Uncertainties in Spiral Galaxy Projection Parameters

Barnes, Eric I.; Sellwood, J. A.

doi:10.1086/346142

Cited by 48 publications

(67 citation statements)

References 16 publications

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“…For late-type galaxies, these models often consider a symmetric velocity distribution, either by assuming a thin disc geometry (e.g., Barnes & Sellwood 2003;Epinat et al 2008) or symmetrical radial distortions with respect to some axis (Spekkens & Sellwood 2007). An alternative approach is a generalisation of the isophote fitting (i.e.…”

Section: Kinematic Position Angles From Velocity Mapsmentioning

confidence: 99%

Kinematic alignment of non-interacting CALIFA galaxies

Barrera-Ballesteros

Falcón-Barroso

García-Lorenzo

et al. 2014

A&A

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We present 80 stellar and ionised gas velocity maps from the Calar Alto Legacy Integral Field Area (CALIFA) survey in order to characterise the kinematic orientation of non-interacting galaxies. The study of galaxies in isolation is a key step towards understanding how fast-external processes, such as major mergers, affect kinematic properties in galaxies. We derived the global and individual (projected approaching and receding sides) kinematic position angles (PAs) for both the stellar and ionised gas line-of-sight velocity distributions. When compared to the photometric PA, we find that morpho-kinematic differences are smaller than 22 degrees in 90% of the sample for both stellar and nebular components and that internal kinematic misalignments are generally smaller than 16 degrees. We find a tight relation between the global stellar and ionised gas kinematic PA consistent with circular-flow pattern motions in both components (∼90% of the sample has differences smaller than 16 degrees). This relation also holds, generally in barred galaxies across the bar and galaxy disc scales. Our findings suggest that even in the presence of strong bars, both the stellar and the gaseous components tend to follow the gravitational potential of the disc. As a result, kinematic orientation can be used to assess the degree of external distortions in interacting galaxies.

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Section: Kinematic Position Angles From Velocity Mapsmentioning

confidence: 99%

Kinematic alignment of non-interacting CALIFA galaxies

Barrera-Ballesteros

Falcón-Barroso

García-Lorenzo

et al. 2014

A&A

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“…It works well when noncircular motions are small, but yields spurious variations of the parameters when the underlying flow contains nonaxisymmetric, especially bisymmetric, distortions. Barnes & Sellwood (2003) adopted a different approach. They assumed the plane of the disk to be flat and determined the rotation center, inclination, and PA by fitting a nonparametric circular flow pattern to the entire velocity map.…”

Section: Previous Approachesmentioning

confidence: 99%

“…The rotcurshape program, recently added to the NEMO (Teuben 1995) package, suffers from the same drawback, because it also assumes a flat, axisymmetric disk. Furthermore, it fits multiple parametric components to a velocity field and thus has less flexibility than the Barnes & Sellwood (2003) technique. Franx et al (1994) and Schoenmakers et al (1997) pioneered efforts to measure and interpret the nonaxisymmetric coefficients that describe an observed velocity field, and expansions up to order m 0 $ 3 are now routinely carried out (e.g., Wong et al 2004;Chemin et al 2006;Simon et al 2005;Gentile et al 2006).…”

Section: Previous Approachesmentioning

confidence: 99%

“…We attempt to fit the above kinematic models to observational data by an extension of the minimization procedure devised by Barnes & Sellwood (2003). In general, we need to determine the systemic velocity V sys , kinematic center (x c ; y c ), ellipticity d , and disk PA We tabulate each of the M independent velocity profiles at a set of concentric circular rings in the disk plane that project to ellipses on the sky with a common center, (x c ; y c ).…”

Section: Fitting Techniquementioning

confidence: 99%

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Modeling Noncircular Motions in Disk Galaxies: Application to NGC 2976

Spekkens

Sellwood

2007

ApJ

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165

263

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We present a new procedure to fit nonaxisymmetric flow patterns to two-dimensional velocity maps of spiral galaxies. We concentrate on flows caused by barlike or oval distortions to the total potential, which may arise either from a nonY axially symmetric halo or a bar in the luminous disk. We apply our method to high-quality CO and H data for the nearby, low-mass spiral NGC 2976, previously obtained by Simon et al., and find that a barlike model fits the data at least as well as their model with large radial flows. We find supporting evidence for the existence of a bar in the baryonic disk. Our model suggests that the azimuthally averaged central attraction in the inner part of this galaxy is larger than estimated by these authors. It is likely that the disk is also more massive, which will limit the increase to the allowed dark halo density. Allowance for barlike distortions in other galaxies may either increase or decrease the estimated central attraction.

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“…Indeed, many galaxies appear to have lopsided light distributions (e.g., Zaritsky & Rix 1997;Kornreich et al 1998;Conselice et al 2000;Bournaud et al 2005), H i distributions (e.g., Baldwin et al 1980), integrated H i line profiles (Richter & Sancisi 1994), or kinematic features (e.g., Richter & Sancisi 1994;Swaters et al 1999;Kornreich et al 2000, Chemin et al 2006, especially in LSB galaxies (Swaters et al 2003;Simon et al 2003). However, a direct measurement of disk ellipticity is challenging because it is difficult to disentangle the intrinsic shape of galaxy disks from both projection effects and spiral structure (e.g., Rix & Zaritsky 1995;Schoenmakers et al 1997;Andersen et al 2001;Barnes & Sellwood 2003). If better estimates of ellipticity existed, tighter limits could be placed on halo triaxiality.…”

Section: Introductionmentioning

confidence: 99%

The Photometric and Kinematic Structure of Face‐on Disk Galaxies. I. Sample Definition, Hα Integral Field Spectroscopy, and H i Line Widths

Andersen¹,

Bershady²,

Sparke³

et al. 2006

ASTROPHYS J SUPPL S

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We present a survey of the photometric and kinematic properties of 39 nearby, nearly face-on disk galaxies. Our approach exploits echelle-resolution integral-field spectroscopy of the H regions, obtained with DensePak on the WIYN 3.5 m telescope Bench Spectrograph. These data are complemented by H i line profiles observed with the Nançay radio telescope for 25 of these sample galaxies. Twelve additional line widths are available for sample galaxies from the literature. In this paper, we introduce the goals of this survey, define the sample selection algorithm, and amass the integral field spectroscopic data and H i line widths. We establish spatially integrated H line widths for the sample. We test the veracity of these spatially integrated line profiles by convolving narrowband imaging data with velocity field information for one of the sample galaxies, PGC 38268, and also by comparing to H i line profiles. We find H i and H line profiles to be similar in width but different in shape, indicating that we are observing different spatial distributions of ionized and neutral gas in largely axisymmetric systems with flat outer rotation curves. We also find vertical velocity dispersions of the ionized disk gas within several disk scale lengths have a median value of 18 km s À1 and an 80% range of 12Y26 km s À1 . This is only a factor of $2 larger than what is observed for neutral atomic and molecular gas. With standard assumptions for intrinsic and thermal broadening for H , this translates into a factor of 3 range in turbulent velocities, between 8 and 25 km s À1 .

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Uncertainties in Spiral Galaxy Projection Parameters

Cited by 48 publications

References 16 publications

Kinematic alignment of non-interacting CALIFA galaxies

Kinematic alignment of non-interacting CALIFA galaxies

Modeling Noncircular Motions in Disk Galaxies: Application to NGC 2976

The Photometric and Kinematic Structure of Face‐on Disk Galaxies. I. Sample Definition, Hα Integral Field Spectroscopy, and H i Line Widths

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