Search Publications
Cosmic ray diffusion tensor throughout the heliosphere
Matthaeus, W. H.; Bieber, J. W.; Burger, R. A. +3 more
We calculate the cosmic ray diffusion tensor based on a recently developed model of magnetohydrodynamic (MHD) turbulence in the expanding solar wind. Parameters of this MHD model are tuned by using published observations from Helios, Voyager 2, and Ulysses. We present solutions of two turbulence parameter sets and derive the characteristics of the…
Mineralogy of recent volcanic plains in the Tharsis region, Mars, and implications for platy-ridged flow composition
Mangold, N.; Gondet, B.; Langevin, Y. +12 more
Volcanism on Mars occurred until recently, but the mineralogy of recent lava plains is poorly known because few regions display fresh outcrops devoid of dust. Using visible and near infrared data of the Mars Express probe, two new volcanic plains in Noctis Labyrinthus have been identified, and the existence of a volcanic plain on the floor of Echu…
Explaining the hard excesses in active galactic nuclei
Fabian, A. C.; Reis, R. C.; Walton, D. J.
A common model invoked to describe the X-ray spectra of active galaxies includes a relativistically blurred reflection component, which in some cases can be the dominant contributor to the received flux. Alternative interpretations are often based around complex absorption, and to date it has proven difficult to determine between these two viable …
Multi-wavelength observations of H 2356-309
Klochkov, D.; Santangelo, A.; Quirrenbach, A. +184 more
Aims: The properties of the broad-band emission from the high-frequency peaked BL Lac H 2356-309 (z = 0.165) are investigated.
Methods: Very high energy (VHE; E > 100 GeV) observations of H 2356-309 were performed with the High Energy Stereoscopic System (HESS) from 2004 through 2007. Simultaneous optical/UV and X-ray observations wer…
Reconnection of a Kinking Flux Rope Triggering the Ejection of a Microwave and Hard X-ray Source I. Observations and Interpretation
Kliem, B.; Karlický, M.
Imaging microwave observations of an eruptive, partially occulted solar flare on 18 April 2001 suggest that the global structure of the event can be described by the helical kink instability of a twisted magnetic flux rope. This model is suggested by the inverse gamma shape of the source exhibiting crossing legs of a rising flux loop and by eviden…
Cosmic Evolution of Virial and Stellar Mass in Massive Early-type Galaxies
Treu, Tommaso; Bradač, Maruša; Gavazzi, Raphaël +7 more
We measure the average mass properties of a sample of 41 strong gravitational lenses at moderate redshift (z ~ 0.4-0.9) and present the lens redshift for six of these galaxies for the first time. Using the techniques of strong and weak gravitational lensing on archival data obtained from the Hubble Space Telescope, we determine that the average ma…
On the origin of Saturn's outer auroral emission
Gérard, Jean-Claude; Grodent, Denis; Radioti, Aikaterini +1 more
Ultraviolet Hubble Space Telescope images reveal a faint but distinct auroral emission equatorward of the main ring of emission of Saturn's southern polar region. This outer auroral emission is only visible near the nightside limb for the strongly tilted viewing geometry achieved in January 2004. We model the limb-brightening amplification of this…
Suzaku Observations of Hard X-ray-selected Seyfert 2 Galaxies
Fiore, F.; Vignali, C.; Gilli, R. +4 more
We present Suzaku observations of five hard X-ray-selected nearby Seyfert 2 galaxies. All the sources were clearly detected with the PIN Hard X-ray Detector up to several tens of keV, allowing for a fairly good characterization of the broadband X-ray continuum. We find that a unique model, even including multiple components, fails to represent the…
Projected Central Dark Matter Fractions and Densities in Massive Early-type Galaxies from the Sloan Digital Sky Survey
Grillo, C.
We investigate in massive early-type galaxies the variation of their two-dimensional central fraction of dark over total mass and dark matter density as a function of stellar mass, central stellar velocity dispersion, effective radius, and central surface stellar mass density. We use a sample of approximately 1.7 × 105 galaxies from the…
VLT diffraction-limited imaging at 11 and 18µm of the nearest active galactic nuclei
Siebenmorgen, R.; Prieto, M. A.; Reunanen, J.
Mid-infrared (mid-IR) imaging at resolutions of 300mas of the central kpc region of 13 nearby, well-known active galaxies is presented. The bulk of the mid-IR emission is concentrated on an unresolved central source within a size of less than 5-130pc, depending on the object distance. Further resolved emission is detected in 70 per cent of the sam…