8th HEAD Meeting, 8-11 September, 2004
Session 18 Gamma-ray Bursts
Poster, Thursday, September 9, 2004, 9:00am-10:00pm

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[18.11] A Search for Prompt Microwave Emission from Gamma-Ray Bursts Using Archival COBE and WMAP Datasets

M. Mbonye (Southern University), J. G. Stacy (Southern University and LSU), P. D. Jackson (GST, Inc.), C. Winkler (ESA-ESTEC)

We report on an extension of earlier work to search the archival database of the Differential Microwave Radiometers (DMR) aboard the COBE satellite, and the more recent public time-ordered datasets acquired with the Wilkinson Microwave Anisotropy Probe (WMAP), for transient signals associated with cosmic gamma-ray bursts (GRBs). Over the course of its 4-year mission the COBE/DMR serendipitously observed a number of GRBs and we previously established the first limits on prompt microwave emission from GRBs using a 9-month sample of data from the COBE/DMR instrument. We have been remotivated to extend our earlier search following the detection in recent years of a small number of bright optical and radio flares from GRBs. The prompt multiwavelength burst emission, presumed to arise from reverse shocks in the burst ejecta, provides insight into burst physics and the physical environments in which bursts occur. We present here the status of our extended search. We also describe how the increased sensitivity and angular resolution of the WMAP radiometers compared to the COBE/DMR lead to a factor of ~10,000 improvement in overall point-source sensitivity. Such limits approach the signal levels predicted in the microwave band for the peak prompt emission arising from reverse shocks in GRBs. We acknowledge partial support for this work through NASA grant NAG5-10253.

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Bulletin of the American Astronomical Society, 36 #3
© 2004. The American Astronomical Soceity.