The Mass Distribution in the Central Few Parsecs of the Galaxy

1989 ◽  
pp. 493-499 ◽  
Author(s):  
John H. Lacy
Keyword(s):  
Mass Distribution ◽  
The Galaxy

scholarly journals The effect of the Magellanic Clouds on the mass distribution in the galaxy

1991 ◽  
Vol 148 ◽  
pp. 487-488
Author(s):  
G. X. Song
Keyword(s):  
Mass Distribution ◽  
Milky Way ◽  
Galactic Disk ◽  
Initial Position ◽  
Tidal Effect ◽  
Magellanic Clouds ◽  
The Galaxy

The disk of the Milky Way suffered from the tidal effect as the Magellanic Clouds were passing by. Numerical stimulations were performed to study the evolution of the mass distribution in this disk. These simulations were run with the galactic disk initially flat, and different sets of the initial position and velocity of the Magellanic Clouds were considered. One of the most conspicuous observational facts is the warp of the disk of the Milky Way. Results show that the characteristics of this warp are related to the orbit of the Magellanic Clouds.

scholarly journals Modelling the Structure of the Ringed Spiral NGC 4736

1996 ◽  
Vol 157 ◽  
pp. 253-255
Author(s):  
Wim van Driel ◽  
Pieter Mulder ◽  
Françoise Combes
Keyword(s):  
Mass Distribution ◽  
Spiral Structure ◽  
Optical Spectra ◽  
Spectral Lines ◽  
Time Interval ◽  
Limited Time ◽  
The Galaxy ◽  
Dynamical Simulations ◽  
Pattern Speed ◽  
Limited Time Interval

AbstractWe studied the ringed RSab(r)-type spiral NGC 4736, which has a probably slightly oval disk and a very small bar. We mapped the galaxy in the HI and Hα spectral lines and we obtained long-slit optical spectra. These data were modeled using a 2-D gas dynamical code. The 2-D potential used is axisymmetric in the inner and outer regions and oval (b/a=0.8) at intermediate radii only. The oval component rotates at a pattern speed of 40 km s–1 kpc–1, close to the observed value. Inner and outer rings, like those observed, form at the inner and outer Lindblad resonances, though they co-exist only during a limited time interval in the simulations. The morphology and kinematics of the inner ring and spiral structure as observed in neutral and ionized hydrogen can be well understood in terms of gas dynamical simulations, given the form of the (stellar) potential. What remains to be explained is the origin of the nonaxisymmetric features in the mass distribution defining the potential.

scholarly journals An Upper Limit to the Mass Loss from the Centre of the Galaxy

1974 ◽  
Vol 64 ◽  
pp. 36-36
Author(s):  
Arcadio Poveda ◽  
Christine Allen
Keyword(s):  
Mass Loss ◽  
Gravitational Waves ◽  
Mass Distribution ◽  
Globular Clusters ◽  
Loss Rate ◽  
Galactic Centre ◽  
Isotropic Source ◽  
The Past ◽  
Upper Limit ◽  
The Galaxy

A mass loss of 200 M⊙ per year, as conservatively suggested if Weber is detecting gravitational waves from an isotropic source at the galactic centre, is shown to be incompatible with the existence of (a) globular clusters, (b) old wide binaries, if this loss rate has been constant over the past 1010 yr.From the orbit of ω Centauri in the galactic field and its observed mass distribution and tidal radius an upper limit to the mass loss from the galactic centre is found to be 1 M⊙ yr-1 over the past 1010 yr.

scholarly journals The Dark Blue Compact Dwarf Galaxy NGC 2915

1997 ◽  
Vol 14 (1) ◽  
pp. 77-80 ◽  
Author(s):  
Gerhardt R. Meurer
Keyword(s):  
Dark Matter ◽  
Mass Distribution ◽  
Dwarf Galaxy ◽  
Dark Matter Halo ◽  
High Mass ◽  
Mass Star ◽  
Normal Galaxies ◽  
The Galaxy ◽  
Dark Blue ◽  
Blue Compact Dwarf Galaxy

AbstractRecent results on NGC 2915, the first blue compact dwarf galaxy to have its mass distribution modelled, are summarised. NGC 2915 is shown to have HI well beyond its detected optical extent. Its rotation curve is well determined and fit with maximum disk mass models. The dark matter halo dominates the mass distribution at nearly all radii, and has a very dense core compared to those of normal galaxies. High-mass star formation energises the HI in the centre of the galaxy, but appears to be maintained in viriai equilibrium with the dark matter halo. The implications of these results are briefly discussed.

scholarly journals Rapid evolution and transformation into quiescence?: ALMA view on z > 6 low-luminosity quasars

2019 ◽  
Vol 15 (S352) ◽  
pp. 139-143
Author(s):  
Takuma Izumi ◽  
Masafusa Onoue ◽  
Yoshiki Matsuoka ◽  
Tohru Nagao ◽  
Michael A. Strauss ◽  
...  
Keyword(s):  
Black Holes ◽  
Mass Distribution ◽  
Rapid Evolution ◽  
Far Infrared ◽  
Significant Fraction ◽  
Host Galaxies ◽  
Dynamical Mass ◽  
The Galaxy ◽  
Order Of Magnitude ◽  
Wide Scatter

AbstractWe present ALMA [CII] line and far-infrared (FIR) continuum observations of seven z > 6 low-luminosity quasars (M1450 > −25 mag) discovered by our on-going Subaru Hyper Suprime-Cam survey. The [CII] line was detected in all targets with luminosities of ∼(2−10) × 108 L⊙, about one order of magnitude smaller than optically luminous quasars. Also found was a wide scatter of FIR continuum luminosity, ranging from LFIR < 1011L⊙ to ∼2 × 1012L⊙. With the [CII]-based dynamical mass, we suggest that a significant fraction of low-luminosity quasars are located on or even below the local Magorrian relation, particularly at the massive end of the galaxy mass distribution. This is a clear contrast to the previous finding that luminous quasars tend to have overmassive black holes relative to the relation. Our result is expected to show a less-biased nature of the early co-evolution of black holes and their host galaxies.

scholarly journals Constraining the abundance of dark matter in the central region of the galaxy cluster MACS J1206.2−0847 with a free-form strong lensing analysis

2020 ◽  
Vol 639 ◽  
pp. A125
Author(s):  
Alberto Manjón-García ◽  
Jose M. Diego ◽  
Diego Herranz ◽  
Daniel Lam
Keyword(s):  
Dark Matter ◽  
Mass Distribution ◽  
Central Region ◽  
Total Mass ◽  
Galaxy Cluster ◽  
Free Form ◽  
Matter Distribution ◽  
Strong Lensing ◽  
The Galaxy ◽  
Dark Matter Distribution

We performed a free-form strong lensing analysis of the galaxy cluster MACS J1206.2−0847 in order to estimate and constrain its inner dark matter distribution. The free-form method estimates the cluster total mass distribution without using any prior information about the underlying mass. We used 97 multiple lensed images belonging to 27 background sources and derived several models, which are consistent with the data. Among these models, we focus on those that better reproduce the radial images that are closest to the centre of the cluster. These radial images are the best probes of the dark matter distribution in the central region and constrain the mass distribution down to distances ∼7 kpc from the centre. We find that the morphology of the innermost radial arcs is due to the elongated morphology of the dark matter halo. We estimate the stellar mass contribution of the brightest cluster galaxy and subtracted it from the total mass in order to quantify the amount of dark matter in the central region. We fitted the derived dark matter density profile with a gNFW, which is characterised by rs = 167 kpc, ρs = 6.7 × 106 M⊙ kpc−3, and γgNFW = 0.70. These results are consistent with a dynamically relaxed cluster. This inner slope is smaller than the cannonical γ = 1 predicted by standard CDM models. This slope does not favour self-interacting models for which a shallower slope would be expected.

scholarly journals The Mass Distribution in the Central Few Parsecs of the Galaxy

1989 ◽  
Vol 136 ◽  
pp. 493-499
Author(s):  
John H. Lacy
Keyword(s):  
Mass Distribution ◽  
Gas Dynamics ◽  
Good Evidence ◽  
Ionized Gas ◽  
Massive Black Hole ◽  
Central Mass ◽  
Magnetic Forces ◽  
Gravitational Forces ◽  
The Galaxy

The determination of the mass distribution in the central few parsecs of the Galaxy, primarily from the ionized gas dynamics, is discussed. The gas motions are described and interpreted assuming that the orbits are determined by gravitational forces. It is shown that there is good evidence for a central mass of ~ 2 × 106 M⊙. The primary uncertainty in this conclusion results from the possibility of significant magnetic forces. In the absence of corroborating evidence, the case for a massive black hole cannot be considered proven.

scholarly journals Structural and Kinematic Properties of Populations of the Andromeda Galaxy

1972 ◽  
Vol 44 ◽  
pp. 37-45 ◽  
Author(s):  
J. Einasto
Keyword(s):  
Mass Distribution ◽  
Globular Clusters ◽  
Velocity Dispersion ◽  
Strong Dependence ◽  
Stellar Content ◽  
Distribution Models ◽  
Model Calculations ◽  
The Galaxy ◽  
Spectrophotometric Data ◽  
Virial Mass

New observational data (Spinrad, 1970; Van den Bergh, 1970; Rubin and Ford, 1970) are used to determine structural and kinematic parameters of the nucleus, the subsystem of globular clusters, and interstellar hydrogen in M31.The mass derived for the nucleus from the new spectrophotometric data is in good agreement with the virial mass 6 × 108M⊙. Model calculations show that there is no appreciable exchange of stars between the nucleus and the bulge. The rotation energy of the nucleus is only 7.5% of the total kinetic energy; the central density is 2 × 106M⊙ pc−3.The mean radius of the subsystem of globular clusters is 4.5 kpc. This indicates that the subsystem of old stars is not identical with the spheroidal component of the galaxy, whose mean radius is only 1 kpc. Radial velocity dispersion of globular clusters is only half of that of the nucleus. This shows a strong dependence of the velocity dispersion on distance to the center of the galaxy and a bias in mass determination of a galaxy from velocity dispersion near the nucleus.On the basis of data on rotation two mass distribution models have been found, differing from each other in respect of the mass concentration to the center. Spectrophotometric data on the stellar content of the bulge are urgently needed to solve the mass distribution problem.

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