A COMPACT X-RAY SOURCE IN THE RADIO PULSAR-WIND NEBULA G141.2+5.0

Abstract

ABSTRACT 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 that 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 ) × 10 21 ?> cm−2 and photon index Γ = 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 × 10 32 ?> erg s−1 (90% confidence intervals). Both L X and Γ are quite typical of pulsars in PWNe. No extended emission is seen; we estimate a conservative 3 &sgr; ?> upper limit to the surface brightness of any X-ray PWN near the point source to be 3 × 10 − 17 ?> erg cm−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 ″ ?> , the flux limit is 6% of the flux of the point source. The steep radio spectrum of the PWN ( &agr; ∼ − 0.7 ?> ), if continued to the X-ray without a break, predicts L X (nebula) ∼ 1 × 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.