Velocity and abundance precisions for future high-resolution
  spectroscopic surveys: a study for 4MOST
  In preparation for future, large-scale, multi-object, high-resolution
spectroscopic surveys of the Galaxy, we present a series of tests of the
precision in radial velocity and chemical abundances that any such project can
achieve at a 4m class telescope. We briefly discuss a number of science cases
that aim at studying the chemo-dynamical history of the major Galactic
components (bulge, thin and thick disks, and halo) - either as a follow-up to
the Gaia mission or on their own merits. Based on a large grid of synthetic
spectra that cover the full range in stellar parameters of typical survey
targets, we devise an optimal wavelength range and argue for a moderately
high-resolution spectrograph. As a result, the kinematic precision is not
limited by any of these factors, but will practically only suffer from
systematic effects, easily reaching uncertainties <1 km/s. Under realistic
survey conditions (namely, considering stars brighter than r=16 mag with
reasonable exposure times) we prefer an ideal resolving power of R~20000 on
average, for an overall wavelength range (with a common two-arm spectrograph
design) of [395;456.5] nm and [587;673] nm. We show for the first time on a
general basis that it is possible to measure chemical abundance ratios to
better than 0.1 dex for many species (Fe, Mg, Si, Ca, Ti, Na, Al, V, Cr, Mn,
Co, Ni, Y, Ba, Nd, Eu) and to an accuracy of about 0.2 dex for other species
such as Zr, La, and Sr. While our feasibility study was explicitly carried out
for the 4MOST facility, the results can be readily applied to and used for any
other conceptual design study for high-resolution spectrographs.
