A5068664227- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Dark Matter and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Particle Detector Development and Performance
- Radio Astronomy Observations and Technology
- Radiomics and Machine Learning in Medical Imaging
- Neutrino Physics Research
- Cosmology and Gravitation Theories
- Particle physics theoretical and experimental studies
- Radiation Detection and Scintillator Technologies
- Astronomical Observations and Instrumentation
- Astrophysics and Star Formation Studies
- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Geophysics and Gravity Measurements
- CCD and CMOS Imaging Sensors
- Particle Accelerators and Free-Electron Lasers
- Noncommutative and Quantum Gravity Theories
- Radiation Therapy and Dosimetry
- Nuclear Physics and Applications
- Scientific Research and Discoveries
- Ionosphere and magnetosphere dynamics
- Atomic and Subatomic Physics Research
Université Paris-Saclay
2019-2024
Université Paris Cité
2009-2024
Institut de Recherche sur les Lois Fondamentales de l'Univers
2015-2024
CEA Paris-Saclay
2015-2024
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2015-2024
Astrophysique, Instrumentation et Modélisation
2023-2024
Heidelberg University
2021-2024
Laboratoire AstroParticule et Cosmologie
2012-2024
Centre National de la Recherche Scientifique
2009-2023
Friedrich-Alexander-Universität Erlangen-Nürnberg
2021-2023
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...
The inner region of the Milky Way halo harbors a large amount dark matter (DM). Given its proximity, it is one most promising targets to look for DM. We report on search annihilations DM particles using γ-ray observations towards 300 pc Way, with H.E.S.S. array ground-based Cherenkov telescopes. analysis based 2D maximum likelihood method Galactic Center (GC) data accumulated by over last 10 years (2004-2014), and does not show any significant signal above background. Assuming Einasto...
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...
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...
Gamma-ray bursts (GRBs), which are bright flashes of gamma rays from extragalactic sources followed by fading afterglow emission, associated with stellar core collapse events. We report the detection very-high-energy (VHE) GRB 190829A, between 4 and 56 hours after trigger, using High Energy Stereoscopic System (H.E.S.S.). The low luminosity redshift 190829A reduce both internal external absorption, allowing determination its intrinsic energy spectrum. Between energies 0.18 3.3 tera-electron...
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...
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 accretion of matter onto a massive black hole is believed to feed the relativistic plasma jets found in many active galactic nuclei (AGN). Although some AGN accelerate particles energies exceeding 10^12 electron Volts (eV) and are bright sources very-high-energy (VHE) gamma-ray emission, it not yet known where VHE emission originates. Here we report on radio observations galaxy M87, revealing period extremely strong flares accompanied by increase flux from its nucleus. These results...
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 nine-year H.E.S.S. Galactic Plane Survey (HGPS) yielded the most uniform observation scan of inner Milky Way in TeV gamma-ray band to date. sky maps and source catalogue HGPS allow for a systematic study population pulsar wind nebulae found throughout last decade. To investigate nature evolution nebulae, first time we also present several upper limits regions around pulsars without detected nebula. Our data exhibit correlation surface brightness with spin-down power $\dot{E}$. This seems...
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...
Spectral lines are among the most powerful signatures for dark matter (DM) annihilation searches in very-high-energy $\gamma$-rays. The central region of Milky Way halo is one promising targets given its large amount DM and proximity to Earth. We report on a search monoenergetic spectral line from self-annihilations particles energy range 300 GeV 70 TeV using two-dimensional maximum likelihood method taking advantage both spatial features signal versus background. analysis makes use Galactic...
A light on the origin of cosmic rays There's a new lab for studying origins rays: our neighbor galaxy, Large Magellanic Cloud. Astronomers are now making progress this topic by examining gamma that produced when interact with gas or lower-energy photons. The H.E.S.S. Collaboration has detected three sources in variety forms galactic satellite to Milky Way. include pulsar wind nebula N 157B, supernova remnant 132D, and superbubble 30 Dor C. Oddly, 1987A was not detected. Science , issue p. 406
Supernova remnants exhibit shock fronts (shells) that can accelerate charged particles up to very high energies. In the past decade, measurements of a handful shell-type supernova in very-high-energy gamma rays have provided unique insights into acceleration process. Among those objects, RX$~$J1713.7-3946 (also known as G347.3-0.5) has largest surface brightness, allowing us perform most comprehensive study morphology and spatially resolved spectra any such gamma-ray source. Here we present...
Diffuse $\ensuremath{\gamma}$-ray emission is the most prominent observable signature of celestial cosmic-ray interactions at high energies. While already being investigated GeV energies over several decades, assessments diffuse TeV remain sparse. After completion systematic survey inner Galaxy, H.E.S.S. experiment in a prime position to observe large-scale Data Galactic Plane Survey are regions off known sources. Corresponding flux measurements were made an extensive grid locations....
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...
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\%}...
<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...