We report the discovery of gas streaming motions along nuclear spiral arms towards the LINER nucleus of the galaxy NGC6951. The observations, obtained using the GMOS integral field spectrograph on the Gemini North telescope, yielded maps of the flux distributions and gas kinematics in the H , [Nii] 6584 and [S ii] 6717,31 emission lines of the inner 7′′×15′′ of the galaxy. This region includes a circumnuclear star-forming ring with radius 500 pc, a nuclear spiral inside the ring and the LINER nucleus. The kinematics of the ionized gas is dominated by rotation, but subtraction of a kinematic model of a rotating exponential disk reveals deviations from circular rotation within the nuclear ring which can be attributed to (1) streaming motions along the nuclear spiral arms and (2) a bipolar outflow which seems to be associated to a – 2 – nuclear jet. On the basis of the observed streaming velocities and geometry of the spiral arms we estimate a mass inflow rate of ionized gas of 3× 10−4M⊙ yr−1, which is of the order of the accretion rate necessary to power the LINER nucleus of NGC6951. Similar streaming motions towards the nucleus of another galaxy with LINER nucleus – NGC1097 – have been reported by our group in a previous paper. Taken together, these results support a scenario in which nuclear spirals are channels through which matter is transferred from galactic scales to the nuclear region to feed the supermassive black hole.
Department, Program, or Center
School of Physics and Astronomy (COS)
Astrophysical Journal Letters 641 (2006) L25-L28
RIT – Main Campus