The Spin of the Black Hole Microquasar XTE J1550–564 via the Continuum-Fitting and Fe-Line Methods arXiv: arXiv: by James F. Steiner et al. The 5th Group Seminar Yan Wang 王炎 Oct. 28, 2010

Microquasar XTE J1550–564 is a dynamically confirmed black hole binary with black hole primary in a 1.55-day orbit with a late G or early K companion. During its principal 1998–1999 outburst cycle, the bright X-ray transient XTE J1550–564 produced one of the most remarkable flare events ever observed for a black hole binary. For ≈ 1 day, the source intensity rose fourfold relative to neighbouring plateau values, reaching 6.8 Crab. Four days later, AU-scale superluminal radio jets were observed. Their separation angle ( ∼ 255 mas) and relative velocity ( ∼ 65 mas d−1) links the birth of these jets to the impulsive X-ray flare. The subsequent detection of large-scale radio jets in 2000 led to the discovery of relativistic X-ray jets.

For the continuum-fitting analysis, we use a data sample consisting of several dozen RXTE spectra. (90 per cent confidence), with a most likely spin of For the Fe-Kα analysis, we use a pair of ASCA spectra from a single epoch. Our estimate of spin is Combining these results, we conclude that the spin of this black hole is moderate,

This result suggests that the jet of this microquasar is powered largely by its accretion disc rather than by the spin energy of the black hole. The low spins of both J1550 and A0620–00 indicate that, for at least some microquasars, BZ-type mechanisms are not primary in driving powerful episodic jets, and that other mechanisms (perhaps BP) are at play. The near Eddington-limited 7 Crab flare observed for J1550 suggests that radiation-pressure support from a thermal disc is one possible way that low-spin black holes are aided in driving large-scale relativistic jets.