Search Publications
The messy environment of Mrk 6
Schurch, N. J.; Warwick, R. S.; Griffiths, R. E.
In recent years it has become clear that understanding the absorption present in active galactic nuclei (AGN) is essential given its bearing on unification models. We present the most recent XMM-Newton observation of Mrk 6, with the goal of understanding the nature and origin of the complex absorption intrinsic to this source. X-ray spectral fitti…
Kinematics of O-B5 giants
Branham, Richard L.
To study the kinematics of O-B5 giant stars (luminosity class III), 290 non-Gould belt stars with proper motions taken from the Hipparcos catalogue are used, of which 107 have radial velocities taken from other sources. Semidefinite programming solves for the kinematical parameters and the coefficients of the velocity ellipsoid. The condition that…
The colour-magnitude relations of ClJ1226.9+3332, a massive cluster of galaxies at z = 0.89
Ebeling, H.; Jones, L. R.; Donovan, D. +2 more
The colour-magnitude relations (CMRs) of one of the most massive (~1015Msolar), high-redshift (z = 0.89) clusters of galaxies known have been studied. Photometry has been measured in the V, R, I, z, F606W, F814W, J and K bands to a depth of K ~ 20.5 = K* + 2.5 and spectroscopy confirms 27 K-band selected galaxies as members o…
A ultraluminous X-ray source associated with a cloud collision in M99
Soria, Roberto; Wong, Diane Sonya
The Sc galaxy M99 in the Virgo Cluster has been strongly affected by tidal interactions and recent close encounters, responsible for an asymmetric spiral pattern and a high star formation rate. Our XMM-Newton study shows that the inner disc is dominated by hot plasma at kT ~ 0.30 keV, with a total X-ray luminosity of ~1041ergs-1
The Serendipitous XMM-Newton Cluster Athens Survey (SEXCLAS): sample selection and the cluster logN-logS
Georgakakis, A.; Georgantopoulos, I.; Plionis, M. +4 more
In this paper we serendipitously identify X-ray cluster candidates using XMM-Newton archival observations complemented by five-band optical photometric follow-up observations (r~ 23 mag) as part of the X-ray Identification (XID) programme. Our sample covers an area of ~2.1 deg2 (15 XMM-Newton fields) and comprises a total of 21 (19 sere…
X-ray spectral variations of U Gem from quiescence to outburst
Göǧüş, E.; Güver, T.; Uluyazı, C. +1 more
In this paper, we report the discovery of a high-energy component of the X-ray spectra of U Gem, which can be observed while the source is in outburst. We used Chandra and XMM-Newton observations to compare the quiescence and outburst X-ray spectra of the source. The additional component may be the result of the reflection of X-rays emitted from a…
Red active galactic nuclei in XMM-Newton/Sloan Digital Sky Survey fields
Georgantopoulos, I.; Akylas, A.; Georgakakis, A. E.
In this paper we combine archival and proprietary XMM-Newton observations (about 5deg2) that overlap with the Sloan Digital Sky Survey to explore the nature of the moderate-z X-ray population. We focus on X-ray sources with optically red colours (g - r > 0.4), which we argue are important for understanding the origin of the X-ray bac…
XMM-Newton discovery of the X-ray transient XMMU J181227.8-181234 in the Galactic plane
Cackett, Edward M.; Wijnands, Rudy; Remillard, Ron
We report the discovery of an X-ray transient, observed in outburst with XMM-Newton on 2003 March 20, and with position (J2000, approximate positional error 2arcsec). No known source is present at this position and the source was not detected during published ROSAT or ASCA observations of that region. However, the source may be associated with 1H1…
The infrared void in the Lupus dark clouds revisited: a polarimetric approach
Franco, G. A. P.; Alves, F. O.
The results of B-band CCD imaging linear polarimetry obtained for stars from the Hipparcos catalogue are used to re-examine the distribution of the local interstellar medium towards the IRAS 100-µm emission void in the Lupus dark clouds. The analysis of the obtained parallax-polarization diagram assigns to the dark cloud Lupus1 a distance be…
X-rays from the radio-quiet quasar PG 1407+265: relativistic jet or accretion disc emission?
Gallo, L. C.
We present two XMM-Newton observations of the luminous (Lx > 1046ergs-1), radio-quiet quasar PG 1407+265, separated by 11 months. The data indicate two distinct states: a highly variable, bright state (first epoch); and a quiescent, low-flux one (second epoch). During the low-flux state the spectrum is consisten…