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CIAO: Chandra's data analysis system
The CIAO (Chandra Interactive Analysis of Observations) software package was first released in 1999 following the launch of the Chandra X-ray Observatory and is used by astronomers across the world
A huge reservoir of ionized gas around the Milky Way: Accounting for the Missing Mass?
Most of the baryons from galaxies have been "missing" and several studies have attempted to map the circumgalactic medium (CGM) of galaxies in their quest. We report on X-ray observations made with
Chandra Discovery of a Tree in the X-Ray Forest toward PKS 2155–304: The Local Filament?
We present the first X-ray detection of resonant absorption from warm/hot local gas either in our Galaxy, or in the intergalactic space surrounding our Galaxy, along the line of sight toward the
The Compact, Conical, Accretion-Disk Warm Absorber of the Seyfert 1 Galaxy NGC?4051 and Its Implications for IGM-Galaxy Feedback Processes
Using a 100 ks XMM-Newton exposure of NGC 4051, we show that the time evolution of the ionization state of the X-ray absorbers in response to the rapid and highly variable X-ray continuum constrains
The Hot and Energetic Universe: A White Paper presenting the science theme motivating the Athena+ mission
This White Paper, submitted to the recent ESA call for science themes to define its future large missions, advocates the need for a transformational leap in our understanding of two key questions in
Ubiquitous Variability of X-Ray-absorbing Column Densities in Seyfert 2 Galaxies
We present a study of the variations in the absorbing column density of 25 X-ray-defined Seyfert 2 galaxies, as inferred from hard X-ray observations, on timescales from months to several years. We
Testing Comptonisation models using BeppoSAX observations of Seyfert 1 galaxies
We have used realistic Comptonization models to fit high quality BeppoSAX data of 6 Seyfert galaxies. Our main effort was to adopt a Comptonization model taking into account the anisotropy of the
Is RX J1856.5-3754 a Quark Star?
Deep Chandra Low Energy Transmission Grating and High Resolution Camera spectroscopic observations of the isolated neutron star candidate RX J1856.5-3754 have been analyzed to search for metallic and
The WISSH Quasars Project III. X-ray properties of hyper-luminous quasars
We perform a survey of the X-ray properties of 41 objects from the WISE/SDSS selected Hyper-luminous (WISSH) quasars sample, composed by 86 broad-line quasars (QSOs) with bolometric luminosity