We present the high-resolution spectrum of the accretion-powered millisecond pulsar XTE J0929 - 314 during its 2002 outburst , measured using the Low Energy Transmission Grating Spectrometer onboard the Chandra X-ray Observatory .
The 1.5–25.3 Å ( 0.5–8.3 keV ) Chandra spectrum is well fit by a power-law + blackbody model with photon index \Gamma = 1.55 \pm 0.03 , blackbody temperature kT _ { bb } = 0.65 \pm 0.03 keV , and blackbody normalization R _ { bb,km } / d _ { 10 kpc } = 7.6 \pm 0.8 .
No emission or absorption features are found in the high-resolution spectrum , with a 3 \sigma equivalent width upper limit of < 0.007 Å at 1.5 Å and < 0.12 Å at 24 Å .
The neutral absorption edge depths are consistent with the estimated interstellar absorption along the line of sight to the source .
We found no orbital modulation of the 2–10 keV X-ray flux , to a 3 \sigma upper limit of 1.1 % , which implies an upper limit on the binary inclination angle of i \lesssim 85 ^ { \circ } for a Roche-lobe–filling companion .
We also present the broadband spectrum measured over the course of the outburst by the Rossi X-ray Timing Explorer ( RXTE ) .
The RXTE spectrum of XTE J0929 - 314 is also well fit with a power-law + blackbody model , with average values of \Gamma = 1.76 \pm 0.03 , kT _ { bb } = 0.66 \pm 0.06 keV , and R _ { bb,km } / d _ { 10 kpc } = 5.9 \pm 1.3 in the 2–50 keV energy range .
The blackbody flux remained constant over the course of the outburst , while the power-law flux was strongly correlated to the ( decreasing ) flux of the source .
We find that the difference in power-law photon indices measured from Chandra and RXTE spectra can be explained by a change in the power-law photon index at low energies .