123063882
Direct evidence of the interplanetary magnetic field effect on the cosmic ray shadow by the sun
The Tibet air-shower array, being successively operated at an altitude of 4300 m above sea level since 1990, has detected the shadows of the Sun and Moon in the 10 TeV cosmic-ray flux. In particular, the shadow of the Sun was observed in the direction significantly away from the apparent solar position, under the influence of the solar and interplanetary magnetic fields. A further analysis shows that the shadows by cosmic rays coming from the away and toward field sectors in the interplanetary space are shifted in opposite directions to one another according to the polarity of the fields. This is the first direct observation of the influence of the interplanetary magnetic field on the shadow's displacement
117043052
SEARCH FOR 10 TeV BURST-LIKE EVENTS COINCIDENT WITH THE BATSE BURSTS USING THE TIBET AIR SHOWER ARRAY
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.
121925364
SEARCH FOR 10 TEV GAMMA-RAY EMISSION FROM ACTIVE GALACTIC NUCLEI WITH THE TIBET AIR SHOWER ARRAY
118436059
The Correlated Multi-color Optical Variations of BL Lac Object S5 0716+714
S5 0716+714 is a well-studied BL Lac object in the sky. Verifying the existence of correlations among the flux variations in different bands serves as an important tool to investigate the emission processes. To examine the possible existence of a lag between variations in different optical bands on this source, we employ a discrete correlation function analysis on the light curves. In order to obtain statistically meaningful values for the cross-correlation time lags and their related uncertainties, we perform Monte Carlo simulations called 'flux redistribution/random subset selection'. Our analysis confirms that the variations in different optical light curves are strongly correlated. The time lags show a hint of the variations in high frequency band leading those in low frequency band of the order of a few minutes.
123646598
Progress in Very High Energy Neutrino Astronomic Experiments
In this review, I will report progress in UHE neutrino search using existing experiments and status of constructing detectors. Physics relevant to UHE neutrinos are updated as well.
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.
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.
8231444
Hawking Radiation from Spherically Symmetrical Gravitational Collapse to an Extremal R-N Black Hole for a Charged Scalar Field*
Si-Jie Gao has recently investigated Hawking radiation from spherically symmetrical gravitational collapse to an extremal R-N black hole for a real scalar field. Especially he estimated the upper bound for the expected number of particles in any wave packet belonging to H-out spontaneously produced from the state \0>(in), which confirms the traditional belief that extremal black holes do not radiate particles. Making some modifications, we demonstrate that the analysis can go through for a charged scalar field.
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.