Related papers: Soft gamma-ray polarimetry with COSI using maximum…
The Cadmium Zinc Telluride Imager (CZTI) onboard AstroSat is designed for hard X-ray imaging and spectroscopy in the energy range of 20 - 100 keV. The CZT detectors are of 5 mm thickness and hence have good efficiency for Compton…
X-ray polarimetry promises to give qualitatively new information about high-energy astrophysical sources, such as binary black hole systems, micro-quasars, active galactic nuclei, and gamma-ray bursts. We designed, built and tested a hard…
Emission from X-ray binaries in the hard spectral state is dominated by high-energy radiation attributed to the Compton scattering of seed photons. The prevalent model of the Comptonization by hot electrons or pairs faces the problem of…
EGRET (20 MeV to 30 GeV) on board the Compton GRO has observed high-energy emission from about 40-50 Active Galactic Nuclei. Theoretical models of this emission based on the upscattering of thermal disk photons by cooling, relativistic…
We discuss several constraints on the properties of gamma-ray bursts (GRB) at cosmological distances. First we use the requirement that burst sources must be optically thin to pair production by photon-photon collisions in order to produce…
POLAR is a compact wide field space-borne detector dedicated for precise measurements of the linear polarization of hard X-rays emitted by transient sources in the energy range from 50 keV to 500 keV. It consists of 1600 plastic…
We present a new estimation method for mapping the gravitational lensing potential from observed CMB intensity and polarization fields. Our method uses Bayesian techniques to estimate the average curvature of the potential over small local…
The Compton Spectrometer and Imager (COSI) is a balloon-borne compact Compton telescope designed to survey the 0.2-5 MeV sky. COSI's energy resolution of $\sim$0.2% at 1.8 MeV, single-photon reconstruction, and wide field of view make it…
Polarimetry provides key physical information on the properties of interacting binary systems, sometimes difficult to obtain by any other type of observation. Indeed, radiation processes such as scattering by free electrons in the hot…
Complementary views of galaxy clusters in the radio synchrotron, hard X-ray inverse Compton, and high-energy gamma-ray regimes are critical in calibrating them as high-precision cosmological probes. We present predictions for scaling…
Nonlinear Compton scattering is a promising source of bright gamma-rays. Using readily available intense laser pulses to scatter off the energetic electrons on the one hand allows to significantly increase the total photon yield, but on the…
The electric alpha and magnetic beta pion Compton polarizabilities characterize the pion's deformation in the electromagnetic field of the gamma during gamma-pi Compton scattering. The chi_PT effective Lagrangian, using data from radiative…
We describe a feasible implementation of a novel X-ray detector for highly energetic x-ray photons with a large solid angle coverage, optimal for the detection of Compton x-ray scattered photons. The device consists of a 20~cm-thick…
We have obtained measurements and upper limits on the emission of Cyg X-1 in the photon energy range of 0.03--300 GeV based on observations by Fermi. We present the results separately for the hard and soft spectral states, as well for all…
All gamma-ray telescopes suffer from source confusion due to their inability to focus incident high-energy radiation, and the resulting background contamination can obscure the periodic emission from faint pulsars. In the context of the…
In recent years, a number of purpose-built scintillator-based polarimeters have studied bright astronomical sources for the first time in the hard X-ray band (tens to hundreds of keV). The addition of polarimetry can help data…
Plasma scattering measurement is effective technique to observe low frequency density fluctuations excited in plasma. The spatial and wave number resolutions and the S/N ratio of measurement depend on the wavelength range, the size and the…
Many studies have shown that high-energy $\gamma$-photon beams can be efficiently generated via nonlinear Compton scattering driven by laser pulses with intensities $> 10^{22}\rm{W/cm^2}$ recently available in laboratories. Here, we propose…
Three different methods of measuring cosmology with gamma-ray bursts (GRBs) have been proposed since a relation between the $\gamma$-ray energy $E_{\gamma} $ of a GRB jet and the peak energy $E_p$ of the $\nu F_{\nu}$ spectrum in the burst…
Gamma-Ray Bursts are among the most powerful events in the Universe. Despite half a century of observations of these transient sources, many open questions remain about their nature. Polarization measurements of the GRB prompt emission have…