Mass Distribution Of Galaxies Research Articles

On the possibility of Bose-star formation

The relaxation time of a gravitationally bounded cloud of bosons is estimated for the case of a large phase-space density of particles. The axionic mass and self-coupling relaxation time are compatible to the age of the Universe if the escape velocity and the mass in the core region satisfy the relation M < 10 8v e 5 2 φ 10 − 1 4 M ⊙ . In the central part of such a cloud an axionic cosmic matter with luminosity ∼ 10 −2v r 5 2 φ 10 − 1 4 M ⊙/ yr will form. An upper bound on the self-coupling is obtained provided the mass distribution in galaxies is dominated by this kind of dark matter.

Gravitational lensing limits on the cosmological constant in a flat universe

Inflationary cosmological theories predict, and some more general aesthetic criteria suggest, that the large-scale spatial curvature of the universe k should be accurately zero (i.e., flat), a condition which is satisfied when the universe's present mean density and the value of the cosmological constant Lambda have certain pairs of values. Available data on the frequency of multiple image-lensing of high-redshift quasars by galaxies suggest that the cosmological constant cannot make a dominant contribution to producing a flat universe. In particular, if the mean density of the universe is as small as the baryon density inferred from standard cosmic nucleosynthesis calculations or as determined from typical dynamical studies of galaxies and galaxy clusters, then a value of Lambda large enough to produce a k = 0 universe would result in a substantially higher frequency of multiple-image lensing of quasars than has been observed so far. Shortcomings of the available lens data and uncertainties concerning galaxy properties allow some possibility of escaping this conclusion, but systematic searches for a gravitational lenses and continuing investigations of galaxy mass distributions should soon provide decisive information. It is also noted that nonzero-curvature cosmological models can account for the observed frequency of galaxy-quasar lens systems and for a variety of other constraints.

A simple analytic model for the evolution of captured galactic disks

view Abstract Citations (22) References (25) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Simple Analytic Model for the Evolution of Captured Galactic Disks Steiman-Cameron, Thomas Y. ; Durisen, Richard H. Abstract The general analytic solution developed by Steiman-Cameron and Durisen and published in 1988 for the evolution of dissipative nonplanar disks is applied to captured galactic disks in model galaxies with non-spherical, scale-free, logarithmic gravitational potentials. Such potentials produce flat rotation curves, similar to those seen in real galaxies. In this case, the analytic solution yields a self-similar structure for the warps and twists that develop while the disk is settling. Being scale-free in a simple, analytic form, this solution is completely defined by only a few dimensionless fitting parameters. As a result, it can be utilized as a mathematical tool to fit settling disks in real galaxies. The minimum time it takes for a disk to settle into a steady state orientation is also a scale-free quantity when expressed in units of the precession period or the orbit period. For realistic parameters, settling times are on the order of one-half to two precession periods. The use of the time-dependent structure of settling disks as a probe of the three-dimensional mass distribution of the host galaxies, including dark halos, is discussed. Publication: The Astrophysical Journal Pub Date: July 1990 DOI: 10.1086/168891 Bibcode: 1990ApJ...357...62S Keywords: Disk Galaxies; Galactic Evolution; Galactic Structure; Gravitational Fields; Interacting Galaxies; Galactic Rotation; Mass Distribution; Time Dependence; Astrophysics; GALAXIES: INTERACTIONS; GALAXIES: INTERNAL MOTIONS; GALAXIES: STRUCTURE; HYDRODYNAMICS full text sources ADS | data products SIMBAD (1)

The gravitational collapse of gaseous spheres and galaxy formation

The spherical collapse of a gas cloud initially in hydrostatic equilibrium is examined using self-similar solutions. It is found that the collapse of gas clouds to form galaxies can occur on a hydrodynamic time scale only if the gas dominates the gravitational field and the inflow forms a central dominant mass. The likelihood of a collisionless component and the observation of extended mass distributions in galaxies implies that the collapse of a hot protogalactic cloud is cooling-regulated. The formation of the Galaxy from an initially smooth, hot cloud is examined, showing that some nonlinear substructure must initially be present.

Seeing deconvolution of globular clusters in M31

view Abstract Citations (21) References (64) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Seeing Deconvolution of Globular Clusters in M31 Bendinelli, O. ; Parmeggiani, G. ; Zavatti, F. ; Djorgovski, S. Abstract Seeing deconvolution of surface-brightness profiles using the regularized multi-Gaussian method is potentially a powerful method for extraction of morphological information from digital images. Here we illustrate this method by applying it to CCD images of six globular clusters in M31. We demonstrate that it is possible to make some judgments about the dynamical structure of M31 globulars, using good-seeing, deconvolved CCD images obtained from the ground; for example, whether they have post-core-collapse morphology or not. The effective resolution limit of the method is about 0.1-0.3 arcsec, for the CCD images obtained in FWHM ~ 1 arcsec seeing, and sampling of 0.3 arcsec/pixel. We also demonstrate the robustness of the method, i.e., its insensivity to the exact choices of the functional representation of the point-spread function, details of the deconvolution technique, etc. The situation is equivalent in terms of angular resolution and sampling to observing globular clusters in the Virgo Cluster (e.g., around M87) with the Hubble Space Telescope, and the methods demonstrated here may be applied to HST data in the future. Dynamical structure of globular clusters, e.g., propensity for the post-core-collapse morphology as a function of position in the host galaxy, reflects the global dynamical evolution of a globular cluster system, as was already demonstrated for our galaxy. Similar studies of large samples of globulars in M31 and other Local Group galaxies from the ground, and out to Virgo with the HST, can provide valuable insights about the mass distribution in galaxies, and the formation and evolution of their globular cluster systems. This pilot study is a step in this direction. Publication: The Astronomical Journal Pub Date: March 1990 DOI: 10.1086/115373 Bibcode: 1990AJ.....99..774B Keywords: Andromeda Galaxy; Globular Clusters; Seeing (Astronomy); Brightness Distribution; Charge Coupled Devices; Hubble Space Telescope; Sky Surveys (Astronomy); Astronomy; CLUSTERS: GLOBULAR full text sources ADS | data products NED (7) SIMBAD (4)

The distribution of mass for spiral galaxies in clusters and in the field

view Abstract Citations (9) References (15) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Distribution of Mass for Spiral Galaxies in Clusters and in the Field Forbes, Duncan A. ; Whitmore, Bradley C. Abstract A comparison is made between the mass distributions of spiral galaxies in clusters and in the field using Burstein's mass-type methodology. Both Hα emission-line rotation curves and more extended H I rotation curves are used. The fitting technique for determining mass types used by Burstein and coworkers has been replaced by an objective χ^2^ method. Mass types are shown to be a function of both Hubble type and luminosity, contrary to earlier results. The present data show a difference in the distribution of mass types for spiral galaxies in the field and in clusters, in the sense that mass type I galaxies, where the inner and outer velocity gradients are similar, are generally found in the field rather than in clusters, as Burstein and coworkers previously reported. This can be understood in terms of the results of Whitmore, Forbes, and Rubin, who find that the rotation curves of galaxies in the central region of clusters are generally falling, while the outer galaxies in a cluster and field galaxies tend to have flat or rising rotation curves. Publication: The Astrophysical Journal Pub Date: April 1989 DOI: 10.1086/167326 Bibcode: 1989ApJ...339..657F Keywords: Galactic Clusters; Galactic Structure; Mass Distribution; Spiral Galaxies; Galactic Rotation; H Alpha Line; Luminosity; Astrophysics; GALAXIES: CLUSTERING; GALAXIES: INTERNAL MOTIONS; GALAXIES: STRUCTURE full text sources ADS | data products SIMBAD (101) NED (98)

Mass Distributions of Galaxies by Globular Cluster Systems

Density curves of polytrope index 5 were fitted to the surface density distributions of 26 globular cluster systems. Though we have shown only two of them in Fig. 1, the remaining systems resemble the above cases. No differences exist between elliptical and spiral galaxies.

Globular Clusters as Tracers of the Galaxy Mass Distribution

This review will consist of two parts: (a) a brief description of a new method to determine Vo, the circular speed of the local standard of rest, and which, of course, plays a fundamental role in the mass distribution of the Galaxy, and (b) a review of the globular clusters as tracers of the mass distribution in the Galaxy.

Concerning the limit on the mean mass distribution of galaxies from their gravitational lens effect

view Abstract Citations (17) References (3) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Concerning the Limit on the Mean Mass Distribution of Galaxies from Their Gravitational Lens Effect Kovner, Israel ; Milgrom, Mordehai Abstract Tyson and colleagues deduced bounds on the mass distribution in galaxies, from the (unobserved) distortion of background galaxy images by the gravitational field of foreground galaxies. The authors have checked how critical is their assumption that the background galaxies are at an infinite distance. When the distance distribution of the foreground and background galaxies is taken into account, the upper bounds on the rotation velocities are increased (quite considerably) above those published by Tyson and colleagues in 1984. Publication: The Astrophysical Journal Pub Date: October 1987 DOI: 10.1086/185016 Bibcode: 1987ApJ...321L.113K Keywords: Galactic Mass; Gravitational Lenses; Light Curve; Mass Distribution; Computational Astrophysics; Error Analysis; Astrophysics; GALAXIES: GENERAL; GRAVITATION; GRAVITATIONAL LENSES full text sources ADS |

Distant satellites as probes of our Galaxy's mass distribution

view Abstract Citations (145) References (23) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Distant Satellites as Probes of Our Galaxy's Mass Distribution Little, Blane ; Tremaine, Scott Abstract A new method of statistical analysis based on Bayes' theorem is devised and used directly to yield confidence intervals for the mass of the Galaxy once the eccentricity distribution of its satellites are specified. If the satellites have an isotropic velocity distribution, then the Galactic mass is less than about 5.2 x 10 to the 11th solar masses at the 95 percent confidence level. If the Galaxy is modeled as an infinite halo with constant circular speed v(c) and the velocities are isotropic, then the analysis predicts v(c) of less than about 165 km/s at the 95 percent confidence level. If the satellite orbits are more radial, then the estimates are lower. These results suggest that the Galaxy's massive dark halo extends to less than about 50 kpc from the Galactic center. Publication: The Astrophysical Journal Pub Date: September 1987 DOI: 10.1086/165567 Bibcode: 1987ApJ...320..493L Keywords: Astrometry; Dark Matter; Galactic Structure; Mass Distribution; Milky Way Galaxy; Stellar Motions; Bayes Theorem; Eccentricity; Halos; Orbital Velocity; Radial Velocity; Star Distribution; Astrophysics; GALAXIES: STRUCTURE; GALAXIES: THE GALAXY; STARS: STELLAR DYNAMICS full text sources ADS | data products SIMBAD (16) NED (14)

Mass-to-Light Ratios of Binary Galaxies. III. Analysis

view Abstract Citations (65) References (44) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Mass-to-Light Ratios of Binary Galaxies. III. Analysis Schweizer, Linda Y. Abstract New high-accuracy (< σv > ≡ 9 km s-1) radial velocities and photoelectric magnitudes V for a complete sample of 96 galaxies in 48 southern pairs, published in Papers I and II, are here analyzed with a Monte Carlo method to estimate mass-to-light ratios of galaxies at spatial separations of the order of 10O kpc. Special emphasis has been placed on adopting stringent sample selection procedures based on an objective dynamical model. As part of the analysis, we have applied a probabilistic correction for inclusion of optical pairs, and devised an empirical Monte Carlo procedure to allow for biases due to accidental exclusion of bound pairs. Dynamical simulations were again employed to test a variety of dynamical models, through the variables. From our observations and analysis, the following conclusions are drawn: (1) The ratio of orbital mass to visual luininosity for type Sc galaxies ranges from 12 to 32, with a most likely value of M/Lv = 21±5 solar units; the value for elliptical galaxies ranges from 22 to 60 with a most likely value of M/Lv = 39±9 (H0 = 50). Despite these relatively low values, masses deterinined from our sample are few times larger than masses obtained from rotation curves, adding supporting evidence for a "mass discrepancy." (2) Models with moderately high eccentricity orbits seem to represent the data better than models with nearly circular orbits. (3) Correlations between dynamical variables suggest that Keplerian orbits are a good representation of the true orbits. This, plus the fact that mass appears to be independent of projected separation beyond 60-100 kpc, suggests that mass distributions of binary galaxies extend less far than their mean separation. (4) The distribution of projected pair separations is fitted by a lognormal distribution. Arguments based on the effect of mergers suggest that power-law distributions used in previous analyses are inappropriate and "scale-free" models of binary galaxies should be viewed with caution. A crucial power-law fit made by Turner is shown to be erroneous. (5) The luminosity distribution of galaxies in our sample agrees with that of Schechter, suggesting that there is no excess of bright binary galaxies, and that M/L ratios derived from binaries hold as well for isolated field galaxies. Publication: The Astrophysical Journal Supplement Series Pub Date: June 1987 DOI: 10.1086/191202 Bibcode: 1987ApJS...64..427S Keywords: GALAXIES: CLUSTERING; LUMINOSITY FUNCTION full text sources ADS | data products NED (96) SIMBAD (63) Related Materials (2) Part 1: 1987ApJS...64..411S Part 2: 1987ApJS...64..417S

Mass Distributions in Elliptical Galaxies at Large Radii

Recently, x-ray observations have shown that elliptical galaxies generally contain large quantities of hot gas. Central dominant cluster ellipticals have even more gas, which they have accreted from the surrounding clusters. The mass distributions in these galaxies can be derived from the condition of hydrostatic equilibrium. M87, the best studied central dominant galaxy, has a massive, dark halo with a total mass of about 4 × 1012 M⊙ within a radius of 300 kpc. The total mass-to-light ratio within this radius is at least 150 M⊙/L⊙. The x-ray observations of normal ellipticals also strongly suggest that they have heavy haloes, although the distribution of the mass is much less certain than in M87.

HI Rotation Curves of Galaxies

The observational evidence on the discrepancy between the mass distribution in galaxies derived from HI rotation curves and that derived from the distribution of light is reviewed. In the outer parts the discrepancy is such that in some galaxies there is at least three times as much dark matter as luminous matter. This is a direct consequence of the nearly constant circular velocity far beyond the edge of the visible part of the galaxy, as derived from the motion of HI. The discrepancy is clearly present already near the edge of the visible disk (R25). In the inner regions, i.e. inside approximately 2.5 disk scale-lengths, no dark matter is required, but its presence can not be ruled out. There is no evidence for a dependence on galaxy luminosity or morphological type. These results suggest a strong coupling between luminous matter and dark matter within individual galaxies, and among galaxies as well. Finally attention is drawn to the large-scale asymmetries in the outer parts of galaxies and to possible implications for the vertical distribution of dark matter.

Galaxy Mass Distribution from Galaxy-Galaxy Gravitational Lensing

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.

Is the Universe dominated by relativistic particles?

The decaying dark matter (DM) cosmology1–3 attempts to reconcile the theoretical prejudice that the total energy density of the Universe, Ω=1 with the observations that the matter clustered on scales up to a few megaparsecs amounts only to4,5 Ωcl=0.1–0.3. Decaying DM postulates that a heavy-elementary-particle species X first drives the formation of galaxies and clusters, and then decays nonradiatively, providing a smooth, undetected background of relativistic particles that at present contribute Ωr to the total energy density of the Universe, Ω. We consider here the effects of decaying DM on the radial distribution of mass in spiral galaxies, assumed to have formed through dissipative collapse inside a gravitationally induced protogalaxy consisting initially of a homogeneous mixture of dissipationless DM and a small fraction of dissipative baryonic material6. The baryonic inner parts of galaxies are self gravitating, but mass loss from X decay causes the rotation velocity in the outer parts to decrease. We find that the observed flat rotation curves cannot be obtained in these decaying DM models. Thus, a relativistic, weakly interacting decay product cannot be dominant.

The distribution of mass in spiral galaxies

view Abstract Citations (137) References (20) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The distribution of mass in spiral galaxies. Burstein, D. ; Rubin, V. C. Abstract Rotation curves for the 60 Sa, Sb, and Sc galaxies which the authors have previously studied indicate that galaxies of very different optical morphology and luminosity can have rotation curves of very similar form. This paper examines the dynamical mass distribution (both luminous and nonluminous) in these galaxies by assuming that the relation between the observed rotation curve and the projected mass distribution is the same for all spiral galaxies. It is shown that the derived mass distributions for most of these galaxies can be classified as one of three well-defined integral mass forms, where mass and radius are measured in units of a fiducial mass and a scale length. Galaxies of all Hubble types and luminosities are represented in each integral mass type. The forms of mass distribution do not correlate with Hubble type, bulge-to-disk ratio, luminosity, mass density, size, mass, or other known global properties of these galaxies. Publication: The Astrophysical Journal Pub Date: October 1985 DOI: 10.1086/163541 Bibcode: 1985ApJ...297..423B Keywords: Galactic Structure; Mass Distribution; Rotating Matter; Spiral Galaxies; Hubble Constant; Luminosity; Astrophysics full text sources ADS | data products SIMBAD (61) NED (61)

Image distortion near galaxies: dwarfs or lensing?

Gravitational lensing is a useful tool for studying the mass distribution in galaxies. The average gravitational lens distortion of background galaxy images by foreground galaxies is an independent non-kinematical measurement of galaxy mass distribution M/r (ref. 1), where M is the mass of the galaxy and r its radius. Using an indirect calculation involving estimated luminosity functions and absolute magnitudes, Phillipps2 recently claimed that our measurement of field galaxy mass distribution by galaxy-galaxy gravitational lensing was contaminated by large numbers of foreground dwarf galaxies. I present here a direct measurement of this effect: the cross-correlation between these samples clearly reveals clustering of foreground dwarf galaxies, with an amplitude slightly less than that given by our original simulation1. Thus, this effect does not change our conclusions regarding the average galaxy mass distribution.

Preferred orbit planes in tumbling triaxial galaxies. III Application to the Schwarzschild ellipsoid

We use an analytic method to examine the behavior of preferred orbit planes interior to the mass distribution of a tumbling triaxial galaxy. These planes are directly related to the location of periodic orbits and define the possible orientations of steady state gas disks. We discuss how the properties of these orbits, including stability, vary with the axis ratios of a galaxy's mass distribution and with the tumble rate of its surface figure. In particular, for the triaxial galactic potential of Schwarzschild, we compare the analytic predictions of our preferred plane method with numerical determinations of periodic orbit orientations in galaxies tumbling about their short axis. Outside the harmonic core of the potential, we find agreement to within several percent for the inclinations of periodic orbits at a given orbit energy. Analytic expressions for the location and extent of the retrograde Binney instability strip also agree with numerical results to the same degree of accuracy.

Biased galaxy formation in a universe dominated by cold dark matter

The hypothesis that galaxies form from rare fluctuations in a universe dominated by cold, weakly interacting dark matter is shown to be in reasonable accord with most observed properties of the distribution of galaxies. The role of mass density fluctuations around the mean value on various mass scales is considered. The mass distribution of galaxies and the cluster multiplicity function are calculated for a model in which galaxy formation is biased by the assumption that galaxies form only at a redshift in excess of three. The fraction of gaseous matter that, at the epoch of galaxy formation, has not already collapsed on smaller scales is calculated. On scales which have turned around recently, gas infall to dark-matter potential wells is shown to result in observable diffuse X-ray emission. The galaxy distribution on these scales is found to be highly anisotropic, building up into large-scale filaments or pancakes.

Galaxy mass distribution from gravitational light deflection

view Abstract Citations (153) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Galaxy mass distribution from gravitational light deflection Tyson, J. A. ; Valdes, F. ; Jarvis, J. F. ; Mills, A. P., Jr. Abstract A new technique for measuring galaxy mass, based on the gravitational deflection of light, is described. The method does not require stereoscopic detectability or virial or orbital assumptions and can apply to galaxies of all types. Images from 46,954 galaxies were examined in order to find a particular coherent image distortion associated with gravitational lenses of 11,789 foreground galaxies. The equivalent statistical circular velocities of the galaxies are determined as a function of the mass cutoff radius for the foreground galaxy data set. The 2 sigma upper limit to the average circular velocity is found to be less than 170 km per sec for a mass envelope extending to beyond 50 kpc/h radius. The corresponding total mass limit to this radius is 1.7 x 10 to the 11th solar mass. It is concluded that there is not sufficient mass associated with the individual galaxies to achieve the critical density for closure. Publication: The Astrophysical Journal Pub Date: June 1984 DOI: 10.1086/184285 Bibcode: 1984ApJ...281L..59T Keywords: Cosmology; Galactic Structure; Gravitational Lenses; Mass Distribution; Calibrating; Data Reduction; Distortion; Astrophysics full text sources ADS |