D. Malyshev
A5072580734- Astrophysics and Cosmic Phenomena
- Dark Matter and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Cosmology and Gravitation Theories
- Radio Astronomy Observations and Technology
- Particle Detector Development and Performance
- Radiation Detection and Scintillator Technologies
- Astronomical Observations and Instrumentation
- Particle physics theoretical and experimental studies
- Advanced Topics in Algebra
- Neutrino Physics Research
- Black Holes and Theoretical Physics
- Nuclear Physics and Applications
- Astronomy and Astrophysical Research
- Medical Imaging Techniques and Applications
- Algebraic structures and combinatorial models
- Radioactive Decay and Measurement Techniques
- Galaxies: Formation, Evolution, Phenomena
- Crystallography and Radiation Phenomena
- Stellar, planetary, and galactic studies
- Atomic and Subatomic Physics Research
- Particle Accelerators and Free-Electron Lasers
- Stochastic processes and financial applications
Friedrich-Alexander-Universität Erlangen-Nürnberg
2017-2024
CEA Paris-Saclay
2021-2023
Université Paris-Saclay
2021-2023
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2021-2023
ETH Zurich
2023
University of Würzburg
2023
École Polytechnique
2020-2023
Istituto Nazionale di Fisica Nucleare, Sezione di Padova
2023
Université de Montpellier
2023
Deutsches Elektronen-Synchrotron DESY
2023
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...
Abstract The region around the Galactic Center (GC) is now well established to be brighter at energies of a few GeV than what expected from conventional models diffuse gamma-ray emission and catalogs known sources. We study excess using 6.5 yr data Fermi Large Area Telescope. characterize uncertainty GC spectrum morphology due uncertainties in cosmic-ray source distributions propagation, distribution interstellar gas Milky Way, potential contribution bubbles. also evaluate properties...
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...
The Fermi bubbles are two large structures in the gamma-ray sky extending to 55° above and below Galactic center. We analyze 50 months of Large Area Telescope data between 100 MeV 500 GeV 10° latitude derive spectrum morphology bubbles. thoroughly explore systematic uncertainties that arise when modeling diffuse emission through separate approaches. is well described by either a log parabola or power law with an exponential cutoff. exclude simple more than 7σ significance. cutoff has index...
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...
In this paper, we study the flux of electrons and positrons injected by pulsars annihilating or decaying dark matter in context recent ATIC, PAMELA, Fermi, HESS data. We review from a single pulsar derive distribution pulsars. point out that particle acceleration magnetosphere is insufficient to explain observed excess with energy $E\ensuremath{\sim}1\text{ }\text{ }\mathrm{TeV}$ one has take into account an additional at termination shock between its wind nebula. show energies less than few...
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...
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\%}...
Abstract The Fermi Large Area Telescope (LAT) has opened the way for comparative studies of cosmic rays (CRs) and high-energy objects in Milky Way (MW) other, external, star-forming galaxies. Using 2 yr observations with LAT, Local Group galaxy M31 was detected as a marginally extended gamma-ray source, while only an upper limit been derived other nearby M33. We revisited emission direction M33 using more than 7 LAT Pass 8 data energy range <?CDATA $0.1\mbox{--}100\,\mathrm{GeV}$?> <mml:math...
Abstract We report on the observations of gamma-ray burst (GRB) 190114C by Fermi Gamma-ray Space Telescope and Neil Gehrels Swift Observatory . The prompt emission was detected GRB Monitor (GBM), Large Area (LAT), Burst Alert (BAT) long-lived afterglow subsequently observed GBM, LAT, X-ray (XRT), UV Optical Telescope. early-time reveal multiple components that evolve independently, with a delayed power-law component exhibits significant spectral attenuation above 40 MeV in first few seconds...
The spatial extension of a gamma-ray source is an essential ingredient to determine its spectral properties as well potential multi-wavelength counterpart. capability spatially resolve sources greatly improved by the newly delivered Fermi-Large Area Telescope (LAT) Pass 8 event-level analysis which provides greater acceptance and point spread function, two crucial factors for detection extended sources. Here, we present complete search located within 7 degrees from Galactic plane, using 6...
Young massive stellar clusters are extreme environments and potentially provide the means for efficient particle acceleration. Indeed, they increasingly considered as being responsible a significant fraction of cosmic rays (CRs) accelerated within Milky Way. Westerlund 1, most known young cluster in our Galaxy is prime candidate studying this hypothesis. While very-high-energy $\gamma$-ray source HESS J1646-458 has been detected vicinity 1 past, its association could not be firmly...
We present a complete analysis of Fermi Large Area Telescope (LAT) data GRB 221009A, the brightest Gamma-Ray Burst (GRB) ever detected. The burst emission above 30 MeV detected by LAT preceded 1 s low-energy (< 10 MeV) pulse that triggered Monitor (GBM), as has been observed in other GRBs. prompt phase 221009A lasted few hundred seconds. It was so bright we identify Bad Time Interval (BTI) 64 seconds caused extremely high flux hard X-rays and soft gamma rays, during which event...
An analytic relation between the statistics of photons in pixels and number counts multi-photon point sources is used to constrain distribution gamma-ray below Fermi detection limit at energies above 1 GeV latitudes 30°. The derived source-count consistent with found by Collaboration based on first point-source catalog. In particular, we find that contribution resolved unresolved active galactic nuclei (AGNs) total flux 20%–25%. best-fit model, AGN-like fraction 17% ± 2%. Using fact Galactic...
In classical analyses of $\gamma$-ray data from IACTs, such as H.E.S.S., aperture photometry, or photon counting, is applied in a (typically circular) region interest (RoI) encompassing the source. A key element analysis to estimate amount background RoI due residual cosmic ray-induced air showers data. Various standard estimation techniques have been developed last decades, most them rely on measurement source-free regions within observed field view. However, particular Galactic plane,...
Context. HESS J1809$-$193 is an unassociated very-high-energy $\gamma$-ray source located on the Galactic plane. While it has been connected to nebula of energetic pulsar PSR J1809$-$1917, supernova remnants and molecular clouds present in vicinity also constitute possible associations. Recently, detection emission up energies $\sim$100 TeV with HAWC observatory led renewed interest J1809$-$193. Aims. We aim understand origin Methods. analysed 93.2 h data taken above 0.27 High Energy...
Geminga is an enigmatic radio-quiet gamma-ray pulsar located at a mere 250 pc distance from Earth. Extended very-high-energy emission around the was discovered by Milagro and later confirmed HAWC, which are both water Cherenkov detector-based experiments. However, evidence for wind nebula in gamma rays has long evaded detection imaging atmospheric telescopes (IACTs) despite targeted observations. The of on angular scales > 2 deg poses considerable challenge background estimation IACT data...
We study the local flux of electrons and positrons from annihilating dark matter (DM), investigate how its spectrum depends on choice DM model inhomogeneities in distribution. Below a cutoff energy, is expected to have universal power-law form with an index $n\ensuremath{\approx}\ensuremath{-}2$. The energy behavior near dependent. dependence host halo profile may be significant at energies $E<100\text{ }\text{ }\mathrm{GeV}$ leads softening $n<\ensuremath{-}2$. There additional features...
An excess of $γ$-ray emission from the Galactic Center (GC) region with respect to predictions based on a variety interstellar models and source catalogs has been found by many groups using data {\it Fermi} Large Area Telescope (LAT). Several interpretations this have invoked. In paper we search for members an unresolved population pulsars located in inner Galaxy that are predicted interpretation GC as being due such sources. We use cataloged LAT sources derive criteria efficiently select...
We present the Fermi Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT) observations of LIGO binary black hole merger event GW151226 candi- date LVT151012. No candidate electromagnetic counterparts were detected by either GBM or LAT. a detailed analysis LAT data over range timescales from seconds to years, using automated pipelines new techniques for char- acterizing upper limits across large area sky. Due partial coverage localization regions at trigger times both events, dif-...
Black holes with masses below approximately $10^{15}$ g are expected to emit gamma rays energies above a few tens of MeV, which can be detected by the Fermi Large Area Telescope (LAT). Although black these cannot formed as result stellar evolution, they may have in early Universe and therefore called Primordial Holes (PBHs). Previous searches for PBHs focused on either short timescale bursts or contribution isotropic gamma-ray emission. We show that, case individual PBHs, LAT is most...