Search Publications
An explanation for the soft X-ray excess in active galactic nuclei
Fabian, A. C.; Ross, R. R.; Gallo, L. +1 more
We present a large sample of type 1 active galactic nuclei (AGN) spectra taken with XMM-Newton, and fit them with both the conventional model (a power law and blackbody) and the relativistically blurred photoionized disc reflection model of Ross & Fabian. We find that the disc reflection model is a better fit. The disc reflection model success…
XMM-Newton observations of the brightest ultraluminous X-ray sources
Wilms, J.; Roberts, T. P.; Stobbart, A. -M.
We present an analysis of 13 of the best quality ultraluminous X-ray source (ULX) data sets available from XMM-Newton European Photon Imaging Camera (EPIC) observations. We utilize the high signal-to-noise in these ULX spectra to investigate the best descriptions of their spectral shape in the 0.3-10keV range. Simple models of an absorbed power la…
Constraints on sterile neutrinos as dark matter candidates from the diffuse X-ray background
Neronov, A.; Boyarsky, A.; Ruchayskiy, O. +1 more
Sterile neutrinos with masses in the kilo-electronvolt range are viable candidates for the warm dark matter. We analyse existing data for the extragalactic diffuse X-ray background for signatures of sterile neutrino decay. The absence of a detectable signal within current uncertainties of background measurements puts model-independent constraints …
Adaptive binning of X-ray data with weighted Voronoi tessellations
Statler, Thomas S.; Diehl, Steven
We present a technique to adaptively bin sparse data using weighted Voronoi tessellations (WVTs). WVT binning is a generalization of the Voronoi binning algorithm by Cappellari & Copin, developed for integral field spectroscopy. WVT binning is applicable to many types of data and creates unbiased binning structures with compact bins that do no…
The X-ray nuclei of intermediate-redshift radio sources
Hardcastle, M. J.; Croston, J. H.; Evans, D. A.
We present a Chandra and XMM-Newton spectral analysis of the nuclei of the radio galaxies and radio-loud quasars from the 3CRR sample in the redshift range 0.1 < z < 0.5. In the range of radio luminosity sampled by these objects, mostly Fanaroff-Riley type IIs (FR IIs), it has been clear for some time that a population of radio galaxies [low…
Supernova remnant energetics and magnetars: no evidence in favour of millisecond proto-neutron stars
Vink, Jacco; Kuiper, Lucien
It is generally accepted that anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs) are magnetars, i.e. neutron stars with extremely high surface magnetic fields (B > 1014 G). The origin of these high magnetic fields is uncertain, but a popular hypothesis is that magnetars are born with an initial spin period not much ex…
An XMM-Newton view of the young open cluster NGC 6231 - II. The OB star population
Gosset, E.; Nazé, Y.; Rauw, G. +2 more
In this second paper of the series, we pursue the analysis of the 180-ks XMM-Newton campaign towards the young open cluster NGC 6231 and we focus on its rich OB star population. We present a literature-based census of the OB stars in the field of view with more than one hundred objects, among which 30 per cent can be associated with an X-ray sourc…
XMM-Newton study of the complex and variable spectrum of NGC 4051
Maraschi, L.; Cappi, M.; Ponti, G. +3 more
We study the X-ray spectral variability of the narrow line Seyfert 1 galaxy NGC 4051 as observed during two XMM-Newton observations. To gain insight on the general behaviour, we first apply model-independent techniques such as rms spectra and flux-flux plots. We then perform time-resolved spectral analysis by splitting the observations into 68 spe…
Investigating the nature of narrow-line Seyfert 1 galaxies with high-energy spectral complexity
Gallo, L. C.
With the commissioning of XMM-Newton came the discovery of 2.5-10keV spectral complexity in some narrow-line Seyfert 1 galaxies (NLS1). This high-energy complexity can be manifested as sharp, spectral drops or gradual curvature in the spectrum. Models which are normally considered are ionized reflection and partial covering. In this work, we defin…
The XMM Large-Scale Structure survey: the X-ray pipeline and survey selection function
Chiappetti, L.; Altieri, B.; Valtchanov, I. +11 more
We present the X-ray pipeline developed for the purpose of the cluster search in the XMM Large-Scale Structure (XMM-LSS) survey. It is based on a two-stage procedure via a dedicated handling of the Poisson nature of the signal: (i) source detection on multiresolution wavelet filtered images and (ii) source analysis by means of a maximum likelihood…