English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We report on the X-ray spectral and timing behavior of the recurrent X-raytransient 4U 1630-47 for 51 RXTE observations made during the decay of its 1998outburst. The observations began when the source was still relatively bright,and, during one of the early observations, a QPO with a non-Lorentzian profileoccurred near 6 Hz. As the source decayed, the X-ray flux dropped exponentiallywith an e-folding time of 14.4 d. The exponential decay was interrupted by anincrease in the X-ray flux, and a secondary maximum occurred 89 d after theonset of the outburst. A transition marked by significant changes in the timingand spectral properties of the source occurred 104 d after the start of theoutburst. The transition is similar to soft-to-hard state transitions observedin other black hole candidate X-ray binaries. Most of the changes associatedwith the transition occurred in less than 2 d. The timing changes include anincrease in the continuum noise level from less than 4% RMS to greater than 10%RMS and the appearance of a quasi-periodic oscillation (QPO) at 3.4 Hz with anRMS amplitude of 7.3% in the 2-21 keV energy band. At the transition, theenergy spectrum also changed with an abrupt drop in the soft component flux inthe RXTE band pass. A change in the power-law photon index from 2.3 to 1.8,also associated with the transition, occurred over a time period of 8 d. Afterthe transition, the source flux continued to decrease, and the QPO frequencydecayed gradually from 3.4 Hz to about 0.2 Hz.Comment: Accepted for publication in ApJ, 14 pages, 10 figures, uses  emulateapj style fil

X‐Ray Spectral and Timing Evolution during the Decay of the 1998 Outburst from the Recurrent X‐Ray Transient 4U 1630−47