# Gamma-Ray Burst Afterglows as Analogues of High Frequency-Peaked BL Lac Objects - Astrophysics > Cosmology and Nongalactic Astrophysics

Abstract: The spectral properties from radio to optical bands are compared between the18 optically bright Gamma-ray burst afterglows and well establishedpower-spectrum sequence in Blazars. The comparison shows that the afterglowsare well agreement with the well known Blazar sequence i.e., the $uL { u}\mathrm{5GHz}$-$\alpha {\mathrm{RO}}$ correlation, where$\alpha {\mathrm{RO}}$ is the broad-band spectral slope from radio to opticalbands. The afterglows are, however, clustered at the low luminosity end of thesequence, which is typically occupied by high frequency-peaked BL Lac objects.The correlation suggests that Gamma-ray burst afterglows share the similaremission process with high frequency-peaked BL Lac objects. We further identifya deviation at a significance level larger than 2$\sigma$ from the sequence forthree typical optically -dark- bursts. The deviation favors a heavy extinctionin optical bands for the -dark- bursts. The extinction $A V$ is estimated to belarger than 0.5-0.6 magnitude from the $uL { u}\mathrm{5GHz}$-$\alpha {\mathrm{RO}}$ sequence.

Author: J. Wang, J. Y. Wei

Source: https://arxiv.org/