SUPERNOVA REMNANT CANDIDATES FOR THE SOFT GAMMA-RAY REPEATER 1900+14

Motivated by the association of two soft gamma-ray repeaters (SGRs) wi th supernova remnants (SNR) we have carried out radio, optical and X-r ay studies of two cataloged SNRs in the large KONUS error box (11-degr ees x 8') of SGR 1900 + 14. Our VLA observations of SNR G43.9 + 1.6 do not reveal any obvious plerionic component. A radio flat-spectrum sou rce, close to, but outside the error box was found. We suggest this to be a distant H II region foreground to the SNR. A sensitive VLA image at meter wavelengths show that the other SNR, G42.8 + 0.6, is an ordi nary typical SNR with a shell morphology with no peculiarities such as a plerionic component. No ROSAT source with an apparent flux greater than or similar to 10(-13) ergs cm-2 s-1 is found within the two SNRs. Recently, Hurley et al. have reported a new very small error box clos e to G42.8 + 0.6. There is no radio feature within or close to the err or box. However, a ROSAT source is found just outside this localizatio n. We speculate that this is the quiescent X-ray counterpart of SGR 19 00 + 14. We suggest that SGR 1900 + 14 is a neutron star that was born with high speed which has now overtaken the expanding shell of SNR G4 2.8 + 0.6. Owing to the low confining pressure, there has been no deve lopment of a synchrotron bubble which explains the absence of the radi o plerion. In our picture, SGR 1900 + 14 is the oldest known SGR.