A Compact X-ray Source in the Radio Pulsar-Wind Nebula G141.2+5.0

We report the results of a 50 ks Chandra observation of the recently discovered radio object G141.2+5.0, presumed to be a pulsar-wind nebula. We find a moderately bright unresolved X-ray source which we designate CXOU J033712.8 615302 coincident with the central peak radio emission. An absorbed power-law fit to the 241 counts describes the data well, with absorbing column $N_H=6.7(4.0,9.7)\times {10}^{21}$ cm${}^{-2}$ and photon index $\Gamma = 1.8 (1.4, 2.2)$. For a distance of 4 kpc, the unabsorbed luminosity between 0.5 and 8 keV is $1.7_{-0.3}^{+0.4}\times {10}^{32}$ erg s${}^{-1}$ (90% confidence intervals). Both $L_X$ and $\mathrm{\Gamma }$ are quite typical of pulsars in PWNe. No extended emission is seen; we estimate a conservative $3\sigma$ upper limit to the surface brightness of any X-ray PWN near the point source to be $3 \times 10^{-17}$ergcm$^{-2}$s$^{-1}$arcsec$^{-2}$ between 0.5 and 8 keV, assuming the same spectrum as the point source; for a nebula of diameter $13\mathrm{"}$, the flux limit is 6% of the flux of the point source. The steep radio spectrum of the PWN ($\alpha \sim -0.7$), if continued to the X-ray without a break, predicts $L_X(\mathrm{n}\mathrm{e}\mathrm{b}\mathrm{u}\mathrm{l}\mathrm{a})\sim 1\times {10}^{33}$ erg s${}^{-1}$, so additional spectral steepening between radio and X-rays is required, as is true of all known PWNe. The high Galactic latitude gives a $z$-distance of 350 pc above the Galactic plane, quite unusual for a Population I object.