ITAL]ROSAT[/ITAL] HRI Detection of the 16 [CLC]ms[/CLC] Pulsar PSR J0537−6910 Inside Supernova Remnant N157B

Abstract

Based on a deep ROSAT HRI observation, we have detected a pulsed signal in the 0.1-2 keV band from PSR J0537-6910, the recently discovered pulsar associated with the supernova remnant N157B in the Large Magellanic Cloud. The measured pulse period 0.01611548182 s ± 0.02 ns, epoch MJD 50,540.5, gives a revised linear spin-down rate of 5.1271 × 10−14 s s-1, which is slightly greater than the previously derived value. The narrow pulse shape (FWHM ~ 10% duty cycle) in the ROSAT band resembles those seen in both RXTE and ASCA data ( 2 keV), but there is also marginal evidence for an interpulse. This ROSAT detection enables us to locate the pulsar at R.A.=5h37m472, decl.=-69°10'23'' (J2000). With its uncertainty ~3'', this position coincides with the centroid of a compact X-ray source. But the pulsed emission accounts for only ~10% of the source luminosity of ~2 × 1036 ergs-1 in the 0.1-2 keV band. These results support our previous suggestions: (1) the pulsar is moving at a high velocity ( ~103 km s-1); (2) a bow shock, formed around the pulsar, is responsible for most of the X-ray emission from the source; and (3) a collimated outflow from the bow shock region powers a pulsar wind nebula that accounts for an elongated nonthermal radio and X-ray feature to the northwest of the pulsar.