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Detailed Hard X-Ray Measurements of Nuclear Emission from the Seyfert2 Galaxy NGC4388 with Suzaku
Fukazawa, Yasushi; Murakami, Toshio; Ohno, Masanori +10 more
We report on a Suzaku observation of the nearby Seyfert2 galaxy NGC4388. The overall spectrum is well described by the combination of strongly absorbed power-law plus thin thermal plasma emission, as well as previous observations. Thanks to well-calibrated instruments and a low background level, Suzaku measured the broad-band X-ray spectra more pr…
Optical Surface Brightness Fluctuations of Shell Galaxies toward 100 Mpc
Cantiello, M.; Brocato, E.; Raimondo, G. +1 more
We measure F814W surface brightness fluctuations (SBFs) for a sample of distant shell galaxies with radial velocities ranging from 4000 to 8000 km s-1. The distance at galaxies is then evaluated by using the SBF method. For this purpose, theoretical SBF magnitudes for the HST ACS filters are computed for single-burst stellar populations…
Latitudinal Gradients of Galactic Cosmic Rays during the 2007 Solar Minimum
Mewaldt, R. A.; Gómez-Herrero, R.; Ferreira, S. E. S. +6 more
Ulysses, launched in 1990 October in the maximum phase of solar cycle 22, completed its third out-of-ecliptic orbit in 2008 February. This provides a unique opportunity to study the propagation of cosmic rays over a wide range of heliographic latitudes during different levels of solar activity and different polarities in the inner heliosphere. Com…
Structure of Titan's low altitude ionized layer from the Relaxation Probe onboard HUYGENS
Berthelier, J. J.; Rodrigo, R.; López-Moreno, J. J. +14 more
Some of the secrets of the atmosphere of Titan have been unveiled by the Huygens Probe. The Permitivity Wave and Altimetry system detected a hidden ionosphere much below the main ionosphere, that lies between 600 and 2000 km. Theoretical models predicted a low altitude ionosphere produced by cosmic rays that, contrary to magnetospheric particles a…
Solar Observations of High-Temperature Emission with the Extreme-Ultraviolet Imaging Spectrometer on Hinode
Warren, Harry P.; Brown, Charles M.; Feldman, Uri
We present an analysis of solar coronal emission lines formed above 2.5 MK observed with the Extreme-Ultraviolet Imaging Spectrometer on Hinode during a small flare. Our main purpose is to evaluate the internal consistency of the atomic data available for the observed emission. We find that the observed emission from high-temperature Ca lines (Ca …
Solar coronal rotation determined by X-ray bright points in Hinode/XRT and Yohkoh/SXT full-disc images
Kariyappa, R.
Aims: Our aim is to identify and trace the X-ray bright points (XBPs) over the disc and use them as tracers to determine the coronal rotation. This investigation will help to clarify and understand several issues: (i) whether the corona rotates differentially; (ii) whether the rotation depends on the sizes of the XBPs; and (iii) whether there is a…
Discovery of Hot Gas in Outflow in NGC 3379
Zezas, A.; Gallagher, J.; King, A. R. +10 more
We report the discovery of a faint (LX ~ 4 +/- 1.5 × 1037 ergs s-1, 0.5-2 keV), outflowing gaseous hot interstellar medium (ISM) in NGC 3379. This represents the lowest X-ray luminosity ever measured from a hot phase of the ISM in a nearby early-type galaxy. The discovery of the hot ISM in a very deep Chandra obser…
The nature of the intranight variability of radio-quiet quasars
Siemiginowska, A.; Czerny, B.; Gupta, A. C. +1 more
We select a sample of 10 radio-quiet quasars with confirmed intranight optical variability and with available X-ray data. We compare the variability properties and the broad-band spectral constraints to the predictions of intranight variability by three models: (i) irradiation of an accretion disc by a variable X-ray flux, (ii) an accretion disc i…
Coronal loop oscillations and diagnostics with Hinode/EIS
Taroyan, Y.; Bradshaw, S.
Context: Standing slow (acoustic) waves commonly observed in hot coronal loops offer a unique opportunity to understand the properties of the coronal plasma. The lack of evidence for similar oscillations in cooler loops is still a puzzle.
Aims: The high cadence EIS instrument on board recently launched Hinode has the capability to detect wave …
Cosmological models in scalar tensor theories of gravity and observations: a class of general solutions
Piedipalumbo, E.; Demianski, M.; Rubano, C. +1 more
Aims: We study cosmological models in scalar tensor theories of gravity with power-law potentials as models of an accelerating universe.
Methods: We consider cosmological models in scalar tensor theories of gravity that describe an accelerating universe and study a family of inverse power-law potentials, for which exact solutions of the Einste…