The NUGA project: The Seyfert 2 galaxy NGC3147
V. Casasola, F. Combes, S. Garcia-Burillo, L. K. Hunt, S. Leon, A. Baker
aa r X i v : . [ a s t r o - ph ] D ec **FULL TITLE**ASP Conference Series, Vol. **VOLUME**, **YEAR OF PUBLICATION****NAMES OF EDITORS** The NUGA project: The Seyfert 2 galaxy NGC 3147
V. Casasola , , F. Combes , S. Garc´ıa-Burillo , L. K. Hunt , S. L´eon ,A. Baker Dip. di Astronomia Padova, Observatoire de Paris-LERMA, Observatorio Astron´omico Nacional-OAN Madrid, Istituto diRadioastronomia-INAF Firenze, Instituto de Astrof´ısica de Andaluc´ıaCSIC Granada, Dep. of Physics and Astronomy, Rutgers New Jersey
Abstract.
We present CO(1-0) and CO(2-1) maps of the Seyfert 2 galaxyNGC 3147 of the NUclei of GAlaxies (NUGA) sample at 1.8 ′′ × ′′ and 1.4 ′′ × ′′ resolution respectively. Identifying the presence of a bar in NGC 3147we also compute the gravity torques exerted from the stellar bar on the gas.
1. Molecular gas distribution in NGC 3147: CO rings
NUGA project (Garc´ıa-Burillo et al. 2003) is a combined effort to undertake ahigh resolution (1 ′′ -2 ′′ ) and high-sensitivity CO survey, made with the Plateaude Bure IRAM interferometer, for a sample of nearby AGN spirals.For the galaxy NGC 3147, after merging the interferometer data with the shortspacing observations done with the IRAM-30m, we find that a nuclear peak andtwo molecular rings or pseudo-rings (at r ∼ ′′ ≃ ∼ ′′ ≃ ∼ ′′ (Fig. 1).
2. Comparison between CO and star formation tracers
Fig. 2 shows that the molecular gas distribution has partial counterparts atwavelengths tracing the star formation, e.g. infrared emission (SPITZER) andultraviolet one (GALEX).
3. Computation of the torques
Using a NIR image obtained at the Canada-France-Hawaii Telescope, we identifythe presence of a bar in NGC 3147 classified as non-barred galaxy in the optical.Computing the gravity torques from this stellar bar, we find that the gas in themain central CO pseudo-ring is subject to a dominant negative torque and losesangular momentum. On the contrary, the gas in spiral arms forming the externalpseudo-ring suffers positive torques and is driven outwards. We conclude thatsome molecular gas is presently inflowing to the center, and probably feedingthe low-luminosity Seyfert 2 observed in NGC 3147 (see Casasola et al. 2007).1
Figure 1.
Left panel:
CO(1-0) integrated intensity contours observed withthe IRAM PdBI toward the center of NGC 3147. Contour levels are from 2 σ to 17 σ with 1 σ (= 0.15 Jy/beam km s − ) spacing. Right panel:
Same as
Leftpanel for the CO(2-1) line. The rms noise level is σ = 0.2 Jy/beam km s − .Contour levels are from 2 σ to 18 σ with 1 σ (= 0.2 Jy/beam km s − ) spacing.Figure 2. Left panel:
Superposition of the CO(1-0) contour levels and theFUV-GALEX image.
Right panel:
Superposition of the CO(1-0) contourlevels and the 8 µ m SPITZER/IRAC. There is a good agreement betweenthe CO and the FUV and mid-IR emissions in the nuclear peak and in theinner ring, but the external CO pseudo-ring is found in the FUV and dust“interarm” regions. Acknowledgments.
We would like to thank SOC and LOC of the confe-rence for supporting one of us (V. Casasola).