Search Publications
The spectral energy distribution of PKS 2004-447: a compact steep-spectrum source and possible radio-loud narrow-line Seyfert 1 galaxy
Kataoka, J.; Boller, Th.; Welsh, W. F. +10 more
An investigation of the spectral energy distribution (SED) of the compact steep-spectrum (CSS) source and possible radio-loud narrow-line Seyfert 1 galaxy (NLS1), PKS 2004-447, is presented. Five out of six well-studied radio-loud NLS1 share this dual classification [optically defined as an NLS1 with radio definition of a CSS or gigahertz-peaked s…
A deep XMM-Newton observation of the ultraluminous X-ray source Holmberg II X-1: the case against a 1000-Msolar black hole
Uttley, P.; Reeves, J. N.; Roberts, T. P. +1 more
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 intermediate-mass black holes (IMBHs). Our data comprises the first high-quality XMM-Newton/RGS (reflection grating spectrometer) spectrum of an ULX, an…
Spectral-timing evidence for a very high state in the narrow-line Seyfert 1 Ark 564
Papadakis, I. E.; Uttley, P.; Arévalo, P. +2 more
We use a 100ks long XMM-Newton observation of the narrow-line Seyfert 1 galaxy Ark 564 and combine it with the month-long monitoring of the same source produced by ASCA, to calculate the phase lags and coherence between different energy bands, over frequencies from ~10-6 to 10-3Hz. This is the widest frequency range for which…
On the weakness of disc models in bright ULXs
Soria, R.; Gonçalves, A. C.
It is sometimes suggested that phenomenological power law plus cool disc-blackbody models represent the simplest, most robust interpretation of the X-ray spectra of bright ultraluminous X-ray sources (ULXs); this has been taken as evidence for the presence of intermediate-mass black holes (BHs) (M ~ 103Msolar) in those source…
Unveiling the thermal and magnetic map of neutron star surfaces though their X-ray emission: method and light-curve analysis
Turolla, Roberto; Zane, Silvia
Recent Chandra and XMM-Newton observations of a number of X-ray `dim' pulsating neutron stars have revealed quite unexpected features in the emission from these sources. Their soft thermal spectrum, believed to originate directly from the star surface, shows evidence for a phase-varying absorption line at some hundred eVs. The pulse modulation is …
A weak lensing estimate from GEMS of the virial to stellar mass ratio in massive galaxies to z ~ 0.8
Bell, Eric F.; Wisotzki, Lutz; Wolf, Christian +14 more
We present constraints on the evolution of the virial to stellar mass ratio of galaxies with high stellar masses in the redshift range 0.2 < z < 0.8, by comparing weak lensing measurements of virial mass Mvir with estimates of stellar mass Mstar. For a complete sample of galaxies with log(Mstar/Msolar
Constraints on Type Ia supernova progenitor time delays from high-z supernovae and the star formation history
Wolf, C.; Förster, F.; Podsiadlowski, Ph. +1 more
We re-assess the question of a systematic time delay between the formation of the progenitor and its explosion in a Type Ia supernova (SN Ia) using the Hubble Higher-z Supernova Search sample. While a previous analysis indicated a significant time delay, with a most likely value of 3.4 Gyr, effectively ruling out all previously proposed progenitor…
The XMM Large-Scale Structure survey: a well-controlled X-ray cluster sample over the D1 CFHTLS area
Maccagni, D.; Chiappetti, L.; Altieri, B. +24 more
We present the XMM Large-Scale Structure Survey (XMM-LSS) cluster catalogue corresponding to the Canada-France-Hawaii Telescope Legacy Survey D1 area. The list contains 13 spectroscopically confirmed, X-ray selected galaxy clusters over 0.8deg2 to a redshift of unity and so constitutes the highest density sample of clusters to date. Clu…
Enrichment in the Centaurus cluster of galaxies
Fabian, A. C.; Sanders, J. S.
We perform a detailed spatially resolved, spectroscopic, analysis of the core of the Centaurus cluster of galaxies using a deep Chandra X-ray observation and XMM-Newton data. The Centaurus cluster core has particularly high metallicity, up to twice the solar values, and we measure the abundances of Fe, O, Ne, Mg, Si, S, Ar, Ca and Ni. We map the d…
Confirming the high velocity outflow in PG1211+143
Page, K. L.; Pounds, K. A.
An XMM-Newton observation of the bright quasi-stellar object PG1211+143 was previously reported to show evidence for a massive, energetic outflow, with an outflow velocity of v ~ 0.1c based on the identification of blueshifted absorption lines detected in both EPIC and Reflection Grating Spectrometer (RGS) spectra. Subsequently, an order of magnit…