Astron. Astrophys. 324, L9-L12 (1997)

5. Discussion

The LECS data confirm the recent ASCA detection of excess emission near 1 keV from 4U 1626-67. In addition, the best-fit spectral parameters confirm that the spectral shape remains changed following the mid-1990 torque reversal. Both kT and decreased by a factor of 2, while the X-ray luminosity decreased by a factor of 6. As before the reversal, the new parameters appear stable with time. Chakrabarty et al. (1997) report that the intensity of the source is steadily decreasing with time. The LECS results support this, since the 0.5-10 keV source intensity is 0.6 that measured by ASCA. Extrapolating from previous measurements (see Fig. 8 of Chakrabarty et al. 1997), the expected decrease is a factor of 0.7. The shape of the pulse profile is also different from that measured before the reversal. Prior to the reversal, the profile was strongly energy and phase dependent (e.g., see Levine et al. 1988), while the LECS pulse profile has the same shape, but a variable amplitude, over the 1.0-10.0 keV energy range (see Fig. 2).

© European Southern Observatory (ESO) 1997

Online publication: May 26, 1998

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