Detecting adiabatic contraction in rotation curves

Abstract

We examine the structure of adiabatically contracted Einasto profiles, using the prescriptions of Blumenthal et al. and Gnedin et al., and its impact on rotation curves. Adiabatically contracted halos display a central power index of ∼0.7 ± 0.1 for nearly all values of the Einasto shape parameter α, and are well fit inside ≲ 1kpc by double power laws. However, attempts to fit exponential disk and uncontracted halos to adiabatically contracted rotation curves yield disk masses and central power indices that are too large. We also determine whether or not the rotation curve of NGC6503 displays evidence of adiabatic contraction using previously published bar formation constraints, and find that NGC6503 most likely has a minimally contracted halo. However, this conclusion depends on the correct choice of circular velocity curve. © 2011. The American Astronomical Society. All rights reserved.