Predoctoral Projects, 2015

Project Title: Supermassive Black Holes: Supermassive Black Holes, the Variable Sky, and Carbon Stars

Project Advisor: Paul J. Green

Background: Quasars are extremely luminous galaxies whose cores are inhabited by supermassive blackholes accreting matter from the surrounding environment. The physics of their accretion is poorly understood, but new physical and observational analogies to Galactic ~stellar-mass X-ray binaries hold great promise for tying the physics together a mass range of 100 million, using both multi-wavelength properties and variability from the PanSTARRS survey. I also study the properties of dwarf carbon stars, abundance-enhanced (OK, polluted might be a better word) companions to extinct AGB stars.

Scientific Questions: Do spectral and timing properties scale all the way from stellar-mass X-ray binaries to quasars? What does this tell us about the difference between their accretion and environments? In what Galactic population are dwarf carbon stars predominantly found and why? What are the mass limits of recognizable carbon molecular enhancement?

Scientific Methodology: Now that our X-ray and optical imaging survey is complete, we are emphasizing large sample studies using ChaMP's overlap with the SDSS. Simulations and detailed completeness estimates allow us to accurately characterize space density and luminosity function calculations out to high redshifts. We turn now to the multiwavelength properties of X-ray-selected AGN. I am PI of a large program to obtain ~100k spectra of PanSTARRS-selected variables using the BOSS spectrograph on the APO3.5m (SDSS telescope) starting in 2014. We will study the selection and properties of variables including both stars and AGN. On the (unrelated) carbon star project, the push to characterize a large sample of SDSS dwarf carbon stars is on. I also wish to hunt through the SDSS for a similar post-mass-transfer type star, which must exit, but has never been seen before.

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Clay Fellow Warren Brown