Kinematic Effects of Tidal Interaction on Galaxy Rotation Curves

Barton, Elizabeth J.; Bromley, Benjamin C.; Geller, Margaret J.

doi:10.1086/311830

Cited by 29 publications

(30 citation statements)

References 32 publications

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“…Are the features permanently visible or do they vanish within certain timescales? Some of the questions that we investigate in the present work were also addressed by Barton et al (1999) and Heyl et al (1996), who found qualitatively similar results to ours. However, as both groups used purely N-body models, they were not able to extract RCs as close to the observational procedure as we do (see Sect.…”

Section: Introductionsupporting

confidence: 86%

Internal kinematics of modelled interacting disc galaxies

Kronberger

Kapferer

Schindler

et al. 2006

A&A

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We present an investigation of galaxy-galaxy interactions and their effects on the velocity fields of disc galaxies in combined N-body/hydrodynamic simulations, which include cooling, star formation with feedback, and galactic winds. Rotation curves (RCs) of the gas are extracted from these simulations in a way that follows the procedure applied to observations of distant, small, and faint galaxies as closely as possible. We show that galaxy-galaxy mergers and fly-bys disturb the velocity fields significantly and hence the RCs of the interacting galaxies, leading to asymmetries and distortions in the RCs. Typical features of disturbed kinematics are significantly rising or falling profiles in the direction of the companion galaxy and pronounced bumps in the RCs. In addition, tidal tails can leave strong imprints on the rotation curve. All these features are observable for intermediate redshift galaxies, on which we focus our investigations. We use a quantitative measure for the asymmetry of rotation curves to show that the appearance of these distortions strongly depends on the viewing angle. We also find in this way that the velocity fields settle back into relatively undisturbed equilibrium states after unequal mass mergers and fly-bys. About 1 Gyr after the first encounter, the RCs show no severe distortions anymore. These results are consistent with previous theoretical and observational studies. As an illustration of our results, we compare our simulated velocity fields and direct images with rotation curves from VLT/FORS spectroscopy and ACS images of a cluster at z = 0.53 and find remarkable similarities.

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Section: Introductionsupporting

confidence: 86%

Internal kinematics of modelled interacting disc galaxies

Kronberger

Kapferer

Schindler

et al. 2006

A&A

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“…This contrasts to Elmegreen & Thomasson (1993), who argued that the S-shaped rotation curves, typical for interacting galaxies, are signs of small haloes. On the other hand, our result is consistent with the recent study of Barton, Bromley & Geller (1999), who show that interaction-induced transient velocities may lead to either a fall or a rise of the observed rotation curve, depending on the viewing direction.…”

Section: S U M M a R Y A N D Discussionsupporting

confidence: 93%

N-body model for M51 -- I. Multiple encounter versus single passage?

Salo

Laurikainen

2000

Monthly Notices of the Royal Astronomical Society

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A B S T R A C TA numerical survey of the encounter history of the interacting grand-design system M51 (NGC 5194/5195) is performed with a 3D multiple spherical polar grid code, where both components of the pair are described with self-gravitating star 1 gas discs embedded in rigid analytical halo potentials. Two classes of models are investigated, (1) nearly parabolic single passages, and (2) bound encounters implying several disc-plane crossings. Both types of models can approximate the general morphology of the M51 system and simultaneously fit the projected velocity difference and separation of the components. In both cases the companion disc-plane crossing responsible for the main spiral structure occurred nearly in the south, about 400±500 Myr ago at a distance of 25±30 kpc, but in opposite directions. In the bound encounter model there is also a more recent crossing, at a distance of 20±25 kpc about 50±100 Myr ago.Our models account for some important kinematical observations of the M51 system not explained by the previous models. Especially, we note that the multiple-encounter model with a recent passage produces significant out-of-plane velocities, which manifest as an Sshaped structure of the major axis rotation curve, and which also explain the high peculiar velocities in the north of the companion. In this model the resulting extended tail is tilted 408±508 with respect to the inner disc, leading to a velocity field that appears to suggest counter-rotation of the tail with respect to the inner disc. Also some morphological features, like the direction of the tidal extensions from the companion, are better matched by a model with a recent encounter. Importantly, any pre-existing spiral arms are washed out by the tidally triggered spiral arms.The multiple-encounter model assumes a high inclination i < 858 orbit, with a low current eccentricity e < 0X2X The possible origin of this type of bound orbital configuration is studied by simulations including the orbital decay via the Chandrasekhar formula for dynamical friction, and also by simulations including a self-consistently modelled live halo for the primary. The gross features of the model, including the tilted far tail, are preserved even when allowing for the effects of several earlier passages. The observed well-defined far tail seems to suggest that the previous passages have been at least 30 per cent more distant than the latest two crossings. According to our limited orbital survey, such an orbital decay can be accounted for, provided that M51 has an extended dark halo containing at least a few times the mass within the visible disc region (total M halo aM disc , 10X

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“…Using simulations, those authors reproduced the observations of intermediate redshift galaxies (z ∼ 0.5) by putting a virtual slit along the major axis of each investigated system (see also, Barton et al 1999). They also found that the features associated with Article published by EDP Sciences the perturbations in the RCs strongly depend on the viewing angles, particularly for the derived asymmetry parameters (Dale et al 2001), which presented quite a large dispersion for minor mergers and flybys.…”

Section: Introductionmentioning

confidence: 67%

Rotation curve bifurcations as indicators of close recent galaxy encounters

Pedrosa¹,

Tissera²,

Fuentes-Carrera³

et al. 2008

A&A

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Context. Rotation curves of interacting galaxies often show that velocities are either rising or falling in the direction of the companion galaxy. Aims. We seek to reproduce and analyse these features in the rotation curves of simulated equal-mass galaxies suffering a one-to-one encounter as possible indicators of close encounters. Methods. Using simulations of major mergers in 3D, we study the time evolution of these asymmetries in a pair of galaxies during the first passage. Results. Our main results are: (a) the rotation curve asymmetries appear right at pericentre of the first passage, (b) the significant disturbed rotation velocities occur within a small time interval, of ∼0.5 Gyr h −1 , and, therefore, the presence of bifurcation in the velocity curve could be used as an indicator of the pericentre occurrence. These results are in qualitative agreement with previous findings for minor mergers and flybys.

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Kinematic Effects of Tidal Interaction on Galaxy Rotation Curves

Cited by 29 publications

References 32 publications

Internal kinematics of modelled interacting disc galaxies

Internal kinematics of modelled interacting disc galaxies

N-body model for M51 -- I. Multiple encounter versus single passage?

Rotation curve bifurcations as indicators of close recent galaxy encounters

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