15809457
Hawking radiation, effective actions and covariant boundary conditions
From an appropriate expression for the effective action, the Hawking radiation from charged black holes is derived, using only covariant boundary conditions at the event horizon. The connection of our approach with the Unruh vacuum and the recent analysis [S.P. Robinson, F. Wilczek, Phys. Rev. Lett. 95 (2005) 011303, gr-qc/0502074; S. Iso, H. Umetsu, F. Wilczek, Phys. Rev. Lett. 96 (2006) 151302, hep-th/0602146; R. Banerjee, S. Kulkarni, arXiv: 0707.2449 [hep-th]] of Hawking radiation using anomalies is established.
116599063
Hawking fluxes and covariant anomalies
A non-destructive, direct method and apparatus for producing stretch blow molded articles having at least one physical dimension within a preselected range. The apparatus includes an injection mold defining an injection mold interior surface having a first differentially dimensioned portion disposed at a preselected location thereon and capable of producing a parison having a parison exterior surface including a first marker formed by contact with the first differentially dimensioned portion, and a stretch blow mold defining a stretch blow mold interior surface having a second differentially dimensioned portion disposed at a predetermined location thereon and capable of producing the article from the parison including a second marker formed by contact with the second differentially dimensioned portion. Relative position of the first marker with respect to the second marker indicates whether a dimension is within a preselected range. The method includes injection molding a parison so that a parison exterior surface includes a first marker disposed at a preselected position thereon and formed by contact with a first differentially dimensioned portion disposed at a preselected location on an injection mold interior surface, and stretch blow molding an article from the parison so that an article exterior surface includes a second marker disposed at a predetermined position thereon and formed by contact with a second differentially dimensioned portion disposed at a predetermined location on a stretch blow mold interior surface.
119234273
Hawking radiation and near horizon universality of chiral Virasoro algebra
We show that the diffeomorphism anomaly together with the trace anomaly reveal a chiral Virasoro algebra near the event horizon of a black hole. This algebra is the same irrespective of whether the anomaly is covariant or consistent, thereby manifesting its universal character and the fact that only the outgoing modes are relevant near the horizon. Our analysis therefore clarifies the role of the trace anomaly in the diffeomorphism anomaly approach [Robinson and Wilczek in Phys. Rev. Lett. 95:011303, 2005; Iso et al. in Phys. Rev. Lett. 96:151302, 2006; Banerjee and Kulkarni in Phys. Rev. D 77:024018, 2008; Gangopadhyay and Kulkarni in Phys. Rev. D 77:024038, 2008] to the Hawking radiation.
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.
119246679
Modified dispersion relations and the response of the rotating Unruh-DeWitt detector
We study the response of a rotating monopole detector that is coupled to a massless scalar field which is described by a nonlinear dispersion relation in flat spacetime. Since it does not seem to be possible to evaluate the response of the rotating detector analytically, we resort to numerical computations. Interestingly, unlike the case of the uniformly accelerated detector that has been considered recently, we find that defining the transition probability rate of the rotating detector poses no difficulties. Further, we show that the response of the rotating detector can be computed exactly (albeit, numerically) even when it is coupled to a field that is governed by a nonlinear dispersion relation. We also discuss the response of the rotating detector in the presence of a cylindrical boundary on which the scalar field is constrained to vanish. While superluminal dispersion relations hardly affect the standard results, we find that subluminal dispersion relations can lead to relatively large modifications.
119219712
Non-conformal hydrodynamics in Einstein-dilaton theory
A bstractIn the Einestein-dilaton theory with a Liouville potential parameterized by η, we find a Schwarzschild-type black hole solution. This black hole solution, whose asymptotic geometry is described by the warped metric, is thermodynamically stable only for 0 ≤ η < 2. Applying the gauge/gravity duality, we find that the dual gauge theory represents a non-conformal thermal system with the equation of state depending on η. After turning on the bulk vector fluctuations with and without a dilaton coupling, we calculate the charge diffusion constant, which indicates that the life time of the quasi normal mode decreases with η. Interestingly, the vector fluctuation with the dilaton coupling shows that the DC conductivity increases with temperature, a feature commonly found in electrolytes.
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.
8622960
The Progenitors of Short-Hard Gamma-Ray Bursts from an Extended Sample of Events
The detection of the afterglow emission and host galaxies of short-hard gamma-ray bursts (SHBs) is one of the most exciting recent astronomical discoveries. Indications that SHB progenitors belong to old stellar populations, in contrast to those of the long-soft GRBs, provide a strong clue about their physical nature. Definitive conclusions however are limited by the small number of SHBs with known hosts. Here, we present our investigation of SHBs previously localized by the interplanetary network (IPN) using new and archival optical and X-ray observations. We show that we can likely identify the host galaxies/clusters for additional two bursts, significantly increasing the sample of SHBs with known hosts and/or distances. In particular, we determine that the bright SHB 790613 occurred within the rich galaxy cluster Abell 1892, making it probably the nearest SHB currently known. We show that the brightest galaxy within the error box of SHB 000607, at z=0.14, is most likely the host galaxy of this event. Additionally, we rule out the existence of galaxy overdensities (down to ~21mag) near the locations of two other SHBs, and set a lower limit on their probable redshift. We combine our SHB sample with events discovered recently by the Swift and HETE-2 missions, and investigate the properties of the extended sample. Comparison to SNe Ia shows that the progenitors of SHBs are typically older, implying a typical life time of several Gy. We also show that it is unlikely that there is a significant population of progenitors with life time shorter than 1Gy. This result disfavors the popular model of NS-NS mergers as the progenitors of SHBs.
14167939
Detecting Outer Planets in Edge-on Orbits: Combining Radial Velocity and Astrometric Techniques
The astrometric and radial velocity techniques of extrasolar planet detection attempt to detect the periodic reflex motion of the parent star by extracting this periodic signal from a time-sampled set of observations. The extraction is generally accomplished using periodogram analysis or the functionally equivalent technique of least-squares fitting of sinusoids. In this paper, we use a frequentist approach to examine the sensitivity of the least-squares technique when applied to a combination of radial velocity and astrometric observations. We derive an analytical expression for the sensitivity and show that the combined approach yields significantly better sensitivity than either technique on its own. We discuss the ramifications of this result to upcoming astrometric surveys with the Full-Sky Astrometric Mapping Explorer, the Keck Interferometer, and the Space Interferometry Mission.
5900888
TWO DISTANT HALO VELOCITY GROUPS DISCOVERED BY THE PALOMAR TRANSIENT FACTORY
We report the discovery of two new halo velocity groups (Cancer groups A and B) traced by 8 distant RR Lyrae stars and observed by the Palomar Transient Factory (PTF) survey at R.A.~129°, Dec~20° (l~205°, b~32°). Located at 92 kpc from the Galactic center (86 kpc from the Sun), these are some of the most distant substructures in the Galactic halo known to date. Follow-up spectroscopic observations with the Palomar Observatory 5.1-m Hale telescope and W. M. Keck Observatory 10-m Keck I telescope indicate that the two groups are moving away from the Galaxy at v_(gsr) = 78.0+-5.6 km s^(-1) (Cancer group A) and v_(gsr) = 16.3+-7.1 km s^(-1) (Cancer group B). The groups have velocity dispersions of σ_(v_)gsr))=12.4+-5.0 km s^(-1) and σ _(v_(gsr))=14.9+-6.2 km s^(-1), and are spatially extended (about several kpc) making it very unlikely that they are bound systems, and are more likely to be debris of tidally disrupted dwarf galaxies or globular clusters. Both groups are metal-poor (median metallicities of [Fe/H]^A = -1.6 dex and [Fe/H]^B =-2.1 dex), and have a somewhat uncertain (due to small sample size) metallicity dispersion of ~0.4 dex, suggesting dwarf galaxies as progenitors. Two additional RR Lyrae stars with velocities consistent with those of the Cancer groups have been observed ~25 ° east, suggesting possible extension of the groups in that direction.
15324428
Modeling Supernova-like Explosions Associated with Gamma-ray Bursts with Short Durations
There is now good evidence linking short-hard GRBs with both elliptical and spiral galaxies at relatively low redshifts, redshift of about 0.2. This contrasts with the average redshift of about 2 of long-duration events, which also occur only in star-forming galaxies. The diversity of hosts is reminiscent of type Ia supernovae, which are widely (but not universally) believed to originate from the coalescence of white dwarfs. By analogy, it has been postulated that short-hard bursts originate from neutron star mergers. Mergers, as well as stellar core-collapse events (type II SNe and long-duration GRBs) are accompanied by long-lived sub-relativistic components powered by radioactive decay of unstable elements produced in the explosion. It is therefore interesting to explore whether short duration events also have ejecta powered by radioactivity (i.e. that are supernova-like). Observations already inform us that any supernova like component in the first few well studied short hard bursts must be fainter than those typical of type Ia or core-collapse supernovae. Rather than refer to weaker supernova-like component as ``mini-super nova'', an etymologically indefensible term, I use the term {\it macronova}. I investigate the observability of macronovae powered by neutron decay and by radioactive Nickel. Separately, I note that a macronova will reprocess energetic emission arising from a long lived central source. I find that surprisingly interesting limits on the basic parameters of macronovae can be obtained provided observations are obtained with current 10-m class telescopes over a range of one hour to one day following the burst.