Chemical Characterization of the Inner Galactic bulge:North-South
  Symmetry
  While the number of stars in the Galactic bulge with detailed chemical
abundance measurements is increasingly rapidly, the inner Galactic bulge ( |b|
< 2$^\circ$) remains poorly studied, due to heavy interstellar absorption and
photometric crowding. We have carried out a high-resolution IR spectroscopic
study of 72 M giants in the inner bulge using the CRIRES (ESO/VLT) facility.
Our spectra cover the wavelength range of 2.0818 - 2.1444 $\mu$m with the
resolution of R$\sim$50,000 and have signal-to-noise ratio of 50 - 100. Our
stars are located along the bulge minor axis at l = 0$^\circ$, b =
$\pm$0$^\circ$, $\pm$1$^\circ$, $\pm$2$^\circ$ and +3$^\circ$, selected with
the aim of investigating any North-South asymmetries in the metallicity
distribution function and composition, and comparing them to the outer bulge
fields. Our sample was analysed in a homogeneous way using the most current
K-band line list.
  We clearly detect a bimodal MDF with a metal-rich peak at $\rm \sim
+0.3\,dex$ and a metal-poor peak at $\rm \sim -0.5\,dex$. Only a single star is
found to exceed $\rm [Fe/H]=+0.5\,dex$. They show a symmetric behaviour along
the $\pm$1$^\circ$, $\pm$2$^\circ$ fields. The Galactic Center field reveals in
contrast a mainly metal-rich population with a mean metallicity of $\rm
+0.3\,dex$. We derived $\rm [Mg/Fe]$ and $\rm [Si/Fe]$ abundances which are
consistent with trends from the outer bulge, with a gradually decreasing trend
with increasing metallicity. We confirm for the supersolar metallicity stars
the decreasing trend in \mgfe\ and \sife\ as expected from chemical evolution
models. With the caveat of a relatively small sample, we do not find
significant differences in the chemical abundances between the Northern and the
Southern fields, hence the evidence is consistent with symmetry in chemistry
between North and South.
