2006/08/08 by Kimitake Hayasaki, K. Hayasaki, Atsuo T. Okazaki · 1 citation
Engineering · Physics and Astronomy · #Accretion (finance) #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Light curve #Mechanics and Biomechanics Studies #Neutron star #Physics #X-ray binary #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2006.10917.x
published as Mon.Not.Roy.Astron.Soc.372:1140-1148,2006 · 10 pages, 7 figures, Accepted for publication in MNRAS
arxiv created 2006/08/08 · openalex publication_date 2006/09/27 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We numerically study the long-term evolution of the accretion disc around the neutron star in a coplanar Be/X-ray binary with a short period and a moderate eccentricity. From three-dimensional smoothed particle hydrodynamics simulations, we find that the disc evolves through three distinct phases, each characterized by different mass-accretion patterns. In the first ‘developing phase’, the disc is formed and develops towards a nearly Keplerian disc. It has a relatively large, double-peaked mass accretion rate with the higher peak caused by the direct accretion at periastron, which is followed by the lower peak that is caused by the accretion induced by a one-armed spiral wave. In the second ‘transition phase’, the disc is approximately Keplerian and grows with time. The mass-accretion rate increases as the disc grows. In the second phase, there is a transition in the mass-accretion rate from a double-peaked to a single-peaked pattern. In the final quasi-steady state, the mass-accretion rate is on average balanced with the mass-transfer rate from the Be disc and exhibits a regular orbital modulation. In the quasi-steady state, the mass accretion rate has a single peak that is caused by the wave-induced accretion as in a later stage of the transition phase. The orbital modulation of X-ray maxima could provide not only circumstantial evidence for the persistent disc but also an observational diagnosis of the disc evolutionary state.