A New Test of Lorentz Invariance Violation: the Spectral Lag Transition of GRB 160625B

Understand

Possible violations of Lorentz invariance (LIV) have been investigated for a long time using the observed spectral lags of gamma-ray bursts (GRBs).

• However, these generally have relied on using a single photon in the highest energy range.
• Furthermore, the search for LIV lags has been hindered by our ignorance concerning the intrinsic time lag in different energy bands.
• GRB 160625B, the only burst so far with a well-defined transition from $positive$ lags to $negative$ lags provides a unique opportunity to put new constraints on LIV.