Bibcode
García-Burillo, S.; Combes, F.; Usero, A.; Aalto, S.; Krips, M.; Viti, S.; Alonso-Herrero, A.; Hunt, L. K.; Schinnerer, E.; Baker, A. J.; Boone, F.; Casasola, V.; Colina, L.; Costagliola, F.; Eckart, A.; Fuente, A.; Henkel, C.; Labiano, A.; Martín, S.; Márquez, I.; Muller, S.; Planesas, P.; Ramos Almeida, C.; Spaans, M.; Tacconi, L. J.; van der Werf, P. P.
Bibliographical reference
Astronomy and Astrophysics, Volume 567, id.A125, 24 pp.
Advertised on:
7
2014
Journal
Citations
383
Refereed citations
348
Description
Aims: We investigate the fueling and the feedback of star
formation and nuclear activity in NGC 1068, a nearby
(D = 14 Mpc) Seyfert 2 barred galaxy, by analyzing the distribution and
kinematics of the molecular gas in the disk. We aim to understand if and
how gas accretion can self-regulate. Methods: We have used the
Atacama Large Millimeter Array (ALMA) to map the emission of a set of
dense molecular gas (n(H2) ≃ 105 - 6
cm-3) tracers (CO(3-2), CO(6-5), HCN(4-3),
HCO+(4-3), and CS(7-6)) and their underlying continuum
emission in the central r ~ 2 kpc of NGC 1068 with
spatial resolutions ~0.3″ - 0.5″ (~20-35 pc for the assumed
distance of D = 14 Mpc). Results: The sensitivity and spatial
resolution of ALMA give an unprecedented detailed view of the
distribution and kinematics of the dense molecular gas (n(H2)
≥ 105 - 6cm-3) in NGC 1068.
Molecular line and dust continuum emissions are detected from a r ~ 200
pc off-centered circumnuclear disk (CND), from the 2.6 kpc-diameter bar
region, and from the r ~ 1.3 kpc starburst (SB) ring. Most of the
emission in HCO+, HCN, and CS stems from the CND. Molecular
line ratios show dramatic order-of-magnitude changes inside the CND that
are correlated with the UV/X-ray illumination by the active galactic
nucleus (AGN), betraying ongoing feedback. We used the dust continuum
fluxes measured by ALMA together with NIR/MIR data to constrain the
properties of the putative torus using CLUMPY models and found a torus
radius of 20+6-10pc. The Fourier decomposition of
the gas velocity field indicates that rotation is perturbed by an inward
radial flow in the SB ring and the bar region. However, the gas
kinematics from r ~ 50 pc out to r ~ 400 pc reveal a massive
(Mmol~ 2.7+0.9-1.2 ×
107 M⊙) outflow in all molecular tracers. The
tight correlation between the ionized gas outflow, the radio jet, and
the occurrence of outward motions in the disk suggests that the outflow
is AGN driven. Conclusions: The molecular outflow is likely
launched when the ionization cone of the narrow line region sweeps the
nuclear disk. The outflow rate estimated in the CND, dM/dt~
63+21-37 M⊙ yr-1, is an
order of magnitude higher than the star formation rate at these radii,
confirming that the outflow is AGN driven. The power of the AGN is able
to account for the estimated momentum and kinetic luminosity of the
outflow. The CND mass load rate of the CND outflow implies a very short
gas depletion timescale of ≤1 Myr. The CND gas reservoir is likely
replenished on longer timescales by efficient gas inflow from the outer
disk.
Based on observations carried out with ALMA in Cycle 0.
Related projects
Nuclear Activity in Galaxies: a 3D Perspective from the Nucleus to the Outskirts
This project consists of two main research lines. First, the study of quasar-driven outflows in luminous and nearby obscured active galactic nuclei (AGN) and the impact that they have on their massive host galaxies (AGN feedback). To do so, we have obtained Gran Telescopio CANARIAS (GTC) infrared and optical observations with the instruments
Cristina
Ramos Almeida