RXTE Discovery of Coherent Millisecond Pulsations during an X-ray Burst from KS 1731-260

Kavli Affiliate: Edmund Bertschinger

| First 5 Authors: Donald A. Smith, Edward H. Morgan, Hale Bradt, ,

| Summary:

A highly coherent 523.92+-0.05 Hz periodic X-ray signal has been observed
during a type I X-ray burst from the low-mass X-ray binary system KS 1731-260
with the PCA on RXTE. The spectral evolution of the burst indicates
photospheric-radius expansion and contraction. The 524 Hz signal occurred at
the end of the contraction phase, lasted for ~2 s, was highly coherent (Q >~
900), and had a pulse fraction (ratio of sinusoidal amplitude to mean count
rate) of 6.2+-0.6%. KS 1731-260 is one of only three systems that have
exhibited high-coherence millisecond oscillations during X-ray bursts and the
first reported where the pulsations are associated with photospheric
contraction. These coherent signals may be interpreted as a direct indication
of the neutron star spin.

| Search Query: ArXiv Query: search_query=au:”Hale Bradt”&id_list=&start=0&max_results=10

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