Molecular gas in NUclei of GAlaxies (NUGA)

García‐Burillo, S.; Combes, F.; Schinnerer, E.; Boone, F.; Hunt, L. K.

doi:10.1051/0004-6361:20052900

Cited by 173 publications

(267 citation statements)

References 60 publications

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“…García-Burillo et al (2005) have presented non-circular motions caused by bars, which are of the same orders of magnitude ∼60−70 km s −1 . More recently, with even higher sensitivity and resolution, van der Laan et al (2011) have for the first time seen dedoubled velocity profiles in the CO data towards the barred galaxy NGC 6951.…”

Section: Examples Of Bar Shocksmentioning

confidence: 95%

Molecular gas in the inner 0.7 kpc-radius ring of M 31

Melchior

Combes

2011

A&A

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The study of the gas kinematic in the central 1.5 kpc × 1.5 kpc region of M 31 has revealed several surprises. The starting point of this investigation was the detection at the IRAM-30 m telescope of molecular gas with very large line splittings up to 260 km s −1 within the beam (∼40 pc). In this region, which is known for its low gas content, we also detect an ionised gas outflow in the circumnuclear region (within 75 pc from the centre) extending to the whole area in X-ray. Relying on atomic, ionised, and molecular gas, we account for most observables with a scenario that assumes that a few hundreds Myr ago, M 31 underwent a frontal collision with M 32, which triggered some star-formation activity in the centre, and this collision explains the special configuration of M 31 with two rings observed at 0.7 kpc and 10 kpc. The inner disc (whose rotation is detected in HI and ionised gas ([NII])) has thus been tilted (inclination: 43 deg, PA: 70 deg) with respect to the main disc (inclination: 77 deg, PA: 35 deg). One of the CO velocity components is compatible with this inner disc, while the second one comes from a tilted ring-like material with 40 deg inclination and PA = −35 deg. The relic star formation estimated by previous works to have occurred more than 100 Myr ago could have been triggered by the collision and could be linked to the outflow detected in the ionised gas. Last, we demonstrate that the amplitude of the line splittings detected in CO centred on the systemic velocity with a relatively high spatial resolution (40 pc) cannot be accounted for by a possible weak bar that is roughly aligned along the minor axis. Although M 31 has a triaxial bulge, there are no bar indicators in the gas component (photometry, no strong skewness of the isovelocities, etc.).

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Section: Examples Of Bar Shocksmentioning

confidence: 95%

Molecular gas in the inner 0.7 kpc-radius ring of M 31

Melchior

Combes

2011

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“…As described in previous NUGA papers (e.g., García-Burillo et al 2005), to compute the gravitational torques we assume that NIR images give the best approximation for the total stellar mass distribution, being less affected than optical images by dust extinction or stellar population bias.…”

Section: Computation Of the Torques On The Molecular Gasmentioning

confidence: 99%

“…They yield complementary results, the torques computed from the HST-NICMOS F160W image compared with the 12 CO PdBI contours allow to investigate the nuclear region of NGC 3627, while the torques derived from the Spitzer-IRAC image in combination with the 12 CO BIMA contours are much better adapted to visualize the whole spiral structure of the galaxy. We perform the subtraction of foreground stars, deprojection, and resampling, as described in other NUGA papers (e.g., García-Burillo et al 2005).…”

Section: Evaluation Of the Gravitational Potentialmentioning

confidence: 99%

“…Dynamical friction and viscous torques are often invoked, in addition to gravitational torques, as possible mechanisms of AGN fueling. However, dynamical friction of giant molecular clouds in the stellar bulge of a galaxy tends to be a slow, inefficient process which, to first approximation, can be neglected relative to gravity torques (García-Burillo et al 2005). Viscous torques can be more effective, and are favored in the presence of large density gradients and high galactic shear (see García-Burillo et al 2005, for details).…”

Section: Introductionmentioning

confidence: 99%

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Molecular Gas in NUclei of GAlaxies (NUGA)

Casasola

Hunt

Combes

et al. 2011

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We present 12 CO(1-0) and 12 CO(2-1) maps of the interacting barred LINER/Seyfert 2 galaxy NGC 3627 obtained with the IRAM interferometer at resolutions of 2. 1 × 1. 3 and 0. 9 × 0. 6, respectively. We also present single-dish IRAM 30 m 12 CO(1-0) and 12 CO(2-1) observations used to compute short spacings and complete interferometric measurements. These observations are complemented by IRAM 30 m measurements of HCN(1-0) emission detected in the center of NGC 3627. The molecular gas emission shows a nuclear peak, an elongated bar-like structure of ∼18 (∼900 pc) diameter in both 12 CO maps and, in 12 CO(1-0), a two-arm spiral feature from r ∼ 9 (∼450 pc) to r ∼ 16 (∼800 pc). The inner ∼18 bar-like structure, with a north/south orientation (PA = 14 • ), forms two peaks at the extremes of this elongated emission region. The kinematics of the inner molecular gas shows signatures of non-circular motions associated both with the 18 bar-like structure and the spiral feature detected beyond it. The 1.6 μm H-band 2MASS image of NGC 3627 shows a stellar bar with a PA = −21 • , different from the PA (= 14 • ) of the 12 CO bar-like structure, indicating that the gas is leading the stellar bar. The far-infrared Spitzer-MIPS 70 and 160 μm images of NGC 3627 show that the dust emission is intensified at the nucleus and at the ansae at the ends of the bar, coinciding with the 12 CO peaks. The GALEX far-ultraviolet (FUV) morphology of NGC 3627 displays an inner elongated (north/south) ring delimiting a hole around the nucleus, and the 12 CO bar-like structure is contained in the hole observed in the FUV. The torques computed with the HST-NICMOS F160W image and our PdBI maps are negative down to the resolution limit of our images, ∼60 pc in 12 CO(2-1). If the bar ends at ∼3 kpc, coincident with corotation (CR), the torques are negative between the CR of the bar and the nucleus, down to the resolution limit of our observations. This scenario is compatible with a recently-formed rapidly rotating bar which has had insufficient time to slow down because of secular evolution, and thus has not yet formed an inner Lindblad resonance (ILR). The presence of molecular gas inside the CR of the primary bar, where we expect that the ILR will form, makes NGC 3627 a potential smoking gun of inner gas inflow. The gas is fueling the central region, and in a second step could fuel directly the active nucleus.

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“…As discussed in García-Burillo et al (2005), the timescales for viscose torques only become comparable to those of gravitational torques at 100−200 pc scales when strong density contracts (e.g. gas rings) are present.…”

Section: Introductionmentioning

confidence: 99%

Explaining two circumnuclear star forming rings in NGC 5248

Laan

Schinnerer

Emsellem

et al. 2013

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The distribution of gas in the central kiloparsec of a galaxy has a dynamically rapid evolution. Nonaxisymmetries in the gravitational potential of the galactic disk, such as a large scale stellar bar or spiral, can lead to significant radial motion of gaseous material from larger radii to the central region. The large influx of gas and the subsequent star formation keep the central region constantly changing. However, the ability of gas to reach the nucleus proper to fuel an AGN phase is not guaranteed. Gas inflow can be halted at a circumnuclear star forming ring several hundred parsec away. The nearby galaxy NGC 5248 is especially interesting in this sense since it is said to host 2 circumnuclear star forming rings at 100 pc and 370 pc from its quiescent nucleus. Here we present new subarcsecond PdBI+30 m CO(2−1) emission line observations of the central region. For the first time the molecular gas distribution at the smallest stellar ring is resolved into a gas ring, consistent with the presence of a quiescent nucleus. However, the molecular gas shows no ring structure at the larger ring. We combine analyses of the gaseous and stellar content in the central kiloparsec of this galaxy to understand the gas distribution and dynamics of this star forming central region. We discuss the probability of two scenarios leading to the current observations, given our full understanding of this system, and discuss whether there are really two circumnuclear star forming rings in this galaxy.

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Molecular gas in NUclei of GAlaxies (NUGA)

Cited by 173 publications

References 60 publications

Molecular gas in the inner 0.7 kpc-radius ring of M 31

Molecular gas in the inner 0.7 kpc-radius ring of M 31

Molecular Gas in NUclei of GAlaxies (NUGA)

Explaining two circumnuclear star forming rings in NGC 5248

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