2014/10/13 by S. Laycock, Silas G. T. Laycock, Rigel Cappallo +2 · 1 voice · 27 citations
Engineering · Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Black hole (networking) #Eclipse #Light curve #Mechanics and Biomechanics Studies #Neutron star #Orbital period #Physics #Pulsars and Gravitational Waves Research #Radial velocity #Stars #X-ray binary #astro-ph.HE
paper · pdf · doi:10.1093/mnras/stu2151
published in Monthly Notices of the Royal Astronomical Society 446(2), 1399-1410 (Oxford University Press) · Submitted to MNRAS. 13 Pages with 10 Figures
arxiv created 2014/10/13 · arxiv published 2014/10/13 · arxiv updated 2014/10/13 · openalex publication_date 2014/11/19 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The massive black hole (BH)+Wolf–Rayet (WR) binary IC 10 X-1 was observed in a series of 10 Chandra and two XMM–Newton observations spanning 2003–2012, showing consistent variability around 7 × 1037 erg s−1, with a spectral hardening event in 2009. We phase connected the entire light curve by folding the photon arrival times on a series of trial periods spanning the known orbital period and its uncertainty, refining the X-ray period to P = 1.45175(1) d. The duration of minimum flux in the X-ray eclipse is ∼5 h which together with the optical radial velocity (RV) curve for the companion yields a radius for the eclipsing body of 8–10 R⊙ for the allowed range of masses. The orbital separation (a1 + a2) = 18.5–22 R⊙ then provides a limiting inclination i > 63° for total eclipses to occur. The eclipses are asymmetric (egress duration ∼0.9 h) and show energy dependence, suggestive of an accretion disc hotspot and corona. The eclipse is much (∼5×) wider than the 1.5–2 R⊙ WR star, pointing to absorption/scattering in the dense wind of the WR star. The same is true of the close analog NGC 300 X-1. RV measurements of the He ii [λλ4686] line from the literature show a phase shift with respect to the X-ray ephemeris such that the velocity does not pass through zero at mid-eclipse. The X-ray eclipse leads inferior conjunction of the RV curve by ∼90°, so either the BH is being eclipsed by a trailing shock/plume, or the He ii line does not directly trace the motion of the WR star and instead originates in a shadowed partially ionized region of the stellar wind.