We report on the analysis of an XMM observation of the X-ray source IGR J16320–4751 = AX J1631.9– 4752. Our analysis allowed us to obtain the most accurate X-ray position to date (Rodriguez et al. 2003), and to identify a likely infrared counterpart (Tomsick et al. 2003). We present the detailed analysis of the IGR J16320–4751 XMM spectra. The PN spectrum can be well represented by a single pow...

The spectrum of the diffuse isotropic component of cosmic X-rays over the 13–180 keV range was determined by the UCSD/MIT Hard X-Ray and Gamma-Ray instrument (HEAO A4) on the High Energy Astronomical Observatory–1 (HEAO–1). The instrument consists of a complex of actively shielded and collimated scintillation counters, including the Low Energy Detector set from which the data reported here were...

In this paper I investigate the γ-ray spectra of AGN by summing up the intensity and the power-law fit statistic of Quasars and OVV’s and BL Lac’s separately. The spectrum of the average AGN is softer than that of the extragalactic γ-ray background. It may be that BL Lac’s, of which the average has a harder spectrum than Quasars, make up the bulk of the extragalactic background. We also find cu...

Archival XMM-Newton data on the nearby Seyfert galaxy NGC 4051, taken in relatively high and low flux states, offer a unique opportunity to explore the complexity of its X-ray spectrum. We find the hard X-ray band to be significantly affected by reflection from cold matter, which can also explain a non-varying, narrow Fe K fluorescent line. We interpret major differences between the high and lo...

Supernova remnants are likely to be the accelerators of the galactic cosmic rays. Assuming the correctness of this hypothesis, we develop a method to extract the parent cosmic ray spectrum from the VHE gamma ray flux emitted by supernova remnants (and other gamma transparent sources). We illustrate the use of this technique by applying it to the young SNR RX J1713.7-3946 which has been observed...

We perform Monte Carlo simulations of cosmic-ray induced hard X-ray emission in the Earth’s atmosphere. We find that the shape of the spectrum emergent from the atmosphere in the energy range ∼25–300 keV is determined by Compton scattering and photoabsorption and is virtually independent of the incident cosmic ray spectrum. We provide a fitting formula for the spectral intensity as a function o...

Many X-ray observations of GigaHertz Peaked Spectrum and Compact Steep Spectrum sources have been made with Chandra X-ray Observatory and XMM-Newton Observatory over the last few years. The X-ray spectra contribute the important information to the total energy distribution of the compact radio sources. In addition the spatial resolution of Chandra allows for studies of the X-ray morphology of t...

X iv :0 90 7. 18 51 v1 [ as tr oph .C O ] 1 0 Ju l 2 00 9 GRB 011211: An alternative interpretation of the optical and X-ray spectra in terms of blueshifts D. Basu Abstract The redshift of the gamma ray burst (GRB) GRB 011211 has been determined as 2.14 from several absorption lines seen in the spectrum of its optical afterglow. The spectrum of its X-ray afterglow exhibited several emission lin...

PSR 1706−44 has been observed at energies above several hundred GeV in 2000 and 2001 using the CANGAROO-II 10m telescope. Above 1TeV, the spectrum is a steep power-law, which is consistent with previous results. However, the spectral index seems to change around 1TeV and becomes much flatter at lower energies. In addition, we analyzed Chandra X-Ray Observatory (Chandra) archival data to derive ...

abstract background: coherent scattering leads to diffraction effects and especially constructive interferences. theseinterferences carry some information about the molecular structure of the tissue. as breast cancer isthe most widespread cancer in women, this project evaluated the application of small anglex-ray scattering (saxs) for differentiation between normal and cancerous breast tissues....