The first high quality Mg II reverberation lag measurement (North)
PI:
David Sand
Co-I(s):
Leslie Raganit, Steve Crawford, Peter Williams, Stefano Valenti, Aaron Barth, Tommaso Treu, Keith Horne, Leopoldo Diaz, Encarni Colmenero, Todd Boroson
Abstract
We propose to make the first high-quality reverberation mapping measurement using the MgII emission line in an active galactic nucleus at z~0.35. Virtually everything we know about black hole-galaxy co-evolution and black hole demographics at high-z relies on the extrapolation of scaling relations established by ~50 reverberation measurements made in the local Universe, using the HBeta emission line. This is unjustified as the prominent emission lines that shift into the optical window at moderate to high redshift (e.g., MgII and CIV) likely originate from different regions around the black hole, and will have as yet unknown scaling relations. Gemini/GMOS spectroscopy will play the crucial role of providing MgII (and HBeta) emission line light curves which will be cross-correlated with our photometric light curves, resulting in a `lag' measurement and supermassive black hole mass. This is the first step for producing a R_{BLR} vs. L relation for the MgII line and more direct black hole measurements at high-z.