We present deep observations of the 12CO (1−0) and (3−2) lines in the ultra-luminous infrared and radio galaxy 4C 12.50, carried out with the 30 m telescope of the Institut de Radioastronomie ...Millimétrique. Our observations reveal the cold molecular gas component of a warm molecular gas outflow that was previously known from Spitzer Space Telescope data. The 12CO(3−2) profile indicates the presence of absorption at −950 km s-1 from systemic velocity with a central optical depth of 0.22. Its profile is similar to that of the H i absorption that was seen in radio data of this source. A potential detection of the 0 → 1 absorption enabled us to place an upper limit of 0.03 on its central optical depth, and to constrain the excitation temperature of the outflowing CO gas to ≥65 K assuming that the gas is thermalized. If the molecular clouds fully obscure the background millimeter continuum that is emitted by the radio core, the H2 column density is ≥1.8 × 1022 cm-2. The outflow then carries an estimated cold H2 mass of at least 4.2 × 103 M⊙ along the nuclear line of sight. This mass will be even higher when integrated over several lines of sight, but if it were to exceed 3 × 109 M⊙, the outflow would most likely be seen in emission. Since the ambient cold gas reservoir of 4C 12.50 is 1.0 × 1010 M⊙, the outflowing-to-ambient mass ratio of the warm gas (37%) could be elevated with respect to that of the cold gas.
We report ALMA observations of CO(3–2) emission in the Seyfert/nuclear starburst galaxy NGC 613, at a spatial resolution of 17 pc, as part of our NUclei of GAlaxies (NUGA) sample. Our aim is to ...investigate the morphology and dynamics of the gas inside the central kiloparsec, and to probe nuclear fueling and feedback phenomena. The morphology of CO(3–2) line emission reveals a two-arm trailing nuclear spiral at r ≲ 100 pc and a circumnuclear ring at a radius of ∼350 pc that is coincident with the star-forming ring seen in the optical images. Also, we find evidence for a filamentary structure connecting the ring and the nuclear spiral. The ring reveals two breaks into two winding spiral arms corresponding to the dust lanes in the optical images. The molecular gas in the galaxy disk is in a remarkably regular rotation, however the kinematics in the nuclear region are very skewed. The nuclear spectrum of CO and dense gas tracers HCN(4–3), HCO+(4–3), and CS(7–6) show broad wings up to ±300 km s−1, associated with a molecular outflow emanating from the nucleus (r ∼ 25 pc). We derive a molecular outflow mass Mout = 2 × 106 M⊙ and a mass outflow rate of Ṁout = 27 M⊙ yr−1. The molecular outflow energetics exceed the values predicted by AGN feedback models: the kinetic power of the outflow corresponds to PK, out = 20%LAGN and the momentum rate is Ṁoutv ∼ 400LAGN/c. The outflow is mainly boosted by the AGN through entrainment by the radio jet, but given the weak nuclear activity of NGC 613, we might be witnessing a fossil outflow resulting from a previously strong AGN that has now faded. Furthermore, the nuclear trailing spiral observed in CO emission is inside the inner Lindblad resonance ring of the bar. We compute the gravitational torques exerted in the gas to estimate the efficiency of the angular momentum exchange. The gravity torques are negative from 25 to 100 pc and the gas loses its angular momentum in a rotation period, providing evidence for a highly efficient inflow towards the center. This phenomenon shows that the massive central black hole has significant dynamical influence on the gas, triggering the inflowing of molecular gas to feed the black hole.
We report Atacama Large Millimeter/submillimeter Array (ALMA) observations of CO(3-2) emission in a sample of seven Seyfert/LINER galaxies at the unprecedented spatial resolution of 0.″1 = 4−8 0 . ″ ...1 = 4 − 9 $ 0 {{\overset{\prime\prime}{.}}}1=4{-}9 $ pc. Our aim is to explore the close environment of active galactic nuclei (AGN), and the dynamical structures leading to their fueling, through the morphology and kinematics of the gas inside the sphere of influence of the black hole. The selected galaxies host low-luminosity AGN and have a wide range of activity types (Seyferts 1 to 2, LINERs), and barred or ringed morphologies. The observed maps reveal the existence of circumnuclear disk structures, defined by their morphology and decoupled kinematics, in most of the sample. We call these structures molecular tori, even though they often appear as disks without holes in the center. They have varying orientations along the line of sight, unaligned with the host galaxy orientation. The radius of the tori ranges from 6 to 27 pc, and their mass from 0.7 × 107 to 3.9 × 107 M⊙. The most edge-on orientations of the torus correspond to obscured Seyferts. In only one case (NGC 1365), the AGN is centered on the central gas hole of the torus. On a larger scale, the gas is always piled up in a few resonant rings 100 pc in scale that play the role of a reservoir to fuel the nucleus. In some cases, a trailing spiral is observed inside the ring, providing evidence for feeding processes. More frequently, the torus and the AGN are slightly off-centered with respect to the bar-resonant ring position, implying that the black hole is wandering by a few 10 pc amplitude around the center of mass of the galaxy. Our spatial resolution allows us to measure gas velocities inside the sphere of influence of the central black holes. By fitting the observations with different simulated cubes, varying the torus inclination and the black hole mass, it is possible to estimate the mass of the central black hole, which is in general difficult for such late-type galaxies, with only a pseudo-bulge. In some cases, AGN feedback is revealed through a molecular outflow, which will be studied in detail in a subsequent article.
ABSTRACT We analyzed near-infrared data of the nearby galaxy IC5063 taken with the Very Large Telescope SINFONI instrument. IC5063 is an elliptical galaxy that has a radio jet nearly aligned with the ...major axis of a gas disk in its center. The data reveal multiple signatures of molecular and atomic gas that has been kinematically distorted by the passage of the jet plasma or cocoon within an area of ∼1 kpc2. Concrete evidence that the interaction of the jet with the gas causes the gas to accelerate comes from the detection of outflows in four different regions along the jet trail: near the two radio lobes, between the radio emission tip and the optical narrow-line-region cone, and at a region with diffuse 17.8 GHz emission midway between the nucleus and the north radio lobe. The outflow in the latter region is biconical, centered 240 pc away from the nucleus, and oriented perpendicularly to the jet trail. The diffuse emission that is observed as a result of the gas entrainment or scattering unfolds around the trail and away from the nucleus with increasing velocity. It overall extends for 700 pc parallel and perpendicular to the trail. Near the outflow starting points, the gas has a velocity excess of 600-1200 km s−1 with respect to ordered motions, as seen in Fe ii, , or lines. High (1-0) S(3)/S(1) flux ratios indicate non-thermal excitation of gas in the diffuse outflow.
Using CO (4−3) and (2−1) Atacama Large Millimeter Array (ALMA) data, we prove that the molecular gas in the jet-driven winds of the galaxy IC 5063 is more highly excited than the rest of the ...molecular gas in the disk of the same galaxy. On average, the CO(4 − 3) /CO(2 − 1) flux ratio is 1 for the disk and 5 for the jet accelerated or impacted gas. Spatially-resolved maps reveal that in regions associated with winds, the CO(4 − 3) /CO(2 − 1) flux ratio significantly exceeds the upper limit of 4 for optically thick gas. It frequently takes values between 5 and 11, and it occasionally further approaches the upper limit of 16 for optically thin gas. Excitation temperatures of 30−100 K are common for the molecules in these regions. If all of the outflowing molecular gas is optically thin, at 30−50 K, then its mass is 2 × 106 M⊙. This lower mass limit is an order of magnitude below the mass derived from the CO(2 − 1) flux in the case of optically thick gas. Molecular winds can thus be less massive, but more easily detectable at high z than they were previously thought to be.
With high resolution (0.̋25 × 0.̋18) ALMA CO 3−2 (345 GHz) observations of the nearby (D = 21 Mpc, 1′′ = 102 pc), extremely radio-quiet galaxy NGC 1377, we have discovered a high-velocity, very ...collimated nuclear outflow which we interpret as a molecular jet with a projected length of ±150 pc. The launch region is unresolved and lies inside a radius r< 10 pc. Along the jet axis we find strong velocity reversals where the projected velocity swings from −150km s-1 to +150 km s-1. A simple model of a molecular jet precessing around an axis close to the plane of the sky can reproduce the observations. The velocity of the outflowing gas is difficult to constrain due to the velocity reversals but we estimate it to be between 240 and 850 km s-1 and the jet to precess with a period P = 0.3−1.1 Myr. The CO emission is clumpy along the jet and the total molecular mass in the high-velocity (±(60 to 150 km s-1)) gas lies between 2 × 106M⊙ (light jet) and 2 × 107M⊙ (massive jet). There is also CO emission extending along the minor axis of NGC 1377. It holds > 40% of the flux in NGC 1377 and may be a slower, wide-angle molecular outflow which is partially entrained by the molecular jet. We discuss the driving mechanism of the molecular jet and suggest that it is either powered by a (faint) radio jet or by an accretion disk-wind similar to those found towards protostars. It seems unlikely that a massive jet could have been driven out by the current level of nuclear activity which should then have undergone rapid quenching. The light jet would only have expelled 10% of the inner gas and may facilitate nuclear activity instead of suppressing it. The nucleus of NGC 1377 harbours intense embedded activity and we detect emission from vibrationally excited HCN J = 4−3ν2 = 1f which is consistent with hot gas and dust. We find large columns of H2 in the centre of NGC 1377 which may be a sign of a high rate of recent gas infall. The dynamical age ofthe molecular jet is short (<1 Myr), which could imply that it is young and consistent with the notion that NGC 1377 is caught in a transient phase of its evolution. However, further studies are required to determine the age of the molecular jet, its mass and the role it is playing in the growth of the nucleus of NGC 1377.
We report on Atacama Large Millimeter Array (ALMA) observations of CO(3−2) emission in the Seyfert2/starburst galaxy NGC 1808, at a spatial resolution of 4 pc. Our aim is to investigate the ...morphology and dynamics of the gas inside the central 0.5 kpc and to probe the nuclear feeding and feedback phenomena. We discovered a nuclear spiral of radius 1″ = 45 pc. Within it, we found a decoupled circumnuclear disk or molecular torus of a radius of 0.13″ = 6 pc. The HCN(4−3) and HCO
+
(4−3) and CS(7−6) dense gas line tracers were simultaneously mapped and detected in the nuclear spiral and they present the same misalignment in the molecular torus. At the nucleus, the HCN/HCO
+
and HCN/CS ratios indicate the presence of an active galactic nucleus (AGN). The molecular gas shows regular rotation, within a radius of 400 pc, except for the misaligned disk inside the nuclear spiral arms. The computations of the torques exerted on the gas by the barred stellar potential reveal that the gas within a radius of 100 pc is feeding the nucleus on a timescale of five rotations or on an average timescale of ∼60 Myr. Some non-circular motions are observed towards the center, corresponding to the nuclear spiral arms. We cannot rule out that small extra kinematic perturbations could be interpreted as a weak outflow attributed to AGN feedback. The molecular outflow detected at ≥250 pc in the NE direction is likely due to supernovae feedback and it is connected to the kpc-scale superwind.
The nearby system 4C12.50, also known as IRAS 13451+1217 and PKS 1345+12, is a merger of gas-rich galaxies with infrared and radio activity. It has a perturbed interstellar medium (ISM) and a dense ...configuration of gas and dust around the nucleus. The radio emission at small (∼100 pc) and large (∼100 kpc) scales, as well as the large X-ray cavity in which the system is embedded, are indicative of a jet that could have affected the ISM. We carried out observations of the CO(1−0), (3−2), and (4−3) lines with the Atacama Large Millimeter Array (ALMA) to determine basic properties (i.e., extent, mass, and excitation) of the cold molecular gas in this system, including its already-known wind. The CO emission reveals the presence of gaseous streams related to the merger, which result in a small (∼4 kpc-wide) disk around the western nucleus. The disk reaches a rotational velocity of 200 km s−1, and has a mass of 3.8(±0.4) × 109 M⊙. It is truncated at a gaseous ridge north of the nucleus that is bright in O III. Regions with high-velocity CO emission are seen at signal-to-noise ratios of between 3 and 5 along filaments that radially extend from the nucleus to the ridge and that are bright in O III and stellar emission. A tentative wind detection is also reported in the nucleus and in the disk. The molecular gas speed could be as high as 2200 km s−1 and the total wind mass could be as high as 1.5(±0.1) × 109 M⊙. Energetically, it is possible that the jet, assisted by the radiation pressure of the active nucleus or the stars, accelerated clouds inside an expanding bubble.
We present a comparison of the molecular gas properties in the outflow vs. in the ambient medium of the local prototype radio-loud and ultraluminous-infrared galaxy 4C12.50 (IRAS 13451+1232), using ...new data from the IRAM Plateau de Bure Interferometer and 30 m telescope and from the Herschel space telescope. Previous H2 (0–0) S(1) and S(2) observations with the Spitzer space telescope had indicated that the warm (~400 K) molecular gas in 4C12.50 is made up of a 1.4( ± 0.2) × 108M⊙ ambient reservoir and a 5.2(±1.7) × 107M⊙ outflow. The new CO(1–0) data cube indicates that the corresponding cold (25 K) H2 gas mass is 1.0(±0.1) × 1010M⊙ for the ambient medium and < 1.3 × 108 M⊙ for the outflow, when using a CO-intensity-to-H2-mass conversion factor α of 0.8 M⊙/(K km s-1 pc2). The combined mass outflow rate is high, 230–800 M⊙/yr, but the amount of gas that could escape the galaxy is low. A potential inflow of gas from a 3.3(±0.3) × 108M⊙ tidal tail could moderate any mass loss. The mass ratio of warm-to-cold molecular gas is ≳30 times higher in the outflow than in the ambient medium, indicating that a non-negligible fraction of the accelerated gas is heated to temperatures at which star formation is inefficient. This conclusion is robust against the use of different α factor values and/or different warm gas tracers (H2 vs. H2 plus CO). With the CO-probed gas mass at least 40 times lower at 400 K than at 25 K, the total warm-to-cold mass ratio is always lower in the ambient gas than in the entrained gas. Heating of the molecular gas could facilitate the detection of new outflows in distant galaxies by enhancing their emission in intermediate rotational number CO lines.
Submillimetre and millimetre line and continuum observations are important in probing the morphology, column density, and dynamics of the molecular gas and dust around obscured active galactic nuclei ...(AGNs) and their mechanical feedback. With very high-resolution (0.″02 × 0.″03 (2 × 3 pc)) ALMA 345 GHz observations of CO 3–2, HCO
+
4–3, vibrationally excited HCN 4–3
ν
2
= 1
f
, and continuum we have studied the remarkable, extremely radio-quiet, molecular jet and wind of the lenticular galaxy NGC 1377. The outflow structure is resolved, revealing a 150 pc long, clumpy, high-velocity (∼600 km s
−1
), collimated molecular jet where the molecular emission is emerging from the spine of the jet with an average diameter of 3–7 pc. The jet widens to 10–15 pc about 25 pc from the centre, which is possibly due to jet-wind interactions. A narrow-angle (50°–70°), misaligned and rotating molecular wind surrounds the jet, and both are enveloped by a larger-scale CO-emitting structure at near-systemic velocity. The jet and narrow wind have steep radial gas excitation gradients and appear turbulent with high gas dispersion (
σ
> 40 km s
−1
). The jet shows velocity reversals that we propose are caused by precession, or more episodic directional changes. We discuss the mechanisms powering the outflow, and we find that an important process for the molecular jet and narrow wind is likely magneto-centrifugal driving. In contrast, the large-scale CO-envelope may be a slow wind, or cocoon that stems from jet-wind interactions. An asymmetric, nuclear
r
∼ 2 pc dust structure with a high inferred molecular column density
N
(H
2
) ≃1.8 × 10
24
cm
−2
is detected in continuum and also shows compact emission from vibrationally excited HCN. The nuclear dust emission is hot (
T
d
> 180 K) and its luminosity is likely powered by a buried AGN. The lopsided structure appears to be a warped disk, which is responsible for a significant part of the nuclear obscuration and possibly formed as a result of uneven gas inflows. The dynamical mass inside
r
= 1.4 pc is estimated to 9
−3
+2
× 10
6
M
⊙
, implying that the supermassive black hole (SMBH) has a high mass with respect to the stellar velocity dispersion of NGC 1377. We suggest that the SMBH of NGC 1377 is currently in a state of moderate growth, at the end of a more intense phase of accretion and also evolving from a state of more extreme nuclear obscuration. The nuclear growth may be fuelled by low-angular momentum gas inflowing from the gas ejected in the molecular jet and wind. Such a feedback-loop of cyclic outflows and central accretion could explain why there is still a significant reservoir of molecular gas in this ageing, lenticular galaxy. A feedback-loop would be an effective process in growing the nuclear SMBH and thus would constitute an important phase in the evolution of NGC 1377. This also invites new questions as to SMBH growth processes in obscured, dusty galaxies.
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