2007/08/20 by Sudip Bhattacharyya, Tod E. Strohmayer · 21 citations
Physics and Astronomy · #Amplitude #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Brightness #Gamma-ray bursts and supernovae #Intensity (physics) #Mechanics #Neutron star #Optics #Oscillation (cell signaling) #Physics #Plasma #Pulsars and Gravitational Waves Research #Thermonuclear fusion #astro-ph
paper · pdf · doi:10.1086/521790
published in The Astrophysical Journal 666(2), L85-L88 (IOP Publishing) · 8 pages, 4 figures, accepted for publication in ApJ Letters
openalex publication_date 2007/08/20 · arxiv created 2007/08/27 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Millisecond period brightness oscillations during the intensity rise of thermonuclear X-ray bursts are likely caused by an azimuthally asymmetric, expanding burning region on the stellar surface. The time evolution of the oscillation amplitude during the intensity rise encodes information on how the thermonuclear flames spread across the stellar surface. This process depends on properties of the accreted burning layer, surface fluid motions, and the surface magnetic field structure, and thus can provide insight into these stellar properties. We present two examples of bursts from different sources that show a decrease in oscillation amplitude during the intensity rise. Using theoretical modeling, we demonstrate that the observed amplitude evolution of these bursts is not well described by a uniformly expanding circular burning region. We further show that by including in our model the salient aspects of the Coriolis force (as described by Spitkovsky, Levin, and Ushomirsky) we can qualitatively reproduce the observed evolution curves. Our modeling shows that the evolutionary structure of burst oscillation amplitude is sensitive to the nature of flame spreading, while the actual amplitude values can be very useful to constrain some source parameters.