Welcome to the 10th International LISA Symposium

The eLISA detector will provide measurements of the masses and spins of merging supermassive black holes with unprecedented accuracy. I will show that these measurements will allow for testing competing models for the accretion flow onto supermassive black holes, and more in general explore the co-evolution of these objects with their galactic hosts and the interaction with their surroundings.

Binary black hole mergers in the presence of gaseous accretion flows are prime candidates for simultaneous observations of both gravitational waves and electromagnetic signals. We present the results of 2D hydrodynamical simulations of circumbinary disk accretion using the finite-volume code DISCO. This code solves the 2D viscous Navier-Stokes equations on a high-resolution moving mesh which shears with the fluid flow, greatly reducing advection errors in comparison with a fixed grid. We find that gas is efficiently stripped from the inner edge of the circumbinary disk and enters the cavity along accretion streams, which feed persistent “mini-disks” surrounding each black hole. We identify the mass-ratio dependence of the characteristic periodicity in the measured accretion rate onto each BH. We also find that the magnitude of the accretion onto the secondary is sufficient to drive the binary toward larger mass ratio.

To be submitted

Astronomers now know that supermassive black holes are a natural part of nearly every galaxy, but how these black holes form, grow, and interact within the galactic center is still a mystery. In theory, gas-rich major galaxy mergers can easily generate the central stockpile of fuel needed for a low mass central black hole 'seed' to grow quickly and efficiently into a supermassive one. Because of the clear theoretical link between gas-rich major mergers and supermassive black hole growth, this major merger paradigm has become a well-accepted way to form the billion solar mass black holes that power bright quasars in the early universe. It's much less clear, though, how well this paradigm works for growing the 'lightest' supermassive black holes; these million solar mass black holes tend to lie in galaxies like our own Milky Way, where the supermassive black hole is currently quiescent and major mergers were few and far between. This talk will touch on some current and ongoing work on refining our theories of black hole growth for this lightest supermassive class.