2004/01/09 by D. R. Ballantyne, Tod E. Strohmayer, T. E. Strohmayer · 8 citations
Engineering · Physics and Astronomy · #Accretion (finance) #Accretion disc #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Galaxy #Intermediate polar #Ion #Ionization #Mechanics and Biomechanics Studies #Neutron star #Physics #RADIUS #Stars #Thick disk #White dwarf #astro-ph
paper · pdf · doi:10.1086/382703
published as Astrophys.J. 602 (2004) L105-L108 · 5 pages, 2 figures, accepted by ApJ Letters
arxiv created 2004/01/09 · openalex publication_date 2004/02/05 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Accretion from a disk onto a collapsed, relativistic star—a neutron star or black hole—is the mechanism widely believed to be responsible for the emission from compact X-ray binaries. Because of the extreme spatial resolution required, it is not yet possible to directly observe the evolution or dynamics of the inner parts of the accretion disk where general relativistic effects are dominant. Here we use the bright X-ray emission from a superburst on the surface of the neutron star 4U 1820-30 as a spotlight to illuminate the disk surface. The X-rays cause iron atoms in the disk to fluoresce, allowing a determination of the ionization state, covering factor and inner radius of the disk over the course of the burst. The time-resolved spectral fitting shows that the inner region of the disk is disrupted by the burst, possibly being heated into a thicker, more tenuous flow, before recovering its previous form in ~1000 s. This marks the first instance that the evolution of the inner regions of an accretion disk has been observed in real time.