Search Publications
Is the soft excess in active galactic nuclei real?
Done, Chris; Gierliński, Marek
We systematically analyse all publicly available XMM-Newton spectra of radio-quiet PG quasars. The soft X-ray excess in these objects is well modelled by an additional, cool, Compton scattering region. However, the remarkably constant temperature derived for this component over the whole sample requires a puzzling fine tuning of the parameters. In…
Comparing the temperatures of galaxy clusters from hydrodynamical N-body simulations to Chandra and XMM-Newton observations
Rasia, E.; Mazzotta, P.; Moscardini, L. +1 more
Theoretical studies of the physical processes guiding the formation and evolution of galaxies and galaxy clusters in the X-ray region are mainly based on the results of numerical hydrodynamical N-body simulations, which in turn are often directly compared with X-ray observations. Although trivial in principle, these comparisons are not always simp…
Combined long and short time-scale X-ray variability of NGC 4051 with RXTE and XMM-Newton
Papadakis, I. E.; Page, M. J.; Uttley, P. +2 more
We present a comprehensive examination of the X-ray variability of the narrow-line Seyfert 1 (NLS1) galaxy NGC 4051, one of the most variable active galactic nuclei (AGN) in the sky. We combine over 6.5 years of frequent monitoring observations by RXTE with a >100-ks continuous observation by XMM-Newton and so present an overall 2-10 keV power …
A long hard look at MCG-6-30-15 with XMM-Newton- II. Detailed EPIC analysis and modelling
Vaughan, S.; Fabian, A. C.
The bright Seyfert 1 galaxy MCG-6-30-15 has provided some of the best evidence to date for the existence of supermassive black holes in active galactic nuclei. Observations with ASCA revealed an X-ray iron line profile shaped by strong Doppler and gravitational effects. In this paper the shape of the iron line, its variability characteristics and …
High-resolution imaging of the HeII λ4686 emission line nebula associated with the ultraluminous X-ray source in Holmberg II
Zezas, A.; Kaaret, P.; Ward, M. J.
We present Hubble Space Telescope images of the HeIII region surrounding the bright X-ray source in the dwarf irregular galaxy Holmberg II. Using Chandra, we find a position for the X-ray source of (J2000) with an uncertainty of 0.6 arcsec. We identify a bright, point-like optical counterpart centred in the nebula with the X-ray source. The optica…
X-ray reflection in the narrow-line Seyfert 1 galaxy 1H 0707-495
Vaughan, S.; Fabian, A. C.; Boller, Th. +4 more
We apply a reflection-dominated model to the second XMM-Newton observation of the narrow-line Seyfert 1 galaxy 1H 0707-495. As in the first XMM-Newton observation, a sharp spectral drop is detected with energy that has shifted from 7 to 7.5 keV in two years. The drop is interpreted in terms of relativistically blurred ionized reflection from the a…
Evidence for a multizone warm absorber in the XMM-Newton spectrum of Markarian 304
Guainazzi, M.; Schartel, N.; Rodríguez-Pascual, P. M. +3 more
We present a XMM-Newton observation of Markarian 304, a Seyfert 1 galaxy at z= 0.066. The EPIC data show that MKN 304 is affected by heavy (NH~ 1023 cm-2) obscuration arising from ionized gas. A two-phase warm absorber provides an adequate parametrization of this gas. The ionization parameter of the two components …
XMM-Newton observations of the Perseus cluster - II. Evidence for gas motions in the core
Böhringer, H.; Sunyaev, R.; Churazov, E. +2 more
The 5-9 keV spectrum of the inner ~100 kpc of the Perseus cluster measured by XMM-Newton can be well described by an optically thin plasma emission model as predicted by the APEC code, without any need for invoking a strong Ni overabundance or the effects of resonant scattering. For the strongest 6.7-keV line of He-like iron, the optical depth of …
An X-ray Baldwin effect for the narrow Fe Kα lines observed in active galactic nuclei
O'Brien, P. T.; Reeves, J. N.; Page, K. L. +1 more
The majority of active galactic nuclei (AGN) observed by XMM-Newton reveal narrow Fe Kα lines at ~6.4 keV, due to emission from cold (neutral) material. There is an X-ray Baldwin effect in type I AGN, in that the equivalent width (EW) of the line decreases with increasing luminosity, with weighted linear regression giving EW~L-0.17+/-0.08
Flux and energy modulation of redshifted iron emission in NGC 3516: implications for the black hole mass
Iwasawa, K.; Fabian, A. C.; Miniutti, G.
We report on the tentative detection of the modulation of a transient, redshifted Fe Kα emission feature in the X-ray spectrum of the Seyfert galaxy NGC 3516. The detection of the spectral feature at 6.1 keV, in addition to a stable 6.4-keV line, has been reported previously. We find, on reanalysing the XMM-Newton data, that the feature varies sys…