclay
2019-2024
Universitat de Barcelona
2024
Institut d'Estudis Espacials de Catalunya
2024
Université Paris Cité
2015-2024
American Institute of Mathematics
2024
Laboratoire Univers et Particules de Montpellier
2011-2022
We present the third Fermi Large Area Telescope (LAT) source catalog (3FGL) of sources in 100 MeV–300 GeV range. Based on first 4 yr science data from Gamma-ray Space mission, it is deepest yet this energy Relative to Second LAT catalog, 3FGL incorporates twice as much data, well a number analysis improvements, including improved calibrations at event reconstruction level, an updated model for Galactic diffuse γ-ray emission, refined procedure detection, and methods associating with...
We present the fourth Fermi Large Area Telescope catalog (4FGL) of gamma-ray sources. Based on first eight years science data from Gamma-ray Space mission in energy range 50 MeV to 1 TeV, it is deepest yet this range. Relative 3FGL catalog, 4FGL has twice as much exposure well a number analysis improvements, including an updated model for Galactic diffuse emission, and two sets light curves (1-year 2-month intervals). The includes 5064 sources above 4 sigma significance, which we provide...
We present an incremental version (4FGL-DR3, for Data Release 3) of the fourth Fermi-LAT catalog gamma-ray sources. Based on first twelve years science data in energy range from 50 MeV to 1 TeV, it contains 6658 The analysis improves that used 4FGL over eight data: more sources are fit with curved spectra, we introduce a robust spectral parameterization pulsars, and extend points TeV. parameters, distributions, associations updated all Light curves rebuilt yr intervals (not 2 month...
A search for a very-high-energy (VHE; ≥100 GeV) γ-ray signal from self-annihilating particle dark matter (DM) is performed towards region of projected distance r∼45-150 pc the Galactic center. The background-subtracted spectrum measured with High Energy Stereoscopic System (H.E.S.S.) instrument in energy range between 300 GeV and 30 TeV shows no hint residual flux. Assuming conventional Navarro-Frenk-White Einasto density profiles, limits are derived on velocity-weighted annihilation cross...
ABSTRACT Most of the celestial γ rays detected by Large Area Telescope (LAT) on board Fermi Gamma-ray Space originate from interstellar medium when energetic cosmic interact with nucleons and photons. Conventional point-source extended-source studies rely modeling this diffuse emission for accurate characterization. Here, we describe development Galactic Interstellar Emission Model (GIEM), which is standard adopted LAT Collaboration publicly available. This model based a linear combination...
Gamma-ray line signatures can be expected in the very-high-energy (${E}_{\ensuremath{\gamma}}>100\text{ }\text{ }\mathrm{GeV}$) domain due to self-annihilation or decay of dark matter (DM) particles space. Such a signal would readily distinguishable from astrophysical $\ensuremath{\gamma}$-ray sources that most cases produce continuous spectra span over several orders magnitude energy. Using data collected with H.E.S.S. instrument, upper limits on linelike emission are obtained energy range...
Starburst galaxies exhibit in their central regions a highly increased rate of supernovae, the remnants which are thought to accelerate energetic cosmic rays up energies ~ 10^15 eV. We report detection gamma -- tracers such from starburst galaxy NGC 253 using H.E.S.S. array imaging atmospheric Cherenkov telescopes. The gamma-ray flux above 220 GeV is F = (5.5 +/- 1.0stat 2.8sys) x 10^-13 ph. s-1 cm-2, implying cosmic-ray density about three orders magnitude larger than that center Milky Way....
The extragalactic background light (EBL) is the diffuse radiation with second highest energy density in Universe after cosmic microwave background. aim of this study measurement imprint EBL opacity to γ-rays on spectra brightest sources detected High Energy Stereoscopic System (H.E.S.S.). originality method lies joint fit optical depth and intrinsic sources, assuming smoothness. Analysis a total ~105γ-ray events enables detection an signature at 8.8σ level constitutes first using very-high...
The giant radio galaxy M 87 with its proximity (16 Mpc), famous jet, and very massive black hole ((3 − 6) × 109 M☉) provides a unique opportunity to investigate the origin of high energy (VHE; E > 100 GeV) γ-ray emission generated in relativistic outflows surroundings supermassive holes. has been established as VHE emitter since 2006. displays strong variability on timescales short day. In this paper, results from joint monitoring campaign by MAGIC VERITAS instruments 2010 are reported....
Axionlike particles (ALPs) are hypothetical light (sub-eV) bosons predicted in some extensions of the Standard Model particle physics. In astrophysical environments comprising high-energy gamma rays and turbulent magnetic fields, existence ALPs can modify energy spectrum for a sufficiently large coupling between photons. This modification would take form an irregular behavior limited range. Data from H.E.S.S. observations distant BL Lac object PKS 2155-304 (z = 0.116) used to derive upper...
ABSTRACT To uniformly determine the properties of supernova remnants (SNRs) at high energies, we have developed first systematic survey energies from 1 to 100 GeV using data Fermi Large Area Telescope (LAT). Based on spatial overlap sources detected with SNRs known radio surveys, classify 30 as likely SNRs. We also report 14 marginal associations and 245 flux upper limits. A mock catalog in which positions are scrambled Galactic longitude allows us an limit 22% number candidates falsely...
We present the fourth Fermi Large Area Telescope catalog (4FGL) of gamma-ray sources. Based on first eight years science data from Gamma-ray Space mission in energy range 50 MeV to 1 TeV, it is deepest yet this range. Relative 3FGL catalog, 4FGL has twice as much exposure well a number analysis improvements, including an updated model for Galactic diffuse emission, and two sets light curves (1-year 2-month intervals). The includes 5064 sources above 4 sigma significance, which we provide...
Pulsar wind nebulae (PWNe) have been established as the most populous class of TeV gamma-ray emitters. Since launch, Fermi Large Area Telescope (LAT)identified five high-energy (100MeV <E< 100 GeV) sources PWNe, and detected a large number PWNe candidates, all powered by young energetic pulsars. The wealth multi-wavelength data available new results provided Fermi-LAT give us an opportunity to find explore radiative processes taking place in known ones. unidentifiedsources (UNIDs) are best...
Gammapy is a Python package for high-level gamma-ray data analysis built on Numpy, Scipy and Astropy. It enables to analyse create sky images, spectra lightcurves, from event lists instrument response information, as determine the position, morphology of sources. So far has mostly been used H.E.S.S. Fermi-LAT, now being simulation observations Cherenkov Telescope Array (CTA). We have proposed prototype CTA science tools. This contribution gives an overview shows application example with...
Context. Traditionally, TeV- γ -ray astronomy has been conducted by experiments employing proprietary data and analysis software. However, the next generation of instruments, such as Cherenkov Telescope Array Observatory (CTAO), will be operated open observatories. Alongside data, they also make associated software tools available to a wider community. This necessity prompted development open, high-level, astronomical customized for high-energy astrophysics. Aims. In this article, we present...
<i>Aims. <i/>Recent theoretical predictions of the lowest very high energy (VHE) luminosity SN 1006 are only a factor 5 below previously published HESS upper limit, thus motivating further in-depth observations this source.<i>Methods. <i/>Deep at VHE energies (above 100 GeV) were carried out with stereoscopic system (HESS) Cherenkov Telescopes from 2003 to 2008. More than h data have been collected and subjected an improved analysis procedure.<i>Results. <i/>Observations resulted in...
<i>Context. <i/>Observations of very high-energy <i>γ<i/>-rays from blazars provide information about acceleration mechanisms occurring in their innermost regions. Studies variability these objects lead to a better understanding the play. <i>Aims. <i/>To investigate spectral and temporal VHE (>100 GeV) well-known high-frequency-peaked BL Lac object PKS 2155–304 with HESS imaging atmospheric Cherenkov telescopes over wide range flux states.<i>Methods. <i/>Data collected 2005 2007 were...
Results obtained in very-high-energy (VHE; E > 100 GeV) \gamma-ray observations performed with the H.E.S.S. telescope array are used to investigate particle acceleration processes vicinity of young massive stellar cluster Westerlund 1 (Wd 1). Imaging Cherenkov light from induced cascades Earth's atmosphere is search for VHE \gamma\ rays region around Wd 1. Possible catalogued counterparts searched and discussed terms morphology energetics source. The detection degree-scale extended source...
The quasar PKS 1510-089 (z=0.361) was observed with the H.E.S.S. array of imaging atmospheric Cherenkov telescopes during high states in optical and GeV bands, to search for very energy (VHE, defined as E >= 0.1 TeV) emission. VHE \gamma-rays were detected a statistical significance 9.2 standard deviations 15.8 hours data taken March April 2009. A integral flux I(0.15 TeV < 1.0 = (1.0 +- 0.2 (stat) (sys) x 10^{-11} cm^{-2}s^{-1} is measured. best-fit power law has photon index \Gamma=5.4 0.7...
The Fornax galaxy cluster was observed with the High Energy Stereoscopic System (H.E.S.S.) for a total live time of 14.5 hours, searching very-high-energy (VHE, E>100 GeV) gamma-rays from dark matter (DM) annihilation. No significant signal found in searches point-like and extended emissions. Using several models DM density distribution, upper limits on velocity-weighted annihilation cross-section <sigma v> as function particle mass are derived. Constraints derived different models, such...
The recent discovery of the radio shell-type supernova remnant (SNR), G353.6-0.7, in spatial coincidence with unidentified TeV source HESS J1731-347 has motivated further observations High Energy Stereoscopic System (H.E.S.S.) Cherenkov telescope array to test a possible association gamma-ray emission SNR. With total 59 hours observation, representing about four times initial exposure available paper J1731-347, morphology is investigated and compared morphology. An estimate distance derived...
We study the 0.57 keV (O VII triplet) and 0.65 VIII) diffuse emission generated by charge transfer collisions between solar wind (SW) oxygen ions interstellar H He neutral atoms in inner Heliosphere. These lines which dominate 0.3-1.0 energy interval are also produced hot gas galactic halo (GH) possibly Local Interstellar Bubble (LB). developed a time-dependent model of SW Charge-Exchange (SWCX) X-ray emission, based on localization Parker spiral at each instant. include input conditions...