HALOGAS: Extraplanar gas in NGC 3198
  We present the analysis of new, deep HI observations of the spiral galaxy NGC
3198, as part of the HALOGAS (Westerbork Hydrogen Accretion in LOcal GAlaxieS)
survey, with the main aim of investigating the presence, amount, morphology and
kinematics of extraplanar gas. We present models of the HI observations of NGC
3198: the model that matches best the observed data cube features a thick disk
with a scale height of ~3 kpc and an HI mass of about 15% of the total HI mass;
this thick disk also has a decrease in rotation velocity as a function of
height (lag) of 7-15 km/s/kpc (though with large uncertainties). This
extraplanar gas is detected for the first time in NGC 3198. Radially, this gas
appears to extend slightly beyond the actively star-forming body of the galaxy
(as traced by the Halpha emission), but it is not more radially extended than
the outer, fainter parts of the stellar disk. Compared to previous studies,
thanks to the improved sensitivity we trace the rotation curve out to larger
radii. We model the rotation curve in the framework of MOND (Modified Newtonian
Dynamics) and we confirm that, with the allowed distance range we assumed, fit
quality is modest in this galaxy, but the new outer parts are explained in a
satisfactory way.
