Gravitational Wave Astrophysics
I am currently devoting a significant amount of my time to gravitational wave astrophysics, in particular the science that will be done with LISA, the Laser Interferometer Space Antenna. LISA is a joint space mission between NASA and the European Space Agency which will detect and characterize gravitational wave sources in the frequency range from 0.03 mHz up to about 1 Hz. This frequency region contains a wide range of sources including massive black hole mergers out to very high redshift (z > 10), captures of stellar-mass compact objects by massive black holes in galactic nuclei at moderate redshift, and ultra-compact binaries in our own galaxy. Gravitational wave astronomy will open an entirely new window on the Universe.
I am the US Mission Scientist for LISA and the US chair of the international science team. The NASA Jet Propulsion Laboratory (JPL) has significant efforts in both instrumentation and science analysis for LISA. I have dual interests in both the astrophysics of gravitational wave sources and the analytical methods for their detection and characterization. For instance, I am interested in complementary electromagnetic observations to learn about the ultra-compact binaries that we will eventually see as gravitational wave sources. I am investigating the use of large-area astronomical surveys such as the Palomar Transient Factory to discover new ultra-compact binaries systems through their time variability. We are particularly interested in systems with orbital periods less than about 1 hour which will shed light on a wide range of astrophysics including common envelope evolution, stability of mass transfer in close binary systems, and tidal effects on the white dwarf constituents.
I have a long-standing interest in compact objects and high energy astrophysics. This includes research work on radio pulsars, gamma-ray astrophysics, and cosmic-ray astrophysics. I have also dabbled in algorithms and computing, in particular techniques for detection and characterization of time-variable systems. I was involved in the development of the first massively parallel computing systems and was one of the founders of the Virtual Observatory movement.