A Chandra observation of GRO J1744–28: the bursting pulsar in quiescence

We present a Chandra/ACIS-I observation of GRO J1744–28. We detected a source at a position of R.A = 17 44 33.09 and Dec. = –28 44 27.0 (J2000.0; with a 1σ error of ∼0.8 arcseconds), consistent with both ROSAT and interplanetary network localizations of GRO J1744–28 when it was in outburst. This makes it likely that we have detected the quiescent X-ray counterpart of GRO J1744– 28. Our Chandra position demonstrates that the previously proposed infrared counterpart is not related to GRO J1744–28. The 0.5–10 keV luminosity of the source is 2− 4× 10 erg s (assuming the source is near the Galactic center at a distance of 8 kpc). We discuss our results in the context of the quiescent X-ray emission of pulsating and non-pulsating neutron star X-ray transients. Subject headings: pulsars: individual (GRO J1744–28) — stars: neutron — Xrays: stars