We analyze archived Chandra and XMM-Newton X-ray observations of 536 Sloan Digital Sky Survey (SDSS) Data Release 5 (DR5) quasars (QSOs) at 1.7 ≤ z ≤ 2.7 in order to characterize the relative UV and X-ray spectral properties of QSOs that do not have broad UV absorption lines (BALs). We constrain the fraction of X-ray weak, non-BAL QSOs and find that such objects are rare; for example, sources u...

A recent re-determination of the non-thermal component of the hard X-ray to soft γ-ray emission from the Galactic ridge, using the SPI instrument on the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) Observatory, is shown to be well reproduced as inverse-Compton emission from the interstellar medium. Both cosmic-ray primary electrons and secondary electrons and positrons contribute ...

In this work, copper oxide nanoparticles have been synthesized via extractive Rosmarinus Officinalis leaves by simple and economic co-precipitation method at ambient conditions which it has used (CH3COO)2Cu+H2O individually as Cu sources. It was found that uniform copper oxide nanoparticles have been successfully produced at various temperature, namely 400, 600, and 800 0C. Powder X-ray Diffrac...

We present an accurate X-ray position of the massive globular cluster G1 by using XMM-Newton and the Hubble Space Telescope (HST). The X-ray emission of G1 has been detected recently with XMM-Newton. There are two possibilities for the origin of the X-ray emission. It can be either due to accretion of the central intermediate-mass black hole, or by ordinary low-mass X-ray binaries. The precise ...

We present a catalog of 2-10 keV ASCA Gas Imaging Spectrometer images of fields containing bright sources of GeV emission. The images cover ∼ 85% of the 95% confidence position contour for 28 of the 30 sources with > 1 GeV fluxes above 4× 10−8 ph cm−2s−1. We find an excess of hard X-ray sources with F2−10keV & 10 −12 ergs cm−2s−1 positionally coincident with unidentified sources of GeV emission...

We report on a recent Chandra ACIS-S observation of the Circinus galaxy. These observations confirm that the nuclear spectrum results from reflection of a hard X-ray continuum by “neutral” matter. The nuclear X-ray emission is extended by ∼ 60 pc in the general direction of the optical “ionization cone”. An image in the Fe Kα line has been made and shows that this emission extends up to 200 pc ...

Recently, X-ray emission lines have been observed in X-ray afterglows of several γ-ray bursts. It is a major breakthrough for understanding the nature of the progenitors. It is proposed that the X-ray emission lines can be well explained by the Geometry-Dominated models, but in these models the illuminating angle is much larger than that of the collimated jet of the γ-ray bursts(GRBs). For GRB ...

We report on a short optical monitoring programme of the narrow-line Seyfert 1 Galaxy IRAS 13224-3809. Previous X-ray observations of this object have shown persistent giant variability. The degree of variability at other wavelengths may then be used to constrain the conditions and emission processes within the nucleus. Optical variability is expected if the electron population responsible for ...

Diffuse emission from the Milky Way dominates the γ-ray sky. About 80% of the high-energy luminosity of the Milky Way comes from processes in the interstellar medium. The Galactic diffuse emission traces interactions of energetic particles, primarily protons and electrons, with the interstellar gas and radiation field, thus delivering information about cosmic-ray spectra and interstellar mass i...

We report on our analysis of the 1 Ms Chandra observation of the supernova remnant Cas A in order to localize, characterize and quantify its non-thermal X-ray emission. More specifically, we investigated whether the X-ray synchrotron emission from the inside of the remnant is from the outward shock, but projected toward the inner ring, or from the inner shell. We tackle this problem by employin...