L. Guillemot
A5091186797- Pulsars and Gravitational Waves Research
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Geophysics and Gravity Measurements
- Radio Astronomy Observations and Technology
- Astrophysical Phenomena and Observations
- Dark Matter and Cosmic Phenomena
- Advanced Frequency and Time Standards
- Cosmology and Gravitation Theories
- Superconducting Materials and Applications
- Particle Accelerators and Free-Electron Lasers
- Astronomical Observations and Instrumentation
- High-pressure geophysics and materials
- Stellar, planetary, and galactic studies
- Particle Detector Development and Performance
- Atomic and Subatomic Physics Research
- Solar and Space Plasma Dynamics
- Geophysics and Sensor Technology
- Astronomy and Astrophysical Research
- Particle physics theoretical and experimental studies
- Neutrino Physics Research
- GNSS positioning and interference
- Galaxies: Formation, Evolution, Phenomena
- Particle accelerators and beam dynamics
- Statistical and numerical algorithms
Laboratoire de Physique et Chimie de l’Environnement et de l’Espace
2016-2025
Université Paris Sciences et Lettres
2018-2025
Centre National de la Recherche Scientifique
2015-2024
Université d'Orléans
2015-2024
Observatoire de Paris
2015-2024
Laboratoire Chimie de l'Environnement
2016-2024
Association for Language Learning
2024
Observatoire Radioastronomique de Nançay
2015-2021
Laboratoire de Chimie Physique
2021
Max Planck Institute for Radio Astronomy
2009-2018
(Abridged) The Large Area Telescope (Fermi/LAT, hereafter LAT), the primary instrument on Fermi Gamma-ray Space (Fermi) mission, is an imaging, wide field-of-view, high-energy gamma-ray telescope, covering energy range from below 20 MeV to more than 300 GeV. This paper describes LAT, its pre-flight expected performance, and summarizes key science objectives that will be addressed. On-orbit performance presented in detail a subsequent paper. LAT pair-conversion telescope with precision...
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...
ABSTRACT We present a catalog of high-energy gamma-ray sources detected by the Large Area Telescope (LAT), primary science instrument on Fermi Gamma-ray Space (Fermi) , during first 11 months phase mission, which began 2008 August 4. The First -LAT (1FGL) contains 1451 and characterized in 100 MeV to GeV range. Source detection was based average flux over month period, threshold likelihood Test Statistic is 25, corresponding significance just 4σ. 1FGL includes source location regions,...
We present the second catalog of high-energy gamma-ray sources detected by Large Area Telescope (LAT), primary science instrument on Fermi Gamma-ray Space (Fermi), derived from data taken during first 24 months phase mission, which began 2008 August 4. Source detection is based average flux over 24-month period. The Second Fermi-LAT (2FGL) includes source location regions, defined in terms elliptical fits to 95% confidence regions and spectral power-law, exponentially cutoff or log-normal...
PSR J0740$+$6620 has a gravitational mass of $2.08\pm 0.07~M_\odot$, which is the highest reliably determined any neutron star. As result, measurement its radius will provide unique insight into properties star core matter at high densities. Here we report based on fits rotating hot spot patterns to Neutron Star Interior Composition Explorer (NICER) and X-ray Multi-Mirror (XMM-Newton) observations. We find that equatorial circumferential $13.7^{+2.6}_{-1.5}$ km (68%). apply our measurement,...
Abstract We report on Bayesian estimation of the radius, mass, and hot surface regions massive millisecond pulsar PSR J0740+6620, conditional pulse-profile modeling Neutron Star Interior Composition Explorer X-ray Timing Instrument event data. condition informative distance, orbital inclination priors derived from joint North American Nanohertz Observatory for Gravitational Waves Canadian Hydrogen Intensity Mapping Experiment/Pulsar wideband radio timing measurements Fonseca et al. use...
(Abridged) We have conducted a detailed investigation of the broad-band spectral properties \gamma-ray selected blazars Fermi LAT Bright AGN Sample (LBAS). By combining our accurately estimated gamma-ray spectra with Swift, radio, infra-red, optical and other hard X-ray/gamma-ray data, collected within three months LBAS data taking period, we were able to assemble high-quality quasi-simultaneous Spectral Energy Distributions (SED) for 48 blazars.The SED these sources is similar that...
Designed as a high-sensitivity gamma-ray observatory, the Fermi Large Area Telescope is also an electron detector with large acceptance exceeding 2 m;{2} sr at 300 GeV. Building on analysis, we have developed efficient detection strategy which provides sufficient background rejection for measurement of steeply falling spectrum up to 1 TeV. Our high precision data show that falls energy E-3.0 and does not exhibit prominent spectral features. Interpretations in terms conventional diffusive...
This catalog summarizes 117 high-confidence ⩾0.1 GeV gamma-ray pulsar detections using three years of data acquired by the Large Area Telescope (LAT) on Fermi satellite. Half are neutron stars discovered LAT through periodicity searches in and radio around unassociated source positions. The pulsars evenly divided into groups: millisecond pulsars, young radio-loud radio-quiet pulsars. We characterize pulse profiles energy spectra derive luminosities when distance information exists. Spectral...
Gamma-ray bursts (GRBs) are highly energetic explosions signaling the death of massive stars in distant galaxies. The Burst Monitor and Large Area Telescope onboard Fermi Observatory together record GRBs over a broad energy range spanning about 7 decades gammaray energy. In September 2008, observed exceptionally luminous GRB 080916C, with largest apparent release yet measured. high-energy gamma rays to start later persist longer than lower photons. A simple spectral form fits entire...
We present the results of search for an isotropic stochastic gravitational wave background (GWB) at nanohertz frequencies using second data release European Pulsar Timing Array (EPTA) 25 millisecond pulsars and a combination with first Indian (InPTA). analysed (i) full 24.7-year EPTA set, (ii) its 10.3-year subset based on modern observing systems, (iii) set InPTA ten commonly timed pulsars, (iv) data. These combinations allowed us to probe contributions instrumental noise interstellar...
We report on the first Fermi Large Area Telescope (LAT) measurements of so-called "extragalactic" diffuse gamma-ray emission (EGB). This component is generally considered to have an isotropic or nearly distribution sky with diverse contributions discussed in literature. The derivation EGB based detailed modeling bright foreground Galactic emission, detected LAT sources, and solar emission. find spectrum consistent a power law differential spectral index gamma = 2.41 +/- 0.05 intensity I(>100...
The dramatic increase in the number of known gamma-ray pulsars since launch Fermi Gamma-ray Space Telescope (formerly GLAST) offers first opportunity to study a sizable population these high-energy objects. This catalog summarizes 46 high-confidence pulsed detections using six months data taken by Large Area (LAT), Fermi's main instrument. Sixteen previously unknown were discovered searching for signals at positions bright sources seen with LAT, or objects suspected be neutron stars based on...
The highly stable spin of neutron stars can be exploited for a variety (astro)physical investigations. In particular, arrays pulsars with rotational periods the order milliseconds used to detect correlated signals such as those caused by gravitational waves. Three ‘pulsar timing arrays’ (PTAs) have been set up around world over past decades and collectively form ‘International’ PTA (IPTA). this paper, we describe first joint analysis data from three regional PTAs, i.e. IPTA set. We available...
ABSTRACT Following its launch in 2008 June, the Fermi Gamma-ray Space Telescope ( ) began a sky survey August. The Large Area (LAT) on three months produced deeper and better resolved map of γ-ray than any previous space mission. We present here initial results for energies above 100 MeV 205 most significant (statistical significance greater ∼10σ) sources these data. These are best characterized localized point-like (i.e., spatially unresolved) early mission
We report on the observation of bright, long gamma-ray burst, GRB 090902B, by Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT) instruments on-board Fermi observatory. This was one brightest GRBs to have been observed LAT, which detected several hundred photons during prompt phase. With a redshift z = 1.822, this burst is among most luminous Fermi. Time-resolved spectral analysis reveals significant power-law component in LAT data that distinct from usual Band model emission seen...
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 first three months of sky-survey operation with the Fermi Gamma Ray Space Telescope (Fermi) Large Area (LAT) reveals 132 bright sources at |b|>10 deg test statistic greater than 100 (corresponding to about 10 sigma). Two methods, based on CGRaBS, CRATES and BZCat catalogs, indicate high-confidence associations 106 these known AGNs. This sample is referred as LAT Bright AGN Sample (LBAS). It contains two radio galaxies, namely Centaurus A NGC 1275, 104 blazars consisting 57 flat...
We present a catalog of sources detected above 10 GeV by the Fermi Large Area Telescope (LAT) in first 7 years data using Pass 8 event-level analysis. This is Third Catalog Hard Fermi-LAT Sources (3FHL), containing 1556 objects characterized - 2 TeV energy range. The sensitivity and angular resolution are improved factors 3 relative to previous LAT at same energies (1FHL). vast majority (79%) associated with extragalactic counterparts other wavelengths, including 16 located very high...
Pulsars are rapidly-rotating, highly-magnetized neutron stars emitting radiation across the electromagnetic spectrum. Although there more than 1800 known radio pulsars, until recently, only seven were observed to pulse in gamma rays and these all discovered at other wavelengths. The Fermi Large Area Telescope makes it possible pinpoint through their gamma-ray pulsations. We report detection of 16 pulsars blind frequency searches using LAT. Most coincident with previously unidentified...
We report the discovery with Fermi/LAT of gamma-ray emission from three radio-loud narrow-line Seyfert 1 galaxies: PKS 1502+036 (z=0.409), 1H 0323+342 (z=0.061) and 2004-447 (z=0.24). In addition to PMN J0948+0022 (z=0.585), first source this type be detected in gamma rays, they may form an emerging new class active galactic nuclei (AGN). These findings can have strong implications on our knowledge about relativistic jets unified model AGN.
The origin of Galactic cosmic rays is a century-long puzzle. Indirect evidence points to their acceleration by supernova shockwaves, but we know little escape from the shock and evolution through turbulent medium surrounding massive stars. Gamma can probe spreading ambient gas radiation fields. Fermi Large Area Telescope (LAT) has observed star-forming region Cygnus X. 1- 100-gigaelectronvolt images reveal 50-parsec-wide cocoon freshly accelerated that flood cavities carved stellar winds...
We present a catalog of sources detected above 50 GeV by the {\it Fermi}-Large Area Telescope (LAT) in 80 months data. The newly delivered Pass 8 event-level analysis allows detection and characterization GeV--2 TeV energy range. In this band, Fermi}-LAT has 360 sources, which constitute second hard (2FHL). improved angular resolution enables precise localization point ($\sim$1.7$'$ radius at 68 % C.~L.) spatially extended sources. find that 86 can be associated with counterparts other...