Title : Alcohol chemistry in the galactic center
Authors : MA Requena Torres, J. martin Pintado
Abstract :
We have carried out a systematic study of methanol, ethanol, dimethyl
ether, methyl formate, formic acid and acetic acid in different galactic center
clouds. The abundances of methanol ranges for few $10^{-8}$ to $10^{-6}$. The
abundances of ethanol, dimethyl ether and methyl formate are a factor of
$\sim 20$ smaller than those of methanol. It is interesting to note that the
abundance ratios of these molecules relative to methanol are really constant to
with in a factor $\sim 4-8$. In fact, there is a systematic trend to decrease
the abundance ratio as the methanol abundance increase. Our data is compared
with homogeneous observations of the same molecules in hot cores. The ratios of
these complex  molecules with respect to methanol are similar to that found in
the GC clouds. Alcohol chemistry is believed to be driven by evaporation of
alcohol from grain mantles. If a time dependent model of these characteristics
is applied in the GC clouds, all the galactic center region had to have suffered
large scale shocks in a short period of time of $10^{4}-10^{5}$ years ago. This
is unfeasible since the observed region in the GC cover about 200
parsecs. This fact and the similar comportment presented by the
different molecules suggest that the alcohol chemistry could be
produce in the grain mantles. Also, two different regions, the Sickle
and The Thermal Arches, present lower abundances in the observed
molecules which could be photodissociated by the same source that heat
and ionize these clouds leading a different chemical evolution.