122996811
Newman-Penrose constants of the Kerr-Newman metric
The Newman-Unti formalism of the Kerr-Newman metric near future null infinity is developed, with which the Newman-Penrose constants for both the gravitational and electromagnetic fields of the Kerr-Newman metric are computed and shown to be zero. The multipole structure near future null infinity in the sense of Janis-Newman of the Kerr-Newman metric is then further studied. It is found that up to the ${2}^{4}$-pole, modulo a constant dependent upon the order of the pole, these multipole moments agree with those of Geroch-Hansen multipole moments defined at spatial infinity.
118380186
Numerical evolution of multiple black holes with accurate initial data
We present numerical evolutions of three equal-mass black holes using the moving puncture approach. We calculate puncture initial data for three black holes solving the constraint equations by means of a high-order multigrid elliptic solver. Using these initial data, we show the results for three black hole evolutions with sixth-order waveform convergence. We compare results obtained with the BAM and AMSS- N C KU codes with previous results. The approximate analytic solution to the Hamiltonian constraint used in previous simulations of three black holes leads to different dynamics and waveforms. We present some numerical experiments showing the evolution of four black holes and the resulting gravitational waveform.
119209594
Constructing EOB dynamics with numerical energy flux for intermediate-mass-ratio inspirals
A new scheme for computing dynamical evolutions and gravitational radiations for intermediatemass-ratio inspirals (IMRIs) based on an effective one-body (EOB) dynamics plus Teukolsky perturbation theory is built in this paper. In the EOB framework, the dynamics essentially affects the resulted gravitational waveform for binary compact star system. This dynamics includes two parts. One is the conservative part which comes from effective one-body reduction. The other part is the gravitational back reaction which contributes to the shrinking process of the inspiral of binary compact star system. Previous works used analytical waveform to construct this back reaction term. Since the analytical form is based on post-Newtonian expansion, the consistency of this term is always checked by numerical energy flux. Here we directly use numerical energy flux by solving the Teukolsky equation via the frequency-domain method to construct this back reaction term. And the conservative correction to the leading order terms in mass-ratio is included in the deformed-Kerr metric and the EOB Hamiltonian. We try to use this method to simulate not only quasi-circular adiabatic inspiral but also the nonadiabatic plunge phase. For several different spinning black holes, we demonstrate and compare the resulted dynamical evolutions and gravitational waveforms.
122607999
From binary black hole simulation to triple black hole simulation
Black hole systems are among the most promising sources for a gravitational wave detection project. Now, China is planning to construct a space-based laser interferometric detector as a follow-on mission of LISA in the near future. Aiming to provide some theoretical support to this detection project on the numerical relativity side, we focus on black hole systems simulation in this work. Considering the globular galaxy, multiple black hole systems also likely to exist in our universe and play a role as a source for the gravitational wave detector we are considering. We will give a progress report in this paper on our black hole system simulation. More specifically, we will present triple black hole simulation together with binary black hole simulation. On triple black hole simulations, one novel perturbational method is proposed.
119188076
Reinvestigation of moving punctured black holes with a new code
We report on our code, in which the moving puncture method is applied and an adaptive/fixed mesh refinement is implemented, and on its preliminary performance on black hole simulations. Based on the Baumgarte-Sharpiro-Shibata-Nakamura (BSSN) formulation, up-to-date gauge conditions and the modifications of the formulation are also implemented and tested. In this work, we present our primary results about the simulation of a single static black hole, of a moving single black hole, and of the head-on collision of a binary black hole system. For the static punctured black hole simulations, different modifications of the BSSN formulation are applied. It is demonstrated that both the currently used sets of modifications lead to a stable evolution. For cases of a moving punctured black hole with or without spin, we search for viable gauge conditions and study the effect of spin on the black hole evolution. Our results confirm previous results obtained by other research groups. In addition, we find a new gauge condition, which has not yet been adopted by any other researchers, which can also give stable and accurate black hole evolution calculations. We examine the performance of the code for the head-on collision of a binary black hole system, andmore » the agreement of the gravitational waveform it produces with that obtained in other works. In order to understand qualitatively the influence of matter on the binary black hole collisions, we also investigate the same head-on collision scenarios but perturbed by a scalar field. The numerical simulations performed with this code not only give stable and accurate results that are consistent with the works by other numerical relativity groups, but also lead to the discovery of a new viable gauge condition, as well as clarify some ambiguities in the modification of the BSSN formulation. These results demonstrate that this code is reliable and ready to be used in the study of more realistic astrophysical scenarios and of numerical relativity.« less
11176637
Quasinormal modes for Weyl neutrino field in RN black holes
We employ the WKB approximation up to the third order to determine the low-lying quasinormal modes for the Weyl neutrino field in RN black holes, which are the most relevant to the evolution of the field around a black hole in the intermediate stage. It is shown that the quasinormal mode frequencies for the Weyl neutrino field in RN black holes are different from those in Schwarzschild black holes owing to the charge-induced additional gravitation, and the variations of the quasinormal mode frequencies for the Weyl neutrino field are similar to those for integral spin fields in RN black holes.
2097776
FLUCTUATIONS OF SPATIAL PATTERNS AS A MEASURE OF CLASSICAL CHAOS
In problems where the temporal evolution of a nonlinear system cannot be followed, a method for studying the fluctuations of spatial patterns has been developed. That method is applied to well-known problems in deterministic chaos (the logistic map and the Lorenz model) to check its effectiveness in characterizing the dynamical behaviors. It is found that the indices {mu}{sub q} are as useful as the Lyapunov exponents in providing a quantitative measure of chaos. When applied to the Ising system of finite size, it is shown how {mu}{sub q} can be used to determine the critical temperature. {copyright} {ital 1997} {ital The American Physical Society}
122982997
A measurement of the average longitudinal development profile of cosmic ray air showers between 1017 and 1018 eV
Abstract The average extensive air shower longitudinal development profile is measured. Events between 10 17 and 10 18 eV recorded by the HiRes/MIA hybrid experiment are used for the average profile. Several functional forms are examined using this average profile. The best-fit parameters for the above functions are determined.
15144157
PHASE TRANSITION IN EVOLUTIONARY GAMES
The evolution of cooperative behavior is studied in the deterministic version of the Prisoners' Dilemma on a two-dimensional lattice. The payoff parameter is set at the critical region 1.8<b<2.0, where clusters of cooperators are formed in all spatial sizes. Using the factorial moments developed in particle and nuclear physics for the study of phase transition, the distribution of cooperators is studied as a function of the bin size covering varying numbers of lattice cells. From the scaling behavior of the moments a scaling exponent is determined and is found to lie in the range where phase transitions are known to take place in physical systems. It is therefore inferred that when the payoff parameter is increased through the critical region the biological system of cooperators undergoes a phase transition to defectors. The universality of the critical behavior is thus extended to include also this particular model of evolution dynamics.
118587418
Testing Lorentz invariance with the ultrahigh energy cosmic ray spectrum
The Greisen-Zatsepin-Kuzmin cutoff predicted at the ultrahigh energy cosmic ray spectrum has been observed by the HiRes and Auger experiments. The results put severe constraints on the effect of Lorentz invariance violation (LIV), which has been introduced to explain the absence of the Greisen-Zatsepin-Kuzmin cutoff indicated in the AGASA data. Assuming a homogeneous source distribution with a single power-law spectrum, we calculate the ultrahigh energy cosmic ray spectrum observed on the Earth by taking photopion production, e(+)e(-) pair production, and the adiabatic energy loss into account. The effect of LIV is also taken into account in the calculation. By fitting the HiRes monocular spectra and the Auger combined spectra, we show that the LIV parameter is constrained to xi=-0.8(-0.5)(+3.2)x10(-23) and 0.0(-0.4)(+1.0)x10(-23), respectively, which is very consistent with strict Lorentz invariance up to the highest energy.
117043052
SEARCH FOR 10 TeV BURST-LIKE EVENTS COINCIDENT WITH THE BATSE BURSTS USING THE TIBET AIR SHOWER ARRAY