Search Publications
Constraints on non-Gaussianity from Sunyaev-Zeldovich cluster surveys
Mak, Daisy S. Y.; Pierpaoli, Elena
We perform a Fisher matrix analysis to forecast the capability of ongoing and future Sunyaev-Zeldovich cluster surveys in constraining the deviations from Gaussian distribution of primordial density perturbations. We use the constraining power of the cluster number counts and clustering properties to forecast limits on the fNL parameter…
Twist, Writhe, and Helicity in the Inner Penumbra of a Sunspot
Ruiz Cobo, B.; Puschmann, K. G.
The aim of this work is the determination of the twist, writhe, and self-magnetic helicity of penumbral filaments located in an inner sunspot penumbra. For this purpose, we inverted data taken with the spectropolarimeter on board Hinode with the SIR (Stokes Inversion based on Response function) code. For the construction of a three-dimensional geo…
Two-dimensional Monte Carlo radiative transfer modelling of the disc-shaped secondary of Epsilon Aurigae
Parthasarathy, M.; Muthumariappan, C.
We present two-dimensional Monte Carlo radiative transfer models for the disc of the eclipsing binary Epsilon Aurigae by fitting its spectral energy distribution (SED) from optical to far-infrared (IR) wavelengths. We also report new observations of Epsilon Aurigae made by AKARI in its five mid- and far-IR photometric bands and which were used to …
Suzaku Investigation into the Nature of the Nearest Ultraluminous X-Ray Source, M33 X-8
Isobe, Naoki; Kubota, Aya; Mizuno, Tsunefumi +1 more
The X-ray spectrum of the nearest ultraluminous X-ray source, M 33 X-8, obtained by Suzaku during 2010 January 11-13, was closely analyzed in order to examine its nature. It is, by far, the only data with the highest signal statistic in the 0.4-10 keV range. Despite being able to reproduce the X-ray spectrum, Comptonization of the disk photons fai…
Effects of Hysteresis Between Maximum CME Speed Index and Typical Solar Activity Indicators During Cycle 23
Özgüç, A.; Kilcik, A.; Rozelot, J. P.
Using the smoothed time series of maximum CME speed index for solar cycle 23, it is found that this index, analyzed jointly with six other solar activity indicators, shows a hysteresis phenomenon. The total solar irradiance, coronal index, solar radio flux (10.7 cm), Mg II core-to-wing ratio, sunspot area, and Hα flare index follow different paths…
Intervening broad-line region clouds' effects on the optical/ultraviolet spectrum
Ferland, Gary J.; Du, Pu; Hu, Chen +2 more
Recent X-ray observations of Mrk 766 suggest that broad emission-line region clouds cross our line of sight and produce variable X-ray absorption. Here we investigate what optical/ultraviolet (UV) spectroscopic features would be produced by such 'intervening broad-line region (BLR) clouds' (IBC) crossing our line of sight to the accretion disc, th…
IGR J12319-0749: evidence for another extreme blazar found with INTEGRAL
Masetti, N.; Gehrels, N.; Bird, A. J. +6 more
We report on the identification of a new soft gamma-ray source, IGR J12319-0749, detected with the IBIS imager on board the INTEGRAL satellite. The source, which has an observed 20-100 keV flux of ~8.3 × 10-12 erg cm-2 s-1, is spatially coincident with an active galactic nucleus (AGN) at redshift z = 3.12. The broa…
Thermal history and large scale differentiation of the Saturn's satellite Rhea
Czechowski, Leszek
Thermal history of Rhea from the beginning of accretion is investigated. We developed a numerical model of convection combined with the parameterized theory. Large scale melting of the satellite's matter and gravitational differentiation of silicates from ices are included. The results are confronted with observational data from Cassini spacecraft…
Properties of the magnetospheric backward wave oscillator inferred from CLUSTER measurements of VLF chorus elements
Gurnett, D.; MacúšOvá, E.; SantolíK, O. +6 more
According to the backward wave oscillator (BWO) model, a sharp gradient (or step-like deformation) on the electron distribution function is the most important factor in chorus generation, but such a feature is very difficult to observe directly. The properties of the step in the BWO model determine the dimensionless parameterqquantifying the exces…
Comparison between observed and theoretical O IV line ratios in the UV/EUV solar spectrum as derived by SUMER, CDS and EIS
Fludra, A.; Summers, H. P.; Giunta, A. S. +1 more
Aims: The joint use of SoHO Solar Ultraviolet Measurement of Emitted Radiation (SUMER), Coronal Diagnostic Spectrometer (CDS) and Hinode Extreme-ultraviolet Imaging Spectrometer (EIS) allow observation of several O iv line ratios, useful for temperature plasma diagnostics. Accurate atomic data are required to avoid interpretation errors in de…