Search Publications
The quest for Type 2 quasars: Chandra observations of luminous obscured quasars in the Sloan Digital Sky Survey
Comastri, Andrea; Vignali, Cristian; Alexander, Dave M.
We report on new Chandra exploratory observations of six candidate Type 2 quasars at z = 0.49-0.73 selected among the most [OIII] luminous emitters from the Sloan Digital Sky Survey (SDSS). Under the assumption that [OIII] is a proxy for the intrinsic luminosity of the central source, their predicted rest-frame X-ray luminosities are L2-10keV…
Solar FLAG hare and hounds: on the extraction of rotational p-mode splittings from seismic, Sun-as-a-star data
Baudin, F.; Jiménez-Reyes, S. J.; García, R. A. +18 more
We report on results from the first solar Fitting at Low-Angular degree Group (solar FLAG) hare-and-hounds exercise. The group is concerned with the development of methods for extracting the parameters of low-l solar p-mode data (`peak bagging'), collected by Sun-as-a-star observations. Accurate and precise estimation of the fundamental parameters…
XMM-Newton observations of the Soft Gamma Ray Repeater SGR 1627-41 in a low luminosity state
Tiengo, A.; Mereghetti, S.; Stella, L. +6 more
The sky region containing the soft gamma-ray repeater SGR 1627-41 has been observed three times with XMM-Newton in February and September 2004. SGR 1627-41 has been detected with an absorbed flux of ~9×10-14 erg cm-2 s-1 (2-10 keV). For a distance of 11 kpc, this corresponds to a luminosity of ~3× 1033 e…
Cross-correlation of Lyman α absorbers with gas-rich galaxies
Ryan-Weber, Emma V.
The HI Parkes all-sky survey (HIPASS) galaxy catalogue is cross-correlated with known low redshift, low column density (NHI < 1015cm-2) Lyman α (Lyα) absorbers from the literature. The redshift-space correlation is found to be similar in strength to HIPASS galaxy self-clustering (correlation length s0,ag
Variable iron-line emission near the black hole of Markarian 766
Nandra, K.; Turner, T. J.; Porquet, D. +4 more
Aims.We investigate the link between ionised Fe X-ray line emission and continuum emission in a bright nearby AGN, Mrk 766.
Methods: .A new long (433 ks) XMM-Newton observation is analysed, together with archival data from 2000 and 2001. The contribution from ionised line emission is measured and its time variations on short (5-20 ks) timesca…
Soft gamma-ray background and light dark matter annihilation
Fayet, Pierre; Cordier, Bertrand; Teyssier, Romain +4 more
The bulk of the extragalactic background between 10 keV and 10 GeV is likely to be explained by the emission of Seyfert galaxies, type Ia supernovae, and blazars. However, as revealed by the INTEGRAL satellite, the bulge of our galaxy is an intense source of a 511 keV gamma-ray line, indicating the production of a large number of positrons that an…
Cassini radio occultations of Saturn's ionosphere: Model comparisons using a constant water flux
Moore, Luke; Kliore, Arvydas J.; Mendillo, Michael +3 more
Recent radio occultations of Saturn's equatorial ionosphere by the Cassini spacecraft provide important insight into this poorly constrained region. Twelve new electron density profiles identify a clear dawn/dusk asymmetry as well as two apparently separate electron density peaks. This study uses a 3D general circulation model along with 1D water …
Orientation and motion of a plasma discontinuity from single-spacecraft measurements: Generic residue analysis of Cluster data
Balogh, A.; RèMe, H.; Dunlop, M. W. +3 more
A unified minimum-residue approach is presented to the use of classical conservation laws for determination of the orientation and motion of a plasma discontinuity, using data from a single spacecraft that traverses the discontinuity and makes measurements, not only on its two sides but also within it. The method is a generalization of the minimum…
First ENA observations at Mars: Subsolar ENA jet
Coates, A. J.; Kallio, E.; Fedorov, A. +43 more
The Neutral Particle Detector (NPD), an Energetic Neutral Atom (ENA) sensor of the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3) on board Mars Express, detected intense fluxes of ENAs emitted from the subsolar region of Mars. The typical ENA fluxes are (4-7) × 10 5 cm -2 sr -1 s -1 in the ener…
Multithermal Analysis of a SOHO/CDS Coronal Loop
Schmelz, J. T.; Martens, P. C. H.
The observations from 1998 April 20 taken with the Coronal Diagnostics Spectrometer (CDS) on the Solar and Heliospheric Observatory (SOHO) of a coronal loop on the limb have shown that the plasma was multithermal along each line of sight investigated, both before and after background subtraction. The latter result relied on emission measure (EM) l…