Office: PENGL 113
email: syost ("at") csbsju.edu
My past work on GRBs has involved fitting comprehensive broadband afterglow datasets to an implementation of the relativistic blastwave ''fireball'' model, and participating in the rapid followup efforts of the ROTSE project.
At present, I work with public, archival data. I am particularly interested in how the properties of the gamma-ray event itself may (or may not) be connected to the early afterglow. There are different patterns of behaviour in the transition from GRB to smoothly-decaying afterglow light.
A past paper (2007) on the subject (ApJ 669, 1107, link to free preprint)
I have been working with a student researcher to determine the optical onset properties (delay time, width of the onset bump, etc) of many events and compare them to the variability of the gamma-ray outburst itself. The optical onset delay is connected to the Lorentz factor or kinematically-scaled thickness of the initial relativistic ejecta from the central engine of the GRB. The variability of the prompt gamma-rays is related to the irregularity of that outflow. An initial check of a few events appeared to show evidence for a correlation between these properties, and we are investigating this with a more statistically significant sample. (This work is being prepared for American Astronomical Society meeting 219, January 2012.)
Further information, Useful links. (under construction)
Targets are observed for blocks of time, preferably at least 2 hrs per target, repeated on 2 or 3 nights. Lightcurves are analyzed for periodic variability with a period-finder.
This works best for continuously-variable objects. We cannot rule out widely detatched eclipsing binaries (which have a constant brightness for a large fraction of the time). However, we can determine whether stars are continuously variable with periods of less than or on order of a few hours, with amplitudes of 0.1 mag or more. (Variable types which can potentially be identified include contact binaries, RR Lyraes, and AM CvN stars.)
Further information, useful links, etc