13913623
Hawking fluxes, back reaction and covariant anomalies
Starting from the chiral covariant effective action approach of Banerjee and Kulkarni (2008 Phys. Lett. B 659 827), we provide a derivation of the Hawking radiation from a charged black hole in the presence of gravitational back reaction. The modified expressions for charge and energy flux, due to the effect of one-loop back reaction are obtained.
119114244
Transport in non-conformal holographic fluids
A bstractWe have considered non-conformal fluid dynamics whose gravity dual is a certain Einstein dilaton system with Liouville type dilaton potential, characterized by an intrinsic parameter η. We have discussed the Hawking-Page transition in this framework using hard-wall model and it turns out that the critical temperature of the Hawking-Page transition encapsulates a non-trivial dependence on η. We also obtained transport coefficients such as AC conductivity, shear viscosity and diffusion constant in the hydrodynamic limit, which show non-trivial η dependent deviations from those in conformal fluids, although the ratio of the shear viscosity to entropy density is found to saturate the universal bound. Some of the retarded correlators are also computed in the high frequency limit for case study.
10764639
ASCA Discovery of an X-Ray Pulsar in the Error Box of SGR 1900+14
We present a 2-10 keV ASCA observation of the field around the soft gamma repeater SGR 1900+14. One quiescent X-ray source was detected in this observation, and it was in the SGR error box. In 2-10 keV X-rays, its spectrum may be fitted by a power law with index -2.2, and its unabsorbed flux is 9.6 × 10-12 ergs cm-2 s-1. We also find a clear 5.16 s period. The properties of the three well-studied soft gamma repeaters are remarkably similar to one another, and they provide evidence that all of them are associated with young, strongly magnetized neutron stars in supernova remnants.
118517610
Effective couplings approach to neutralino dark matter relic density
In this work, we analyze the electroweak loop corrections to the Neutralino dark matter relic density in the framework of effective coupling. In the first part, we comment on the generic features of the corrections and quantitative changes to the predicted relic density. We analyze the correlation between the characteristics of effective couplings to the nature of neutralino. Effective couplings, however, absorb only the most dominant one loop corrections and are not an exact calculation. In the second part, we assess the validity of effective couplings by comparing them to the full one loop calculations in various regions of parameter space.
8913778
Spitzer Observations of the New Luminous Red Nova M85 OT2006-1
M85 OT2006-1 is the latest and most brilliant addition to the small group of known luminous red novae (LRNe). An identifying characteristic of the previously detected events (M31 RV, V4332 Sgr, and V838 Mon) was a spectral redward evolution connected with an emerging infrared component following the optical decay. Here we report on the discovery of a similar feature in Keck NIRC and Spitzer photometry of M85 OT2006-1 6 months posteruption. We find that its 2.1-22 μm spectral energy distribution is best described by a blackbody with effective temperature T_(eff) = 950 ± 150 K and bolometric luminosity L = 2.9^(+0.4)_(-0.5) × 10^5 L_⊙. Assuming spherical geometry, the blackbody effective radius, R = 2.0^(+0.6)_(-0.4) × 10^4 R_⊙, and corresponding expansion velocity, v = 870^(+260)_(-180) km s^(-1), are remarkably similar to the properties of M31 RV 70 days after its eruption. Furthermore, we propose a search strategy for LRNe in the local universe making use of the longevity of their infrared excess emission and discuss the expected number of events in the Spitzer Infrared Nearby Galaxies Survey.
15430026
A Late-Time Flattening of Afterglow Light Curves
We present a sample of radio afterglow light curves with measured decay slopes that show evidence of a flattening at late times compared to optical and X-ray decay indices. The simplest origin for this behavior is that the change in slope is due to a jetlike outflow making a transition to subrelativistic expansion. This can explain the late-time radio light curves for some but not all of the bursts in the sample. We investigate several possible modifications to the standard fireball model, which can flatten late-time light curves. Changes to the shock microphysics, which govern particle acceleration, or energy injection to the shock (either radially or azimuthally) can reproduce the observed behavior. Distinguishing between these different possibilities will require simultaneous optical/radio monitoring of afterglows at late times.
35499627
The White Dwarf Companion of a 2 M_☉ Neutron Star
We report the optical discovery of the companion to the 2 M_☉ millisecond pulsar PSR J1614–2230. The optical colors show that the 0.5 M_☉ companion is a 2.2 Gyr old He-CO white dwarf. We infer that M during the accretion phase is <10^(-2), M_(edd). We show that the pulsar was born with a spin close to its current value, well below the rebirth line. The spin-down parameters, the mass of the pulsar, and the age of the system challenge the simple recycling model for the formation of millisecond pulsars.