The Ultraluminous State (2009)
Gladstone, J. C., Roberts, T. P., Done, Chris
(Abridged) We revisit the question of the nature of ULXs through a detailed investigation of their spectral shape, using the highest quality X-ray data available in the XMM-Newton public archives. We...
A Systematic Study of Variability in a Sample of Ultraluminous X-ray Sources (2009)
Heil, L. M., Vaughan, S., Roberts, T. P.
We present results from a study of short term variability in 19 archival observations by XMM-Newton of 16 Ultraluminous X-ray Sources (ULXs). Eight observations (six sources) showed intrinsic...
The ultraluminous X-ray source population of NGC 4485/4490 (2009)
Gladstone, J. C., Roberts, T. P.
We report the results of spectral and temporal variability studies of the ultraluminous X-ray sources (ULXs) contained within the interacting pair of galaxies NGC 4485/4490, combining Chandra and...
Berghea, C. T., Weaver, K. A., Colbert, E. J. M., Roberts, T. P.
To test the idea that ultraluminous X-ray sources (ULXs) in external galaxies represent a class of accreting intermediate-mass black holes (IMBHs), we have undertaken a program to identify ULXs and a...
New Hubble Space Telescope imaging of the counterparts to six ultraluminous X-ray sources (2008)
Roberts, T. P., Levan, A. J., Goad, M. R.
We report the results of new Hubble Space Telescope imaging of the positions of six ultraluminous X-ray sources (ULXs). Using images in three ACS filters we detect good candidate counterparts to four...
New insights into the X-ray properties of the nearby barred spiral galaxy NGC 1672 (2008)
Jenkins, L. P., Brandt, W. N., Colbert, E. J. M., Levan, A. J., Roberts, T. P., Ward, M. J., ...
We present some preliminary results from new Chandra and XMM-Newton X-ray observations of the nearby barred spiral galaxy NGC1672. It shows dramatic nuclear and extra-nuclear star formation activity,...
Barcons, Xavier, Carrera, Francisco J., Ceballos, María Teresa, Page, M. J., Bussons-Gordo, Javier, Corral, Amalia, ...
13 pages, 6 figures, 7 tables.-- ISI Article Identifier: 000251507500014.-- ArXiv pre-print available at: http://arxiv.org/abs/0710.0402
Barcons, X., Carrera, F. J., Ceballos, M. T., Page, M. J., Bussons-Gordo, J., Corral, A., ...
We present the XMM-Newton Medium sensitivity Survey (XMS), including a total of 318 X-ray sources found among the serendipitous content of 25 XMM-Newton target fields. The XMS comprises four largely...
Prestwich, A. H., Kilgard, R., Crowther, P. A., Carpano, S., Pollock, A. M. T., Zezas, A., ...
IC 10 X-1 is a bright (Lx=10^38 ergs/s) variable X-ray source in the local group starburst galaxy IC 10. The most plausible optical counterpart is a luminous Wolf-Rayet star, making IC 10 X-1 a rare...
X-ray observations of ultraluminous X-ray sources (2007)
Ultraluminous X-ray sources (ULXs) are amongst the most intriguing of X-ray source classes. Their extreme luminosities - greater than 10^39 erg/s in the 0.3 - 10 keV band alone - suggest either the...
An XMM-Newton view of M101 - III. Diffuse X-ray emission (2007)
Warwick, R. S., Jenkins, L. P., Read, A. M., Roberts, T. P., Owen, R. A.
We present a study of the X-ray properties of the nearby face-on Scd spiral galaxy M101 based on recent XMM-Newton observations. In this third and final paper in the present series, we focus on the...
An XMM-Newton View of M101: III - Diffuse X-ray Emission (2007)
Warwick, R.S., Jenkins, L.P., Read, A.M., Roberts, T.P., Owen, R.A.
Chandra monitoring observations of the ultraluminous X-ray source NGC 5204 X-1 (2006)
Roberts, T.P., Kilgard, R.E., Warwick, R.S., Goad, Michael R., Ward, M.J.
This is the version of the paper as archived in arXiv.org, subsequently published as Monthly Notices of the Royal Astronomical Society, 2006, 371, pp.1877-1890, available from...
Chandra monitoring observations of the ultraluminous X-ray source NGC 5204 X-1 (2006)
Roberts, T. P., Kilgard, R. E., Warwick, R. S., Goad, M. R., Ward, M. J.
We report the results of a 2-month campaign conducted with the Chandra X-ray observatory to monitor the ultraluminous X-ray source (ULX) NGC 5204 X-1. This was composed of a 50-ks observation,...
XMM-Newton observations of the brightest ultraluminous X-ray sources. (2006)
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...
The X-ray properties of the dwarf Magellanic-type galaxy NGC 55 (2006)
Stobbart, A-M., Roberts, T. P., Warwick, R. S.
We present an analysis of the X-ray properties of the Magellanic-type galaxy NGC 55 based on two contiguous XMM-Newton observations. We detect a total of 137 X-ray sources in the field of view, 42 of...
XMM-Newton observations of the brightest Ultraluminous X-ray sources (2006)
Stobbart, A-M., Roberts, T. P., Wilms, J.
We present an analysis of 13 of the best quality EPIC ULX datasets. We utilise the high signal-to-noise in these ULX spectra to investigate the best descriptions of their spectral shape in the 0.3-10...
New insights into ultraluminous X-ray sources from deep XMM-Newton observations (2006)
Roberts, T.P., Stobbart, A.M., Goad, M.R., Warwick, R.S., Wilms, J., Uttley, P., ...
The controversy over whether ultraluminous X-ray sources (ULXs) contain a new intermediate-mass class of black holes (IMBHs) remains unresolved. We present new analyses of the deepest XMM-Newton...
Goad, M.R., Roberts, T.P., Reeves, J.N., Uttley, P.
We present results from a 112-ks long look by XMM-Newton at the ultraluminous X-ray source (ULX) Holmberg II X-1 (Ho II X-1), long thought to be the one of best candidates for the missing class of...
New Hubble Space Telescope imaging of the counterparts to six ultraluminous X-ray sources (2006)
T. P. Roberts, A. J. Levan, M. R. Goad
We report the results of new Hubble Space Telescope imaging of the positions of six ultraluminous X-ray sources (ULXs). Using images in three ACS filters we detect good candidate counterparts to four...
New insights into ultraluminous X-ray sources from deep XMM-Newton observations (2005)
Roberts, T. P., Goad, M. R., Warwick, R. S., Wilms, J., Uttley, P., ...
The controversy over whether ultraluminous X-ray sources (ULXs) contain a new intermediate-mass class of black holes (IMBHs) remains unresolved. We present new analyses of the deepest XMM-Newton...
Goad, M. R., Roberts, T. P., Reeves, J. N., Uttley, P.
We present results from a 112 ks long look by XMM-Newton at the ultraluminous X-ray source (ULX) Holmberg II X-1, long thought to be the one of best candidates for the missing class of intermediate...
M74 X-1 (CXOU J013651.1+154547): An Extremely Variable Ultraluminous X-Ray Source (2005)
Krauss, M. I., Kilgard, R. E., Garcia, M. R., Roberts, T. P., Prestwich, A. H.
Ultraluminous X-ray sources (ULXs) have been described variously as the most luminous normal X-ray binaries, as hypernovae, and as "intermediate-mass" black holes with masses of hundreds to thousands...
Discovery of multiple ultraluminous X-ray sources in the galaxy KUG 0214-057 (2005)
Watson, M. G., Roberts, T. P., Akiyama, M., Ueda, Y.
We report the serendipitous discovery of several unresolved X-ray sources lying in the prominent spiral arms of the galaxy KUG 0214-057 in XMM-Newton observations. The location of these X-ray sources...
XMM-Newton EPIC observations of the ultraluminous X-ray source NGC 5204 X-1 (2004)
Roberts, T. P., Warwick, R. S., Ward, M. J., Goad, M. R., Jenkins, L. P.
We present the results of two XMM-Newton observations of the ultraluminous X-ray source (ULX) NGC 5204 X-1. The EPIC spectra are well-fit by the standard spectral model of a black-hole X-ray binary,...
An XMM-Newton view of M101 - II. Global X-ray source properties (2004)
Jenkins, L. P., Roberts, T. P., Warwick, R. S., Kilgard, R. E., Ward, M. J.
We present the global X-ray properties of the point source population in the grand-design spiral galaxy M101, as seen with XMM-Newton. 108 X-ray sources are detected within the D25 ellipse of M101,...
XMM-Newton observations of the interacting galaxy pairs NGC7771/0 and NGC2342/1 (2004)
Jenkins, L. P., Roberts, T. P., Ward, M. J., Zezas, A.
We present XMM-Newton X-ray observations of the interacting galaxy pairs NGC7771/7770 and NGC2342/2341. In NGC7771, for the first time we are able to resolve the X-ray emission into a bright central...
XMM-Newton observations of the starburst merger galaxies NGC 3256 & NGC 3310 (2004)
Jenkins, L. P., Roberts, T. P., Ward, M. J., Zezas, A.
We present XMM-Newton EPIC observations of the two nearby starburst merger galaxies NGC 3256 & NGC 3310. The broad-band (0.3-10 keV) integrated X-ray emission from both galaxies shows evidence of...
Chandra observations of five ultraluminous X-ray sources in nearby galaxies. (2004)
Roberts, T. P., Warwick, R. S., Ward, M. J., Goad, M. R.
We report the results of a programme of dual-epoch Chandra ACIS-S observations of five ultraluminous X-ray sources (ULXs) in nearby spiral galaxies. All five ULXs are detected as unresolved,...
A dipping black-hole X-ray binary candidate in NGC 55 (2004)
Stobbart, A-M., Roberts, T. P., Warwick, R. S.
XMM-Newton EPIC observations have revealed a bright point-like X-ray source in the nearby Magellanic-type galaxy NGC 55. At the distance of NGC 55, the maximum observed X-ray luminosity of the...
Chandra observations of five ultraluminous X-ray sources in nearby galaxies (2004)
Roberts, T. P., Warwick, R. S., Ward, M. J., Goad, M. R.
We report the results of a programme of dual-epoch Chandra ACIS-S observations of five ultraluminous X-ray sources (ULXs) in nearby spiral galaxies. All five ULXs are detected as unresolved,...
An XMM-Newton view of M101: I. The luminous X-ray source population (2003)
Jenkins, L. P., Roberts, T. P., Warwick, R. S., Kilgard, R. E., Ward, M. J.
We present the first results of an XMM-Newton EPIC observation of the luminous X-ray source population in the supergiant spiral galaxy M101. We have studied the properties of the fourteen most...
The unusual supernova remnant surrounding the ultraluminous X-ray source IC 342 X-1. (2003)
Roberts, T. P., Goad, M. R., Ward, M. J., Warwick, R. S.
We report the results of an observation of a large-diameter (110 pc) supernova remnant (SNR) found to encircle the position of the ultraluminous X-ray source (ULX) IC 342 X-1. The inferred initial...
Chandra reveals a black-hole X-ray binary within the ultraluminous supernova remnant MF 16 (2003)
Roberts, T. P., Colbert, E. J. M.
We present evidence, based on Chandra ACIS-S observations of the nearby spiral galaxy NGC 6946, that the extraodinary X-ray luminosity of the MF 16 supernova remnant actually arises in a black-hole...
The unusual supernova remnant surrounding the ultraluminous X-ray source IC 342 X-1 (2003)
Roberts, T. P., Goad, M. R., Ward, M. J., Warwick, R. S.
We report the results of an observation of a large diameter (110 pc) supernova remnant (SNR) found to encircle the position of the ultraluminous X-ray source (ULX) IC 342 X-1. The inferred initial...
A Chandra observation of the interacting pair of galaxies NGC 4485/NGC 4490 (2002)
Roberts, T. P., Warwick, R. S., Ward, M. J., Murray, S. S.
(Abridged) We report the results of a 20 ks Chandra ACIS-S observation of the interacting galaxy pair NGC 4485/4490. A total of 29 discrete X-ray sources are found coincident with NGC 4490, but only...
The optical counterpart of the ultra-luminous x-ray source NGC 5204 X-1 (2002)
Goad, M. R., Roberts, T. P., Knigge, C., Lira, P.
We use archival HST/WFPC2 V and I band images to show that the optical counterpart to the ultra-luminous x-ray source NGC 5204 X-1, reported by Roberts et al., is composed of two sources separated by...
Schurch, N. J., Roberts, T. P., Warwick, R. S.
We utilize the complimentary capabilities of XMM-Newton and Chandra, to conduct a detailed imaging and spectral study of the nearby galaxy NGC 4945 focussing on its nucleus and immediate surroundings...
The nature of ultraluminous X-ray sources in nearby galaxies (2002)
Roberts, T. P., Goad, M. R., Ward, M. J., Warwick, R. S., Lira, P.
The advanced capabilities of the Chandra and XMM-Newton observatories mean that, for the first time, the detailed study of the brightest point-like X-ray sources in nearby galaxies outside of the...
The optical counterpart of the ultraluminous X-ray source NGC 5204 X-1 (2002)
Goad, M.R., Roberts, T.P., Knigge, C., Lira, P.
We use archival HST/WFPC2 V and I band images to show that the optical counterpart to the ultra-luminous x-ray source NGC 5204 X-1, reported by Roberts et al., is composed of two sources separated by...
Barcons, X., Carrera, F. J., Watson, M. G., McMahon, R. G., Aschenbach, B., Freyberg, M. J., ...
We present the first results on the identifications of a medium sensitivity survey (X-ray flux limit 2 x 10(-14) erg cm(-2) s(- 1) in the 0.5-4.5 keV band) at high galactic latitude (\b\ > 20degrees)...
Barcons, X., Carrera, F. J., Watson, M. G., McMahon, R. G., Aschenbach, B., Freyberg, M. J., ...
We present the first results on the identifications of a medium sensitivity survey (X-ray flux limit 2E-14 erg/cm2/s in the 0.5-4.5 keV band) at high galactic latitude (|b|>20 deg) carried out with...
The identification of an optical counterpart to the super-Eddington X-ray source NGC 5204 X-1 (2001)
Roberts, T.P., Goad, M.R., Ward, M.J., Warwick, R.S., O'Brien, P.T., Lira, P., ...
We report the identification of a possible optical counterpart to the super-Eddington X-ray source NGC 5204 X-1. New Chandra data show that the X-ray source is point-like, with a luminosity of...
Roberts, T. P., Goad, M. R., Ward, M. J., Warwick, R. S., O'Brien, P. T., Lira, P., ...
We report the identification of a possible optical counterpart to the super-Eddington X-ray source NGC 5204 X-1. New Chandra data shows that the X-ray source is point-like, with a luminosity of 5.2 x...
Do LINER 2 galaxies harbour low-luminosity Active Galactic Nuclei? (2001)
Roberts, T. P., Schurch, N. J., Warwick, R. S.
We use ROSAT HRI spatial data and ASCA spectral measurements for a sample of seven nearby, early type spiral galaxies, to address the question of whether a low-luminosity Active Galactic Nucleus...
The identification of an optical counterpart to the super-Eddington X-ray source NGC 5204 X-1 (2001)
Roberts, T.P., Goad, Michael R., Ward, M.J., Warwick, R.S., O'Brien, Paul T., Lira, P., ...
The XMM-Newton Serendipitous Survey I. The role of XMM-Newton Survey Science Centre (2001)
Watson, M.G., Augueres, J-L., Ballet, J., Barcons, X., Barret, D., Boer, M., ...
Only the first eight authors, plus University of Leicester authors, listed. Please see published work for complete list.
Pietsch, W., Roberts, T. P., Freyberg, M. J., Read, A. M., Borozdin, K. N., Branduardi-Raymont, G., ...
The high XMM-Newton throughput allows a detailed investigation of the spatial, spectral and variability properties of the extended and point source emission of the starburst galaxy NGC 253...
A ROSAT HRI survey of bright nearby galaxies (2000)
Roberts, T. P., Warwick, R. S.
We use the extensive public archive of ROSAT High Resolution Imager (HRI) observations to carry out a statistical investigation of the X-ray properties of nearby galaxies. Specifically we focus on...
The X-ray properties of the nearby LINER galaxy, NGC 4736 (1998)
Roberts, T. P., Warwick, R. S., Ohashi, T.
NGC 4736 is a nearby Sab spiral galaxy, hosting one of the closest examples of a LINER nucleus. We have utilized recent observations by ROSAT and ASCA to characterise the X-ray properties of this...
Vexler, Z S, Ayus, J C, Roberts, T P, Fraser, C L, Kucharczyk, J, Arieff, A I
Hypoxemia is a major comorbid factor for permanent brain damage in several metabolic encephalopathies. To determine whether hypoxia impairs brain adaptation to hyponatremia, worsening brain edema, we...
Transient cerebral ischemia. Association of apoptosis induction with hypoperfusion.
Vexler, Z S, Roberts, T P, Bollen, A W, Derugin, N, Arieff, A I
Apoptosis is thought to be important in the pathogenesis of cerebral ischemia. The mechanism of apoptosis induction remains unclear but several studies suggest that it is preferentially triggered by...
Vexler, Z S, Ayus, J C, Roberts, T P, Fraser, C L, Kucharczyk, J, Arieff, A I
Hypoxemia is a major comorbid factor for permanent brain damage in several metabolic encephalopathies. To determine whether hypoxia impairs brain adaptation to hyponatremia, worsening brain edema, we...
Transient cerebral ischemia. Association of apoptosis induction with hypoperfusion.
Vexler, Z S, Roberts, T P, Bollen, A W, Derugin, N, Arieff, A I
Apoptosis is thought to be important in the pathogenesis of cerebral ischemia. The mechanism of apoptosis induction remains unclear but several studies suggest that it is preferentially triggered by...