18983818
Deformed symmetry in Snyder space and relativistic particle dynamics
We describe the deformed Poincare-conformal symmetries implying the covariance of the noncommutative space obeying Snyder's algebra. Relativistic particle models invariant under these deformed symmetries are presented. A gauge (reparametrisation) independent derivation of Snyder's algebra from such models is given. The algebraic transformations relating the deformed symmetries with the usual (undeformed) ones are provided. Finally, an alternative form of an action yielding Snyder's algebra is discussed where the mass of a relativistic particle gets identified with the inverse of the noncommutativity parameter.
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.
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.
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.
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.
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.
51783412
The Redshift and the Host Galaxy of GRB 980613: A Gamma-Ray Burst from a Merger-induced Starburst?*
We present the optical and near-IR identification and spectroscopy of the host galaxy of gamma-ray burst GRB 980613. The burst was apparently associated with the optically (rest-frame UV) brightest component of an apparent system of at least five galaxies or galaxy fragments, at least two of which are at a redshift of z = 1.0969. The component we identify as the host galaxy shows a moderately high unobscured star formation rate, SFR ~ 5 M☉ yr-1, but a high SFR per unit mass, indicative of a starburst. The image components show a broad range of (R-K) colors, with two of them being very red, possibly due to dust. The overall morphology of the system can be naturally interpreted as a strong tidal interaction of two or more galaxies, at a redshift where such events were much more common than now. Given the well-established causal link between galaxy mergers and starbursts, we propose that this is a strong case for a GRB originating from a merger-induced starburst system. This supports the proposed link between GRBs and massive star formation.
16081265
THE NATURE OF THE DLS FAST TRANSIENTS
The discovery and study of highly transient sources, especially those which rise to high brightness and then fade to obscurity, has been a major part of modern astrophysics. Well known examples include supernovae and novae. A byproduct of the Deep Lens Survey (DLS) was the discovery of three transients which varied on a timescale of less than an hour. All three had faint and red counterparts, the brightest of which was identified with an M star. However, the remaining two showed hints of an extra-galactic origin (spatially extended counterpart and projected on the outskirts of a bright elliptical galaxy in a cluster). Such an origin implies an entirely new class of exotic explosive transients. We undertook spectroscopic observations with the Keck telescope and find the remaining two counterparts are also late type Galactic dwarfs. Flares from M dwarfs constitute a dense foreground fog and dominate over any conceivable class of extragalactic fast transients by at least two orders of magnitude. Overcoming this fog will likely require dedicated surveys with careful optimization of target field location, filter(s) and cadence, pre-search imaging to filter out late type dwarfs and a well planned rapid followup plan. In the first half of the twentieth century the search for and study of variable sources was a major focus of optical astronomy. This area is widely expected to undergo a renaissance, thanks to significant technological changes (sensors, computing, storage and dissemination). Apart from existing wide-field imagers dedicated facilities such as the Panoramic Survey Telescope & Rapid Response System (Pan-STARRS; Kaiser et al. 2002) and the Large Synoptic Survey Telescope (LSST) are motivated in part to explore transient phenomena in the optical sky. In our opinion the following three already completed projects serve as exemplars for future surveys: (1) the Deep Lens Survey 1 (DLS) notable for its comprehensive scope and almost real time alerts (Becker et al. 2004), (2) the orphan GRB afterglow search at the 2.2-m MPG/ESO telescope and noted for its complete follow up of all the candidate transients sources (Rau et al. 2006) and (3) the Faint Sky Variability Survey aimed at characterizing variability at the faint end (Groot et al. 2003, Morales-Rueda et al. 2005). The MPG/ESO survey was primarily focussed on tran-sients with timescales of a few days. Nonetheless, a small piece of sky with an exposure of 0.24 deg 2 days was covered with a cadence of 1000 s in …
91177292
SModelS: a tool for interpreting simplified-model results from the LHC and its application to supersymmetry
We present a general procedure to decompose Beyond the Standard Model (BSM) collider signatures presenting a $$\mathbb {Z}_2$$Z2 symmetry into Simplified Model Spectrum (SMS) topologies. Our method provides a way to cast BSM predictions for the LHC in a model independent framework, which can be directly confronted with the relevant experimental constraints. Our concrete implementation currently focusses on supersymmetry searches with missing energy, for which a large variety of SMS results from ATLAS and CMS are available. As show-case examples we apply our procedure to two scans of the minimal supersymmetric standard model. We discuss how the SMS limits constrain various particle masses and which regions of parameter space remain unchallenged by the current SMS interpretations of the LHC results.
17558963
The Bright Gamma-Ray Burst 991208: Tight Constraints on Afterglow Models from Observations of the Early-Time Radio Evolution
The millimeter wavelength emission from GRB 991208 is the second brightest ever detected, yielding a unique data set. We present here well-sampled spectra and light curves over more than two decades in frequency for a 2 week period. This data set has allowed us for the first time to trace the evolution of the characteristic synchrotron self-absorption frequency νa, peak frequency νm, and the peak flux density Fm; we obtain νa ∝ t-0.15±0.23, νm ∝ t-1.7±0.7, and Fm ∝ t-0.47±0.20. From the radio data we find that models of homogeneous or wind-generated ambient media with a spherically symmetric outflow can be ruled out. A model in which the relativistic outflow is collimated (a jet) can account for the observed evolution of the synchrotron parameters, the rapid decay at optical wavelengths, and the observed radio-to-optical spectral flux distributions that we present here, provided that the jet transition has not been fully completed in the first 2 weeks after the event. These observations provide additional evidence that rapidly decaying optical/X-ray afterglows are due to jets and that such transitions either develop very slowly or perhaps never reach the predicted asymptotic decay F(t) ∝ t-p.
16648604
The Redshift and the Ordinary Host Galaxy of GRB 970228
The gamma-ray burst of 1997 February 28 (GRB 970228) ushered in the discovery of the afterglow phenomenon. Despite intense study of the nearby galaxy, however, the nature of this galaxy and the distance to the burst eluded the community. Here we present the measurement of the redshift of the galaxy, the putative host galaxy of GRB 970228, and, based on its spectroscopic and photometric properties, identify the galaxy as a subluminous but otherwise normal galaxy at redshift z = 0.695 undergoing a modest level of star formation. At this redshift, the GRB released an isotropic-equivalent energy of (1.4 ± 0.3) × 1052 ergs (20-2000 keV rest frame). We find no evidence that the host is significantly bluer or is forming stars more vigorously than the general field population. In fact, by all accounts in our analysis (color-magnitude, magnitude-radius, star formation rate, and Balmer-break amplitude), the host properties appear typical for faint blue field galaxies at comparable redshifts.