Closing in on a Short-Hard Burst Progenitor Constraints from Early-Time Optical Imaging and(16)

Whilethesepossibleassociationsaretantalizing,aposterioristatisticsareverysuspect.HadtheGRBbeennearabrightspiralgalaxy,wemighthavemadesimilarclaimsbasedonchanceprobabilities.Nevertheless,itremainsthecasethatmanyworkershadpredictedthedistinctpossibilitythatawell-localizedcompactmergerand/orshortburstcouldbenearanellipticalgalaxy(Bagotetal.1998;Bloometal.1999;Panchenkoetal.1999)(seealsoLivioetal.1998),andsowesuggestthattheseargumentsmightreasonablyre ectatrueassociation.Moreover,thepossibleassociationwithanearly-typehoststandsinstarkcontrasttoresultsfromlong-durationGRBs(Bloometal.2002;LeFloc’hetal.2003;Djorgovskietal.2003),andisreminiscent(e.g.,Bloometal.2002;Dar2004)ofthedichotomybetweencore-collapseandthermonuclear(TypeIa)supernovae.OnlyalargersampleofshortGRBswillprovidetrulycompellingevidenceforsuch