Search Publications
Ensemble X-ray variability of active galactic nuclei. II. Excess variance and updated structure function
Paolillo, M.; Middei, R.; Vagnetti, F. +2 more
Context. Most investigations of the X-ray variability of active galactic nuclei (AGN) have been concentrated on the detailed analyses of individual, nearby sources. A relatively small number of studies have treated the ensemble behaviour of the more general AGN population in wider regions of the luminosity-redshift plane.
Aims: We want to det…
Dust particle flux and size distribution in the coma of 67P/Churyumov-Gerasimenko measured in situ by the COSIMA instrument on board Rosetta
Altobelli, Nicolas; Langevin, Yves; Fischer, Henning +14 more
Context. The COmetary Secondary Ion Mass Analyzer (COSIMA) on board Rosetta is dedicated to the collection and compositional analysis of the dust particles in the coma of 67P/Churyumov-Gerasimenko (67P).
Aims: Investigation of the physical properties of the dust particles collected along the comet trajectory around the Sun starting at a helio…
Tracing extended low-velocity shocks through SiO emission. Case study of the W43-MM1 ridge
Hill, T.; Schneider, N.; Maury, A. +8 more
Aims: Previous literature suggests that the densest structures in the interstellar medium form through colliding flows, but patent evidence of this process is still missing. Recent literature proposes using SiO line emission to trace low-velocity shocks associated with cloud formation through collision. In this paper we investigate the bright…
Density diagnostics derived from the O iv and S iv intercombination lines observed by IRIS
Mason, H. E.; Del Zanna, G.; Reeves, K. K. +3 more
The intensity of the O iv 2s2 2p 2P-2s2p24P and S iv 3 s2 3p 2P-3s 3p24 P intercombination lines around 1400 Å observed with the Interface Region Imaging Spectrograph (IRIS) provide a useful tool to diagnose the electron number density (Ne) in the so…
Fan-shaped jets above the light bridge of a sunspot driven by reconnection
Rouppe van der Voort, Luc; Leenaarts, Jorrit; Robustini, Carolina +1 more
We report on a fan-shaped set of high-speed jets above a strongly magnetized light bridge (LB) of a sunspot observed in the Hα line. We study the origin, dynamics, and thermal properties of the jets using high-resolution imaging spectroscopy in Hα from the Swedish 1m Solar Telescope and data from the Solar Dynamics Observatory and Hinode. The Hα j…
Measuring the stellar wind parameters in IGR J17544-2619 and Vela X-1 constrains the accretion physics in supergiant fast X-ray transient and classical supergiant X-ray binaries
Sander, A.; Hamann, W. -R.; Shenar, T. +9 more
Context. Classical supergiant X-ray binaries (SGXBs) and supergiant fast X-ray transients (SFXTs) are two types of high-mass X-ray binaries (HMXBs) that present similar donors but, at the same time, show very different behavior in the X-rays. The reason for this dichotomy of wind-fed HMXBs is still a matter of debate. Among the several explanation…
The F-GAMMA programme: multi-frequency study of active galactic nuclei in the Fermi era. Programme description and the first 2.5 years of monitoring
Pearson, T. J.; Nestoras, I.; Zensus, J. A. +15 more
Context. To fully exploit the scientific potential of the Fermi mission for the physics of active galactic nuclei (AGN), we initiated the F-GAMMA programme. Between 2007 and 2015 the F-GAMMA was the prime provider of complementary multi-frequency monitoring in the radio regime.
Aims: We quantify the radio variability of γ-ray blazars. We inve…
Timing the warm absorber in NGC 4051
Costantini, E.; Uttley, P.; Silva, C. V.
We investigated, using spectral-timing analysis, the characterization of highly ionized outflows in Seyfert galaxies, the so-called warm absorbers. Here, we present our results of the extensive 600 ks of XMM-Newton archival observations of the bright and highly variable Seyfert 1 galaxy NGC 4051 whose spectrum has revealed a complex multicomponent…
Subarcsecond international LOFAR radio images of Arp 220 at 150 MHz. A kpc-scale star forming disk surrounding nuclei with shocked outflows
Beswick, R.; Gallagher, J. S.; Horellou, C. +16 more
Context. Arp 220 is the prototypical ultra luminous infrared galaxy (ULIRG). Despite extensive studies, the structure at MHz-frequencies has remained unknown because of limits in spatial resolution.
Aims: This work aims to constrain the flux and shape of radio emission from Arp 220 at MHz frequencies.
Methods: We analyse new observations…
Plasma code for astrophysical charge exchange emission at X-ray wavelengths
Raassen, A. J. J.; Gu, Liyi; Kaastra, Jelle
Charge exchange X-ray emission provides unique insight into the interactions between cold and hot astrophysical plasmas. Besides its own profound science, this emission is also technically crucial to all observations in the X-ray band, since charge exchange with the solar wind often contributes a significant foreground component that contaminates …