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On the identification of time interval threshold in the twin-CME scenario
Li, Gang; Ding, Liu-Guan; Jiang, Yong +3 more
Recently it has been suggested that the "twin-CME" scenario may be a very effective mechanism in causing extreme solar energetic particle (SEP) events and, in particular, ground level enhancement (GLE) events. Ding et al. (2013) performed a statistical examination of the twin-CME scenario with a total of 126 fast and wide western coronal mass ejec…
Observation of a retreating x line and magnetic islands poleward of the cusp during northward interplanetary magnetic field conditions
Fuselier, S. A.; Trattner, K. J.; Eriksson, S. +3 more
When the interplanetary magnetic field is northward, reconnection occurs in each hemisphere on lobe field lines, poleward of the cusp. We have identified a case where the Cluster spacecraft crossed the magnetopause and encountered a tailward retreating x line. The x line is identified by the encounter of both a tailward and sunward jet, as well as…
From Predicting Solar Activity to Forecasting Space Weather: Practical Examples of Research-to-Operations and Operations-to-Research
Biesecker, D. A.; Steenburgh, R. A.; Millward, G. H.
The successful transition of research to operations (R2O) and operations to research (O2R) requires, above all, interaction between the two communities. We explore the role that close interaction and ongoing communication played in the successful fielding of three separate developments: an observation platform, a numerical model, and a visualizati…
Fifty M31 Black Hole Candidates Identified by Chandra and XMM-Newton
Murray, S. S.; Garcia, M. R.; Barnard, R. +1 more
Over approximately the last five years, we have identified ~35 black hole candidates (BHCs) in M31 from their X-ray spectra. Our BHCs exhibited 0.3-10 keV spectra consistent with the X-ray binary (XB) hard state at luminosities that are above the upper limit for neutron star (NS) XBs. When our BHC spectra were modeled with a disk blackbody + black…
Oblique Alfvén Instabilities Driven by Compensated Currents
De Keyser, J.; Malovichko, P.; Voitenko, Y.
Compensated-current systems created by energetic ion beams are widespread in space and astrophysical plasmas. The well-known examples are foreshock regions in the solar wind and around supernova remnants. We found a new oblique Alfvénic instability driven by compensated currents flowing along the background magnetic field. Because of the vastly di…
Resolving different sources of fast X-ray variability of the dwarf nova RU Peg in quiescence
Ness, J. -U.; Dobrotka, A.; Mineshige, S.
We analysed an X-ray light curve of the dwarf nova RU Peg taken by XMM-Newton with a duration of 46300 s. The power density spectrum has a complicated shape with two red noise and two white noise components, indicating the presence of two turbulent regions. We developed a statistical `toy model' to study light curves with variability produced by a…
Heating and Dynamics of Two Flare Loop Systems Observed by AIA and EIS
Ding, M. D.; Li, Y.; Qiu, J.
We investigate heating and evolution of flare loops in a C4.7 two-ribbon flare on 2011 February 13. From Solar Dynamics Observatory/Atmospheric Imaging Assembly (AIA) imaging observations, we can identify two sets of loops. Hinode/EUV Imaging Spectrometer (EIS) spectroscopic observations reveal blueshifts at the feet of both sets of loops. The evo…
Scale-dependent hemispherical asymmetry from general initial state during inflation
Gong, Jinn-Ouk; Firouzjahi, Hassan; Namjoo, Mohammad Hossein
We consider a general initial state for inflation as the mechanism for generating scale-dependent hemispherical asymmetry. An observable scale-dependent non-Gaussianity is generated that leads to observable hemispherical asymmetry from the super-horizon long mode modulation. We show that the amplitude of dipole asymmetry falls off exponentially on…
An Upper Bound from Helioseismology on the Stochastic Background of Gravitational Waves
Roth, Markus; Siegel, Daniel M.
The universe is expected to be permeated by a stochastic background of gravitational radiation of astrophysical and cosmological origin. This background is capable of exciting oscillations in solar-like stars. Here we show that solar-like oscillators can be employed as giant hydrodynamical detectors for such a background in the µHz to mHz fr…
Spectral Analysis in Orbital/Superorbital Phase Space and Hints of Superorbital Variability in the Hard X-Rays of LS I +61°303
Torres, Diego F.; Li, Jian; Zhang, Shu
We present an INTEGRAL spectral analysis in the orbital/superorbital phase space of LS I +61°303. A hard X-ray spectrum with no cutoff is observed at all orbital/superorbital phases. The hard X-ray index is found to be uncorrelated with the radio index (non-simultaneously) measured at the same orbital and superorbital phases. In particular, the ab…