2016/08/24 by Ming Lyu, Mariano Méndez, Mariano Mendez +3 · 1 citation
Earth and Planetary Sciences · Physics and Astronomy · #Accretion (finance) #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Convexity #Equator #High-pressure geophysics and materials #Light curve #Neutron star #Physics #Pulsars and Gravitational Waves Research #Quasi periodic #astro-ph.HE
paper · pdf · doi:10.1093/mnras/stw2158
Accepted for publication in MNRAS; 12 pages, 3 figures
arxiv created 2016/08/24 · openalex publication_date 2016/08/26 · arxiv updated 2016/09/07 · openalex created_date 2016/09/16 · openalex updated_date 2026/08/05
We investigated the convexity of all type I X-ray bursts with millihertz quasi-periodic oscillations (mHz QPOs) in 4U 1636−53 using archival observations with the Rossi X-ray Timing Explorer. We found that, at a 3.5σ confidence level, in all 39 cases in which the mHz QPOs disappeared at the time of an X-ray burst, the convexity of the burst is positive. The convexity measures the shape of the rising part of the burst light curve and, according to recent models, it is related to the ignition site of bursts on the neutron-star surface. This finding suggests that in 4U 1636−53 these 39 bursts and the marginally stable nuclear burning process responsible for the mHz QPOs take place at the neutron-star equator. This scenario could explain the inconsistency between the high accretion rate required for triggering mHz QPOs in theoretical models and the relatively low accretion rate derived from observations.