In some models of quantum gravity, space-time is thought to have a foamy
structure with non-trivial optical properties. We probe the possibility that
photons propagating in vacuum may exhibit a non-trivial refractive index, by
analyzing the times of flight of radiation from gamma-ray bursters (GRBs) with
known redshifts. We use a wavelet shrinkage procedure for noise removal and a
wavelet `zoom' technique to define with high accuracy the timings of sharp
transitions in GRB light curves, thereby optimizing the sensitivity of
experimental probes of any energy dependence of the velocity of light. We apply
these wavelet techniques to 64 ms and TTE data from BATSE, and also to OSSE
data. A search for time lags between sharp transients in GRB light curves in
different energy bands yields the lower limit $M \ge 6.9 \cdot 10^{15}$ GeV on
the quantum-gravity scale in any model with a linear dependence of the velocity
of light $~ E/M$. We also present a limit on any quadratic dependence.Comment: This version is accepted for publication in Astronomy & Astrophysics.
  The discussion and introduction are extended making clear why the wavelet
  analysis should be superior to straight cross-correlation analysis. More
  details on compiled data are elaborated. 18 pages, 9 figures, A&A forma

Ellis, J.

Mavromatos, N. E.

Nanopoulos, D. V.

Sakharov, A. S.

English

arXiv

In some models of quantum gravity, space-time is thought to have a foamy structure with non-trivial optical properties. We probe the possibility that photons propagating in vacuum may exhibit a non-trivial refractive index, by analyzing the times of flight of radiation from gamma-ray bursters (GRBs) with known redshifts. We use a wavelet shrinkage procedure for noise removal and a wavelet `zoom' technique to define with high accuracy the timings of sharp transitions in GRB light curves, thereby optimizing the sensitivity of experimental probes of any energy dependence of the velocity of light. We apply these wavelet techniques to 64 ms and TTE data from BATSE, and also to OSSE data. A search for time lags between sharp transients in GRB light curves in different energy bands yields the lower limit $M \ge 6.9 \cdot 10^{15}$ GeV on the quantum-gravity scale in any model with a linear dependence of the velocity of light $~ E/M$. We also present a limit on any quadratic dependence

Ellis, Jonathan Richard

Mavromatos, Nikolaos E

Nanopoulos, Dimitri V

Sakharov, Alexander S

CERN Document Server

aa graphicx txfonts[1]Eq. (1)document Quantum-Gravity Analysis of Gamma-Ray Bursts using WaveletsJ. Ellis1 N.E. Mavromatos 2 D.V. Nanopoulos 3 A.S. Sakharov 4A.S. SakharovTheory Division, CERN, 1211 Geneva 23, SwitzerlandReceived 29 October 2002 / Accepted 14 February 2003In some models of quantum gravity, space-time is thought to have a foamy structure with non-trivialoptical properties. We probe the possibility that photons propagating in vacuum may exhibit a non-trivialrefractive index, by analyzing the times of flight of radiation from gamma-ray bursters (GRBs) with knownredshifts. We use a wavelet shrinkage procedure for noise removal and a wavelet ‘zoom’ technique to denewith high accuracy the timings of sharp transitions in GRB light curves, thereby optimizing the sensitivity ofexperimental probes of any energy dependence of the velocity of light. We apply these wavelet techniques to64 ms and TTE data from BATSE, and also to OSSE data. A search for time lags between sharp transientsin GRB light curves in dierent energy bands yields the lower limit M ≥ 6.9 · 1015 GeV on the quantum-gravity scale in any model with a linear dependence of the velocity of light ∝ E/M . We also present a limiton any quadratic dependence. distance scale { gamma ray: bursts { methods: statisticalflushright astro-ph/0210124IntroductionIn standard relativistic quantum eld theory, space{time is considered as a xed arena in which physicalprocesses take place. The characteristics of the propagation of light are considered as a classical input to thetheory. In particular, the special and general theories of relativity postulate a single universal velocity of lightc. However, starting in the early 1960s (Wheller 1963), eorts to nd a synthesis of general relativity andquantum mechanics, called quantum gravity, have suggested a need for greater sophistication in discussingthe propagation of light in vacuum.A satisfactory theory of quantum gravity is likely to require a drastic modication of our deterministicrepresentation of space{time, endowing it with structure on characteristic scales approaching the Plancklength `P ' m−1P . There is at present no complete mathematical model for quantum gravity, and there aremany dierent approaches to the modelling of space-time foam. Several of these approaches suggest that thevacuum acquires non-trivial optical properties, because of gravitational recoil eects induced by the motion ofenergetic particles. In particular, it has been suggested that these may induce a non-trivial refractive index,with photons of dierent energies travelling at dierent velocities. Such an apparent violation of Lorentzinvariance can be explored by studying the propagation of particles through the vacuum, in particularphotons emitted by distant astrophysical sources (Amelino-Camelia et al. 1998). In some quantum-gravitymodels, light propagation may also depend on the photon polarization (Gambini & Pullin 1999), inducingbirefringence. Stochastic eects are also possible, giving rise to an energy-dependent diusive spread in thevelocities of dierent photons with the same energy (Ford 1995; Ellis et al. 2000a).One may discuss the eects of space{time foam on the phase velocity, group velocity or wave-frontvelocity of light. In this paper, we discuss only the signature of a modication of the group velocity,related to a non-trivial refractive index n(E): v(E) = c/n(E). This may be derived theoretically froma (renormalized) eective Maxwell action Γeff [E,B], where E and B are the electric and magnetic eldstrengths of the propagating wave, in the background metric induced by the quantum gravity model underconsideration. Once the eective Maxwell action is known, at least in a suitable approximation, one cananalyze the photon dispersion using the eective Maxwell equations (Ellis et al. 2000b).One generally considers the propagation of photons with energies E much smaller than the mass scaleM characterizing the quantum gravity model, which may be of the same order as the Planck mass MP , orperhaps smaller in models with large extra dimensions. In the approximation E  M , the distortion of thestandard photon dispersion relation may be represented as an expansion in E/M :equationdisprel E2 = k2(1 + ξ1(k/M) + ξ2(k/M)2 + . . .),1

Quantum-Gravity Analysis of Gamma-Ray Bursts using Wavelets

In some models of quantum gravity, space-time is thought to have a foamy structure with non-trivial optical properties. We probe the possibility that photons propagating in vacuum may exhibit a non-trivial refractive index, by analyzing the times of flight of radiation from gamma-ray bursters (GRBs) with known redshifts. We use a wavelet shrinkage procedure for noise removal and a wavelet "zoom" technique to define with high accuracy the timings of sharp transitions in GRB light curves, thereby optimizing the sensitivity of experimental probes of any energy dependence of the velocity of light. We apply these wavelet techniques to 64 ms and TTE data from BATSE, and also to OSSE data. A search for time lags between sharp transients in GRB light curves in different energy bands yields the lower limit M greater than or equal to 6.9 x 10(15) GeV on the quantum-gravity scale in any model with a linear dependence of the velocity of light proportional to E/M. We also present a limit on any quadratic dependence

Ellis, J

Mavromatos, N E

Nanopoulos, D V

Sakharov, A S

King's Research Portal

Quantum-gravity analysis of gamma-ray bursts using wavelets

In some models of quantum gravity, space-time is thought to have a foamy
structure with non-trivial optical properties. We probe the possibility
that photons propagating in vacuum may exhibit a non-trivial refractive
index, by analyzing the times of flight of radiation from gamma-ray
bursters (GRBs) with known redshifts. We use a wavelet shrinkage procedure
for noise removal and a wavelet “zoom” technique to define with high
accuracy the timings of sharp transitions in GRB light curves, thereby
optimizing the sensitivity of experimental probes of any energy dependence
of the velocity of light. We apply these wavelet techniques to 64 ms and
TTE data from BATSE, and also to OSSE data. A search for time lags between
sharp transients in GRB light curves in different energy bands yields the
lower limit $M \ge 6.9 \times  10^{15}$ GeV on the quantum-gravity scale in
any model with a linear dependence of the velocity of light $\propto E/M$.
We also present a limit on any quadratic dependence

Quantum-Gravity Analysis of Gamma-Ray Bursts using Wavelets

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Quantum-Gravity Analysis of Gamma-Ray Bursts using Wavelets

Abstract

Similar works

Full text

Available Versions

CERN Document Server

King's Research Portal

EDP Sciences OAI-PMH repository (1.2.0)

Texas A&M University

Texas A&amp;M Repository

Texas A&M Repository