Metallicity Gradients at Large Galactocentric Radii Using the
  Near-infrared Calcium Triplet
  We describe a new spectroscopic technique for measuring radial metallicity
gradients out to large galactocentric radii. We use the DEIMOS multi-object
spectrograph on the Keck telescope and the galaxy spectrum extraction technique
of Proctor et al. (2009). We also make use of the metallicity sensitive
near-infrared (NIR) Calcium triplet (CaT) features together with single stellar
population models to obtain metallicities. Our technique is applied as a pilot
study to a sample of three relatively nearby (<30 Mpc) intermediate-mass to
massive early-type galaxies. Results are compared with previous literature
inner region values and generally show good agreement. We also include a
comparison with profiles from dissipational disk-disk major merger simulations.
Based on our new extended metallicity gradients combined with other
observational evidence and theoretical predictions, we discuss possible
formation scenarios for the galaxies in our sample. The limitations of our new
technique are also discussed.
