Related papers: X-ray Astronomical Point Sources Recognition Using…
We present preliminary results of a statistical analysis obtained with a sample of blazars observed at the Perugia Astronomical Observatory since 1992. We briefly show how these statistical results can be useful to discriminate faint…
In the latest data release from the Fermi $\gamma$-ray Space Telescope (the 4th Fermi LAT 14 yr Catalog, or 4FGL), more than 50% of the Galactic sources are yet to be identified. We observed 13 unidentified Fermi LAT sources with the…
Investigating the spatial correlation between different emissions in an extended astrophysical source can provide crucial insights into their physical connection, hence it can be the key to understand the nature of the system. The…
We discuss the possibility of identification of point-like gamma-ray sources (PGS) with small scale dark matter (DM) clumps in our Galaxy. Gamma-rays are supposed to originate from annihilation of DM particles in the clumps, where…
One of the challenges of X-ray astronomy is how to both collect large numbers of photons yet attain high angular resolution. Because X-ray telescopes utilize grazing optics, to collect more photons requires a larger acceptance angle which…
Locating sources on the sky is one of the largest challenges in gravitational wave astronomy, owing to the omni-directional nature of gravitational wave detection techniques, and the often intrinsically weak signals being observed.…
Gravitational lensing is proven to be one of the most efficient tools for studying the Universe. The spectral confirmation of such sources requires extensive calibration. This paper discusses the spectral extraction technique for the case…
Astrophysical sources outside the Milky Way, such as active galactic nuclei and star-forming galaxies, leave their imprint on the gamma-ray sky as nearly isotropic emission referred to as the Extragalactic Gamma-Ray Background (EGB). While…
We present the results of a Chandra/HST study of the point sources of the NGC 4472. We identify 144 X-ray sources, 72 with HST matches. The optical data show 1102 sources, 829 with globular cluster colors. Thirty matches are found - likely…
The European gamma-ray observatory INTEGRAL has found a group of hard X-ray sources which are highly absorbed, i.e., with column densities higher than about 10^{23}/cm^2. Here I give an overview of this class of INTEGRAL sources. The X-ray,…
We present an analysis of the X-ray spectral properties of 61 hard X-ray selected (2-8 keV) sources from the bright ($f_{2-8 keV}>10^{-14}$ \funits) {\it XMM-Newton}/2dF survey. This comprises of 9 {\it XMM-Newton} pointings in the North…
The study of unobscured active galactic nuclei (AGN) and quasars depends on the reliable decomposition of the light from the AGN point source and the extended host galaxy light. The problem is typically approached using parametric fitting…
Data from the Fermi Large Area Telescope suggests that there is an extended excess of GeV gamma-ray photons in the Inner Galaxy. Identifying potential astrophysical sources that contribute to this excess is an important step in verifying…
A large fraction of the recently discovered Galactic Very High Energy (VHE) source population remains unidentified to date. VHE gamma-ray emission traces high energy particles in these sources, but for example in case of hadronic processes…
We present a new technique called "quantile analysis" to classify spectral properties of X-ray sources with limited statistics. The quantile analysis is superior to the conventional approaches such as X-ray hardness ratio or X-ray color…
Astronomical observations typically provide three-dimensional maps, encoding the distribution of the observed flux in (1) the two angles of the celestial sphere and (2) energy/frequency. An important task regarding such maps is to…
Large-scale astronomical surveys can capture numerous images of celestial objects, including galaxies and nebulae. Analysing and processing these images can reveal intricate internal structures of these objects, allowing researchers to…
An analysis of the sensitivity of gaussian and mexican hat wavelet family filters to the detection of point sources of ultra-high energy cosmic rays was performed. A source embedded in a background was simulated and the number of events and…
(Abridged) We present the LogN-LogS and spatial distributions of X-ray point sources in seven Galactic Bulge (GB) fields within 4 deg from the Galactic Center (GC). We compare the properties of 1159 X-ray point sources discovered in our…
We examine the expected X-ray polarization properties of neutron-star X-ray sources of various types, e.g., accretion and rotation powered pulsars, magnetars, and low-mass X-ray binaries. We summarize the model calculations leading to these…