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 Do All Spiral Galaxies Have a Massive Dark Halo?

1999 ◽  
Vol 183 ◽  
pp. 157-157 ◽  
Author(s):  
M. Honma ◽  
Y. Sofue
Keyword(s):  
Dark Matter ◽  
Spiral Galaxies ◽  
The Other ◽  
Dark Halo ◽  
Rotation Curves ◽  
Other Hand ◽  
Flat Rotation Curves ◽  
The Masses ◽  
Scale Length

We have investigated the masses and extents of dark halos of spiral galaxies by two methods. First, we have reanalyzed HI outer rotation curves so far obtained considering the velocity uncertainties. We confirmed that many HI rotation curves indicate the existence of dark matter to some extent. However, we also found that only few rotation curves provide direct evidences for halos extended beyond 10 disk scale length. On the other hand, recent HI observations revealed that several galaxies have declining rotation curves that are approximated by Keplerian in the outermost regions. Considering the velocity uncertainties in the outer rotation curves, we found that these declining rotation curves are not rare compared to flat rotation curves. If these declining rotation curves indeed trace the mass truncation, these results indicate that some dark halos have moderate masses that are comparable or slightly larger than disk masses.

Dark matter bar evolution in triaxial spinning haloes

2020 ◽  
Vol 15 (S359) ◽  
pp. 446-447
Author(s):  
Daniel A. Marostica ◽  
Rubens E. G. Machado
Keyword(s):  
Dark Matter ◽  
The Other ◽  
Barred Galaxies ◽  
Other Hand ◽  
Dynamical Instabilities

AbstractDark matter bars are structures that may form inside dark matter haloes of barred galaxies. Haloes can depart from sphericity and also be subject to some spin. The latter is known to have profound impacts on the evolution of both stellar and DM bars, such as stronger dynamical instabilities, more violent vertical bucklings and dissolution or impairment of stellar bar growth. On the other hand, dark matter bars of spherical haloes become initially stronger in the presence of spin. In this study, we add spin to triaxial halos in order to quantify and compare the strength of their bars. Using N-body simulations, we find that spin accelerates main instabilities and strengthens the halo bars, although their final strength depends only on triaxiality. The most triaxial halo barely forms a halo bar, showing that flattening opposes to DM bar strengthening and indicating that there is a limit on how flattened the parent structure can be.

scholarly journals Rotation of Galaxy Dark Matter Halos

2006 ◽  
Vol 2 (S235) ◽  
pp. 104-104
Author(s):  
Stéphane Herbert-Fort ◽  
Dennis Zaritsky ◽  
Yeun Jin Kim ◽  
Jeremy Bailin ◽  
James E. Taylor
Keyword(s):  
Dark Matter ◽  
Angular Momentum ◽  
Numerical Simulations ◽  
Galaxy Formation ◽  
Spiral Galaxy ◽  
Observational Studies ◽  
Spiral Galaxies ◽  
Satellite System ◽  
Dark Matter Halos ◽  
The Mean

AbstractThe degree to which outer dark matter halos of spiral galaxies rotate with the disk is sensitive to their accretion history and may be probed with associated satellite galaxies. We use the Steward Observatory Bok telescope to measure the sense of rotation of nearby isolated spirals and combine these data with those of their associated satellites (drawn from SDSS) to directly test predictions from numerical simulations. We aim to constrain models of galaxy formation by measuring the projected component of the halo angular momentum that is aligned with that of spiral galaxy disks, Jz. We find the mean bulk rotation of the ensemble satellite system to be co-rotating with the disk with a velocity of 22 ± 13 km/s, in general agreement with previous observational studies and suggesting that galaxy disks could be formed by halo baryons collapsing by a factor of ≈10. We also find a prograde satellite fraction of 51% and Jz, of the satellite system to be positively correlated with the disk, albeit at low significance (2655 ± 2232 kpc km/s).

scholarly journals Primordial black holes and scotogenic dark matter

2021 ◽  
pp. 2150139
Author(s):  
Teruyuki Kitabayashi
Keyword(s):  
Black Holes ◽  
Dark Matter ◽  
Energy Scale ◽  
The Other ◽  
Initial Mass ◽  
Primordial Black Holes ◽  
Upper Limit ◽  
Other Hand

We study the effect of the scotogenic dark matter on the primordial black holes (PBHs) and vice versa. We show that if the PBHs evaporate in the radiation dominated era, the upper limit of the initial mass of the PBHs [Formula: see text] should be constrained as [Formula: see text] for [Formula: see text] TeV scotogenic dark matter [Formula: see text] TeV is the most appropriate energy scale in the scotogenic model). On the other hand, if the PBHs evaporate in the PBH dominated era, a quite heavy scotogenic dark matter ([Formula: see text] GeV) for [Formula: see text] may be allowed.

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 Dissipation and Formation of Galactic Halos

1988 ◽  
Vol 130 ◽  
pp. 421-425
Author(s):  
George R. Blumenthal
Keyword(s):  
Dark Matter ◽  
Mass Distribution ◽  
Spiral Galaxies ◽  
Galactic Halos ◽  
Rotation Curves ◽  
Striking Effect

When protogalaxies collapse, the cooling and infall of what will become the visible galactic component affects the mass distribution of dissipationless dark matter particles which constitute the halo. For spiral galaxies, the reaction of the dissipationless halo can have a striking effect on the resulting rotation curves [1–5].

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 Exploring Properties of Dark and Visible Mass Distribution on Different Scales in the Universe

2005 ◽  
Vol 20 (14) ◽  
pp. 3124-3127
Author(s):  
Yuriy Mishchenko ◽  
Chueng-Ryong Ji
Keyword(s):  
Dark Matter ◽  
Galaxy Clusters ◽  
Mass Distribution ◽  
Linear Correlation ◽  
Spiral Galaxies ◽  
Recent Observation ◽  
Short Note ◽  
Dark Matter Particle ◽  
The Universe

In this short note we discuss recent observation of linear correlation on log-log scale between distribution of dark and visible mass in gravitationally bound systems. The coefficient of such correlation appears to be essentially the same for various systems of dramatically different scales such as spiral galaxies of different luminosities and galaxy clusters. We briefly touch possible interpretations of this observation and implications for the mass of dark matter particle.

TECHNICAL ASPECTS IN DARK MATTER DIRECT DETECTION

2013 ◽  
Vol 23 ◽  
pp. 309-313
Author(s):  
R. BERNABEI ◽  
P. BELLI ◽  
A. DI MARCO ◽  
F. MONTECCHIA ◽  
F. CAPPELLA ◽  
...  
Keyword(s):  
Dark Matter ◽  
Direct Detection ◽  
Theoretical Models ◽  
The Other ◽  
Technical Aspects ◽  
Other Hand ◽  
The One

In the field of dark matter direct detection, on the one hand, it is predicted by theoretical models that many dark matter candidates and scenarios are possible. On the other hand, a variety of detectors has been proposed, but most of them — by the fact — are still at R&D stage. Such a situation leads to some considerations on technical aspects on dark matter direct detection.

scholarly journals A Unified Electro-Gravity Theory to Model Spiral Galaxies without Dark Matter

2019 ◽  
Author(s):  
Nirod K. Das
Keyword(s):  
Elementary Particle ◽  
Dark Matter ◽  
Spiral Galaxy ◽  
Surface Brightness ◽  
Spiral Galaxies ◽  
Rotation Speed ◽  
Modified Newtonian Dynamics ◽  
Newtonian Dynamics ◽  
The Galaxy ◽  
Flat Rotation Curves

A unified electro-gravity (UEG) theory, which has been successfully used for modeling an elementary particle, is applied in this paper to model gravitation in spiral galaxies. The new UEG model would explain the “flat rotation curves” commonly observed in the spiral galaxies, without need for any hypothetical dark matter. The UEG theory is implemented in a somewhat different manner for a spiral galaxy, as compared to the simple application of the UEG theory to an elementary particle. This is because the spiral galaxy, unlike the elementary particle, is not spherically symmetric. The UEG constant $\gamma$, required in the new model to support the galaxies' flat rotation speeds, is estimated using measured data from a galaxy survey, as well as for a selected galaxy for illustration. The estimates are compared with the $\gamma$ derived from the UEG model of an elementary particle. The UEG model for the galaxy is shown to explain the empirical Tully-Fisher Relationship (TFR), is consistent with the Modified Newtonian Dynamics (MOND), and is also independently supported by measured trends of galaxy thickness with surface brightness and rotation speed.

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