A5081384824- Astrophysics and Cosmic Phenomena
- Dark Matter and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Radio Astronomy Observations and Technology
- Astrophysical Phenomena and Observations
- Nuclear physics research studies
- Particle physics theoretical and experimental studies
- Pulsars and Gravitational Waves Research
- Particle Detector Development and Performance
- Cosmology and Gravitation Theories
- Neutrino Physics Research
- Nuclear Physics and Applications
- Atomic and Molecular Physics
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Advanced Chemical Physics Studies
- Astro and Planetary Science
- Particle Accelerators and Free-Electron Lasers
- Astronomical Observations and Instrumentation
- Galaxies: Formation, Evolution, Phenomena
- Atomic and Subatomic Physics Research
- Astronomical and nuclear sciences
- Quantum Chromodynamics and Particle Interactions
- Scientific Research and Discoveries
- Solar and Space Plasma Dynamics
Universität Hamburg
2010-2024
University of Southern Denmark
2022-2024
Deutsches Elektronen-Synchrotron DESY
2023-2024
Massachusetts Institute of Technology
1978-2024
Helmut Schmidt University
2024
Hebrew University of Jerusalem
2024
National Institute of Standards and Technology
2024
Centre National de la Recherche Scientifique
2002-2023
Institut de Recherche sur les Lois Fondamentales de l'Univers
2021-2023
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2021-2023
The dwarf spheroidal satellite galaxies (dSphs) of the Milky Way are some most dark matter (DM) dominated objects known. We report on gamma-ray observations dSphs based 6 years Fermi Large Area Telescope data processed with new Pass 8 event-level analysis. None significantly detected in gamma rays, and we present upper limits DM annihilation cross section from a combined analysis 15 dSphs. These constraints among strongest robust to date lie below canonical thermal relic for mass $\lesssim$...
The blazar Mrk 501 was observed at energies above 0.10 TeV with the MAGIC Telescope from 2005 May through July. high sensitivity of instrument enabled determination flux and spectrum source on a night-by-night basis. Throughout our observational campaign, found to vary by an order magnitude. Intranight variability flux-doubling times down 2 minutes during two most active nights, namely, June 30 July 9. These are fastest variations ever in 501. ~20 minute long flare 9 showed indication 4 ± 1...
The atmospheric Cherenkov gamma-ray telescope MAGIC, designed for a low-energy threshold, has detected very-high-energy gamma rays from giant flare of the distant Quasi-Stellar Radio Source (in short: radio quasar) 3C 279, at distance more than 5 billion light-years (a redshift 0.536). No quasar been observed previously in radiation, and this is also most object emitting above 50 gigaelectron volts. Because high-energy may be stopped by interacting with diffuse background light universe,...
Microquasars are binary star systems with relativistic radio-emitting jets. They potential sources of cosmic rays and can be used to elucidate the physics We report detection variable gamma-ray emission above 100 gigaelectron volts from microquasar LS I 61 + 303. Six orbital cycles were recorded. Several detections occur at a similar phase, which suggests that is periodic. The strongest not observed when two stars closest one another, implying strong modulation or absorption processes.
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...
ABSTRACT We search for excess γ -ray emission coincident with the positions of confirmed and candidate Milky Way satellite galaxies using six years data from Fermi Large Area Telescope (LAT). Our sample 45 stellar systems includes 28 kinematically dark-matter-dominated dwarf spheroidal (dSphs) 17 recently discovered that have photometric characteristics consistent population known dSphs. For each these targets, relative predicted flux due to dark matter annihilation is taken kinematic...
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...
The fourth catalog of active galactic nuclei (AGNs) detected by the Fermi Gamma-ray Space Telescope Large Area (4LAC) between 2008 August 4 and 2016 2 contains 2863 objects located at high Galactic latitudes (|b|>10{\deg}). It includes 85% more sources than previous 3LAC based on years data. AGNs represent least 79% high-latitude in Fermi-Large Source Catalog (4FGL), which covers energy range from 50 MeV to 1 TeV. In addition, 344 gamma-ray are found low latitudes. Most 4LAC blazars (98%),...
We report about very high energy (VHE) γ-ray observations of the Crab Nebula with MAGIC telescope. The flux from nebula was measured between 60 GeV and 9 TeV. spectrum can be described by a curved power law dF/dE = f0(E/300 GeV)[a+blog10(E/300 GeV)] normalization f0 (6.0 ± 0.2stat) × 10−10 cm−2 s−1 TeV−1, − 2.31 0.06stat, b 0.26 0.07stat. peak in spectral distribution is estimated at 77 35 GeV. Within observation time experimental resolution telescope, emission steady pointlike. emission's...
We report on the search for spectral irregularities induced by oscillations between photons and axionlike-particles (ALPs) in γ-ray spectrum of NGC 1275, central galaxy Perseus cluster. Using 6 years Fermi Large Area Telescope data, we find no evidence ALPs exclude couplings above 5×10^{-12} GeV^{-1} ALP masses 0.5≲m_{a}≲5 neV at 95% confidence. The limits are competitive with sensitivity planned laboratory experiments, and, together other bounds, strongly constrain possibility that can...
Abstract The Large Area Telescope (LAT) aboard the Fermi spacecraft routinely observes high-energy emission from gamma-ray bursts (GRBs). Here we present second catalog of LAT-detected GRBs, covering first 10 yr operations, 2008 to 2018 August 4. A total 186 GRBs are found; these, 91 show in range 30–100 MeV (17 which seen only this band) and 169 detected above 100 MeV. Most these sources were discovered by other instruments ( /GBM, Swift /BAT, AGILE, INTEGRAL ) or reported Interplanetary...
Abstract We present a search for spatial extension in high-latitude ( ) sources recent Fermi point source catalogs. The result is the High-Latitude Extended Sources Catalog, which provides extensions (or upper limits thereof) and likelihood profiles suite of tested morphologies. find 24 extended sources, 19 were not previously characterized as extended. These include that are potentially associated with supernova remnants star-forming regions. also found γ -ray emission vicinity Cen A radio...
Abstract We report the discovery of GRB 221009A, highest flux gamma-ray burst (GRB) ever observed by Fermi Gamma-ray Burst Monitor (Fermi-GBM). This has continuous prompt emission lasting more than 600 s, which smoothly transitions to afterglow visible in Fermi-GBM energy range (8 keV–40 MeV), and total energetics higher any other sample. By using a variety new existing analysis techniques we probe spectral temporal evolution 221009A. find no prior trigger time ( t 0 ; 2022 October 9 at...
The Fermi Large Area Telescope (LAT) light curve repository (LCR) is a publicly available, continually updated library of gamma-ray curves variable Fermi-LAT sources generated over multiple timescales. LCR aims to provide publication-quality binned on timescales 3 days, 7 and 30 days for 1525 deemed in the source catalog first 10 years observations. consists through full likelihood analyses that model surrounding region, providing fluxes photon indices each time bin. intended as resource...
We analyze the timing of photons observed by MAGIC telescope during a flare active galactic nucleus Mkn 501 for possible correlation with energy, as suggested some models quantum gravity (QG), which predict vacuum refractive index ≃1+(E/MQGn)n, n=1,2. Parametrizing delay between γ-rays different energies Δt=±τlE or Δt=±τqE2, we find τl=(0.030±0.012) s/GeV at 2.5-σ level, and τq=(3.71±2.57)×10−6 s/GeV2, respectively. use these results to establish lower limits MQG1>0.21×1018 GeV...
We report on the results from observations in very high energy band (VHE; Eγ ≥ 100 GeV) of black hole X-ray binary (BHXB) Cygnus X-1. The were performed with MAGIC telescope, for a total 40 hr during 26 nights, spanning period between 2006 June and November. Searches steady γ-ray signals yielded no positive result, upper limits to integral flux ranging 1% 2% Crab Nebula flux, depending energy, have been established. also analyzed each observation night independently, obtaining evidence at...
One fundamental question about pulsars concerns the mechanism of their pulsed electromagnetic emission. Measuring high-end region a pulsar's spectrum would shed light on this question. By developing new electronic trigger, we lowered threshold Major Atmospheric gamma-ray Imaging Cherenkov (MAGIC) telescope to 25 GeV. In configuration, detected gamma-rays from Crab pulsar that were greater than GeV, revealing relatively high cutoff energy in phase-averaged spectrum. This indicates emission...
We report the detection of a new source very high energy (VHE; Eγ ≥ 100 GeV) γ-ray emission located close to Galactic plane, MAGIC J0616+225, which is spatially coincident with supernova remnant IC 443. The observations were carried out telescope in periods 2005 December-2006 January and 2006 December-2007 January. Here we present results from this source, leading VHE signal statistical significance 5.7 σ 2006/2007 data measured differential flux consistent power law, described as dNγ/(dA dt...
The intrinsic flux of very high energy (VHE, Energy > 100 GeV) gamma-rays from extragalactic sources is attenuated due to pair production in the interaction with photons background light (EBL). Depending on distance source, Universe should be opaque VHE above a certain energy. However, indications exist that more transparent than previously thought. A recent statistical analysis large sample spectra shows correction for absorption current EBL models too strong data points highest...
The continuum high-energy gamma-ray emission between 1 GeV and 100 TeV from the Crab Nebula has been measured for first time in overlapping energy bands by Fermi large-area telescope (Fermi/LAT) below ~ ground-based imaging air Cherenkov telescopes (IACTs) above 60 GeV. To follow up on phenomenological approach suggested Hillas et al. (1998), broad band spectral spatial measurement (from radio to low-energy gamma-rays < GeV) is used extract shape of electron spectrum. While this model per...
Recently, the Galactic center has been reported to be a source of very high energy (VHE) γ-rays by CANGAROO, VERITAS, and HESS experiments. The spectra as measured these experiments show substantial differences. In this Letter we present MAGIC observations center, resulting in detection differential γ-ray flux consistent with steady, hard-slope power law, described dNγ/(dA dt dE) = (2.9 ± 0.6) × 10-12(E/TeV)-2.2±0.2 cm-2 s-1 TeV-1. is centered at (R.A., decl.) (17h45m20s, -29°2'). This...
In the recent years, number of detected very high energy (VHE: E > 100 GeV) gamma-ray sources has increased rapidly. The have been observed at redshifts up to z = 0.536 without strong indications for presence absorption features in spectra. Absorption is however expected due pair-production processes propagating photons with photon bath intergalactic space. Even though this density not well known, lower limits can be firmly set by resolved emission from galaxy counts. Using guaranteed...
Gamma rays reveal the Universe's history How many stars have formed in Universe, and when did they do so? These fundamental questions are difficult to answer because there systematic uncertainties converting light we observe into total mass of galaxies. The Fermi-LAT Collaboration addressed these by exploiting way that gamma from distant blazars propagate through intergalactic space, which depends on amount emitted all collaboration found star formation peaked about 3 billion years after Big...