References of "Risaliti, G"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailThe XXL survey: First results and future
Pierre, M.; Adami, C.; Birkinshaw, M. et al

in Astronomische Nachrichten (2017), 338

The XXL survey currently covers two 25 sq. deg. patches with XMM observations of ~10ks. We summarise the scientific results associated with the first release of the XXL data set, that occurred mid 2016 ... [more ▼]

The XXL survey currently covers two 25 sq. deg. patches with XMM observations of ~10ks. We summarise the scientific results associated with the first release of the XXL data set, that occurred mid 2016. We review several arguments for increasing the survey depth to 40 ks during the next decade of XMM operations. X-ray (z<2) cluster, (z<4) AGN and cosmic background survey science will then benefit from an extraordinary data reservoir. This, combined with deep multi-$\lambda$ observations, will lead to solid standalone cosmological constraints and provide a wealth of information on the formation and evolution of AGN, clusters and the X-ray background. In particular, it will offer a unique opportunity to pinpoint the z>1 cluster density. It will eventually constitute a reference study and an ideal calibration field for the upcoming eROSITA and Euclid missions. [less ▲]

Detailed reference viewed: 23 (2 ULiège)
Full Text
See detailShowing variability in AGN by principal component analysis (PCA)
Agis-Gonzalez, Beatriz ULiege; Risaliti, G.; Miniutti, G.

Poster (2015, July 01)

Principal component analysis (PCA) is a powerful tool for studying spectral variability. The technique consists of splitting relatively long exposures into a series of shorter-exposure spectra, and ... [more ▼]

Principal component analysis (PCA) is a powerful tool for studying spectral variability. The technique consists of splitting relatively long exposures into a series of shorter-exposure spectra, and returns a minimal set of independent spectral shapes representing the variable components. If the initial spectra are made up of a linear sum of variable, uncorrelated and spectrally distinct physical components, the PCA will return detailed spectra of each variable component in a model independent way. This is a big advantage to analyze and study the origin of the observed variability without being limited by available spectral models (and by the systematic uncertainties that are inherent to any spectral analysis). We are applying the PCA analysis to several XMM-Newton observations from the brightest and most variable AGN with sufficiently long exposures. We shall present the most interesting results obtained so far. [less ▲]

Detailed reference viewed: 10 (1 ULiège)
Full Text
Peer Reviewed
See detailBlack hole spin and size of the X-ray-emitting region(s) in the Seyfert 1.5 galaxy ESO 362-G18
Agis-Gonzalez, Beatriz ULiege; Miniutti, G.; Kara, E. et al

in Monthly Notices of the Royal Astronomical Society (2014), 443

We report results from multi-epoch X-ray observations of the Seyfert 1.5 galaxy ESO 362-G18 performed between 2005 November and 2010 June. ESO 362-G18 generally exhibits the typical X-ray spectrum of type ... [more ▼]

We report results from multi-epoch X-ray observations of the Seyfert 1.5 galaxy ESO 362-G18 performed between 2005 November and 2010 June. ESO 362-G18 generally exhibits the typical X-ray spectrum of type 1 active galactic nuclei. A disc-reflection component accounts for broad residuals in the iron K band and above 10 keV, as well as for a significant soft excess. From our best-fitting reflection model, we measure a black hole spin a ≥ 0.92 at the 99.99 per cent confidence level. ESO 362-G18 is also (typically) mildly absorbed by a column of neutral gas. The absorber is variable and one observation, performed ˜2 months after a typical mildly absorbed one, is heavily absorbed by a cold column density of ˜ 3-4 × 10[SUP]23[/SUP] cm[SUP]-2[/SUP], nearly two orders of magnitude higher than that during any other observation. UV variability between the heavily absorbed observation and the others suggests that the absorber can be identified with a dusty, clumpy torus. The absorption variability time-scale enables us to locate the X-ray-emitting region within the innermost ˜50 gravitational radii. Such result holds not only for the X-ray continuum, but also for the soft excess. [less ▲]

Detailed reference viewed: 11 (1 ULiège)