Quantifying non-circular streaming motions in disc galaxies

Sellwood, J. A.; Sánchez, Ricardo Zanmar

doi:10.1111/j.1365-2966.2010.16430.x

Cited by 83 publications

(129 citation statements)

References 40 publications

(74 reference statements)

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“…Although the bar in NGC3627 is more accurately a 'strong' bar, motions at the bar end are qualitatively similar to those in the weak case. We follow Sellwood & Sánchez (2010) to estimate the magnitude of azimuthal streaming adopting the (weak) bar perturbation to the gravitational potential…”

Section: Bar Streaming Motionsmentioning

confidence: 99%

Interactions of the Galactic bar and spiral arm in NGC 3627

Beuther

Meidt

Schinnerer

et al. 2017

A&A

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Aims. To gain insight into the expected gas dynamics at the interface of the Galactic bar and spiral arms in our own Milky Way galaxy, we examine as an extragalactic counterpart the evidence for multiple distinct velocity components in the cold, dense molecular gas populating a comparable region at the end of the bar in the nearby galaxy NGC 3627. Methods. We assemble a high resolution view of molecular gas kinematics traced by CO(2-1) emission and extract line-of-sight velocity profiles from regions of high and low gas velocity dispersion. Results. The high velocity dispersions arise with often double-peaked or multiple line-profiles. We compare the centroids of the different velocity components to expectations based on orbital dynamics in the presence of bar and spiral potential perturbations. A model of the region as the interface of two gas-populated orbits families supporting the bar and the independently rotating spiral arms provides an overall good match to the data. An extent of the bar to the corotation radius of the galaxy is favored. Conclusions. Using NGC3627 as an extragalactic example, we expect situations like this to favor strong star formation events such as observed in our own Milky Way since gas can pile up at the crossings between the orbit families. The relative motions of the material following these orbits is likely even more important for the build up of high density in the region. The surface densities in NGC3627 are also so high that shear at the bar end is unlikely to significantly weaken the star formation activity. We speculate that scenarios in which the bar and spiral rotate at two different pattern speeds may be the most favorable for intense star formation at such interfaces.

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Section: Bar Streaming Motionsmentioning

confidence: 99%

Interactions of the Galactic bar and spiral arm in NGC 3627

Beuther

Meidt

Schinnerer

et al. 2017

A&A

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“…Also, they found some cases where these deviations from the circular motion are more prominent when the PABAR is at ∼ 45 • from the kinematic major axis (in agreement with the models by, e.g., van Albada & Roberts 1981). The nature and characterisation of these non-circular motions is a topic still under debate, and many studies of the streaming motions have been performed (e.g., Knapen et al 2000;Fresneau, Vaughan & Argyle 2005;Spekkens & Sellwood 2007;Castillo-Morales et al 2007;Shetty et al 2007;Tamburro et al 2008;García-Burillo et al 2009;Sellwood & Sánchez 2010;Meidt et al 2013;Font et al 2014b). In Sect.…”

Section: Non-circular Motionsmentioning

confidence: 99%

Hα kinematics of S4G spiral galaxies – II. Data description and non-circular motions

Erroz-Ferrer¹,

Knapen²,

Leaman³

et al. 2015

Monthly Notices of the Royal Astronomical Society

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We present a kinematical study of 29 spiral galaxies included in the Spitzer Survey of Stellar Structure in Galaxies, using Hα Fabry-Perot data obtained with the Galaxy Hα Fabry-Perot System instrument at the William Herschel Telescope in La Palma, complemented with images in the R band and in Hα. The primary goal is to study the evolution and properties of the main structural components of galaxies through the kinematical analysis of the FP data, complemented with studies of morphology, star formation and mass distribution. In this paper we describe how the FP data have been obtained, processed and analysed. We present the resulting moment maps, rotation curves, velocity model maps and residual maps. Images are available in FITS format through the NASA/IPAC Extragalactic Database and the Centre de Données Stellaires. With these data products we study the non-circular motions, in particular those found along the bars and spiral arms. The data indicate that the amplitude of the non-circular motions created by the bar does not correlate with the bar strength indicators. The amplitude of those non-circular motions in the spiral arms does not correlate with either arm class or star formation rate along the spiral arms. This implies that the presence and the magnitude of the streaming motions in the arms is a local phenomenon.

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“…We are more concerned about potential systematic patterns in the velocity field that we cannot account for in our fitting routine. Sellwood & Sanchez (2010) advertise a concept that uses the residuals of the fit as a noise source. The idea is that every residual structure not included in the model is in fact noise to the fit, and the residuals can be used as a prior to create a noise field with statistical characteristics that are well matched to the data.…”

Section: Error Estimationmentioning

confidence: 99%

Radial gas motions in The H i Nearby Galaxy Survey (THINGS)

Schmidt

Bigiel

Klessen

et al. 2016

Mon. Not. R. Astron. Soc.

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The study of 21 cm line observations of atomic hydrogen allows detailed insight into the kinematics of spiral galaxies. We use sensitive high-resolution VLA data from The HI Nearby Galaxy Survey (THINGS) to search for radial gas flows primarily in the outer parts (up to 3 × r 25 ) of ten nearby spiral galaxies. Inflows are expected to replenish the gas reservoir and fuel star formation under the assumption that galaxies evolve approximately in steady state. We carry out a detailed investigation of existing tilted ring fitting schemes and discover systematics that can hamper their ability to detect signatures of radial flows. We develop a new Fourier decomposition scheme that fits for rotational and radial velocities and simultaneously determines position angle and inclination as a function of radius. Using synthetic velocity fields we show that our novel fitting scheme is less prone to such systematic errors and that it is well suited to detect radial inflows in disks. We apply our fitting scheme to ten THINGS galaxies and find clear indications of, at least partly previously unidentified, radial gas flows, in particular for NGC 2403 and NGC 3198 and to a lesser degree for NGC 7331, NGC 2903 and NGC 6946. The mass flow rates are of the same order but usually larger than the star formation rates. At least for these galaxies a scenario in which continuous mass accretion feeds star formation seems plausible. The other galaxies show a more complicated picture with either no clear inflow, outward motions or complex kinematic signatures.

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Quantifying non-circular streaming motions in disc galaxies

Cited by 83 publications

References 40 publications

Interactions of the Galactic bar and spiral arm in NGC 3627

Interactions of the Galactic bar and spiral arm in NGC 3627

Hα kinematics of S4G spiral galaxies – II. Data description and non-circular motions

Radial gas motions in The H i Nearby Galaxy Survey (THINGS)

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