J. Bolmont
A5074945209- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Dark Matter and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Neutrino Physics Research
- Pulsars and Gravitational Waves Research
- Radio Astronomy Observations and Technology
- Particle Detector Development and Performance
- Particle physics theoretical and experimental studies
- Cosmology and Gravitation Theories
- Noncommutative and Quantum Gravity Theories
- Radiation Detection and Scintillator Technologies
- Astronomical Observations and Instrumentation
- Particle Accelerators and Free-Electron Lasers
- Galaxies: Formation, Evolution, Phenomena
- Solar and Space Plasma Dynamics
- Black Holes and Theoretical Physics
- Astronomy and Astrophysical Research
- Geophysics and Gravity Measurements
- Nuclear Physics and Applications
- Atomic and Subatomic Physics Research
- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Gyrotron and Vacuum Electronics Research
- CCD and CMOS Imaging Sensors
Laboratoire de Physique Nucléaire et de Hautes Énergies
2016-2025
Sorbonne Paris Cité
2016-2024
Université Paris Cité
2015-2024
Sorbonne Université
2015-2024
Centre National de la Recherche Scientifique
2015-2024
Institut National de Physique Nucléaire et de Physique des Particules
2006-2024
TU Dortmund University
2008-2023
University of Łódź
2023
Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas
2023
Massachusetts Institute of Technology
2023
A precision measurement by the Alpha Magnetic Spectrometer on International Space Station of positron fraction in primary cosmic rays energy range from 0.5 to 350 GeV based $6.8\ifmmode\times\else\texttimes\fi{}{10}^{6}$ and electron events is presented. The very accurate data show that steadily increasing 10 $\ensuremath{\sim}250\text{ }\text{ }\mathrm{GeV}$, but, 20 250 GeV, slope decreases an order magnitude. spectrum shows no fine structure, ratio observable anisotropy. Together, these...
Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build next generation instrument, factor 5-10 improvement sensitivity 100 GeV 10 TeV range extension energies well below above TeV. will consist two arrays (one north, one south) for full sky coverage be operated as open observatory....
The Cherenkov Telescope Array, CTA, will be the major global observatory for very high energy gamma-ray astronomy over next decade and beyond. scientific potential of CTA is extremely broad: from understanding role relativistic cosmic particles to search dark matter. an explorer extreme universe, probing environments immediate neighbourhood black holes voids on largest scales. Covering a huge range in photon 20 GeV 300 TeV, improve all aspects performance with respect current instruments....
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...
We present the results of most comprehensive survey Galactic plane in very high-energy (VHE) gamma-rays, including a public release sky maps, catalog VHE sources, and discovery 16 new sources gamma-rays. The High Energy Spectroscopic System (H.E.S.S.) (HGPS) was decade-long observation program carried out by H.E.S.S. I array Cherenkov telescopes Namibia from 2004 to 2013. observations amount nearly 2700 h data, covering at longitudes l = 250 deg 65 latitudes |b| < 3 deg. In addition...
The exploration of the universe has recently entered a new era thanks to multi-messenger paradigm, characterized by continuous increase in quantity and quality experimental data that is obtained detection various cosmic messengers (photons, neutrinos, rays gravitational waves) from numerous origins. They give us information about their sources properties intergalactic medium. Moreover, astronomy opens up possibility search for phenomenological signatures quantum gravity. On one hand, most...
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...
The long gamma-ray burst (GRB) 100621A, at the time brightest X-ray transient ever detected by Swift-XRT in $0.3\textrm{--}10$ keV range, has been observed with H.E.S.S. imaging air Cherenkov telescope array, sensitive to gamma radiation very-high-energy (VHE, $>100$ GeV) regime. Due its relatively small redshift of $z\sim0.5$, favourable position southern sky and short follow-up ($<700 \rm{s}$ after satellite trigger) observations, this GRB could be within sensitivity reach instrument....
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...
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...
Abstract The unification of quantum mechanics and general relativity has long been elusive. Only recently have empirical predictions various possible theories gravity put to test, where a clear signal properties is still missing. dawn multi-messenger high-energy astrophysics tremendously beneficial, as it allows us study particles with much higher energies travelling longer distances than in terrestrial experiments, but more progress needed on several fronts. A thorough appraisal current...
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....
We analyze the MeV/GeV emission from four bright Gamma-Ray Bursts (GRBs) observed by Fermi-Large Area Telescope to produce robust, stringent constraints on a dependence of speed light in vacuo photon energy (vacuum dispersion), form Lorentz invariance violation (LIV) allowed some Quantum Gravity (QG) theories. First, we use three different and complementary techniques constrain total degree dispersion data. Additionally, using maximally conservative set assumptions possible source-intrinsic...
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...
A search for muon neutrinos from neutralino annihilations in the Sun has been performed with IceCube 22-string neutrino detector using data collected 104.3 days of live time 2007. No excess over expected atmospheric background observed. Upper limits have obtained on annihilation rate captured neutralinos and converted to weakly interacting massive particle (WIMP) proton cross sections WIMP masses range 250-5000 GeV. These results are most stringent date Sun.
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...