Black Hole Accretion with Magnetic Fields

  • The original motivation for much of my research is to understand the way that black hole accretion disks operate and shine. Standard models of such incandescent ``tortillas" are wildly inadequate to explain some of the latest X-ray observations emanating from the hottest, innermost regions of black hole disks, i.e., the very wide Fe fluorescence line from material plunging onto a super-massive, extra-galactic black hole, and the discoveries of pairs of high frequency quasi-periodic oscillations in two stellar-mass--scale ``micro-quasars": GRO J1655-40 and GRO 1915+105. Given the non-thermal nature of the high energy X-ray emission, magnetically active coronae are most likely involved in both of these observations. Magnetic fields are also known to play a fundamental role in the general process of accretion. In the context of black hole accretion, the complexity of the problem in compound by general relativistic effects and by the ultra high energy density environment. I addressed the former problem in terms of linear hydromagnetic (MHD) wavemodes in a recent paper. The latter aspect, which treats the ``plasma of photons" (plus the usual electrons and protons) in a similar fashion, is the object of an ongoing collaboration with Ethan Vishniac of the Johns Hopkins University (my alma matter). This research aims to elucidate how accreting black holes operate. To address the shining part (Fe fluorescence and QPO emission), I have a keen interest on observations and theoretical models of magnetic reconnection and coronal heat deposition in the Sun.