463 citations · 6.1k across the 68 of their papers we have counts for
35 papers · 1 filter
A Comprehensive X-ray Spectral Analysis of the Seyfert 1.5 NGC 3227
A. Markowitz, J. N. Reeves, I. M. George +5
We present results of a 100 ks XMM observation of the Seyfert 1.5 NGC 3227. Our best-fit broadband model to the pn spectrum consists of a moderately flat (photon index 1.57) hard X…
On the evidence for narrow, relativistically shifted X-ray lines
S. Vaughan, P. Uttley
In recent years there have been many reported detections of highly redshifted or blueshifted narrow spectral lines (both emission or absorption) in the X-ray spectra of active gala…
Line Searches in Swift X-ray Spectra
C. P. Hurkett, S. Vaughan, J. P. Osborne +14
Prior to the launch of the Swift mission several X-ray line detections were reported in Gamma Ray Burst afterglow spectra. To date, these pre-Swift era results have not been conclu…
Studying accreting black holes and neutron stars with time series: beyond the power spectrum
S. Vaughan, P. Uttley
The fluctuating brightness of cosmic X-ray sources, particularly accreting black holes and neutron star systems, has enabled enormous progress in understanding the physics of turbu…
X-ray reflection in the nearby Seyfert 2 galaxy NGC 1068
K. Pounds, S. Vaughan
We use the full broad-band XMM-Newton EPIC data to examine the X-ray spectrum of the nearby Seyfert 2 galaxy NGC 1068, previously shown to be complex with the X-ray continuum being…
An origin for short g-ray bursts unassociated with current star formation
S. D. Barthelmy, G. Chincarini, D. N. Burrows +28
Two short (<2 s) g-ray bursts (GRBs) have recently been localized and fading afterglow counterparts detected. The combination of these two results left unclear the nature of the ho…
Discovery of an Afterglow Extension of the Prompt Phase of Two Gamma Ray Bursts Observed by Swift
S. D. Barthelmy, J. K. Cannizzo, N. Gehrels +19
BAT and XRT observations of two recent well-covered GRBs observed by Swift, GRB 050315 and GRB 050319, show clearly a prompt component joining the onset of the afterglow emission.…
The dust-scattered X-ray halo around Swift GRB 050724
S. Vaughan, R. Willingale, P. Romano +12
This paper discusses the X-ray halo around the Swift gamma-ray burst GRB 050724 (z=0.258), detected by the Swift X-Ray Telescope. The halo, which forms a ring around the fading X-r…
Swift observations of the X-ray bright GRB 050315
S. Vaughan, M. R. Goad, A. P. Beardmore +30
This paper discusses Swift observations of the gamma-ray burst GRB 050315 (z=1.949) from 80 s to 10 days after the onset of the burst. The X-ray light curve displayed a steep early…
The soft X-ray blast in the apparently sub-luminous GRB 031203
D. Watson, S. A. Vaughan, R. Willingale +11
GRB031203 was a very low apparent luminosity gamma-ray burst (GRB). It was also the first GRB with a dust-scattered X-ray halo. The observation of the halo allowed us to infer the…
Detecting X-ray QPOs in Active Galaxies
S. Vaughan, P. Uttley
Since EXOSAT produced the first good quality X-ray light curves of Seyfert galaxies there have been several claims of quasi-periodic oscillations (QPOs). None of these have withsto…
Where are the X-ray QPOs in active galaxies?
S. Vaughan, P. Uttley
In this paper we address the question of whether existing X-ray observations of Seyfert galaxies are sufficiently sensitive to detect quasi-periodic oscillations (QPOs) similar to…
Rapid X-ray Variability of Seyfert 1 Galaxies
S. Vaughan, A. C. Fabian, K. Iwasawa
The rapid and seemingly random fluctuations in X-ray luminosity of Seyfert galaxies provided early support for the standard model in which Seyferts are powered by a supermassive bl…
The exceptional X-ray variability of the dwarf Seyfert nucleus NGC 4395
S. Vaughan, K. Iwasawa, A. C. Fabian +1
An analysis of the X-ray variability of the low luminosity Seyfert nucleus NGC 4395, based on a long XMM-Newton observation, is presented. The power spectrum shows a clear break fr…
The narrow-line quasar NAB 0205+024 observed with XMM-Newton
L. C. Gallo, Th. Boller, W. N. Brandt +2
The XMM-Newton observation of the narrow-line quasar NAB 0205+024 reveals three striking differences since it was last observed in the X-rays with ASCA. Firstly, the 2-10 keV power…
X-ray reflection in the NLS1 1H 0707-495
A. C. Fabian, G. Miniutti, L. Gallo +4
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…
Long-term spectral changes in the partial-covering candidate NLS1 1H 0707-495
L. C. Gallo, Y. Tanaka, Th. Boller +3
We compare two XMM-Newton observations of the Narrow-Line Seyfert 1 galaxy 1H 0707-495 separated by two years, and discuss the results in terms of the partial-covering phenomenon.…
An XMM-Newton observation of Ark 120: the X-ray spectrum of a `bare' Seyfert 1 nucleus
S. Vaughan, A. C. Fabian, D. R. Ballantyne +3
We report on a long (100 ks) XMM-Newton observation of the bright Seyfert 1 galaxy Arakelian 120. The source previously showed no signs of intrinsic reddening in its infrared-ultra…
Chandra observations of five X-ray transient galactic nuclei
S. Vaughan, R. Edelson, R. S. Warwick
We report on exploratory Chandra observations of five galactic nuclei that were found to be X-ray bright during the ROSAT all-sky survey (with L_X > 10^43 erg s^-1) but subsequentl…
A long, hard look at MCG-6-30-15 with XMM-Newton II: detailed EPIC analysis and modelling
S. Vaughan, A. C. Fabian
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 AS…
A long hard look at MCG-6-30-15 with XMM-Newton and BeppoSAX
S. Vaughan, A. C. Fabian, K. Iwasawa +1
We summarise the primary results from a 320 ks observation of the bright Seyfert 1 galaxy MCG-6-30-15 with XMM-Newton and Beppo-SAX.
XMM-Newton spectral properties of the Narrow-Line Seyfert 1 galaxy IRAS 13224--3809
Th. Boller, Y. Tanaka, A. Fabian +5
We report on the first XMM-Newton observation of the highly X-ray variable, radio-quiet, Narrow-Line Seyfert 1 galaxy IRAS 13224-3809 obtained during the guaranteed time programme…
A two-component ionized reflection model of MCG--6-30-15
D. R. Ballantyne, S. Vaughan, A. C. Fabian
Ionized reflection has often been considered as the explanation for the unusual Fe K variability observed in MCG--6-30-15. In this paper, we test this model using a 325 ks observat…
The iron line in MCG-6-30-15 from XMM-Newton: evidence for gravitational light-bending?
A. C. Fabian, S. Vaughan
The lack of variability of the broad iron line seen in the Seyfert 1 galaxy MCG-6-30-15 is studied using the EPIC pn data obtained from a 2001 observation of 325 ks, during which t…