Stellar velocity dispersion and mass estimation for galactic disks

Засов, А. В.; Хоперсков, А. В.; Tyurina, N.

doi:10.1134/1.1795948

Cited by 34 publications

(36 citation statements)

References 28 publications

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“…First, disk mass-to-light ratios, which follow from the stability condition are in good agreement with the estimates based on stellar population evolution photometrical models (see e.g. Bottema (1997), Zasov et al (2004)). Second, the assumption of disk marginal stability enables to explain a positive correlation of relative disks thicknesses and their relative masses within the optical borders ).…”

Section: Introductionsupporting

confidence: 70%

Gravitational stability and dynamical overheating of galactic stellar disks

Засов¹,

Хоперсков

Saburova³

2011

Astron. Lett.

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We use the marginal stability condition for galactic disks and the stellar velocity dispersion data published by different authors to place upper limits on the disk local surface density at two radial scalelengths R = 2h. Extrapolating these estimates, we constrain the total mass of the disks and compare these estimates to those based on the photometry and color of stellar populations.The comparison reveals that the stellar disks of most of spiral galaxies in our sample cannot be substantially overheated and are therefore unlikely to have experienced a significant merging event in their history. The same conclusion applies to some, but not all of the S0 galaxies we consider. However, a substantial part of the early type galaxies do show the stellar velocity dispersion well in excess of the gravitational stability threshold suggesting a major merger event in the past. We find dynamically overheated disks among both seemingly isolated galaxies and those forming pairs. The ratio of the marginal stability disk mass estimate to the total galaxy mass within four radial scalelengths remains within a range of 0.4-0.8. We see no evidence for a noticeable running of this ratio with either the morphological type or color index.

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Section: Introductionsupporting

confidence: 70%

Gravitational stability and dynamical overheating of galactic stellar disks

Засов¹,

Хоперсков

Saburova³

2011

Astron. Lett.

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“…Of the four galaxies considered, the observed parameters of only onethe SBa galaxy NGC 2273-are consistent with the hypothesis that the stellar disk was not subject to dynamical heating, with the stellar velocity dispersion corresponding to the minimum level sufficient to maintain a quasi-stationary equilibrium state. In this respect, NGC 2273 resembles many later-type spiral galaxies, whose stellar velocity dispersions are close to their threshold levels throughout a considerable fraction of the disk (see, e.g., [8,22,36,37]). …”

Section: Discussionmentioning

confidence: 99%

“…This also follows from an analysis of the velocity dispersions of old stars in the galaxy disks. This shows that, in some early-type disk galaxies, the stellar velocity dispersion substantially exceeds the minimum level required for the gravitational stability of the disk, whereas, in later-type spiral galaxies, the velocity dispersion of the disk stars appears to be close to its threshold value [8]. However, the relatively low accuracy of the estimated velocity dispersions for disk stars beyond the bright bulges and problems with decomposing the velocity dispersion into r, ϕ, and z components lead us to treat this conclusion as being tentative.…”

Section: Introductionmentioning

confidence: 94%

“…In this case, it appears that dynamical instabilities during the formation of the bulk of the disk mass have brought the stellar disk to a marginally stable state, where the stellar velocity dispersion is determined by the surface density of the disk, its rotational velocity as a function of galactocentric distance r, and its internal structure. This appears to be the most common case among noninteracting spiral galaxies (see, e.g., [8]). …”

Section: Introductionmentioning

confidence: 95%

See 1 more Smart Citation

10.1007/s11444-008-2001-2

Засов

Моисеев

Хоперсков

et al. 2010

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Spectroscopic observations of three lenticular (S0) galaxies (NGC 1167, NGC 4150, and NGC 6340) and one SBa galaxy (NGC 2273) have been taken with the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences aimed to study the structure and kinematic properties of early-type disk galaxies. The radial profiles of the stellar radial velocities and the velocity dispersion are measured. N -body simulations are used to construct dynamical models of galaxies containing a stellar disk, bulge, and halo. The masses of individual components are estimated for maximum-mass disk models. A comparison of models with estimated rotational velocities and the stellar velocity dispersion suggests that the stellar disks in lenticular galaxies are "overheated"; i.e., there is a significant excess velocity dispersion over the minimum level required to maintain the stability of the disk. This supports the hypothesis that the stellar disks of S0 galaxies were subject to strong gravitational perturbations. The relative thickness of the stellar disks in the S0 galaxies considered substantially exceed the typical disk thickness of spiral galaxies.PACS numbers: 98.52. Lp, 98.52.Nr, 98.62.Ck, 98.62.Dm, 98.62.Hr

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“…Strictly speaking, the half-thickness estimates obtained in this way are minimal. However, analysis of the observational data shows that the velocity dispersion for most spiral galaxies is actually close to its critical value (see, e.g., Bottema 1993;Zasov et al 2002;Zasov and Khoperskov 2004). In the second, simpler model, the stellar disk thickness was assumed to be constant along R. The pressure estimation procedure for this case is described in the next section.…”

Section: The Sample Of Galaxies and Adopted Parametersmentioning

confidence: 99%

10.1007/s11443-008-3003-4

2010

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Based on an axisymmetric galactic disk model, we estimate the equilibrium gas pressure P/k in the disk plane as a function of the galactocentric distance R for several galaxies (MW, M33, M51, M81, M100, M101, M106, and the SMC). For this purpose, we solve a self-consistent system of equations by taking into account the gas self-gravity and the presence of a dark pseudo-isothermal halo. We assume that the turbulent velocity dispersions of the atomic and molecular gases are fixed and that the velocity dispersion of the old stellar disk corresponds to its marginal stability (except for the Galaxy and the SMC). We also consider a model with a constant disk thickness. Of the listed galaxies, the SMC and M51 have the highest pressure at a given relative radius R/R 25 , while M81 and the Galaxy has the lowest pressure. The pressure dependence of the relative molecular gas fraction confirms the existence of a positive correlation between these quantities, but it is not so distinct as that obtained previously when the pressure was estimated very roughly. This dependence breaks down for the inner regions of M81 and M106, probably because the gas pressure has been underestimated in the bulge region. We discuss the possible effects of factors other than the pressure affecting the relative content of the molecular gas in the galaxies under consideration.PACS numbers : 98.58.-w; 98.52.Nr

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Stellar velocity dispersion and mass estimation for galactic disks

Cited by 34 publications

References 28 publications

Gravitational stability and dynamical overheating of galactic stellar disks

Gravitational stability and dynamical overheating of galactic stellar disks

10.1007/s11444-008-2001-2

10.1007/s11443-008-3003-4

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