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XMM-Newton spectroscopy of the accreting magnetar candidate 4U0114+65
Torrejón, J. M.; Postnov, K.; Oskinova, L. +3 more
Aims: 4U0114+65 is one of the slowest known X-ray pulsars. We present an analysis of a pointed observation by the XMM-Newton X-ray telescope in order to study the nature of the X-ray pulsations and the accretion process, and to diagnose the physical properties of the donor's stellar wind.
Methods: We analysed the energy-resolved light cu…
Small electron acceleration episodes in the solar corona
James, Tomin; Subramanian, Prasad; Kontar, Eduard P.
We study the energetics of non-thermal electrons produced in small acceleration episodes in the solar corona. We carried out an extensive survey spanning 2004-2015 and shortlisted six impulsive electron events detected at 1 au that were not associated with large solar flares (GOES soft X-ray class > C1) or with coronal mass ejections. Each of t…
Constraining cosmological ultralarge scale structure using numerical relativity
Peiris, Hiranya V.; Braden, Jonathan; Johnson, Matthew C. +1 more
Cosmic inflation, a period of accelerated expansion in the early universe, can give rise to large amplitude ultralarge scale inhomogeneities on distance scales comparable to or larger than the observable universe. The cosmic microwave background (CMB) anisotropy on the largest angular scales is sensitive to such inhomogeneities and can be used to …
Improved Diffuse Foreground Subtraction with the ILC Method: CMB Map and Angular Power Spectrum Using Planck and WMAP Observations
Aluri, Pavan K.; Souradeep, Tarun; Saha, Rajib +2 more
We report an improved technique for diffuse foreground minimization from Cosmic Microwave Background (CMB) maps using a new multiphase iterative harmonic space internal-linear-combination (HILC) approach. Our method nullifies a foreground leakage that was present in the old and usual iterative HILC method. In phase 1 of the multiphase technique, w…
Dayside and nightside magnetic field responses at 780 km altitude to dayside reconnection
Snekvik, K.; Østgaard, N.; Tenfjord, P. +4 more
During southward interplanetary magnetic field, dayside reconnection will drive the Dungey cycle in the magnetosphere, which is manifested as a two-cell convection pattern in the ionosphere. We address the response of the ionospheric convection to changes in the dayside reconnection rate by examining magnetic field perturbations at 780 km altitude…
A Comparison of Two Methods for Estimating Black Hole Spin in Active Galactic Nuclei
Haggard, Daryl; Capellupo, Daniel M.; Wafflard-Fernandez, Gaylor
Angular momentum, or spin, is a fundamental property of black holes (BHs), yet it is much more difficult to estimate than mass or accretion rate (for actively accreting systems). In recent years, high-quality X-ray observations have allowed for detailed measurements of the Fe Kα emission line, where relativistic line broadening allows constraints …
Temperature and density structure of a recurring active region jet
Del Zanna, Giulio; Mulay, Sargam M.; Mason, Helen
Aims: We present a study of a recurring jet observed on October 31, 2011 by the Atmosphereic Imaging Assembly (AIA) on board the Solar Dynamic Observatory, the X-ray Telescope (XRT) and EUV Imaging Spectrometer (EIS) on board Hinode. We discuss the physical parameters of the jet that are obtained using imaging and spectroscopic observations, …
The parameterization of wave-particle interactions in the Outer Radiation Belt
Forsyth, C.; Rae, I. J.; Murphy, K. R. +3 more
We explore the use of mean value empirical wave models in diffusion models of the Outer Radiation Belt. We show that magnetospheric wave power is not normally distributed in time and that geomagnetic activity does not provide a deterministic proxy for the temporal variability of wave activity. Our findings indicate that current diffusion models si…
IUVS echelle-mode observations of interplanetary hydrogen: Standard for calibration and reference for cavity variations between Earth and Mars during MAVEN cruise
Bertaux, Jean-Loup; Chaufray, Jean-Yves; Stewart, Ian +11 more
The high-resolution echelle mode of the Imaging Ultraviolet Spectrograph (IUVS) instrument on the Mars Atmosphere and Volatile Evolution mission has been designed to measure D and H Lyman α emissions from the Martian atmosphere to obtain key information about the physical processes by which water escapes into space. Toward this goal, the absolute …
Far-UV spectroscopy of two extremely hot, helium-rich white dwarfs
Rauch, T.; Werner, K.; Kruk, J. W.
A large proportion of hot post-asymptotic giant branch stars and white dwarfs (WDs) are hydrogen-deficient. Two distinct evolutionary sequences have been identified. One of them comprises stars of spectral type [WC] and PG1159, and it originates from a late helium-shell flash, creating helium-rich stellar atmospheres with significant admixtures of…