We present near-infrared VLT ISAAC imaging and spectroscopy of the peculiar Virgo galaxy NGC 4438 , whose nucleus has been classified as a LINER .
The data are supplemented by mid-infrared imaging , and compared to previous WFPC2 HST broadband images .
Images and position-velocity maps of the [ Fe ii ] and H _ { 2 } line emissions are presented and compared with the distribution of the optical narrow-line region and radio features .
Our results show that shocks ( possibly driven by a radio jet ) contribute to an important fraction of the excitation of [ Fe ii ] , while X-ray heating from a central AGN may be responsible for the H _ { 2 } excitation .
We address the question whether the outflow has an AGN or a starburst origin by providing new estimates of the central star formation rate and the kinetic energy associated with the gas .
By fitting a Sérsic bulge , an exponential disc and a compact nuclear source to the light distribution , we decomposed NGC 4438 ’ s light distribution and found an unresolved nuclear source at 0.8 \arcsec resolution with M _ { K } = -18.7 and J - H = 0.69 .
Our measured bulge velocity dispersion , 142 \mathrm { km~ { } s ^ { -1 } } , together with the standard \mathcal { M } _ { bh } - \sigma relation , suggests a central black hole mass of \log ( \mathcal { M } _ { bh } / \mbox { M$ { } _ { \odot } $ } ) \sim 7.0 .
The stellar kinematics measured from the near-infrared CO lines shows a strong peak in the velocity dispersion of \sigma _ { 0 } \sim 178 \mathrm { km~ { } s ^ { -1 } } in the central 0.5″ , which is possible kinematic evidence of a central black hole .
We calculated a general expression for the integrated Sérsic profile flux density in elliptical geometry , including the case of ‘ disky ’ isophotes .