118457510
YNOGK: A NEW PUBLIC CODE FOR CALCULATING NULL GEODESICS IN THE KERR SPACETIME
Following the work of Dexter & Agol, we present a new public code for the fast calculation of null geodesics in the Kerr spacetime. Using Weierstrass's and Jacobi's elliptic functions, we express all coordinates and affine parameters as analytical and numerical functions of a parameter p, which is an integral value along the geodesic. This is the main difference between our code and previous similar ones. The advantage of this treatment is that the information about the turning points does not need to be specified in advance by the user, and many applications such as imaging, the calculation of line profiles, and the observer-emitter problem, become root-finding problems. All elliptic integrations are computed by Carlson's elliptic integral method as in Dexter & Agol, which guarantees the fast computational speed of our code. The formulae to compute the constants of motion given by Cunningham & Bardeen have been extended, which allow one to readily handle situations in which the emitter or the observer has an arbitrary distance from, and motion state with respect to, the central compact object. The validation of the code has been extensively tested through applications to toy problems from the literature. The source FORTRAN code is freely available for download on our Web site http://www1.ynao.ac.cn/similar to yangxl/yxl.html.
17321754
Implications of Bulk Velocity Structures in AGN Jets
Synchrotron self-Compton (SSC) models and External Compton (EC) models of AGN jets with continually longitudinal and transverse bulk velocity structures have been constructed. The observed spectra show complex and interesting patterns in different velocity structures and viewing angles. These models were used to calculate the synchrotron and inverse Compton spectra of two typical BL Lac objects (BLO) (Mrk 421 and 0716+714) and (one) Flat Spectrum Radio Quasars (FSRQs) (3C 279), and to discuss the implications of jet bulk velocity structures in a unification of the BLO and FR I radio galaxies (FRI). By calculating the synchrotron spectra and SSC spectra of BL Lac object jets with continually bulk velocity structures, we have found that the spectra are much different from those in jets with a uniform velocity structure under increasing viewing angles. The unification of BLO and FRI is less constrained by the viewing angles, and would be imprinted by velocity structures intrinsic to the jets, themselves. By considering jets with bulk velocity structures constrained by the apparent speed, we discuss the velocity structures imprinted on the observed spectra for different viewing angles. We find that the spectra are greatly impacted by longitudinal velocity structures, because the volume elements are compressed or expanded. Finally, we present the EC spectra of FSRQs and FR II radio galaxies (FRII), and find that they are weakly affected by the velocity structures compared to synchrotron and SSC spectra.
17685255
Knot in centaurus A: A stochastic magnetic field for diffusive synchrotron radiation?
The emission of relativistic electrons moving in the random and small-scale magnetic field is presented by diffusive synchrotron radiation (DSR). In this Letter, we revisit the perturbative treatment of DSR. We propose that a random and small-scale magnetic field might be generated by the turbulence. As an example, multiband radiation of the knot in Cen A comes from the electrons with energy gamma(e) similar to 10(3 -) 10(4) in the magnetic field of 10(-3) G. The multiband spectrum of DSR is well determined by the feature of a stochastic magnetic field. These results put strong constraints on the models of particle acceleration.
118436895
Mechanism of very high energy radiation in BL Lacertae object 3C 66A
Aims. Our goal is to understand the nature of blazars and the mechanisms for generating high-energy.-rays, through investigation of the blazar 3C 66A. Methods. We model the high-energy spectrum of 3C 66A, which was observed recently with the Fermi-LAT and VERITAS telescopes. The spectrum has a hard change from the energy range of 0.2-100 GeV to 200-500 GeV in recent almost contemporaneous observations of two telescopes. Results. The de-absorbed VERITAS spectrum depends strongly on redshift, which is highly uncertain. If z = 0.444 is adopted, we are able to use the SSC model to produce the Fermi-LAT component and the EC model to the VERITAS component. However, if z = 0.1, the intrinsic VERITAS spectrum will be softer, and there will be a smooth link between the Fermi-LAT and VERITAS spectra that can be explained using an SSC model.
14071619
The Mass Distribution of Black Holes in BL Lacertae Objects
In this {\it Letter}, we make an attempt to estimate the masses of black holes and their distributions in BL Lac objects. We find there is a bimodal population of black hole masses in BL Lacs: the first has a lower-mass peak centred at $\sim 7.0 \times 10^6\sunm$ composed of high frequency-peaked BL Lacs (HBLs) and the second is a higher-mass ($>10^9\sunm$) population composed of low frequency-peaked BL Lacs (LBLs). The low mass family of black holes in HBLs does not satisfy the Magorrian et al. relation whereas the high mass family in LBLs does this relation and is in agreement with Laor's limit. The origination of the bimodal distribution of black hole mass remains open.
118677286
Gamma-ray Burst Prompt Emission: Jitter Radiation in Stochastic Magnetic Field Revisited
We revisit the radiation mechanism of relativistic electrons in the stochastic magnetic field and apply it to the high-energy emissions of gamma-ray bursts (GRBs). We confirm that jitter radiation is a possible explanation for GRB prompt emission in the condition of a large electron deflection angle. In the turbulent scenario, the radiative spectral property of GRB prompt emission is decided by the kinetic energy spectrum of turbulence. The intensity of the random and small-scale magnetic field is determined by the viscous scale of the turbulent eddy. The microphysical parameters epsilon(e) and epsilon(B) can be obtained. The acceleration and cooling timescales are estimated as well. Due to particle acceleration in magnetized filamentary turbulence, the maximum energy released from the relativistic electrons can reach a value of about 10(14) eV. The GeV GRBs are possible sources of high-energy cosmic-ray.
118460517
INTEGRAL observations of the gamma-ray binary 1FGL J1018.6-5856
The Fermi-LAT collaboration has recently reported that one of their detected sources, namely, 1FGL J1018.6-5856, is a new gamma-ray binary similar to LS 5039. This has prompted efforts to study its multi-frequency behavior. In this report, we present the results from 5.78-Ms INTEGRAL IBIS/ISGRI observations on the source 1FGL J1018.6-5856. 
By combining all the available INTEGRAL data, a detection is made at a significance level of 5.4 sigma in the 18-40 keV band, with an average intensity of 0.074 counts/s . However, we find that, there is non-statistical noise in the image that effectively reduces the significance to about 4 sigma and a significant part of the signal appears to be located in a 0.2-wide phase region, at phases 0.4-0.6 (where even the corrected significance amounts to 90% of the total signal found). Given the scarcity of counts, a variability is hinted at about 3 sigma at the hard X-rays, with an anti-correlation with the Fermi-LAT periodicity. Should this behavior be true, it would be similar to that found in LS 5039, and prompt observations with TeV telescopes at phases anti-correlated with the GeV maximum.
7591156
Observation of Cabibbo suppressed B --> D(*)K- decays at Belle.
We report observations of the Cabibbo suppressed decays B-->D((*))K- using a 10.4 fb(-1) data sample accumulated at the Upsilon(4S) resonance with the Belle detector at the KEKB e(+)e(-) storage ring. We find that the ratios of Cabibbo suppressed to Cabibbo favored branching fractions are B(B--->D0K-)/B(B--->D0pi(-)) = 0.079+/-0.009+/-0.006, B(B(0)-->D+K-)/B(B(0)-->D+pi(-)) = 0.068+/-0.015+/-0.007, B(B--->D(*0)K-)/B(B--->D(*0)pi(-)) = 0.078+/-0.019+/-0.009, and B(B(0)-->D(*+)K-)/B(B(0)-->D(*+)pi(-)) = 0.074+/-0.015+/-0.006. These are the first observations of the B-->D+K-, D(*0)K-, and D(*+)K- decay processes.
126069612
Implications of infalling Fe II - emitting clouds in AGN: anisotropic properties
125128095
Search for tau --> mu gamma decay at Belle
122372922
A GENERAL-METHOD FOR CALCULATING PRINCIPAL VALUE INTEGRALS NUMERICALLY IN AN N-DIMENSIONAL REGION
Abstract Based on the antithetic cancellation technique, we propose a numerical method to calculate the N -dimensional principal value integrals. This method is powerful for numerically evaluating a multi-dimensional Feynman parameter integral with the singularity which occurs in loop calculations of quantum field theories, when some internal lines of the related Feynman diagrams are allowed by kinematics to approach to the corresponding mass shells.