TY - JOUR
T1 - The Vertical Variation of HI Velocity Dispersion in Disk Galaxies
AU - Peters, Stephan Pieter Cornelis
AU - Freeman, Ken
AU - van der Kruit, Pieter C.
PY - 2010/10
Y1 - 2010/10
N2 - One of the key assumptions in dynamical applications of the HI velocity
dispersion in disk galaxies (e.g. to the flattening of the dark halo)
has always been the isothermal nature of the HI distribution. There is
no physical reason for this assumption: it is made because until now it
has not been possible to measure how the HI velocity dispersion changes
with height above the galactic plane. If the velocity dispersion is not
isothermal, then the inferred HI pressure gradient is incorrect and the
dynamical conclusions will be in error. We have recently published a new
technique for measuring the radial and vertical variation of the HI
velocity dispersion in edge-on disk galaxies. By carefully observing the
HI velocity dispersion in edge-on galaxies ESO 138-G014 and ESO 274-G001
as a function of radius and height above the plane, we will be able for
the first time to use the hydrostatics of the HI layer near the plane to
probe the shape of the halo and the contribution of the stellar
component to the rotation curve.
AB - One of the key assumptions in dynamical applications of the HI velocity
dispersion in disk galaxies (e.g. to the flattening of the dark halo)
has always been the isothermal nature of the HI distribution. There is
no physical reason for this assumption: it is made because until now it
has not been possible to measure how the HI velocity dispersion changes
with height above the galactic plane. If the velocity dispersion is not
isothermal, then the inferred HI pressure gradient is incorrect and the
dynamical conclusions will be in error. We have recently published a new
technique for measuring the radial and vertical variation of the HI
velocity dispersion in edge-on disk galaxies. By carefully observing the
HI velocity dispersion in edge-on galaxies ESO 138-G014 and ESO 274-G001
as a function of radius and height above the plane, we will be able for
the first time to use the hydrostatics of the HI layer near the plane to
probe the shape of the halo and the contribution of the stellar
component to the rotation curve.
KW - interstellar medium of other galaxies
KW - spectroscopy and imaging of nearby galaxies
KW - ATCA
UR - http://adsabs.harvard.edu/abs/2010atnf.prop.3584P
M3 - Editorial
JO - ATNF
JF - ATNF
ER -