Populations and Mass Distributions in Spiral Galaxies

1983 ◽  
Vol 5 (2) ◽  
pp. 136-143 ◽  
Author(s):  
P. C. van der Kruit
Keyword(s):  
Mass Distribution ◽  
Rotation Curve ◽  
Gravitational Force ◽  
Velocity Dispersion ◽  
Spiral Galaxies ◽  
Low Velocity ◽  
Mass Distributions ◽  
Circular Velocity ◽  
Detailed Interpretation ◽  
Disk Component

The distribution of mass in a spiral galaxy is usually inferred from its rotation curve. The curve is most conveniently measured using part of its extreme population I such as HI or HII. This has a low velocity dispersion so that the observed tangential motion is in the absence of non-circular motions (van der Kruit and Allen 1978; Bosma 1981a, b) close to the circular velocity required to balance the gravitational force. The main difficulty is that for a detailed interpretation of the rotation curve one has to make assumptions on some general properties of the mass distribution, even though it is true that one can estimate the total mass within the last measured point to an accuracy of about a factor two. That of axial symmetry is only the simplest of assumptions. On the basis of the light distribution with a usually prominent disk component one often assumes that the mass distribution is also basically highly flattened.

scholarly journals Disks and Dark Haloes of Dwarf Spirals

1995 ◽  
Vol 164 ◽  
pp. 414-414
Author(s):  
V. Friese ◽  
B. Fuchs ◽  
R. Wielen
Keyword(s):  
Rotation Curve ◽  
Velocity Dispersion ◽  
Spiral Galaxies ◽  
Hydrostatic Equilibrium ◽  
Dark Halo ◽  
Rotation Curves ◽  
Mass Distributions ◽  
Dynamical State ◽  
Vertical Scale ◽  
Velocity Dispersions

We have investigated the dynamical state of the disks of a set of 9 spiral galaxies fainter than MB = −18 and with Hubble types Scd or later for which rotation curves are available in the literature. The rotation curve of each galaxy is decomposed in disk and dark halo contributions in order to determine the mass distributions of both components. The velocity dispersion of dwarf spirals is not known, but we use the vertical scale heights of the disks assuming vertical hydrostatic equilibrium to derive estimates of the velocity dispersions. For this purpose we have performed a statistical flattening analysis of faint dwarf spirals in the ESO-Uppsala catalogue. We find that the intrinsic ratio of vertical to radial scalelengths of these types of galaxies is z0/h = 0.2 corresponding to an intrinsic flattening of q0 = 0.14.

scholarly journals Differences in Mass Distribution for Field and Cluster Spiral Galaxies

1987 ◽  
Vol 117 ◽  
pp. 66-66 ◽  
Author(s):  
David Burstein ◽  
Vera C. Rubin
Keyword(s):  
Mass Distribution ◽  
Classification Scheme ◽  
Spiral Galaxies ◽  
Three Dimensional ◽  
Rotation Curves ◽  
Mass Distributions ◽  
Distribution Form ◽  
Simple Classification ◽  
Observational Fact

Our group has now obtained rotation curves for 80 spiral galaxies, Hubble types Sa through Sd. As described in Rubin et al. (Ap. J. 289, 81; 1985), the forms of these rotation curves are similar for all Hubble types. Given this observational fact, we have chosen to analyze the mass distributions for these galaxies under the assumption that the mass distributions for all spirals can be described by the same three-dimensional form, here taken to be spherical for simplicity. The mass distribution forms for 71 of these galaxies can be placed into a simple classification scheme based on the curvature of mass distribution form in a log(radius) - log (integral mass) diagram. The three most common mass forms among this continuum are termed Types I, II and III, the forms of which are displayed below (see also the discussion by Rubin elsewhere in this Symposium).

scholarly journals Vertical Motion and the Thickness of Hi Disks: Implications for Galactic Mass Models

1983 ◽  
Vol 100 ◽  
pp. 69-76
Author(s):  
P. C. van der Kruit ◽  
G. S. Shostak
Keyword(s):  
Dark Matter ◽  
Mass Distribution ◽  
Rotation Curve ◽  
Spiral Galaxies ◽  
Galactic Plane ◽  
Vertical Motion ◽  
Late Type ◽  
Rotation Curves ◽  
Central Bulge ◽  
Local Value

Most studies of the mass distribution in spiral galaxies have been based on the observed rotation curves. A serious ambiguity in this approach has always been that the rotation curve contains in itself no information on the mass distribution in the direction perpendicular to the galactic plane. The usual assumption has been that the mass in late type galaxies is distributed as the light, namely outside the central bulge in a highly flattened disk. In recent years it has been found that the rotation curves decline little or not at all, indicating large increases in the local value of M/L with increasing galactocentric radius (e.g. Bosma and van der Kruit, 1979). On the basis of dynamical arguments involving stability it has been suspected that the material giving rise to the large values of M/L - the “dark matter” - is distributed in the halos of these galaxies, so that the assumption of a flat mass distribution would have to be wrong.

scholarly journals The σc — Vcirc correlation in high and low surface brightness galaxies

2004 ◽  
Vol 220 ◽  
pp. 339-340 ◽  
Author(s):  
A. Pizzella ◽  
E. Dalla Bontà ◽  
E. M. Corsini ◽  
L. Coccato ◽  
F. Bertola
Keyword(s):  
Surface Brightness ◽  
Velocity Dispersion ◽  
Spiral Galaxies ◽  
High Surface ◽  
Linear Scale ◽  
High Surface Brightness ◽  
Circular Velocity ◽  
Straight Line ◽  
Low Surface Brightness ◽  
Low Surface Brightness Galaxies

We investigate the relation between the central velocity dispersion, σc, and the circular velocity, Vcirc, in galaxies. in addition to previously obtained data, we consider an observationally homogeneus sample of 52 high surface brightness and 11 low surface brightness spiral galaxies. We performed a straight line regression analysis in a linear scale, finding a good fit, also for low σc galaxies, always rejected in the previous studies. Low surface brightness galaxies seem to behave differently, showing either higher values of Vcirc or lower values of σc with respect to their high surface brightness counterparts.

scholarly journals Hα kinematics of nearby galaxies using Fabry-Perot and IFU data

2016 ◽  
Vol 11 (S321) ◽  
pp. 275-275
Author(s):  
Santiago Erroz-Ferrer ◽  
Keyword(s):  
Spectral Resolution ◽  
Total Mass ◽  
Rotation Curve ◽  
Spiral Galaxies ◽  
Rotation Curves ◽  
Large Sample ◽  
Mass Distributions ◽  
Fabry Perot ◽  
Nearby Galaxies

AbstractI present here analysis of the shapes of the rotation curves of a large sample of nearby spiral galaxies with high angular and spectral resolution Hα (Fabry-Perot GHαFaS) kinematics, and the resulting constraints on their total mass distributions. In particular I discuss how their rotation curve shapes relate to key galaxy properties. Finally I present related results from the MUSE Atlas of Disks (MAD) program, which is dissecting the nearby disk population with IFU spectroscopy at ~100pc resolution.

scholarly journals Halo Parameters of Spiral Galaxies

1987 ◽  
Vol 117 ◽  
pp. 133-133
Author(s):  
E. Athanassoula ◽  
A. Bosma ◽  
S. Papaioannou
Keyword(s):  
Dark Matter ◽  
Mass Distribution ◽  
Rotation Curve ◽  
Spiral Galaxies ◽  
Curve Analysis ◽  
Hollow Core ◽  
Constant Mass ◽  
Kinematical Data

We have made a rotation curve analysis of a sample of spiral galaxies for which both photometric and kinematical data of reasonable quality are available in the literature. From the photometric radial luminosity profile, assuming constant mass-to-light ratios for bulge and disk separately, we calculate a rotation curve due to the luminous mass in a galaxy. Comparison with the observed rotation velocities allows us to derive a halo rotation curve, which can be used to derive characteristic halo parameters. The decomposition into luminous and dark matter is not unique, with as extremes a “minimum” disk (M/L = 0) and a “maximum” disk (M/L as high as possible while requiring a realistic halo mass distribution without a hollow core).

scholarly journals The contribution of the dark matter to the rotation of spiral galaxies and its mass distribution

1999 ◽  
pp. 1-4
Author(s):  
S. Ninkovic
Keyword(s):  
Dark Matter ◽  
Mass Distribution ◽  
Spiral Galaxy ◽  
Axial Symmetry ◽  
Spiral Galaxies ◽  
The Other ◽  
Continuous Increase ◽  
Homogeneous Sphere ◽  
Circular Velocity ◽  
Other Hand

The rotation of a test spiral galaxy with two contributors - the disc and the corona - is considered. The disc is exponential, whereas the corona is the dark subsystem. For the latter several variants of mass distribution are considered. It is found that the homogeneous sphere is almost unavoidable if the circular velocity has a continuous increase, at least in its observable part. On the other hand the rather often applied quasi-isothermal law offers the most satisfactory fit for the case of constant circular velocity though the classical Schuster law may also be used, especially taking into account its simplicity and the consequent possibility of generalising its potential towards the more general case of axial symmetry.

scholarly journals Theoretical Considerations on the Dynamics of Normal Galactic Nuclei

1980 ◽  
Vol 5 ◽  
pp. 197-204
Author(s):  
Robert H. Sanders
Keyword(s):  
Spatial Distribution ◽  
Gravitational Field ◽  
Mass Distribution ◽  
Rotation Curve ◽  
Spiral Galaxies ◽  
Neutral Hydrogen ◽  
Galactic Nuclei ◽  
The Galaxy ◽  
Theoretical Considerations ◽  
Normal Spiral

I want to discuss the origin of non-circular gas motions observed in the nuclei of normal spiral galaxies and the possibility that recurring violent activity in normal nuclei excites such motion. But first, let us review several basic aspects of the nearest normal galactic nucleus — the nucleus of our own Galaxy.The rotation curve as observed in the 21-cm line of neutral hydrogen gives some indication of the form of the gravitational field in the central region of the Galaxy. Figure 1 is a smooth fit to the rotation curve in the inner few kiloparsecs (solid line) taken essentially from the data of Rougoor and Oort (1960) and Simonson and Mader (1973). This rotation curve, within 1 kpc of the centre, is completely accounted for by the mass distribution implied by the extended 2.2-μ emission (Becklin and Neugebauer 1968, Oort 1971). Moreover, there is little doubt that this centrally condensed mass distribution should be identified with the bulge or spheroidal component of the Galaxy, because the spatial distribution of the 2.2-μ intensity is practically identical to the distribution of visible starlight in the bulge of M31 (Sandage, Becklin, and Neugebauer 1969). The conclusion is that the bulge overwhelmingly dominates the gravitational field inside of 1 kpc.

scholarly journals Galaxy Mass Distribution from Galaxy-Galaxy Gravitational Lensing

1987 ◽  
Vol 117 ◽  
pp. 241-241
Author(s):  
J. Anthony Tyson
Keyword(s):  
Mass Distribution ◽  
Gravitational Lensing ◽  
Binary Data ◽  
Rotation Curve ◽  
Gravitational Lens ◽  
Lens Distortion ◽  
Circular Velocity ◽  
Upper Limit ◽  
Luminosity Functions ◽  
Cutoff Radius

The average gravitational lens distortion of background galaxy images by foreground galaxies is an independent, non-kinematical measurement of galaxy mass distribution M(r)/r (Tyson, et al. 1984). The upper limit we obtained for the equivalent circular velocity, while small compared with some heavy halo models, is consistent with dynamical estimates for samples of galaxies of all types (e.g. Turner's binary data and the Rubin, et al. rotation curves). For example, for a mean cutoff radius of 65 kpc/h, our 3σ upper limit for the equivalent circular velocity (GM/r)1/2 = 190 km/sec. For a mass cutoff at 190 kpc/h our 2σ upper limit is 175 km/sec. If I weight a sample of asymptotical rotation curve velocities by recent field luminosity functions, I get mean circular velocities less than 170 km/sec.

scholarly journals Tracing the relation between black holes and dark haloes

2004 ◽  
Vol 220 ◽  
pp. 317-318
Author(s):  
Pieter Buyle ◽  
Maarten Baes ◽  
Herwig Dejonghe
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Galaxy Formation ◽  
Velocity Dispersion ◽  
Spiral Galaxies ◽  
Circular Velocity ◽  
Supermassive Black Hole ◽  
Galaxy Formation And Evolution ◽  
Formation And Evolution ◽  
Fisher Relation

We present new velocity dispersion measurements for a set of 12 spiral galaxies and use them to derive a more accurate υc – σ relation which holds for a wide morphological range of galaxies. Combined with the MBH – σ relation, this relation can be used as a tool to estimate supermassive black hole (SMBH) masses by means of the asymptotic circular velocity. Together with the Tully-Fisher relation, it serves as a constraint for galaxy formation and evolution models.

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