Chandra and XMM Monitoring of the Black Hole X-ray Binary IC 10 X-1

Abstract

The massive black hole + Wolf-Rayet binary IC10 X-1 was observed in a series of 10 Chandra and 2 XMM-Newton observations spanning 2003-2012, showing consistent variability around 7 x10^37 erg/s, 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 hr which together with the optical radial velocity curve for the companion yields a radius for the eclipsing body of 8-10 Rsun for the allowed range of masses. The orbital separation of 18.5-22 Rsun then provides a limiting inclination i>63 degrees for total eclipses to occur. The eclipses are asymmetric (egress duration 0.9 hr) and show energy dependence, suggestive of an accretion-disk hotspot and corona. The eclipse is much (5X) wider than the 1.5-2 Rsun 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 [4686] 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 degrees, 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.

Submitted to MNRAS. 13 Pages with 10 Figures

References in corpus (10)

• X-ray Properties of Black-Hole Binaries
• A 15.65 solar mass black hole in an eclipsing binary in the nearby spiral galaxy Messier 33
• On IC 10 X-1, the Most Massive Known Stellar-Mass Black Hole
• The Orbital Period of the Wolf-Rayet Binary IC 10 X-1; Dynamic Evidence that the Compact Object is a Black Hole
• The prototype colliding-wind pinwheel WR 104
• M 33 X-7: ChASeM33 reveals the first eclipsing black hole X-ray binary
• A 33 hour period for the Wolf-Rayet/black hole X-ray binary candidate NGC 300 X-1
• A Study of the Evolution of the Close Binaries Cyg X-3, IC 10 X-1, NGC 300 X-1, SS 433, and M33 X-7 Using the "Scenario Machine"
• Asymmetric Wolf-Rayet winds: implications for GRB afterglows
• A Transient Supergiant X-ray Binary in IC10. An Extragalactic SFXT?

Cited by in corpus (10)

• Gemini/GNIRS infrared spectroscopy of the Wolf-Rayet stellar wind in Cygnus X-3
• Two eclipsing ultraluminous X-ray sources in M 51
• Stronger Reflection from Black Hole Accretion Disks in Soft X-ray States
• CG X-1: an eclipsing Wolf-Rayet ULX in the Circinus galaxy
• The Wolf-Rayet + Black Hole Binary NGC 300 X-1: What is the Mass of the Black Hole?
• CI Camelopardalis: The first sgB[e]-High Mass X-ray Binary Twenty Years on, a Supernova Imposter in our own Galaxy?
• Wolf-Rayet stars, black holes and the first detected gravitational wave source
• Probing the Stellar Wind of the Wolf-Rayet Star in IC 10 X-1
• Accreting Black Holes Skewing and Bending the Optical Emission from Massive Wolf-Rayet Companions -- A Case Study of IC10 X-1
• Diagnosing the Properties and Evolutionary Fates of Black Hole and Wolf-Rayet X-ray Binaries as Potential Gravitational Wave Sources for the LIGO-Virgo-KAGRA Network