Search Publications
2003-2005 INTEGRAL and XMM-Newton observations of 3C 273
Walter, R.; Page, K. L.; Staubert, R. +9 more
Aims:The aim of this paper is to study the evolution of the broadband spectrum of one of the brightest and nearest quasars 3C 273.
Methods: We analyze the data obtained during quasi-simultaneous INTEGRAL and XMM-Newton monitoring of the blazar 3C 273 in 2003-2005 in the UV, X-ray and soft γ-ray bands and study the results in the context of the…
Water vapor and silicon monoxide maser observations in the protoplanetary nebula OH 231.8+4.2
Sánchez Contreras, C.; Alcolea, J.; Bujarrabal, V. +2 more
Context: OH 231.8+4.2 is a well studied preplanetary nebula (pPN) around a binary stellar system that shows a remarkable bipolar outflow.
Aims: To study the structure and kinematics of the inner 10-80 AU nebular regions probed by SiO and H2O maser emission, where the agents of wind collimation are expected to operate, in order to gain insights…
XMM-Newton observations of the Lockman Hole. V. Time variability of the brightest AGN
Page, M. J.; Barcons, X.; Fabian, A. C. +4 more
This paper presents the results of a study of X-ray spectral and flux variability on time scales from months to years, of the 123 brightest objects (including 46 type-1 AGN and 28 type-2 AGN) detected with XMM-Newton in the Lockman Hole field. We detected flux variability with a significance ≥3σ in ~50% of the objects, including 68 ± 11% and 48 ± …
Five years of SGR 1900+14 observations with BeppoSAX
Tiengo, A.; Mereghetti, S.; Sidoli, L. +3 more
We present a systematic analysis of all the BeppoSAX data of the soft gamma-ray repeater SGR 1900+14: these observations allowed us to study the long term properties of the source quiescent emission. In the observation carried out before the 1998 giant flare the spectrum in the 0.8-10 keV energy range was harder and there was evidence for a 20-150…
XMM-Newton observation of the deep minimum state of PG 2112+059. A spectrum dominated by reflection from the accretion disk?
Clavel, J.; Guainazzi, M.; Schartel, N. +5 more
Context: Highly ionised absorbers and the frequent occurrence of relativistically broad iron fluorescence lines characterize the 0.2-10 keV spectra of (soft) X-ray weak quasars.
Aims: We constrain the physical conditions of the absorber and the broad iron line of the X-ray weak quasar
Photospheric flows around a quiescent filament
Bommier, V.; Schmieder, B.; Rondi, S. +7 more
Context: The horizontal photospheric flows below and around a filament are one of the components in the formation and evolution of filaments. Few studies exist because they require multiwalength time sequences at high spatial resolution.
Aims: Our objective is to measure the horizontal photospheric flows associated with the evolution and erupt…
Interaction of magnetic field systems leading to an X1.7 flare due to large-scale flux tube emergence
Bommier, V.; Schmieder, B.; Li, H. +1 more
Aims:The aim of this paper is to understand the magnetic configuration and evolution of an active region, which permitted an X1.7 flare to be observed during the decaying phase of a long-duration X1.5 flare on 2005 September 13.
Methods: We performed a multi-wavelength analysis using data from space-borne (Solar and Heliospheric Observatory (S…
The velocity structure of moving magnetic feature pairs around sunspots: support for the U-loop model
Woch, J.; Solanki, S. K.; Zhang, J. +1 more
Context: Moving magnetic feature (MMF) pairs are among the most significant fine-scale structures around sunspots. Several models have been proposed to interpret the origin and evolution of MMF pairs. These models provide important clues to understanding MMF pairs.
Aims: We present an analysis of the velocity structure of MMF pairs in order to…
Optical colours of AGN in the extended Chandra deep field South: obscured black holes in early type galaxies
Georgantopoulos, I.; Rovilos, E.
We investigate the optical colours of X-ray sources from the Extended Chandra Deep Field South (ECDFS) using photometry from the COMBO-17 survey, aiming to explore AGN - galaxy feedback models. The X-ray sources populate both the “blue” and the “red sequence” on the colour-magnitude diagram. However, sources in the “red sequence” appear systematic…
Are supergranule sizes anti-correlated with magnetic activity?
Meunier, N.; Roudier, T.; Tkaczuk, R.
Context: The variation of supergranule cell sizes with the magnetic environment is still controversial.
Aims: We study this relation in detail to understand the discrepancies observed between previous results.
Methods: We determine the cell size using divergence of horizontal flows derived from local correlation tracking of intensity maps …