4 research outputs found
Go Long, Go Deep: Finding Optical Jet Breaks for Swift-Era GRBs with the LBT
Using the 8.4m Large Binocular Telescope, we observed six GRB afterglows from
2.8 hours to 30.8 days after the burst triggers to systematically probe the
late time behaviors of afterglows including jet breaks, flares, and supernova
bumps. We detected five afterglows with Sloan r' magnitudes ranging from
23.0-26.3 mag. The depth of our observations allows us to extend the temporal
baseline for measuring jet breaks by another decade in time scale. We detected
two jet breaks and a third candidate, all of which are not detectable without
deep, late time optical observations. In the other three cases, we do not
detect the jet breaks either because of contamination from the host galaxy
light, the presence of a supernova bump, or the intrinsic faintness of the
optical afterglow.
This suggests that the basic picture that GRBs are collimated is still valid
and that the apparent lack of Swift jet breaks is due to poorly sampled
afterglow light curves, particularly at late times.Comment: Accepted by ApJ Letters, 14 pages, 2 figure