Model-independent Constraints on Lorentz Invariance Violation: Implication from Updated Gamma-Ray Burst Observations

Abstract

Astrophysical observations provide a unique opportunity to test possible signatures of Lorentz Invariance Violation (LIV), due to the high energies and long distances involved. In quantum theory of gravity, one may expect the modification of the dispersion relation between energy and momentum for photons, which can be probed with the time-lag (the arrival time delay between light curves in different energy bands) of Gamma-ray bursts (GRBs). In this paper, by using the detailed time-delay measurements of GRB 160625B at different energy bands, as well as 23 time-delay GRBs covering the redshifts range of z = 0.168 − 2.5 (which were measured at different energy channels from the light curves), we propose an improved model-independent method (based on the newly-compiled sample of H(z) measurements) to probe the energy-dependent velocity due to the modified dispersion relation for photons. In the framework of a more complex and reasonable theoretical expression to describe the time delays, our results imply that the intrinsic time lags can be better described with more GRBs time delay data. More importantly, through direct fitting of the time-delay measurements of a sample of GRBs, our limit on the LIV energy scale is comparable to that with unknown constant for the intrinsic time lag, much lower than the Planck energy scale in both linear LIV and quadratic LIV cases.

Light speed variation with brane/string-inspired space-time foam

“…More striking regularity is that 9 out of these 14 photons falls very nicely on a same mainline, giving a strong indication of a light speed variation suppressed by a single power of the Planck scale. 5 It is worth noting that such a LIV scale ( 21) is consistent with various constraints from high-energy γ-ray observations of pulsars [36,37,38,39], active galactic nuclei (AGNs) [40,41,42,43,44] as well as GRBs [6,7,8,45,46,47,48,49,50] and it is also compatible with the strongest robust limit to date [51] from a recent study on 8 Fermi-LAT GRBs with bright emissions in multi-GeV energies [52]. We need to mention that there can be more stringent limits on this characteristic scale of LIV from individual analyses of flaring PKS 2155-304 [53,54], 6 short GRB 090510 [5,56,57] or striking TeV event of GRB 190114C lately found by MAGIC [58,59], which tend to place lower bounds E LIV (0.1 − 10) × E Pl , stronger than that in Eq.…”

Light Speed Variation in a String Theory Model for Space-Time Foam

“…which is close to the Planck scale E Pl ≃ 1.22 × 10 19 GeV. It is worth noting that such a LV scale ( 7) is consistent with various constraints from high-energy γ-ray observations of pulsars [19], AGNs [21,22,23] as well as GRBs [24,25,26,27,28], and it is also compatible with the strongest robust limit to date from a recent study [29] on 8 Fermi-LAT GRBs. We should mention that there can be severer bounds to E LV from other time-delay studies (see, e.g., Ref.…”

Constraints on quantum gravity and the photon mass from gamma ray bursts

“…for the massive photon. We will assume a ΛCDM cosmology to determine the Hubble parameter H(z); in general one should consider a variety of cosmological models [45][46][47][48], although this is beyond the scope of this work. In both cases we see that the parameter of interest (E QG or m γ ) and the observed energy bands appear as scaling factors.…”