A novel method for measuring spectral lags by dynamic time warping

Measuring spectral lags in gamma-ray bursts (GRBs) across different energy bands is important for studying prompt-emission physics and related applications. We assessed the reliability and applicability of the constrained dynamic time warping (DTW) method for measuring spectral lags in GRBs. We applied the constrained DTW method to a sample of 50 single-pulse GRBs observed by /GBM and compared the resulting spectral lags with those obtained using Gaussian peak-time fitting and the modified cross-correlation function (MCCF). We also performed simulation-based tests with known input lags to validate the method. Fermi The spectral lags derived from DTW are overall consistent with those obtained from Gaussian fitting and MCCF, with no significant differences found within 3σ. For evidently asymmetric pulses, fitting the full pulse with a symmetric Gaussian function can bias the inferred lag, while peak-focused Gaussian fitting yields results more consistent with DTW and MCCF. Simulations show that DTW can reliably recover the input lag and provide robust uncertainty estimates. Dynamic time warping provides a robust and complementary approach to spectral-lag measurement in GRBs and is promising for future applications to more complex light curves and related studies such as gravitational-lensing searches.