Related papers: Probing Intergalactic Magnetic Fields in the GLAST…
Recent claims that the strength B_IGMF of the intergalactic magnetic field (IGMF) is >~ 1e-15 G are based on upper limits to the expected cascade flux in the GeV band produced by blazar TeV photons absorbed by the extragalactic background…
We propose a method of measurement of extragalactic magnetic fields in observations of TeV gamma-rays from distant blazars. Multi-TeV gamma-rays are emitted by these sources in narrow jet with opening angle of few degrees. These primary…
Intergalactic space is believed to contain non-zero magnetic fields (the Intergalactic Magnetic Field: IGMF) which at scales of Mpc would have intensities below $10^{-9}$ G. Very high energy (VHE $>$100 GeV) gamma rays coming from blazars…
The existence of intergalactic magnetic fields (IGMF) has so far not been established through observations. The IGMF is expected to be generated either via processes mainly connected to astrophysical processes or it could be a relic of…
The origin of intergalactic magnetic fields (IGMFs) remains one of the key open questions in cosmology. Gamma-ray pair halos produced by electromagnetic cascades from TeV-emitting blazars provide a powerful indirect probe of these fields.…
Delayed "pair echo" signal from interactions of very-high-energy gamma rays in the intergalactic medium can be used for detection of the inter-galactic magnetic field (IGMF). We use the data of Fermi/LAT telescope coupled with LHAASO…
Intergalactic weak magnetic fields can have non-negligible effects on the electromagnetic cascades induced by blazar gamma-ray emission. Secondary electrons and positrons are produced by primary gamma rays of energies ~TeV and can be…
Extended and delayed emission around distant TeV sources induced by the effects of propagation of gamma rays through the intergalactic medium can be used for the measurement of the intergalactic magnetic field (IGMF). We search for delayed…
Magnetic fields of the order of $\mu$-Gauss are observationally detected in galaxies and galaxy clusters, which can be (at least) in part originated by the amplification of much weaker primordial seed fields. These fields should be carried…
We investigate the delayed, secondary GeV-TeV emission of gamma-ray bursts and its potential to probe the nature of intergalactic magnetic fields. Geometrical effects are properly taken into account for the time delay between primary high…
Very high energy (VHE $>$100 GeV) gamma rays coming from blazars can produce pairs when interacting with the Extragalactic Background Light (EBL) and the Cosmic Microwave Background, generating an electromagnetic cascade. Depending on the…
We study the four BL Lac objects (RGB J0152+017, 1ES 0229+200, 1ES 0347-121 and PKS 0548-322) detected in the TeV band but not present in the 1FGL catalogue of the Fermi/Large Area Telescope. We analize the 24 months of LAT data deriving…
Inverse-Compton cascades initiated by energetic gamma rays (E>100 GeV) enhance the GeV emission from bright, extragalactic TeV sources. The absence of this emission from bright TeV blazars has been used to constrain the intergalactic…
At TeV energies and above gamma rays can induce electromagnetic cascades, whose charged component is sensitive to intervening intergalactic magnetic fields (IGMFs). When interpreting gamma-ray measurements in the energy range between a few…
Electromagnetic cascades are initiated by TeV gamma rays propagating through the intergalactic medium (IGM), and they can be used to constrain the weak intergalactic magnetic field (IGMF) in cosmic voids. Primary TeV photons produce…
An intergalactic magnetic field stronger than $3\times10^{-13}$~G would explain the lack of a bright, extended degree-scale, GeV-energy inverse Compton component in the gamma-ray spectra of TeV-blazars. A robustly predicted consequence of…
Magnetic fields in galaxies and galaxy clusters are believed to be the result of the amplification of intergalactic seed fields during the formation of large-scale structures in the universe. However, the origin, strength, and morphology of…
Relativistic pair beams produced in the intergalactic medium (IGM) by TeV gamma rays from blazars are expected to generate a detectable GeV-scale electromagnetic cascade, yet this cascade is absent in the observed spectra of hard-spectrum…
Primary gamma rays emitted by extragalactic sources, such as blazars, will generate electromagnetic cascades in intergalactic space. These cascades proceed via electron-positron pair production and inverse Compton scattering on cosmic…
High-energy emission from gamma-ray bursts (GRBs) is widely expected but had been sparsely observed until recently when the Fermi satellite was launched. If >TeV gamma rays are produced in GRBs and can escape from the emission region, they…