Dark matter particles and the flat rotation curves of spiral galaxies

It is shown that a gas of massive bosonic particles (m 60 eV), e.g. Higgs particles, surrounding disk galaxies is able to generate the flat rotation curves of spiral galaxies without internal difficulties with physical principles. We have analyzed 36 galaxies and find good agreement with the empirical data.     

On the gravitomagnetic origins of the anomalous flat rotation curves of spiral galaxies

We demonstrate that in-principle, one of the five solutions presented in the reading Nyambuya (2015b), i.e., a solution of the Four Poisson-Laplace equation of gravitation [or Nordström (1912) equation of gravitation] can be used to explain the anomalous flat rotation curves of spiral galaxies. The proposed solution does not invoke the exotic hypothesis of darkmatter but makes the assumption that our existing Laws of Gravitation need to be amended. Our proposed amendment falls well within the accepted domain of legitimate gravitational field equations.     

A new scalar tensor theory for gravity and the flat rotation curves of spiral galaxies

In this paper we reproduce flat rotation curves of spiral galaxies by discussing a scalar tensor theory of gravity which includes the Higgs field as scalar field. The galaxy density distribution is assumed to be homogeneous or polytropic and in the galaxy core there exists a large concentrated mass.     

On the understanding of the observed flat or slowly rising rotation curves in large disk galaxies

Recent observations of the rotation curves of large disk galaxies of all Hubble-types have shown that they possess flat or slowly rising rotation curves up to large distances from the centre. It has been suggested here that such rotation curves are understood under normal fluid dynamical considerations provided that viscous (and/or magnetic) transfer of mass and angular momentum from inner to outer regions of these galaxies is efficient. Flow of gas from halo to the disk in regions close to the axis of rotation is also suggested. The existence of rising rotation curves in some galaxies with varying gradients and flat rotation curves in others suggest that probably these galaxies are not coeval. The formers are probably of more recent origin.     

The shape of the rotation curves of edge-on galaxies

We consider the effects of projection, internal absorption, and gas-or stellar-velocity dispersion on the measured rotation curves of galaxies with edge-on disks. Axisymmetric disk models clearly show that the rotational velocity in the inner galaxy is highly underestimated. As a result, an extended portion that imitates nearly rigid rotation appears. At galactocentric distances where the absorption is low (i.e., it does not exceed 0.3–0.5^m kpc^?1), the line profiles can have two peaks, and a rotation curve with minimum distortions can be obtained by estimating the position of the peak that corresponds to a higher rotational velocity. However, the high-velocity peak disappears in high-absorption regions and the actual shape of the rotation curve cannot be reproduced from line-of-sight velocity estimates. In general, the optical rotation curves for edge-on galaxies are of little use in reconstructing the mass distribution in the inner regions, particularly for galaxies with a steep velocity gradient in the central region. In this case, estimating the rotation velocities for outer (transparent) disk regions yields correct results.     

Companions' influence on the emission-line rotation curves of galaxies

The sample of members of isolated pairs of galaxies and close binary interacting systems — demonstrating a systematic falling of the emission-line rotation curves after the maxima — are considered. It is found that there is a significant correlation between the characteristics of the galaxies' emission-line velocity fields and the spatial distance to the companion. The different factors affecting the investigated relationships are discussed.     

Dark matter and rotation curves of stars in galaxies

The dark matter accretion theory (around a central body) of the author on the basis of his 5‐dimensional Projective Unified Field Theory (PUFT) is applied to the orbital motion of stars around the center of the Galaxy. The departure of the motion from Newtonian mechanics leads to approximately flat rotation curves being in rough accordance with the empirical facts. The spirality of the motion is investigated.     

Flat rotation curves of spiral galaxies and the dark matter particles

It is shown that a gas of massive bosonic particles ( eV), e.g. Higgs particles, surrounding the disk galaxies is able to generate flat rotation curves without internal difficulties with physical principles.     

Ionized gas rotation curves in nearby dwarf galaxies

We present the results of study of the ionized gas velocity fields in 28 nearby (systemic velocity below 1000 km s^?1) dwarf galaxies. The observations were made at the 6-m BTA telescope of the SAO RAS with the scanning Fabry-Perot interferometer in the Hα emission line. We were able to measure regular circular rotation parameters in 25 galaxies. As a rule, rotation velocities measured in HII are in a good agreement with the data on the HI kinematics at the same radii. Three galaxies reveal position angles of the kinematic axis in the HII velocity fields that strongly (tens of degrees) differ from the measurements in neutral hydrogen at large distances from the center or from the orientation of the major axis of optical isophotes. The planes of the gaseous and stellar disks in these galaxies most likely do not coincide. Namely, in DDO99 the gaseous disk is warped beyond the optical radius, and in UGC3672 and UGC8508 the inclination of orbits of gas clouds varies in the inner regions of galaxies. It is possible that the entire ionized gas in UGC8508 rotates in the plane polar to the stellar disk.     

Testing the nonsysmmetric gravitational theory with rotation curves of galaxies

We use the rotation curves of 13 galaxies to test the nonsymmetric gravitaional theory (NGT). If we follow Moffat's assumption of a constant mass-to-light for all galaxies then we shall find that the two supposedly universal constants r₀, L₀ to show a large scatter. By regarding the mass-to-light ratio as a free parameter for each galaxy, and adjusting the values of r₀, L₀, we find that NGT can well account for the observed rotation curves. Further, the mass-to-light ratios so found show the well-known trend along the Hubble morphological sequence.     

General relativistic dynamics applied to the rotation curves of galaxies

We extend our general relativistic analysis of galactic rotation curves (see Cooperstock and Tieu in Int. J. Mod. Phys. A 22:2293, 2007) with galaxies NGC 2841, NGC 2903 and NGC 5033. As before, we employ the solution of the Einstein field equations of general relativity with an expansion in Bessel functions. As in our earlier studies, the fits to the data are found to be very precise and the calculated baryonic masses are lower than those based upon Newtonian gravity. Also as in our previous studies, the galactic radii at which the optical luminosities terminate are seen to correlate with densities near 10^−21.75 kg m⁻³. This concordance lends further support to the correctness of the procedure as well as providing a potentially valuable piece of information in the understanding of galactic evolution.     

Cosmological constant as integration constant

Einstein's field theory of elementary particles (Einstein 1919) yields black holes with a mass M ˜ G⁻¹ Λ^−1/2c² and a charge Q ˜ G^−1/2λ^−1/2c², their curvatu re radius is Λ^−1/2. Here 4Λ is an integration constant of Einstein's ‘trace-less’ gravitation equations. The choice λ = G⁻¹h⁻¹c³ for this constant defines Planckions and implies “strong gravity”. The choice λ = λ = 3H_inf²c⁻² (where H_inf means the Hubble parameter of a final de Sitter cosmos) involves “weak gravity” and describes an electro-vac spherical universe.     

An analysis of 900 rotation curves of southern sky spiral galaxies: Do rotation curves fall into discrete classes?

One of the largest rotation curve data bases of spiral galaxies currently available is that provided by Persic& Salucci (1995; hereafter, PS) which has been derived by them from unreduced rotation curve data of 965 southern sky spirals obtained by Mathewson, Ford& Buchhorn (1992; hereafter, MFB). Of the original sample of 965 galaxies, the observations on 900 were considered by PS to be good enough for rotation curve studies, and the present analysis concerns itself with these 900 rotation curves. The analysis is performed within the context of the hypothesis that velocity fields within spiral discs can be described by generalized power-laws. Rotation curve data was found to impose an extremely strong and detailed correlation between the free parameters of the power-law model, and this correlation accounts for virtually all the variation in the pivotal diagram. In the process, the analysis reveals completely unexpected structure which indicates that rotation curves can be partitioned into well-defined discrete subclasses.     

Flat rotation curves and mass distribution for spiral galaxies with a disk model

A method to fit flat rotation curves is presented, wherein the galactic density for a disk model is expressed in terms of a Dirichlet polynomial. This procedure allows us to obtain the total galactic mass and to predict the circular velocity at large galactocentric distances.Application of the method to the Galaxy, M31 and four Sc galaxies shows that a significant galactic mass is located beyond the optical radius although it is considerably smaller than the integral mass values obtained from current models with a massive corona included. Observed rotation curves and convergent total mass are obtained, thus the total mass for the Milky Way Galaxy is 5.69×10¹¹ M .     

Cosmological models with shear and rotation

Cosmological models involving shear and rotation are considered, first in the general relativistic and then in the Newtonian framework with the aim of investigating singularities in them by using numerical and analytical techniques. The dynamics of these rotating models are studied. It is shown that singularities are unavoidable in such models and that the centrifugal force arising due to rotation can never overcome the gravitational and shearing force over a length of time.     

Model rotation curves of disk galaxies oriented at an arbitrary angle to the plane of the sky

We consider the effects of projection, absorption, and velocity dispersion on the shape of the rotation curve for a galaxy as a function of its disk inclination to the plane of the sky. We conclude that for galaxies with a fairly massive compact bulge these effects lead to a marked discrepancy between the rotation curve and the circular velocity curve even if their disks are viewed far from edge-on, especially for the rotation curves constructed from observations of the stellar component.