Search Publications
Intrinsic disc emission and the soft X-ray excess in active galactic nuclei
Done, Chris; Ward, M.; Jin, C. +2 more
Narrow-line Seyfert 1 (NLS1) galaxies have low-mass black holes and mass accretion rates close to (or exceeding) Eddington, so a standard blackbody accretion disc should peak in the extreme ultraviolet. However, the lack of true absorption opacity in the disc means that the emission is better approximated by a colour temperature corrected blackbod…
Supernova remnants: the X-ray perspective
Vink, Jacco
Supernova remnants are beautiful astronomical objects that are also of high scientific interest, because they provide insights into supernova explosion mechanisms, and because they are the likely sources of Galactic cosmic rays. X-ray observations are an important means to study these objects. And in particular the advances made in X-ray imaging s…
Ubiquitous equatorial accretion disc winds in black hole soft states
Ponti, G.; Fender, R. P.; Neilsen, J. +3 more
High-resolution spectra of Galactic black holes (GBHs) reveal the presence of highly ionized absorbers. In one GBH, accreting close to the Eddington limit for more than a decade, a powerful accretion disc wind is observed to be present in softer X-ray states and it has been suggested that it can carry away enough mass and energy to quench the radi…
Using the Bright Ultrahard XMM-Newton survey to define an IR selection of luminous AGN based on WISE colours
Stern, D.; Barcons, X.; Blain, A. +7 more
We present a highly complete and reliable mid-infrared (MIR) colour selection of luminous active galactic nucleus (AGN) candidates using the 3.4, 4.6 and 12 µm bands of the Wide-field Infrared Survey Explorer (WISE) survey. The MIR colour wedge was defined using the wide-angle Bright Ultrahard XMM-Newton survey (BUXS), one of the largest com…
Understanding Dual Active Galactic Nucleus Activation in the nearby Universe
Koss, Michael; Veilleux, Sylvain; Mushotzky, Richard +3 more
We study the fraction of dual active galactic nuclei (AGNs) in a sample of 167 nearby (z < 0.05), moderate-luminosity, ultra-hard X-ray-selected AGNs from the all-sky Swift Burst Alert Telescope (BAT) survey. Combining new Chandra and Gemini observations together with optical and X-ray observations, we find that the dual AGN frequency at scales…
CAIXA: a catalogue of AGN in the XMM-Newton archive. III. Excess variance analysis
Bianchi, S.; Ponti, G.; Guainazzi, M. +4 more
Context. We report on the results of the first XMM-Newton systematic "excess variance" study of all the radio quiet, X-ray un-obscured AGN. The entire sample consist of 161 sources observed by XMM-Newton for more than 10 ks in pointed observations, which is the largest sample used so far to study AGN X-ray variability on time scales less than a da…
Using the Fundamental Plane of black hole activity to distinguish X-ray processes from weakly accreting black holes
Anderson, Scott F.; Plotkin, Richard M.; Markoff, Sera +2 more
The Fundamental Plane of black hole activity is a relation between X-ray luminosity, radio luminosity and black hole mass for hard-state Galactic black holes and their supermassive analogues. The Fundamental Plane suggests that, at low-accretion rates, the physical processes regulating the conversion of an accretion flow into radiative energy coul…
X-ray variability of 104 active galactic nuclei. XMM-Newton power-spectrum density profiles
Vaughan, S.; González-Martín, O.
Context. Active galactic nuclei (AGN), powered by accretion onto supermassive black holes (SMBHs), are thought to be scaled up versions of Galactic black hole X-ray binaries (BH-XRBs). In the past few years evidence of such correspondence include similarities in the broadband shape of the X-ray variability power spectra, with characteristic bend t…
Evidence for ultrafast outflows in radio-quiet AGNs - III. Location and energetics
Cappi, M.; Tombesi, F.; Reeves, J. N. +1 more
Using the results of a previous X-ray photoionization modelling of blueshifted Fe K absorption lines on a sample of 42 local radio-quiet AGNs observed with XMM-Newton, in this Letter we estimate the location and energetics of the associated ultrafast outflows (UFOs). Due to significant uncertainties, we are essentially able to place only lower/upp…
X-ray surface brightness and gas density fluctuations in the Coma cluster
Böhringer, H.; Sunyaev, R.; Churazov, E. +6 more
X-ray surface brightness fluctuations in the core (650 × 650 kpc) region of the Coma cluster observed with XMM-Newton and Chandra are analysed using a 2D power spectrum approach. The resulting 2D spectra are converted to 3D power spectra of gas density fluctuations. Our independent analyses of the XMM-Newton and Chandra observations are in excelle…