Search Publications
X-ray narrow line region variability as a geometry probe. The case of NGC 5548
Kaastra, J. S.; Detmers, R. G.; McHardy, I. M.
We study the long time scale variability of the gas responsible for the X-ray narrow emission lines in the Seyfert 1 galaxy NGC 5548, in order to constrain the location and geometry of the emitting gas. Using X-ray spectra taken with the Chandra-LETGS and HETGS instruments and with XMM-Newton RGS and combining them with long-term monitoring observ…
Monitoring campaign of 1RXS J171824.2-402934, the low-mass X-ray binary with the lowest mass accretion rate
in't Zand, J. J. M.; Bassa, C. G.; Jonker, P. G. +2 more
An X-ray monitoring campaign with Chandra and Swift confirms that 1RXS J171824.2-402934 is accreting at the lowest rate among the known persistently accreting low-mass X-ray binaries. A thermonuclear X-ray burst was detected with the all-sky monitor on RXTE. This is only the second such burst seen in 1RXS J171824.2-402934 in more than 20 Ms of obs…
Two types of flare-associated coronal mass ejections
Michalek, G.
Aims: Here, we study the relationship between flares and CMEs.
Methods: For this purpose a statistical analysis of 578 flare-associated CMEs is presented. We considered two types of flare-associated CMEs: CMEs that follow and precede flare onset.
Results: We shown that both samples have quite different characteristics. The first type of CM…
A wave scattering theory of solar seismic power haloes
Hanasoge, S. M.
Spatial maps of the high-pass frequency filtered time-averaged root-mean-squared (RMS) Doppler velocities tend to show substantial decrements within regions of strong field and curiously, randomly distributed patches of enhancement in the vicinity. We propose that these haloes or enhancements are a consequence of magnetic-field-induced mode mixing…
On the statistical detection of propagating waves in polar coronal holes
Doyle, J. G.; Gupta, G. R.; Banerjee, D. +2 more
Context: Waves are important to the study of dynamical processes in coronal holes and the acceleration of the fast solar wind. A spectral time series was taken with the SUMER spectrometer on-board SoHO on 20 October 1996. The observations were obtained in the N iv 765 Å transition region line and the Ne viii 770 Å line of the low corona.
Aims:…
The Cartwheel galaxy with XMM-Newton
Wolter, A.; Trinchieri, G.; Crivellari, E.
Aims: The extreme environment provided by the Cartwheel ring is analyzed to study its X-ray and optical-UV properties. We compare the Cartwheel with the other members of its group and study the system as a whole in the X-ray band.
Methods: We analyze the data of the Cartwheel galaxy obtained with XMM-Newton in two different periods (December 2…
A search for massive ultra-compact dwarf galaxies in the Centaurus galaxy cluster
Infante, L.; Hilker, M.; Kissler-Patig, M. +3 more
Context: In a previous paper, we initiated a search for ultra-compact dwarf galaxies (UCDs) in the Centaurus galaxy cluster, resulting in the discovery of 27 compact objects with -12.2<M_V<-10.9 mag. Our overall survey completeness was 15-20% within 120 kpc projected clustercentric distance.
Aims: To constrain the luminosity distribution…
The role of small versus large scale magnetic topologies in global waves
Delannée, C.
Context: Coronal waves are large-scale structures that propagate through the lower corona over distances of hundreds of megameters. They are believed to be related to coronal mass ejections (CMEs). Attrill and collaborators suggested that the propagation of the wave front is due to consecutive reconnections in the quiet Sun of favourably orientate…
Normal galaxies in the XMM-Newton fields. X-rays as a star formation indicator
Georgantopoulos, I.; Rovilos, E.; Whiting, M. +4 more
Context: We use the first XMM serendipitous source catalogue (1XMM) to compile a sample of normal X-ray galaxies.
Aims: We seek to expand the database of X-ray selected normal galaxies at intermediate redshifts and examine the relation between X-ray emission and star formation for late-type systems.
Methods: The candidates are selected bas…
Suzaku observation of the Phoenix galaxy
Bianchi, S.; Guainazzi, M.; Comastri, A. +5 more
Context: In recent years, several Seyfert 2 galaxies have been discovered that change state when observed in X-rays a few years apart, switching from Compton-thin to reflection-dominated or viceversa.
Aims: We observed a member of this class of "Changing-look" sources, the Phoenix galaxy, with {Suzaku}, with the aim of better understanding the…