Carbon-Enhanced Metal-Poor Stars in the Inner and Outer Halo Components
  of the Milky Way
  (Abridged) Carbon-enhanced metal-poor (CEMP) stars in the halo components of
the Milky Way are explored, based on accurate determinations of the
carbon-to-iron ([C/Fe]) abundance ratios and kinematic quantities for over
30000 calibration stars from the Sloan Digital Sky Survey (SDSS). Using our
present criterion that low-metallicity stars exhibiting [C/Fe] ratios
("carbonicity") in excess of [C/Fe]$ = +0.7$ are considered CEMP stars, the
global frequency of CEMP stars in the halo system for \feh\ $< -1.5$ is 8%; for
\feh\ $< -2.0$ it is 12%; for \feh\ $<-2.5$ it is 20%. We also confirm a
significant increase in the level of carbon enrichment with declining
metallicity, growing from $<$[C/Fe]$>$ $\sim +1.0$ at \feh\ $= -1.5$ to
$<$[C/Fe]$>$ $\sim +1.7$ at \feh\ $= -2.7$. The nature of the carbonicity
distribution function (CarDF) changes dramatically with increasing distance
above the Galactic plane, $|$Z$|$. For $|$Z$|$ $< 5$ kpc, relatively few CEMP
stars are identified. For distances $|$Z$|$ $> 5$ kpc, the CarDF exhibits a
strong tail towards high values, up to [C/Fe] $>$ +3.0. We also find a clear
increase in the CEMP frequency with $|$Z$|$. For stars with $-2.0 <$ [Fe/H] $<
-$1.5, the frequency grows from 5% at $|$Z$|$ $\sim 2$ kpc to 10% at $|$Z$|$
$\sim 10$ kpc. For stars with [Fe/H] $< -$2.0, the frequency grows from 8% at
$|$Z$|$ $\sim 2$ kpc to 25% at $|$Z$|$ $\sim 10$ kpc. For stars with $-2.0 <$
[Fe/H] $< -$1.5, the mean carbonicity is $<$[C/Fe]$>$ $\sim +1.0$ for 0 kpc $<$
$|$Z$|$ $<$ 10 kpc, with little dependence on $|$Z$|$; for [Fe/H] $< -$2.0,
$<$[C/Fe]$>$ $\sim +1.5$, again roughly independent of $|$Z$|$.
