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Non-thermal cosmic backgrounds from blazars: the contribution to the CMB, X-ray and γ-ray backgrounds
Cavazzuti, E.; Colafrancesco, S.; Giommi, P. +2 more
We present a new assessment of the contribution of the blazar population to the extragalactic background radiation across the electromagnetic spectrum. Our calculations rely on deep blazar radio counts that we have derived by combining several radio and multi-frequency surveys. We show that blazar emission integrated over cosmic time gives rise to…
Bimodal spectral variability of Cygnus X-1 in an intermediate state
Belloni, T.; Chaty, S.; Rodriguez, J. +11 more
We report the results of an observation of
Cassini observations of flow-like features in western Tui Regio, Titan
Sotin, Christophe; Barnes, Jason W.; Rodriguez, Sebastien +9 more
A large (>3 × 104 km2), lobate, 5-µm-bright region seen by Cassini on Titan's leading equatorial region is best explained as a flow field. We discuss observations from the Visual and Infrared Mapping Spectrometer and Imaging Science Subsystem of the feature and present a map of the field. We establish relative ages o…
A Sample of Low-Redshift BL Lacertae Objects. II. EVN and MERLIN Data and Multiwavelength Analysis
Falomo, R.; Giroletti, M.; Giovannini, G. +1 more
We present new radio observations of 9 members of a sample of 29 nearby (z<0.2) BL Lac objects. The new data have been obtained with the European VLBI Network and/or MERLIN at 1.6 and 5 GHz and complement previous observations. For one object, the TeV source Mrk 421, we also present deep multiepoch VLBA and global VLBI data, which reveal a reso…
The Faint Afterglow and Host Galaxy of the Short-Hard GRB 060121
Bremer, M.; Fruchter, A. S.; Rol, E. +14 more
We present optical and X-ray observations of the afterglow and host galaxy of the short-hard GRB 060121. The faint R-band afterglow is seen to decline as t-0.66+/-0.09 while the X-ray falls as t-1.18+/-0.04, indicating the presence of the cooling break between the two frequencies. However, the R-band afterglow is very faint c…
Solar coronal-hole plasma densities and temperatures
Wilhelm, K.
Polar plumes extending from the Sun into the solar corona have long been seen during eclipses, and can now be studied without this restriction with telescopes and spectrometers on board of spacecraft. Despite the large amount of observational data available on this prominent phenomenon, it is not clear whether plumes contribute substantially to th…
Mapping potential-vorticity dynamics on Jupiter. I: Zonal-mean circulation from Cassini and Voyager 1 data
Fouchet, Thierry; Read, Peter L.; Conrath, Barney J. +3 more
Maps of Ertel potential vorticity on isentropic surfaces (IPV) and/or quasi-geostrophic potential vorticity (QGPV) are well established in dynamical meteorology as powerful sources of insight into dynamical processes involving 'balanced' flow. In the present study, we derive maps of zonal-mean IPV and QGPV in Jupiter's upper troposphere and lower …
X-Rays from the Globular Cluster G1: Intermediate-Mass Black Hole or Low-Mass X-Ray Binary?
Pooley, David; Rappaport, Saul
The globular cluster G1 (Mayall II) in M31 is the most massive (~107 Msolar) stellar cluster in the Local Group, and it has the highest central velocity dispersion (~28 km s-1). It has been claimed to host a central ~20,000 Msolar black hole, but these claims have been controversial. We investigate here …
Spectral-timing evidence for a very high state in the narrow-line Seyfert 1 Ark 564
Papadakis, I. E.; Uttley, P.; Arévalo, P. +2 more
We use a 100ks long XMM-Newton observation of the narrow-line Seyfert 1 galaxy Ark 564 and combine it with the month-long monitoring of the same source produced by ASCA, to calculate the phase lags and coherence between different energy bands, over frequencies from ~10-6 to 10-3Hz. This is the widest frequency range for which…
Hydrostatic Modeling of the Integrated Soft X-Ray and Extreme Ultraviolet Emission in Solar Active Regions
Winebarger, Amy R.; Warren, Harry P.
Many studies of the solar corona have shown that the observed X-ray luminosity is well correlated with the total unsigned magnetic flux. In this paper we present results from the extensive numerical modeling of active regions observed with the Solar and Heliospheric Observatory (SOHO) EUV Imaging Telescope (EIT), the Yohkoh Soft X-Ray Telescope (S…