Search Publications
Cepheid investigations using the Kepler space telescope
Smolec, R.; Szabados, L.; Handler, G. +35 more
We report results of initial work done on selected candidate Cepheids to be observed with the Kepler space telescope. Prior to the launch, 40 candidates were selected from previous surveys and data bases. The analysis of the first 322 d of Kepler photometry, and recent ground-based follow-up multicolour photometry and spectroscopy allowed us to co…
The zCOSMOS-Bright survey: the clustering of early and late galaxy morphological types since z≃ 1
Kneib, J. -P.; Maccagni, D.; Cimatti, A. +53 more
We measure the spatial clustering of galaxies as a function of their morphological type at z≃ 0.8, for the first time in a deep redshift survey with full morphological information. This is obtained by combining high-resolution Hubble Space Telescope imaging and Very Large Telescope spectroscopy for about 8500 galaxies to ? with accurate spectrosco…
How the effects of resonant absorption on black hole reflection spectra can mimic high-velocity outflows
Fabian, A. C.; Gallo, L. C.
Narrow absorption lines seen in the 2-10 keV spectra of active galaxies and Galactic black holes are normally attributed to iron in high-velocity outflows or inflows. We consider the possibility that such features could arise naturally in the accretion disc. Resonant absorption by highly ionized iron (e.g. Fe XXVI and Fe XXV) in an optically thin …
IGR J17354-3255 as a candidate intermediate supergiant fast X-ray transient possibly associated with the transient MeV AGL J1734-3310
Bird, A. J.; Ubertini, P.; Landi, R. +3 more
We present spectral and temporal results from INTEGRAL long-term monitoring of the unidentified X-ray source IGR J17354-3255. We show that it is a weak persistent hard X-ray source spending a major fraction of the time in an out-of-outburst state with an average of 18-60 keV X-ray flux of ∼1.1 milliCrab, occasionally interspersed with fast X-ray f…
The evolution of early-type galaxies in clusters from z∼ 0.8 to z ∼ 0: the ellipticity distribution and the morphological mix
Cava, Antonio; Dressler, Alan; Vulcani, Benedetta +10 more
We present the ellipticity distribution and its evolution for early-type galaxies in clusters from z∼ 0.8 to the current epoch, based on the WIde-field Nearby Galaxy-cluster Survey (0.04 ≤z≤ 0.07) and the ESO Distant Cluster Survey (0.4 ≤z≤ 0.8). We first investigate a mass-limited sample and we find that above a fixed mass limit (M*≥ 1…
A Saturnian cam current system driven by asymmetric thermospheric heating
Smith, C. G. A.
We show that asymmetric heating of Saturn's thermosphere can drive a current system consistent with the magnetospheric ‘cam’ proposed by Espinosa, Southwood & Dougherty. A geometrically simple heating distribution is imposed on the Northern hemisphere of a simplified three-dimensional global circulation model of Saturn's thermosphere. Currents…
On the nature of the absorber in IRAS 09104+4109: the X-ray and mid-infrared view
Maiolino, R.; Pozzi, F.; Fiore, F. +8 more
We present a long (≈76 ks) Chandra observation of IRAS 09104+4109, a hyperluminous galaxy, optically classified as a type 2 active galactic nuclei (AGN) hosted in a cD galaxy in a cluster at z= 0.442. We also report on the results obtained by fitting its broad-band spectral energy distribution. The Compton-thick nature of this source (which has be…
Spectral states evolution of 4U 1728-34 observed by INTEGRAL and RXTE: non-thermal component detection
Belloni, T.; Ubertini, P.; Bazzano, A. +2 more
We report results of a one-year monitoring of the low-mass X-ray binary (LMXB) source (atoll type) 4U 1728-34 with INTEGRAL and RXTE. Three time intervals were covered by INTEGRAL, during which the source showed strong spectral evolution. We studied the broad-band X-ray spectra in detail by fitting several models in the different sections of the h…
Lensed arc statistics: comparison of Millennium simulation galaxy clusters to Hubble Space Telescope observations of an X-ray selected sample
Maoz, Dan; Bartelmann, Matthias; Hilbert, Stefan +1 more
It has been debated for a decade whether there is a large overabundance of strongly lensed arcs in galaxyclusters, compared to expectations from Λ cold dark matter cosmology. We perform ray tracing through the most massive haloes of the Millennium simulation at several redshifts in their evolution, using the Hubble Ultra Deep Field as a source ima…
Probing general relativistic effects during active galactic nuclei X-ray eclipses
Elvis, M.; Brenneman, L.; Nardini, E. +2 more
Long X-ray observations of bright active galactic nuclei (AGN) show that X-ray eclipses, with durations from a few hours to a few days, are rather common. This opens up a new window of opportunity in the search for signatures of relativistic effects in AGN: an obscuring cloud covers/uncovers different parts of the accretion disc at different times…