Optical Observations of GRB 050401 Afterglow : A case for Double Jet Model

Understand

The afterglow of GRB 050401 presents several novel and interesting features : [1] An initially faster decay in optical band than in X-rays.

• [2] A break in the X-ray light curve after $\sim$ 0.06 day with an unusual slope after the break.
• [3] The X-ray afterglow does not show any spectral evolution across the break while the R band light curve does not show any break.
• We have modeled the observed multi-band evolution of the afterglow of GRB 050401 as originating in a two component jet, interpreting the break in X-ray light curve as due to lateral expansion of a narrow collimated outflow which dominates the X-ray emission.