J. Knödlseder
A5016551014- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Dark Matter and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Particle Detector Development and Performance
- Pulsars and Gravitational Waves Research
- Nuclear Physics and Applications
- Radio Astronomy Observations and Technology
- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Radiation Detection and Scintillator Technologies
- Astronomical Observations and Instrumentation
- Particle Accelerators and Free-Electron Lasers
- Neutrino Physics Research
- Particle physics theoretical and experimental studies
- Solar and Space Plasma Dynamics
- Galaxies: Formation, Evolution, Phenomena
- Nuclear physics research studies
- Calibration and Measurement Techniques
- Atomic and Molecular Physics
- Radiation Therapy and Dosimetry
- Atmospheric and Environmental Gas Dynamics
- Advanced X-ray Imaging Techniques
Institut de Recherche en Astrophysique et Planétologie
2015-2024
Université de Toulouse
2014-2023
Université Toulouse III - Paul Sabatier
2014-2023
Centre National de la Recherche Scientifique
2013-2023
University of Groningen
2023
Institute for Resource Analysis and Policy
2021-2022
Osservatorio Astronomico di Padova
2018
American Society for Radiation Oncology
2018
Sciences et Ingénierie de la Matière Molle
2018
Roche (France)
2005-2017
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...
Cosmic rays are particles (mostly protons) accelerated to relativistic speeds. Despite wide agreement that supernova remnants (SNRs) the sources of galactic cosmic rays, unequivocal evidence for acceleration protons in these objects is still lacking. When encounter interstellar material, they produce neutral pions, which turn decay into gamma rays. This offers a compelling way detect sites protons. The identification pion-decay has been difficult because high-energy electrons also via...
The γ-ray sky can be decomposed into individually detected sources, diffuse emission attributed to the interactions of Galactic cosmic rays with gas and radiation fields, a residual all-sky component commonly called isotropic background (IGRB). IGRB comprises all extragalactic emissions too faint or resolved in given survey, as well any foregrounds that are approximately isotropic. first measurement Large Area Telescope (LAT) on board Fermi Gamma-ray Space (Fermi) used 10 months sky-survey...
The gamma-ray sky >100 MeV is dominated by the diffuse emissions from interactions of cosmic rays with interstellar gas and radiation fields Milky Way. Observations these provide a tool to study cosmic-ray origin propagation, medium. We present measurements first 21 months Fermi-LAT mission compare models emission generated using GALPROP code. are fitted data incorporate astrophysical input for distribution sources, fields. To assess uncertainties associated input, grid created varying...
The second catalog of active galactic nuclei (AGNs) detected by the Fermi Large Area Telescope (LAT) in two years scientific operation is presented. LAT AGN (2LAC) includes 1017 γ-ray sources located at high Galactic latitudes (|b| > 10°) that are with a test statistic (TS) greater than 25 and associated statistically AGNs. However, some these affected analysis issues multiple Consequently, we define Clean Sample which 886 AGNs, comprising 395 BL Lacertae objects (BL Lac objects), 310...
We measured separate cosmic-ray electron and positron spectra with the Fermi Large Area Telescope. Because instrument does not have an onboard magnet, we distinguish two species by exploiting Earth's shadow, which is offset in opposite directions for charges due to magnetic field. estimate subtract proton background using different methods that produce consistent results. report electron-only spectrum, positron-only fraction between 20 GeV 200 GeV. confirm rises energy 20-100 range. The...
Satellite galaxies of the Milky Way are among most promising targets for dark matter searches in gamma rays. We present a search consisting weakly interacting massive particles, applying joint likelihood analysis to 10 satellite with 24 months data Fermi Large Area Telescope. No signal is detected. Including uncertainty distribution, robust upper limits placed on annihilation cross sections. The 95% confidence level range from about 10(-26) cm3 s(-1) at 5 GeV 5×10(-23) 1 TeV, depending final...
SPI is a high spectral resolution gamma-ray telescope on board the ESA mission INTEGRAL (International Gamma Ray Astrophysics Laboratory). It consists of an array 19 closely packed germanium detectors surrounded by active anticoincidence shield BGO. The imaging capabilities instrument are obtained with tungsten coded aperture mask located 1.7 m from Ge array. fully field-of-view , partially field view amounts to and angular . energy range extends 20 keV 8 MeV typical 2.5 at 1.3 MeV. Here we...
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 dwarf spheroidal satellite galaxies of the Milky Way are some most dark-matter-dominated objects known. Due to their proximity, high dark matter content, and lack astrophysical backgrounds, widely considered be among promising targets for indirect detection via $\ensuremath{\gamma}$ rays. Here we report on $\ensuremath{\gamma}$-ray observations 25 based 4 years Fermi Large Area Telescope (LAT) data. None significantly detected in rays, present flux upper limits between 500 MeV GeV. We...
The Fermi Large Area Telescope (Fermi-LAT, hereafter LAT), the primary instrument on Gamma-ray Space (Fermi) mission, is an imaging, wide field-of-view, high-energy γ-ray telescope, covering energy range from 20 MeV to more than 300 GeV. During first years of LAT team has gained considerable insight into in-flight performance instrument. Accordingly, we have updated analysis used reduce data for public release as well response functions (IRFs), description provided analysis. In this paper,...
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...
The Fermi Large Area Telescope (LAT) has provided the most detailed view to date of emission towards Galactic centre (GC) in high-energy gamma-rays. This paper describes analysis data taken during first 62 months mission energy range 1-100 GeV from a $15^\circ \times 15^\circ$ region about direction GC, and implications for interstellar emissions produced by cosmic ray (CR) particles interacting with gas radiation fields inner Galaxy point sources detected. Specialised models (IEMs) are...
We present the results of our analysis cosmic-ray electrons using about $8\ifmmode\times\else\texttimes\fi{}{10}^{6}$ electron candidates detected in first 12 months on-orbit by Fermi Large Area Telescope. This work extends previously published spectrum down to 7 GeV, giving a spectral range approximately 2.5 decades up 1 TeV. describe detail and its validation beam-test data. In addition, we measured via subset events selected for best energy resolution as cross-check on measurement full...
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...
A young and energetic pulsar powers the well-known Crab Nebula. Here, we describe two separate gamma-ray (photon energy greater than 100 mega-electron volts) flares from this source detected by Large Area Telescope on board Fermi Gamma-ray Space Telescope. The first flare occurred in February 2009 lasted approximately 16 days. second was September 2010 4 During these outbursts, flux nebula increased factors of four six, respectively. brevity implies that gamma rays were emitted via...
Recent detections of the starburst galaxies M82 and NGC 253 by gamma-ray telescopes suggest that rapidly forming massive stars are more luminous at energies compared to their quiescent relatives. Building upon those results, we examine a sample 69 dwarf, spiral, ultraluminous infrared photon 0.1–100 GeV using 3 years data collected Large Area Telescope (LAT) on Fermi Gamma-ray Space (Fermi). Measured fluxes from significantly detected sources flux upper limits for remaining used explore...
We present detailed observations of the bright short-hard gamma-ray burst GRB 090510 made with Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT) on board Fermi observatory. is first detected by LAT that shows strong evidence for a deviation from Band spectral fitting function during prompt emission phase. The time-integrated spectrum fit sum $\Epeak = 3.9\pm 0.3$\,MeV, which highest yet measured, hard power-law component photon index $-1.62\pm 0.03$ dominates below...
This paper presents light curves as well the first systematic characterization of variability 106 objects in high-confidence Fermi Large Area Telescope Bright AGN Sample (LBAS). Weekly this sample, obtained during 11 months survey (2008 August 4–2009 July 4), are tested for and their properties quantified through autocorrelation function structure analysis. For brightest sources, 3 or 4 day binned extracted order to determine power density spectra (PDSs) fit temporal major flares. More than...
We report on the gamma-ray activity of high-synchrotron-peaked BL Lacertae object Mrk 421 during first 1.5 years Fermi operation, from 2008 August 5 to 2010 March 12. find that Large Area Telescope (LAT) spectrum above 0.3 GeV can be well-described by a power-law function with photon index Gamma=1.78 +/- 0.02 and average flux F(>0.3 GeV)=(7.23 0.16) x 10^{-8} ph cm^{-2} s^{-1}. Over this time period, Fermi-LAT was evaluated 7-day-long intervals, showing significant variations in (up factor...
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...
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...