Optical and X-ray observations of candidate isolated neutron stars in the G315.4-2.3 supernova remnant

G315.4-2.3 is a young Galactic supernova remnant (SNR) whose identification as the remains of a Type II supernova (SN) explosion has been debated for a long time. In particular, recent multiwavelength observations suggest that it is the result of a Type Ia SN, based on spectroscopy of the SNR shell and the lack of a compact stellar remnant. However, two X-ray sources, one detected by Einstein and ROSAT (Source V) and the other by Chandra (Source N), have been proposed as possible isolated neutron star candidates. In both cases, no clear optical identification was available and, therefore, we performed an optical and X-ray study to determine the nature of these two sources. Based on Chandra astrometry, Source V is associated with a bright V ˜ 14 star, which has been suggested based on the less accurate ROSAT position. Similarly, from Very Large Telescope archival observations, we found that Source N is associated with a relatively bright star (V = 20.14). These likely identifications suggest that both X-ray sources cannot be isolated neutron stars. Based on observations collected at ESO, Paranal, under programme 385.D-0198(A).