High-resolution X-ray spectroscopy of the ultracompact LMXB pulsar 4U 1626-67

Details High-resolution X-ray spectroscopy of the ultracompact LMXB pulsar 4U 1626-67 High-resolution X-ray spectroscopy of the ultracompact LMXB pulsar 4U 1626-67

2006-11-27

arxiv.org/abs/astro-ph/0611823v1

Astrophys.J.660:605-614,2007

Astronomy and Astrophysics

Astrophysics

10 pages, 7 figures, submitted to ApJ

Scientific paper

10.1086/513592

[abridged] We report results from four recent observations of the ultracompact LMXB pulsar 4U 1626-67. All the observations obtained high-resolution X-ray spectra of the system, two from the Chandra X-ray Observatory using the HETGS, and two from the XMM-Newton Observatory using the RGS as well as the EPIC PN and MOS. These data allow us to study in detail the prominent Ne and O emission line complexes which make 4U 1626-67 unique among LMXBs. The observations were spaced over a period of 3 years for a total observing time of 238 ks, allowing us to monitor the line regions as well as the overall source flux, continuum spectrum, and timing properties. The structure of the emission lines and the ratios of the components of the helium-like Ne IX and O VII triplets support the hypothesis that they are formed in the high-density environment of the accretion disk. We do not find any significant changes in the line widths or ratios over this time period, though we note that the line equivalent widths decrease. We are able to place constraints on the strengths of the Ne K, Fe L, and O K photoelectric absorption edges, and find that the data do not require an overabundance of Ne or O in the system relative to the expected ISM values. We find that the pulsar is still spinning down, and note that the pulse profile has changed significantly from what was found prior to the torque reversal in 1990, suggesting that this event may be linked to a change in the geometry of the accretion column. The flux of 4U 1626-67 continues to decrease, in keeping with the trend of the last approximately 30 years over which it has been observed. Taking into consideration current theory on disk stability, we expect that 4U 1626-67 will enter a period of quiescence in 2-15 years.

Affiliated with

Also associated with

No associations

Rating

High-resolution X-ray spectroscopy of the ultracompact LMXB pulsar 4U 1626-67 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with High-resolution X-ray spectroscopy of the ultracompact LMXB pulsar 4U 1626-67, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and High-resolution X-ray spectroscopy of the ultracompact LMXB pulsar 4U 1626-67 will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-350006