Search Publications
Multi-wavelength observations of Galactic hard X-ray sources discovered by INTEGRAL. I. The nature of the companion star
Chaty, S.; Rahoui, F.; Foellmi, C. +3 more
Context: The INTEGRAL hard X-ray observatory has revealed an emerging population of highly obscured X-ray binary systems through multi-wavelength observations. Previous studies have shown that many of these sources are high-mass X-ray binaries hosting neutron stars orbiting around luminous and evolved companion stars.
Aims: To better understan…
The multiwavelength variability of 3C 273
Lähteenmäki, A.; Paltani, S.; Walter, R. +11 more
Aims: We present an update of the 3C 273's database hosted by the ISDC, completed with data from radio to gamma-ray observations over the last 10 years. We use this large data set to study the multiwavelength properties of this quasar, especially focussing on its variability behaviour.
Methods: We study the amplitude of the variations and the …
Radial metallicity profiles for a large sample of galaxy clusters observed with XMM-Newton
Molendi, S.; Leccardi, A.
Aims: We measured radial metallicity profiles for a sample of ≈50 hot, intermediate redshift galaxy clusters, selected from the XMM-Newton archive.
Methods: As in our previous paper, we used background modeling rather than background subtraction, and the Cash statistic rather than the χ^2. This method requires a careful characterization of all…
Observations and modeling of a clumpy galaxy at z = 1.6. Spectroscopic clues to the origin and evolution of chain galaxies
Daddi, E.; Elbaz, D.; Bournaud, F. +7 more
We investigate the properties of a clump-cluster galaxy at redshift 1.57. In optical observations, the morphology of this galaxy is dominated by eight star-forming clumps, and its photometric properties are typical of most clump-cluster and chain galaxies. Its complex asymmetrical morphology has led to the suggestion that this system is a group me…
Abundance of minerals in the phyllosilicate-rich units on Mars
Mangold, N.; Bibring, J. -P.; Gondet, B. +4 more
Context: Phyllosilicates were definitely identified on Mars by the OMEGA (Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité) instrument onboard the Mars Express spacecraft. The identification, characterization, and mapping of deposits of these minerals hold clues to the potential past habitability. They also constitute a key elemen…
Quantitative studies of the optical and UV spectra of Galactic early B supergiants. I. Fundamental parameters
Massa, D.; Prinja, R. K.; Searle, S. C. +1 more
Aims: We undertake an optical and ultraviolet spectroscopic analysis of a sample of 20 Galactic B0-B5 supergiants of luminosity classes Ia, Ib, Iab, and II. Fundamental stellar parameters are obtained from optical diagnostics and a critical comparison of the model predictions to observed UV spectral features is made.
Methods: Fundamental param…
Strong horizontal photospheric magnetic field in a surface dynamo simulation
Schüssler, M.; Vögler, A.
Context: Observations with the Hinode spectro-polarimeter have revealed strong horizontal internetwork magnetic fields in the quiet solar photosphere.
Aims: We aim to interpret the observations with results from numerical simulations.
Methods: Radiative MHD simulations of dynamo action by near-surface convection are analyzed with respect t…
High variability in Vela X-1: giant flares and off states
Santangelo, A.; Wilms, J.; Ferrigno, C. +6 more
Aims: We investigate the spectral and temporal behavior of the high mass X-ray binary Vela X-1 during a phase of high activity, with special focus on the observed giant flares and off states.
Methods: INTEGRAL observed Vela X-1 in a long almost uninterrupted observation for two weeks in 2003 Nov/Dec. The data were analyzed with OSA 7.0 and FTO…
Transient horizontal magnetic fields in solar plage regions
Lites, B. W.; Ichimoto, K.; Ishikawa, R. +9 more
Aims:We report the discovery of isolated, small-scale emerging magnetic fields in a plage region with the Solar Optical Telescope aboard Hinode.
Methods: Spectro-polarimetric observations were carried out with a cadence of 34 s for the plage region located near disc center. The vector magnetic fields are inferred by Milne-Eddington inversion. …
X-ray spectral evolution of TeV BL Lacertae objects: eleven years of observations with BeppoSAX, XMM-Newton and Swift satellites
Tramacere, A.; Giommi, P.; Perri, M. +2 more
Context: Many of the extragalactic sources detected in γ rays at TeV energies are BL Lac objects. In particular, they belong to the subclass of “high frequency peaked BL Lacs” (HBLs), as their spectral energy distributions exhibit a first peak in the X-ray band. At a closer look, their X-ray spectra appear to be generally curved into a log-parabol…