نتایج جستجو برای: γ ray
تعداد نتایج: 371341 فیلتر نتایج به سال:
In this paper, a method is proposed to determine the basic properties of γ-ray loud blazars, among them the central black hole mass, M , the Doppler factor, δ, the propagation angle of the γ-rays with respect to the symmetric axis of a twotemperature accretion disk, Φ, and the distance (i.e. the height above the accretion disk), d at which the γ-rays are created, for seven γ-ray loud blazars wi...
We report the first observational indication for extendedMeV emission that may be associatedwith high-velocity clouds (HVCs). Based on a combination of fifteen COMPTEL observations made during the period 1991–1995 we find evidence for intense γ-radiation at 0.75–3 MeV from the general direction of the HVC Complexes M and A, adjacent to the Lockman et al. hole. The γ-ray excess roughly covers a ...
The relation between the γ-ray and the emission line luminosities for a sample of 36 γ-ray loud blazars is investigated; an apparent correlation between them, Lγ ∝ L 0.69±0.11 Line , with a correlation coefficient r = 0.741 and a chance probability of p = 1.9× 10, is found. It is found, however, that there is no intrinsic correlation between them: the apparent correlation is due to the redshift...
Particle acceleration at supernova remnant (SNR) shock waves is regarded as the most probable mechanism for providing Galactic cosmic rays at energies below 10 eV. The Galactic cosmic ray hadron component would in this picture result from the injection of relativistic particles from many SNRs. It is well known that the superposition of individual power law source spectra with dispersion in the ...
Using the data taken from Tibet II High Density (HD) Array (1997 February1999 September) and Tibet-III array (1999 November-2005 November), our previous northern sky survey for TeV γ−ray point sources has now been updated by a factor of 2.8 improved statistics. From 0.0 to 60.0 in declination (Dec) range, no new TeV γ−ray point sources with sufficiently high significance were identified while t...
We discuss the scientific and technical aspects of high-resolution γ-ray and X-ray imaging of solar flares. The scientific necessity for imaging observations of solar flares and the implications of future observations for the study of solar flare electrons and ions are considered. Performance parameters for a future hard X-ray and γ-ray imager are then summarized. We briefly survey techniques f...
We describe a multiwavelength program of monitoring of a sample of bright γ-ray blazars, which the Boston University (BU) group has being carrying out since June 2007. The program includes monthly monitoring with the Very Long Baseline Array at 43 GHz, optical photometric and polarimetric observations, construction and analysis of UV and X-ray light curves obtained with the Rossi X-ray Timing E...
The limited angular resolution of γ–ray telescopes prevents a direct identification of the majority of sources detected so far. This is particularly true for the low latitude, probably galactic, ones only 10 % of which has been identified. Most counterparts of the identified low–latitude γ–ray sources are Isolated Neutron Stars (INS), both radio–loud and radio– quiet (Geminga–like) objects, whi...
An approach is presented to experimentally constrain previously unreachable (p, γ) reaction rates on nuclei far from stability in the astrophysical rp process. Energies of all critical resonances in the (57)Cu(p,γ)(58)Zn reaction are deduced by populating states in (58)Zn with a (d, n) reaction in inverse kinematics at 75 MeV/u, and detecting γ-ray-recoil coincidences with the state-of-the-art ...
In its first three months of operations, the Fermi Gamma-Ray Observatory has detected approximately one quarter of the radio-flux-limited MOJAVE sample of bright flat-spectrum active galactic nuclei (AGNs) at energies above 100 MeV. We have investigated the apparent parsec-scale jet speeds of 26 MOJAVE AGNs measured by the Very Long Baseline Array (VLBA) that are in the LAT bright AGN sample (L...
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