The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Lixin Dai - One of the best experts on this subject based on the ideXlab platform.
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the impact of bound stellar orbits and general relativity on the Temporal Behavior of tidal disruption flares
The Astrophysical Journal, 2013Co-Authors: Lixin Dai, Andres Escala, Paolo De CoppiAbstract:We have carried out general relativistic particle simulations of stars tidally disrupted by massive black holes. When a star is disrupted in a bound orbit with moderate eccentricity instead of a parabolic orbit, the Temporal Behavior of the resulting stellar debris changes qualitatively. The debris is initially all bound, returning to pericenter in a short time about the original stellar orbital timescale. The resulting fallback rate can thus be much higher than the Eddington rate. Furthermore, if the star is disrupted close to the hole, in a regime where general relativity is important, the stellar and debris orbits display general relativistic precession. Apsidal precession can make the debris stream cross itself after several orbits, likely leading to fast debris energy dissipation. If the star is disrupted in an inclined orbit around a spinning hole, nodal precession reduces the probability of self-intersection, and circularization may take many dynamical timescales, delaying the onset of flare activity. An examination of the particle dynamics suggests that quasi-periodic flares with short durations, produced when the center of the tidal stream passes pericenter, may occur in the early-time light curve. The late-time light curve may still show power-law Behavior which is generic to disk accretion processes.more » The detection triggers for future surveys should be extended to capture such 'non-standard' short-term flaring activity before the event enters the asymptotic decay phase, as this activity is likely to be more sensitive to physical parameters such as the black hole spin.« less
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the impact of bound stellar orbits and general relativity on the Temporal Behavior of tidal disruption flares
arXiv: High Energy Astrophysical Phenomena, 2013Co-Authors: Lixin Dai, Andres Escala, Paolo De CoppiAbstract:We have carried out general relativistic particle simulations of stars tidally disrupted by massive black holes. When a star is disrupted in a bound orbit with moderate eccentricity instead of a parabolic orbit, the Temporal Behavior of the resulting stellar debris changes qualitatively. The debris is initially all bound, returning to pericenter in a short time ~ the original stellar orbital timescale. The resulting fallback rate can thus be much higher than the Eddington rate. Furthermore if the star is disrupted close to the hole, in a regime where general relativity is important, the stellar and debris orbits display general relativistic precession. Apsidal precession can make the debris stream cross itself after several orbits, likely leading to fast debris energy dissipation. If the star is disrupted in an inclined orbit around a spinning hole, nodal precession reduces the probability of self-intersection, and circularization may take many dynamical timescales, delaying the onset of flare activity. An examination of the particle dynamics suggests that quasi-periodic flares with short durations, produced when the center of the tidal stream passes pericenter, may occur in the early-time light curve. The late-time light curve may still show power-law Behavior which is generic to disk accretion processes. The detection triggers for future surveys should be extended to capture such "non-standard" short-term flaring activity before the event enters the asymptotic decay phase, as this activity is likely to be more sensitive to physical parameters such as the black hole spin.
Paolo De Coppi - One of the best experts on this subject based on the ideXlab platform.
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the impact of bound stellar orbits and general relativity on the Temporal Behavior of tidal disruption flares
The Astrophysical Journal, 2013Co-Authors: Lixin Dai, Andres Escala, Paolo De CoppiAbstract:We have carried out general relativistic particle simulations of stars tidally disrupted by massive black holes. When a star is disrupted in a bound orbit with moderate eccentricity instead of a parabolic orbit, the Temporal Behavior of the resulting stellar debris changes qualitatively. The debris is initially all bound, returning to pericenter in a short time about the original stellar orbital timescale. The resulting fallback rate can thus be much higher than the Eddington rate. Furthermore, if the star is disrupted close to the hole, in a regime where general relativity is important, the stellar and debris orbits display general relativistic precession. Apsidal precession can make the debris stream cross itself after several orbits, likely leading to fast debris energy dissipation. If the star is disrupted in an inclined orbit around a spinning hole, nodal precession reduces the probability of self-intersection, and circularization may take many dynamical timescales, delaying the onset of flare activity. An examination of the particle dynamics suggests that quasi-periodic flares with short durations, produced when the center of the tidal stream passes pericenter, may occur in the early-time light curve. The late-time light curve may still show power-law Behavior which is generic to disk accretion processes.more » The detection triggers for future surveys should be extended to capture such 'non-standard' short-term flaring activity before the event enters the asymptotic decay phase, as this activity is likely to be more sensitive to physical parameters such as the black hole spin.« less
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the impact of bound stellar orbits and general relativity on the Temporal Behavior of tidal disruption flares
arXiv: High Energy Astrophysical Phenomena, 2013Co-Authors: Lixin Dai, Andres Escala, Paolo De CoppiAbstract:We have carried out general relativistic particle simulations of stars tidally disrupted by massive black holes. When a star is disrupted in a bound orbit with moderate eccentricity instead of a parabolic orbit, the Temporal Behavior of the resulting stellar debris changes qualitatively. The debris is initially all bound, returning to pericenter in a short time ~ the original stellar orbital timescale. The resulting fallback rate can thus be much higher than the Eddington rate. Furthermore if the star is disrupted close to the hole, in a regime where general relativity is important, the stellar and debris orbits display general relativistic precession. Apsidal precession can make the debris stream cross itself after several orbits, likely leading to fast debris energy dissipation. If the star is disrupted in an inclined orbit around a spinning hole, nodal precession reduces the probability of self-intersection, and circularization may take many dynamical timescales, delaying the onset of flare activity. An examination of the particle dynamics suggests that quasi-periodic flares with short durations, produced when the center of the tidal stream passes pericenter, may occur in the early-time light curve. The late-time light curve may still show power-law Behavior which is generic to disk accretion processes. The detection triggers for future surveys should be extended to capture such "non-standard" short-term flaring activity before the event enters the asymptotic decay phase, as this activity is likely to be more sensitive to physical parameters such as the black hole spin.
Larry G Epstein - One of the best experts on this subject based on the ideXlab platform.
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substitution risk aversion and the Temporal Behavior of consumption and asset returns an empirical analysis
Journal of Political Economy, 1991Co-Authors: Larry G Epstein, Stanley E ZinAbstract:This paper investigates the testable restrictions on the time-series Behavior of consumption and asset returns implied by a representative agent model in which interTemporal preferences are represented by utility functions that generalize conventional, time-additive, expected utility. The model based on these preferences allows a clearer separation of observable Behavior attributable to risk aversion and to interTemporal substitution. Further, it nests the predictions of both the consumption CAPM and the static CAPM, and it allows direct tests of the expected utility hypothesis. We find that the performance of the non-expected utility model and tests of the expected utility hypothesis are sensitive to the choice of both consumption measure and instrumental variables.
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substitution risk aversion and the Temporal Behavior of consumption and asset returns an empirical analysis
Journal of Political Economy, 1991Co-Authors: Larry G EpsteinAbstract:This paper investigates the testable restrictions on the time-series behaviour of consumption and asset returns implied by the consumption/portfolio choice problem of an infinitely-lived, representative agent. InterTemporal preferences are characterized by utility functions that generalize conventional, time-additive, expected utility. These generalizations of expected utility, allow for a clear separation of observable behaviour attributable to risk aversion and to interTemporal substitution, and also provide simple nested-tests of the expected utility hypothesis. Using monthly New York Stock Exchange returns data and consumption measured with either per capita expenditures on nondurables or nondurables and services, the expected utility model is rejected. The over-identifying restrictions implied by the non-expected utility model are tested and do not, in general, lead to rejections of the theory.
Tommi Mikkonen - One of the best experts on this subject based on the ideXlab platform.
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formalizing design patterns
International Conference on Software Engineering, 1998Co-Authors: Tommi MikkonenAbstract:Design patterns facilitate reuse of good design practices. They are typically given by using conventional notations that lack well-defined semantics and, therefore reasoning about their Behaviors requires formalization. Even when formalized, conventional communication abstractions may lead to too laborious formalizations when addressing the Temporal Behavior of a pattern as a whole instead of Behaviors local to its components. We show that rigorous reasoning can be eased by formalizing Temporal Behaviors of patterns in terms of high-level abstractions of communication, and that by using property-preserving refinements, specifications can be naturally composed by using patterns as building blocks.
Stanley E Zin - One of the best experts on this subject based on the ideXlab platform.
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substitution risk aversion and the Temporal Behavior of consumption and asset returns an empirical analysis
Journal of Political Economy, 1991Co-Authors: Larry G Epstein, Stanley E ZinAbstract:This paper investigates the testable restrictions on the time-series Behavior of consumption and asset returns implied by a representative agent model in which interTemporal preferences are represented by utility functions that generalize conventional, time-additive, expected utility. The model based on these preferences allows a clearer separation of observable Behavior attributable to risk aversion and to interTemporal substitution. Further, it nests the predictions of both the consumption CAPM and the static CAPM, and it allows direct tests of the expected utility hypothesis. We find that the performance of the non-expected utility model and tests of the expected utility hypothesis are sensitive to the choice of both consumption measure and instrumental variables.
