Search Publications
Evidence of a type 1/type 2 dichotomy in the correlation between quasar optical polarization and host-galaxy/extended emission position angles
Magain, P.; Hutsemékers, D.; Borguet, B. +2 more
Aims:For Seyfert galaxies, the AGN unification model provides a simple and well-established explanation of the type 1/type 2 dichotomy through orientation-based effects. The generalization of this unification model to the higher luminosity AGNs that quasars are remains a key question. The recent detection of type 2 radio-quiet quasars seems to sup…
Spitzer Space Telescope observations of the nucleus of comet 67P/Churyumov-Gerasimenko
Jorda, L.; Lamy, P. L.; Groussin, O. +3 more
Context: Comet 67P/Churyumov-Gerasimenko is the target of the Rosetta mission, and an early characterization of its nucleus is required to assist in preparing the orbital strategy of the spacecraft, the delivery of the Philae surface module and the science operations. We detected the nucleus using the Hubble Space Telescope in March 2003, but had …
Hen 2-104: a close-up look at the Southern Crab
Morisset, C.; Schirmer, M.; Balick, B. +5 more
Aims: The kinematics, shaping, density distribution, expansion distance, and ionized mass of the nebula Hen 2-104, and the nature of its symbiotic Mira are investigated.
Methods: A combination of multi-epoch HST images and VLT integral field high-resolution spectroscopy is used to study the nebular dynamics both along the line of sight and in …
An X-ray view of absorbed INTEGRAL AGN
de Rosa, A.; Walter, R.; Ubertini, P. +4 more
Aims: We present a 0.2-200 keV broadband study of absorbed Active Galactic Nuclei (AGN) observed with INTEGRAL, XMM-Newton, Chandra, and ASCA to investigate the continuum shape and the absorbing/reflecting medium properties.
Methods: The sources are selected in the INTEGRAL AGN sample to have a 20-100 keV flux below 8× 10-11 erg cm<…
Comet 67P/Churyumov-Gerasimenko at a large heliocentric distance
Tubiana, C.; Boehnhardt, H.; Drahus, M. +1 more
Aims: The Jupiter family comet 67P/Churyumov-Gerasimenko (67P/C-G) is the target comet of ESA's ROSETTA mission. A detailed portrait of this comet has been drawn from observations around perihelion, but what needs to be enhanced is the description of the comet's behaviour at large heliocentric distance. It is not only important for planning the re…
XMM-Newton X-ray spectra of the SNR 0509-67.5: data and models
Vink, J.; Kosenko, D.; Blinnikov, S. +1 more
Aims: We report on X-ray observations of the supernova remnant 0509-67.5 in the Large Magellanic Cloud acquired by the XMM-Newton X-ray observatory. We use the imaging spectroscopy (EPIC) and Reflective Grating Spectrometer (RGS) data to investigate properties of the remnant and its environment.
Methods: The X-ray spectra were analyzed with SP…
Star formation in the hosts of GHz peaked spectrum and compact steep spectrum radio galaxies
O'Dea, C. P.; Labiano, A.; Baum, S. A. +2 more
Aims:We are searching for star formation regions in the hosts of potentially young radio galaxies (gigahertz peaked spectrum and compact steep spectrum sources).
Methods: We used near-UV imaging with the Hubble Space Telescope Advanced Camera for Surveys.
Results: We find near-UV light could be the product of recent star formation in five …
An X-ray and optical study of the ultracompact X-ray binary A 1246-58
Verbunt, F.; in't Zand, J. J. M.; Méndez, M. +4 more
Results are discussed of an X-ray and optical observation campaign of the low-mass X-ray binary A 1246-58 performed with instruments on Satellite per Astronomia X (“BeppoSAX”), the Rossi X-ray Timing Explorer (RXTE), the X-ray Multi-mirror Mission (“XMM-Newton”), the Swift mission, and the Very Large Telescope. Spectra and flux time histories are …
Electron-impact excitation of Be-like Mg
Del Zanna, G.; Badnell, N. R.; Rozum, I.
We present an R-matrix calculation of electron-impact excitation of Be-like Mg. The calculation is similar to that one presented for Be-like Fe by Chidichimo et al. (2005, A&A, 430, 331), and was done with the intermediate-coupling frame transformation method and including a total of 98 fine-structure levels, up to n=4. We find significant dif…
Swift observations of IBL and LBL objects
Tosti, G.; Giommi, P.; Nesci, R. +5 more
Context: BL Lacs are an enigmatic class of active galactic nuclei (AGNs), characterized by the non-thermal continuum typically attributed to synchrotron and inverse Compton emission. Depending on the frequency location of the maxima of these components, they are subdivided into three subclasses LBLs, IBLs, and HBLs. We present the results of a set…