118654249
Particle acceleration on the background of the Kerr―Taub―NUT spacetime
Abstract We study the collision of two particles with the different rest masses moving in the equatorial plane of a Kerr–Taub–NUT spacetime and get the center-of-mass (CM) energy for the particles. We find that the CM energy depends not only on the rotation parameter, a , but also on the NUT charge of the Kerr–Taub–NUT spacetime, n . Especially, for the extremal Kerr–Taub–NUT spacetime, an unlimited CM energy can be approached if the parameter a is in the range [ 1 , 2 ] , which is different from that of the Kerr and Kerr–Newman black holes.
118567951
Phantom scalar emission in the Kerr black hole spacetime
We study the absorption probability and Hawking radiation spectra of a phantom scalar field in the Kerr black hole spacetime. We find that the presence of negative kinetic energy terms modifies the standard results in the graybody factor, super-radiance and Hawking radiation. Comparing with the usual scalar particle, the phantom scalar emission is enhanced in the black hole spacetime.
119285485
$P-V$ criticality of AdS black hole in $f(R)$ gravity
We study thermodynamics of a charged AdS black hole in the special $f(R)$ correction with the constant Ricci scalar curvature. Our results show that the the $f(R)$ correction influences the Gibbs free energy and the phase transition of system. The ratio $\rho_c$ occurred at the critical point increases monotonically with the derivative term $f'(R_0)$. We also disclose that the critical exponents are the same as those of the liquid-gas phase transition in the Van der Waals model, which does not depend on the $f(R)$ correction considered here.
118397512
Dynamical evolution of scalar perturbation in Hořava-Lifshitz black-hole spacetimes
We study the dynamical evolution of a massless scalar perturbation in the Ho\ifmmode \check{r}\else \v{r}\fi{}ava-Lifshitz black-hole spacetimes with the coupling constants $\ensuremath{\lambda}=\frac{1}{3}$, $\ensuremath{\lambda}=\frac{1}{2}$ and $\ensuremath{\lambda}=3$, respectively. Our calculation shows that, for the three cases, the scalar perturbations decay without any oscillation in which the decay rate imprints the parameter of the Ho\ifmmode \check{r}\else \v{r}\fi{}ava-Lifshitz black hole. The results are quite different from those in the Schwarzschild AdS black hole and can help us understand more about the Ho\ifmmode \check{r}\else \v{r}\fi{}ava-Lifshitz gravity.
118610112
Scalar emission in a rotating Gödel black hole
We study the absorption probability and Hawking radiation of the scalar field in the rotating G\"odel black hole in minimal five-dimensional gauged supergravity. We find that G\"odel parameter $j$ imprints in the greybody factor and Hawking radiation. It plays a different role from the angular momentum of the black hole in the Hawking radiation and super-radiance. This information can help us know more about rotating G\"odel black holes in minimal five-dimensional gauged supergravity.
118415919
Wave dynamics of phantom scalar perturbation in the background of Schwarzschild black hole
Using Leaver's continue fraction and time domain method, we investigate the wave dynamics of phantom scalar perturbation in the background of Schwarzschild black hole. We find that the presence of the negative kinetic energy terms modifies the standard results in quasinormal spectrums and late-time behaviors of the scalar perturbations. The phantom scalar perturbation in the late-time evolution will grow with an exponential rate.
53497918
THE SSRF ACCELERATOR COMPLEX
The Shanghai Synchrotron Radiation Facility (SSRF) is an intermediate energy light source under design and R&D at Shanghai National Synchrotron Radiation Center (SSRC). Its accelerator complex consists of a 3.5GeV electron storage ring, a full energy booster and a 300MeV linac. Since the SSRF R&D program began in 1999, the design of the SSRF accelerator complex has been evolved smoothly towards a cost-effective machine. The key component prototypes of the SSRF accelerators have been manufactured and tested up to their design specifications. This paper reviews the design and R&D progress of the SSRF accelerator complex and reports its present status.
11090952
Cosmic ray threshold anomaly and kinematics in the dS spacetime
We present a covariant framework of kinematics in the dS spacetime, which is a natural postulate of recent astronomical observations ($\Lambda>0)$. One-particle states are presented explicitly. It is noticed that the dispersion relation of free particles is dependent on the degrees of freedom of angular momentum and spin. This fact can be referred to as the effects of the cosmological constant on kinematics of particles. The kinematics in dS spacetime is used to investigate the phenomenon of ultra high energy cosmic rays. We emphasize the possibility of solving the threshold anomalies of the interactions between ultra high energy cosmic rays and soft photons in the covariant framework of kinematics in the dS spacetime.
195378147
Effects of cosmological constant on motion of UHECR particles
Recent astronomical observations manifest that about two-thirds of the whole energy in the Universe is contributed by a small positive cosmological constant Λ (>0). Then, an asymptotically de Sitter spacetime is premised naturally. However, physics in the de Sitter spacetime is very different from that in the Minkowski spacetime. As the first step, a covariant formalism of the kinematics in the de Sitter spacetime is presented here. By solving exactly the equations of motion for a field, we obtain the dispersion relation of a free particle. It is noticed that the dispersion relation is dependent on the degree of freedom of angular momentum of the particle. We show the threshold anomaly of the ultra high energy cosmic ray disappears naturally in the framework of the de Sitter kinematics.
15997425
A Multiwavelength Study of 1WGA J1346.5-6255: A New γ Cas Analog Unrelated to the Background Supernova Remnant G309.2-00.6
WGA J1346.5-6255 is a ROSAT X-ray source found within the radio lobes of the supernova remnant (SNR) G309.2-00.6. This source also appears to coincide with the bright and early-type star HD 119682, which is in the middle of the galactic open cluster NGC 5281. The radio morphology of the remnant, consisting of two brightened and distorted arcs of emission on opposite sides of the 1WGA J1346.5-6255 source and of a jet-like feature and break in the shell, led to the suggestion that 1WGA J1346.5-6255/G309.2-00.6 is a young analog of the microquasar SS 433 powering the W50 nebula. This motivated us to study this source at X-ray and optical wavelengths. We here present new Chandra observations of 1WGA J1346.5-6255, archival XMM- Newton observations of G309.2-00.6, and optical spectroscopic observations of HD 119682, in order to search for X-ray jets from 1WGA J1346.5-6255, study its association with the SNR, and test for whether HD 119682 represents its optical counterpart. We do not nd evidence for jets from 1WGA J1346.5-6255 down to an unabsorbed ux of 2.6 10 -13 ergs cm -2 s (0.5n7.5 keV), we rule out its association with G309.2-00.6, and we conrm that HD 119682 is its optical counterpart. We derive a distance of 1.2 0.3 kpc, which is consistent with the distance estimate to NGC 5281 (1.3 0.3 kpc), and much smaller than the distance derived to the SNR G309.2-00.6. We discuss the nature of the source, unveil that HD 119682 is a Be star and suggest it is a new member of the recently proposed group of -Cas analogs. The Chandra and XMM-Newton X-ray lightcurves show variability on timescales of hundreds of seconds, and the presence of a possible period of 1500 s that could be the rotational period of an accreting neutron star or white dwarf in this -Cas analog.
14584846
Effects of the Cosmological Constant as the Origin of the Cosmic-Ray Paradox
We show that a tiny but non-zero positive cosmological constant, which has been strongly suggested by the recent astronomical observations on supernovae and CMBR, may change notably the behaviors of the ultrahigh energy cosmic ray interacting with soft photons. The threshold anomaly of the ultrahigh energy cosmic ray disappears naturally after the effects of the cosmological constant are taken into account.