Understand
In astronomy, the problem of black holes is arguably second in importance only to the problem of cosmology.
- A current frontier in black hole research is the measurement of spin.
- During the past three years, the spins of several stellar-mass black holes in X-ray binaries have been measured via two techniques: fitting the X-ray continuum spectrum and modeling the profile of the Fe K line.
- This fledgling enterprise motivates the following decadal goals: (1) Firmly establish the continuum-fitting and Fe K methods; obtain precise values of spin for 10-20 black holes, several using both methods; (2) use the derived masses and spins to test models of jets, GRBs, supernovae, black hole formation, black hole binary evolution, etc.; (3) serve the IXO mission by securing the Fe K methodology, which is currently the only means to measure the spins of supermassive black holes in AGN; (4) identify the correct model of high-frequency QPOs, thereby opening a third channel for measuring spin; (5) pursue X-ray polarimetry as a means of securing the continuum-fitting and Fe K methods, and also as a possible fourth avenue to spin; and (6) develop and test MHD models of thin disks in strong gravity.