Bibcode
DOI
Storchi-Bergmann, Thaisa; Dors, Oli L., Jr.; Riffel, Rogemar A.; Fathi, Kambiz; Axon, David J.; Robinson, Andrew; Marconi, Alessandro; Östlin, Göran
Bibliographical reference
The Astrophysical Journal, Volume 670, Issue 2, pp. 959-967.
Advertised on:
12
2007
Journal
Citations
99
Refereed citations
81
Description
We report the discovery of gas streaming motions along nuclear spiral
arms toward the LINER nucleus of the galaxy NGC 6951. 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 Hα, [N II] λ6584, and [S II] λλ6717, 6731
emission lines of the inner 7''×15'' of the
galaxy. This region includes a circumnuclear star-forming ring with a
radius of ~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 that can be
attributed to (1) streaming motions along the nuclear spiral arms and
(2) a bipolar outflow that seems to be associated with a 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
~3×10-4 Msolar yr-1, which is on
the order of the accretion rate necessary to power the LINER nucleus of
NGC 6951. Similar streaming motions toward the nucleus of another galaxy
with a LINER nucleus, NGC 1097, 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.