2001/04/17 by J. J. M. in ’t Zand, J. J. M. in 't Zand, R. Cornelisse +10 · 7 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Gamma-ray bursts and supernovae #Pulsars and Gravitational Waves Research #astro-ph
paper · pdf · doi:10.1051/0004-6361:20010546
Accepted for publication in Astronomy & Astrophysics
arxiv created 2001/04/17 · openalex publication_date 2001/06/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
Data of the 1996 outburst of the single-known accreting millisecond pulsar SAX J1808.4-3658, taken with the Wide Field Cameras (WFCs) on BeppoSAX, are revisited with more complete data coverage and more comprehensive analysis techniques than in a previous report. An additional type-I X-ray burst was identified which occurred at a time when the persistent emission is below the detection limit, roughly 30 days after outburst maximum. This burst is three times longer than the first two bursts, and 50% brighter. It is the brightest burst within the ~1700 type-I bursts detected so far with the WFCs. A spectral analysis of the data reveals a distance to SAX J1808.4-3658 of ~2.5 kpc. This is an update from a previously reported value of 4 kpc. We present the evidence that we have for the presence of oscillations at the pulsar frequency during part of the newly found burst. Such an oscillation would lend support to the idea that the frequency of millisecond burst oscillations in other objects is very close to the neutron star rotation frequency.