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Markus J Aschwanden - One of the best experts on this subject based on the ideXlab platform.
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reconciliation of waiting time statistics of solar flares observed in Hard x rays
The Astrophysical Journal, 2010Co-Authors: Markus J Aschwanden, James M MctiernanAbstract:We study the waiting time distributions of solar flares observed in Hard X-Rays with ISEE-3/ICE, HXRBS/SMM, WATCH/GRANAT, BATSE/CGRO, and RHESSI. Although discordant results and interpretations have been published earlier, based on relatively small ranges (<2 decades) of waiting times, we find that all observed distributions, spanning over 6 decades of waiting times (?t 10?3-103?hr), can be reconciled with a single distribution function, N(?t) ?0(1 + ?0?t)?2, which has a power-law slope of p 2.0 at large waiting times (?t 1-1000?hr) and flattens out at short waiting times ?t ?t 0 = 1/?0. We find a consistent breakpoint at ?t 0 = 1/?0 = 0.80 ? 0.14?hr from the WATCH, HXRBS, BATSE, and RHESSI data. The distribution of waiting times is invariant for sampling with different flux thresholds, while the mean waiting time scales reciprocically with the number of detected events, ?t 0 1/n det. This waiting time distribution can be modeled with a nonstationary Poisson process with a flare rate ? = 1/?t that varies as f(?) ??1exp ? (?/?0). This flare rate distribution requires a highly intermittent flare productivity in short clusters with high rates, separated by relatively long quiescent intervals with very low flare rates.
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reconciliation of waiting time statistics of solar flares observed in Hard x rays
arXiv: Solar and Stellar Astrophysics, 2010Co-Authors: Markus J Aschwanden, James M MctiernanAbstract:We study the waiting time distributions of solar flares observed in Hard X-Rays with ISEE-3/ICE, HXRBS/SMM, WATCH/GRANAT, BATSE/CGRO, and RHESSI. Although discordant results and interpretations have been published earlier, based on relatively small ranges ($< 2$ decades) of waiting times, we find that all observed distributions, spanning over 6 decades of waiting times ($\Delta t \approx 10^{-3}- 10^3$ hrs), can be reconciled with a single distribution function, $N(\Delta t) \propto \lambda_0 (1 + \lambda_0 \Delta t)^{-2}$, which has a powerlaw slope of $p \approx 2.0$ at large waiting times ($\Delta t \approx 1-1000$ hrs) and flattens out at short waiting times $\Delta t \lapprox \Delta t_0 = 1/\lambda_0$. We find a consistent breakpoint at $\Delta t_0 = 1/\lambda_0 = 0.80\pm0.14$ hours from the WATCH, HXRBS, BATSE, and RHESSI data. The distribution of waiting times is invariant for sampling with different flux thresholds, while the mean waiting time scales reciprocically with the number of detected events, $\Delta t_0 \propto 1/n_{det}$. This waiting time distribution can be modeled with a nonstationary Poisson process with a flare rate $\lambda=1/\Delta t$ that varies as $f(\lambda) \propto \lambda^{-1} \exp{-(\lambda/\lambda_0)}$. This flare rate distribution represents a highly intermittent flaring productivity in short clusters with high flare rates, separated by quiescent intervals with very low flare rates.
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physics of the solar corona an introduction with problems and solutions
2006Co-Authors: Markus J AschwandenAbstract:Thermal Radiation.- Hydrostatics.- Hydrodynamics.- Magnetic Fields.- Magneto-Hydrodynamics (MHD).- MHD Oscillations.- Propagating MHD Waves.- Coronal Heating.- Magnetic Reconnection.- Particle Acceleration.- Particle Kinematics.- Hard X-Rays.- Gamma-Rays.- Radio Emission.- Flare Plasma Dynamics.- Coronal Mass Ejections (CMEs).
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physics of the solar corona an introduction
Physics of the Solar Corona, 2004Co-Authors: Markus J AschwandenAbstract:Thermal Radiation.- Hydrostatics.- Hydrodynamics.- Magnetic Fields.- Magneto-Hydrodynamics (MHD).- MHD Oscillations.- Propagating MHD Waves.- Coronal Heating.- Magnetic Reconnection.- Particle Acceleration.- Particle Kinematics.- Hard X-Rays.- Gamma-Rays.- Radio Emission.- Flare Plasma Dynamics.- Coronal Mass Ejections (CMEs).
James M Mctiernan - One of the best experts on this subject based on the ideXlab platform.
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reconciliation of waiting time statistics of solar flares observed in Hard x rays
The Astrophysical Journal, 2010Co-Authors: Markus J Aschwanden, James M MctiernanAbstract:We study the waiting time distributions of solar flares observed in Hard X-Rays with ISEE-3/ICE, HXRBS/SMM, WATCH/GRANAT, BATSE/CGRO, and RHESSI. Although discordant results and interpretations have been published earlier, based on relatively small ranges (<2 decades) of waiting times, we find that all observed distributions, spanning over 6 decades of waiting times (?t 10?3-103?hr), can be reconciled with a single distribution function, N(?t) ?0(1 + ?0?t)?2, which has a power-law slope of p 2.0 at large waiting times (?t 1-1000?hr) and flattens out at short waiting times ?t ?t 0 = 1/?0. We find a consistent breakpoint at ?t 0 = 1/?0 = 0.80 ? 0.14?hr from the WATCH, HXRBS, BATSE, and RHESSI data. The distribution of waiting times is invariant for sampling with different flux thresholds, while the mean waiting time scales reciprocically with the number of detected events, ?t 0 1/n det. This waiting time distribution can be modeled with a nonstationary Poisson process with a flare rate ? = 1/?t that varies as f(?) ??1exp ? (?/?0). This flare rate distribution requires a highly intermittent flare productivity in short clusters with high rates, separated by relatively long quiescent intervals with very low flare rates.
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reconciliation of waiting time statistics of solar flares observed in Hard x rays
arXiv: Solar and Stellar Astrophysics, 2010Co-Authors: Markus J Aschwanden, James M MctiernanAbstract:We study the waiting time distributions of solar flares observed in Hard X-Rays with ISEE-3/ICE, HXRBS/SMM, WATCH/GRANAT, BATSE/CGRO, and RHESSI. Although discordant results and interpretations have been published earlier, based on relatively small ranges ($< 2$ decades) of waiting times, we find that all observed distributions, spanning over 6 decades of waiting times ($\Delta t \approx 10^{-3}- 10^3$ hrs), can be reconciled with a single distribution function, $N(\Delta t) \propto \lambda_0 (1 + \lambda_0 \Delta t)^{-2}$, which has a powerlaw slope of $p \approx 2.0$ at large waiting times ($\Delta t \approx 1-1000$ hrs) and flattens out at short waiting times $\Delta t \lapprox \Delta t_0 = 1/\lambda_0$. We find a consistent breakpoint at $\Delta t_0 = 1/\lambda_0 = 0.80\pm0.14$ hours from the WATCH, HXRBS, BATSE, and RHESSI data. The distribution of waiting times is invariant for sampling with different flux thresholds, while the mean waiting time scales reciprocically with the number of detected events, $\Delta t_0 \propto 1/n_{det}$. This waiting time distribution can be modeled with a nonstationary Poisson process with a flare rate $\lambda=1/\Delta t$ that varies as $f(\lambda) \propto \lambda^{-1} \exp{-(\lambda/\lambda_0)}$. This flare rate distribution represents a highly intermittent flaring productivity in short clusters with high flare rates, separated by quiescent intervals with very low flare rates.
A. O. Benz - One of the best experts on this subject based on the ideXlab platform.
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high resolution imaging of solar flare ribbons and its implication on the thick target beam model
The Astrophysical Journal, 2011Co-Authors: Sam Krucker, Eduard P Kontar, A. O. Benz, H S Hudson, Natasha L S Jeffrey, Marina Battaglia, A CsillaghyAbstract:We report on high-resolution optical and Hard X-ray observations of solar flare ribbons seen during the GOES X6.5 class white-light flare of 2006 December 6. The data consist of imaging observations at 430 nm (the Fraunhofer G band) taken by the Hinode Solar Optical Telescope with the Hard X-Rays observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager. The two sets of data show closely similar ribbon structures, strongly suggesting that the flare emissions in white light and in Hard X-Rays have physically linked emission mechanisms. While the source structure along the ribbons is resolved at both wavelengths (length ~ 30''), only the G-band observations resolve the width of the ribbon, with values between ~05 and ~18. The unresolved Hard X-ray observations reveal an even narrower ribbon in Hard X-Rays (the main footpoint has a width perpendicular to the ribbon of 5 × 1012 erg s–1 cm–2 provided by an electron flux of 1 × 1020 electrons s–1 cm–2 above 18 keV. This requires that the beam density of electrons above 18 keV be at least 1 × 1010 cm–3. Even if field lines converge toward the chromospheric footpoints, the required beam in the corona has too high a density to be described as a dilute tail population on top of a Maxwellian core. We discuss this issue and others associated with this extreme event, which poses serious questions to the standard thick target beam interpretation of solar flares.
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Particle acceleration in flares
Solar Physics, 1994Co-Authors: A. O. Benz, T. Kosugi, M. J. Aschwanden, S. G. Benka, E. L. Chupp, S. Enome, H. Garcia, G. D. Holman, V. G. Kurt, T. SakaoAbstract:Particle acceleration is intrinsic to the primary energy release in the impulsive phase of solar flares, and we cannot understand flares without understanding acceleration. New observations in soft and Hard X-Rays, γ-rays and coherent radio emissions are presented, suggesting flare fragmentation in time and space. X-ray and radio measurements exhibit at least five different time scales in flares. In addition, some new observations of delayed acceleration signatures are also presented. The theory of acceleration by parallel electric fields is used to model the spectral shape and evolution of Hard X-Rays. The possibility of the appearance of double layers is further investigated.
T Kampfer - One of the best experts on this subject based on the ideXlab platform.
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optical control of Hard x ray polarization by electron injection in a laser wakefield accelerator
Nature Communications, 2013Co-Authors: Michael Schnell, Alexander Savert, I Uschmann, Maria Reuter, Maria Nicolai, T KampferAbstract:Radiation sources driven by laser-plasma accelerators have the potential to produce shorter bursts of radiation at lower cost than those based on conventional accelerators. Schnell et al. demonstrate the ability to control the polarization of the bursts of Hard X-Rays produced by such a source.
T. Sakao - One of the best experts on this subject based on the ideXlab platform.
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Particle acceleration in flares
Solar Physics, 1994Co-Authors: A. O. Benz, T. Kosugi, M. J. Aschwanden, S. G. Benka, E. L. Chupp, S. Enome, H. Garcia, G. D. Holman, V. G. Kurt, T. SakaoAbstract:Particle acceleration is intrinsic to the primary energy release in the impulsive phase of solar flares, and we cannot understand flares without understanding acceleration. New observations in soft and Hard X-Rays, γ-rays and coherent radio emissions are presented, suggesting flare fragmentation in time and space. X-ray and radio measurements exhibit at least five different time scales in flares. In addition, some new observations of delayed acceleration signatures are also presented. The theory of acceleration by parallel electric fields is used to model the spectral shape and evolution of Hard X-Rays. The possibility of the appearance of double layers is further investigated.
