GRB Spectral Lags in The Source Frame: An Investigation of Fermi-GBM Bursts

T. N. Ukwatta2, K.S. Dhuga3, A. Shenoy3, G. A. MacLachlan3, P. N. Bhat4, C. Dermer5, J. Hakkila6, N. Gehrels1, W.C. Parke3, L.C. Maximon3 1NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA. 2Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA. 3Department of Physics, The George Washington University, Washington, D.C. 20052, USA. 4 University of Alabama Huntsville, Huntsville, AL 5Space Science Division, Code 7653, Naval Research Laboratory, Washington, DC 20375, USA. 6 Department of Physics and Astronomy, College of Charleston, SC 29424-0001