Galactic Rotation Velocity Research Articles

Conformal Theory of Gravitation and Cosmic Expansion

The postulate of universal Weyl conformal symmetry for all elementary physical fields introduces nonclassical gravitational effects in both conformal gravitation (CG) and the conformal Higgs model (CHM). The resulting theory is found to explain major observed phenomena, including excessive galactic rotation velocities and accelerating Hubble expansion, without invoking dark matter (DM). The recent history of this development is surveyed here. The argument is confined to implications of classical field theory, which include galactic baryonic Tully–Fisher relationships and dark galactic haloes of a definite large radius. Cosmological CHM parameters exclude a massive Higgs boson but are consistent with a novel alternative particle of the observed mass.

Estimation of the Galactocentric Distance of the Sun from Cepheids Close to the Solar Circle

Based on Cepheids located near the solar circle, we have determined the Galactocentric distance of the Sun R0 and the Galactic rotation velocity at the solar distance V0. For our analysis we used a sample of -200 classical Cepheids from the catalogue by Skowron et al. (2019), where the distances to them were determined from the period–luminosity relation. For these stars the proper motions and line-of-sight velocities were taken from the Gaia DR3 catalogue. The values of R0 found lie within the range 7.8–8.3 kpc, depending on the heliocentric distance of the sample stars, on the adopted solar velocity relative to the local standard of rest, and on whether or not the perturbations caused by the Galactic spiral density wave are taken into account. The dispersion of the R0 estimates is -2 kpc. Similarly, the values of V0 lie within the range 240–270 km s-1 with a dispersion of the estimates of 70–90 km s-1. We consider the following estimates to be the final ones: R0=8,24+0,20 kpc and V0=268+8 km s-1 found by taking into account the perturbations from the Galactic spiral density wave.

Research on the Galaxy Rotation Model based on 21 cm Hydrogen Spectrum

Glon sky survey is a data acquisition method of 21 cm neutral hydrogen spectrum. Recently, the author has conducted a series of studies on the data of the gLon sky survey. After transforming and analyzing the data, the author found that in the region of the center of the Milky Way galaxy, the linear velocity of galactic rotation increases with the distance away from the center. For the region 15 light-years away, the linear velocity of rotation remains almost unchanged. By transforming the variation of velocity with radius into the chart, it can be found that there are deviations in the early galactic rotation structure model. For the newly proposed combined Exponential and Isothermal model, there is a high degree of agreement. The model confirms that there is a huge dark matter halo at the outer edge of the Galaxy. The weak gravitational interaction between dark matter halo and visible matter affects the current rotational structure of the Galaxy.

Galaxy rotation curve measurements with low cost 21 cm radio telescope

Probing the Universe with atomic hydrogen 21 cm emission is a fascinating and challenging work in astronomy. Radio telescopes play a vital role in detecting and imaging these faint signals. Powerful radio telescopes are complex to construct and operate. We have built a simple, low-cost 21 cm radio telescope primarily for educational training purposes. The design uses a custom horn antenna, ready-to-use radio-frequency components, and a software-defined radio module. The telescope operates efficiently from a rooftop in a city environment. Using this telescope, we have conducted observations and successfully detected the 21 cm line emissions from the different directions of our galactic plane. Based on the Doppler-shift observed in these measurements, we have successfully derived the Galactic rotation velocity (rotation curve) in those directions. The paper presents the details of the telescope construction, 21 cm observation, and the Galactic rotation curve derivation.

Galactic Route to the Strong Coupling Constant <i>α</i><sub>s</sub>(<i>m</i><sub>z</sub>) and Its Implication on the Mass Constituents of the Universe

Some fundamental physical quantities need an alternative description. We derive the word average value of interaction coupling constant αs(mz) from the observed maximum galactic rotation velocity by the simple relation , where is the velocity, at which the difference between galactic rotation velocity and Thomas precession is equal, and α is Sommerfeld’s constant. The result is in excellent agreement with the value of αs = 0.1170 ± 0.0019, recently measured and verified via QCE analysis by CERN researchers. One can formulate a reciprocity relation, connecting αs with the circle constant: . It is the merit of Preston Guynn to derive the Milky Way maximum value of the galactic rotation velocity βg, pointing to its “extremely important role in all physics”. The mass (energy) constituents of the Universe follow a golden mean hierarchy and can simply be related to the maximum of Guynn’s difference velocity respectively to αs(mz), therewith excellently confirming Bouchet’s WMAP data analysis. We conclude once more that the golden mean concept is the leading one of nature.

Kinematics of the Galaxy from Young Open Star Clusters with Data from the Gaia EDR3 Catalogue

We have analyzed the kinematics of open star clusters (OSCs) with the proper motions and distances calculated by Hao et al. based on Gaia EDR3 data. The mean line-of-sight velocities are known for a number of clusters from this list. We show that the Galactic rotation parameters determined from samples of OSCs with various ages are in good agreement between themselves. The most interesting results have been obtained from a sample of 967 youngest OSCs with a mean age of 18 Myr. In particular, we have found the following parameters of the angular velocity of Galactic rotation using only their proper motions and distances: $\Omega_0 =28.01\pm0.15$ km s$^{-1}$ kpc$^{-1},$ $\Omega^{'}_0=-3.674\pm0.040$ km s$^{-1}$ kpc$^{-2},$ and $\Omega^{''}_0=0.565\pm0.023$ km s$^{-1}$ kpc$^{-3}$. The circular rotation velocity of the solar neighborhood around the Galactic center here is $V_0=226.9\pm3.1$ km s$^{-1}$ for the adopted Galactocentric distance of the Sun $R_0=8.1\pm0.1$ kpc. The parameters of the spiral density wave have been determined from the space velocities of 233 young clusters. The amplitudes of the radial and tangential velocity perturbations produced by the spiral density wave are $f_R=9.1\pm0.8$ km s$^{-1}$ and $f_\theta=4.6\pm1.2$ km s$^{-1}$, respectively; the perturbation wavelengths are $\lambda_R=3.3\pm0.5$ kpc and $\lambda_\theta=2.6\pm0.6$ kpc for the the adopted four-armed spiral pattern. The Sun's phase in the spiral density wave has been found to be $(\chi_\odot)_R\approx-180^\circ$.

A Review of Inconsistencies and Unfounded Assumptions in Physics Enables A Path Forward

It is widely recognized significant parts of leading-edge physics are at an impasse. Perhaps it is time to re-evaluate long-standing inconsistencies and assumptions that have become dogma but are erroneous and blocking progress. Newtonʼs gravitational constant GN is assumed a natural constant, having originated via Newtonʼs notion of gravity as radial force acting on mass in flat observer space. But Einstein showed gravity due to curved space time with “mass” dimensionally c2 remote from the observer energy domain. Dirac stated (elementary) particles are “no more than electromagnetic energy localized in observer space”. This suggests gravity is emergent at the particle scale by spacetime curved in three dimensions. But Newtonʼs assumed radial force is consistent only with spacetime curvature in the two dimensions orthogonal to the radial, so how can GN be fundamental? Do the different dimensionalities of Newtonʼs and Einsteinʼs theories relate to the Dark Matter issue? Describing the electron as a photon in a relativistic quantum loop localized by curved spacetime enables derivation of an expression for GN giving a value within the empirical uncertainty. The electron is posited as relativistic electromagnetic energy in dynamic equilibrium between circumferential metric tension at the Strong Force scale and radial electrostatic force, satisfying the Planck “Force Equality” premise. As historically long suspected GN contains a numerical factor of c4, derived from the cgs units, in which it was first measured, and a relativistic factor, α-4/3, which move the Planck scale into exact correspondence with the electron parameters. General Relativity is shown a fundamental femto-scale theory where the strong force in a metric curved at the particle scale is manifest in observer space reduced by the classical “Large Number” of 5.7x1044 and is evident as gravity. The expression obtained for GN is supported by deriving the MOND constant and the observed flat galactic star rotation velocity curves. Resolving identified erroneous assumptions and inconsistencies will significantly impact cosmology and particle physics and bring gravitational and electromagnetic unification closer.

Extended galactic rotational velocity profiles in f(R) gravity background

An attempt has been made to explore the geometric effects of f(R) action on the galactic dynamics under the weak field approximation. The rotational velocity is calculated beyond the Einstein’s geometric theory of gravity. It is inspired by the cosmological geometric relation obtained in the power-law f(R) gravity model in vacuum. We analyse the action with a small positive deviation from the Einstein–Hilbert gravity action (taking R as f(R)propto R^{1+delta }) at the galactic scales for the explanation of the flatness paradox associated with the clustered galactic dark matter. We obtain the contribution of a dynamical f(R) cosmological background geometry on accelerating the test mass. Furthermore, the integrated effective acceleration of the test mass due to a massive spherically symmetric source in f(R) background is calculated via the study of geodesics for the suitable spacetime metric and an equation for the effective rotational velocity has been developed. We test the viability of the proposed model by tracing the motion of a test mass far from the disk of galactic matter for smaller delta . The possible galactic rotational velocity curves in f(R) background are discussed for the formula obtained with delta<< 1. We also obtain constraints on delta O(10^{-6}) confirmed by observations.

Study of the Galactic Rotation Based on Masers and Radio Stars with VLBI Measurements of Their Parallaxes

Based on published data, we have produced a sample of 256 radio sources whose trigonometric parallaxes and proper motions were measured by VLBI. This sample contains Galactic masers associated with massive protostars and stars in active star-forming regions. It also includes young low-mass stars from the Gould Belt region whose radio observations were performed in continuum. Based on this, most complete sample of sources to date, we have estimated the velocities $(U,V,W)_\odot$ and the parameters of the angular velocity of Galactic rotation $\Omega_0, \Omega^{(1)}_0, ... , \Omega^{(4)}_0$ and obtained a new estimate of the distance fromthe Sun to the Galactic center, $R_0=8.15^{+0.04}_{-0.20}$ kpc. The parameters of the Galactic spiral density wave have been found from the series of radial, $V_R$, and residual tangential, $\Delta V_{circ}$, velocities of stars. The amplitudes of the radial and tangential velocity perturbations are $f_R=7.0\pm0.9$ km s$^{-1}$ and $f_\theta=3.8\pm1.1$ km s$^{-1}$, the perturbation wavelengths are $\lambda_R=2.3\pm0.2$ kpc and $\lambda_\theta=2.0\pm0.4$ kpc, and the Sun's phases in the spiral density wave are $(\chi_\odot)_R=-163^\circ\pm9^\circ$ and $(\chi_\odot)_\theta=-137^\circ\pm10^\circ$ for the adopted four-armed spiral pattern.

Conformal theory of gravitation and cosmology

The postulate of universal local Weyl scaling (conformal) symmetry modifies both general relativity and the Higgs scalar field model. Conformal gravity (CG) has recently been fitted to rotation data for 138 galaxies. The conformal Higgs model (CHM) acquires a gravitational effect that fits observed Hubble expansion for redshifts (7.33 Gyr) accurately with only one free constant parameter. Conformal theory explains dark energy and does not require dark matter, providing a viable alternative to the ΛCDM standard paradigm. Vanishing of centripetal acceleration outside a galactic halo boundary is a unique implication of the theory. The fit to observed astrophysical data by conformal models CG and CHM is shown here to account for both parameters w2 and λ of postulated Higgs potential , responsible for symmetry-breaking finite in particle theory. Recent criticism of CG is resolved here by showing that CG and CHM are interdependent but compatible. Nonclassical CG radial acceleration parameter γ is determined by the CHM. A recently established empirical relationship between classical and nonclassical galactic radial acceleration requires parameter γ to be independent of galactic mass. Conformal theory is shown here to be consistent with this and with the v4 baryonic Tully-Fisher relation for galactic rotation velocities.

Galactic Rotation Parameters Based on Stars from Active Star-Forming Regions with Data from the Gaia DR2 Catalogue

We have studied a sample of more than 25 000 young stars with proper motions and trigonometric parallaxes from the Gaia DR2 catalogue. The relative errors of their parallaxes do not exceed 10\%. The selection of stars belonging to active star-forming regions was made by Marton et al. based on data from the Gaia DR2 catalogue by invoking infrared measurements from the WISE and Planck catalogues. Low-mass T Tauri stars constitute the majority of sample stars. The following parameters of the angular velocity of Galactic rotation have been found from them: $\Omega_0 =28.40\pm0.11$ km s$^{-1}$ kpc$^{-1}$, $\Omega^{'}_0=-3.933\pm0.033$ km s$^{-1}$ kpc$^{-2}$ and $\Omega^{''}_0=0.804\pm0.040$ km s$^{-1}$ kpc$^{-3}$. The Oort constants are $A=15.73\pm0.32$ km s$^{-1}$ kpc$^{-1}$ and $B=-12.67\pm0.34$ km s$^{-1}$ kpc$^{-1}$, while the circular rotation velocity of the solar neighborhood around the Galactic center is $V_0=227\pm4$ km s$^{-1}$ for the adopted Galactocentric distance of the Sun $R_0=8.0\pm0.15$ kpc.

High-velocity runaway binaries from supernovae in triple systems

Recent studies on hypervelocity stars (HVSs) have generated a need to understand the high velocity limits of binary systems. If runaway binary systems with high movement speeds well in excess of 200km/s were to exist, it would have implications on how HVS candidates are selected, and our current understanding of how they form needs to be reinforced. In this paper, we explore the possibility that such high velocity runaway binaries (HVRBs) can be engendered by supernova explosions of the tertiary in close hierarchical triple systems. We find that such explosions can lead to significant remnant binary velocities, and demonstrate via constraining the velocity distribution of such HVRBs that this mechanism can lead to binaries with centre of mass velocities of 350 km/s or more, relative to the original centre of mass of the progenitor triple system. This translates into potential observations of binaries with velocities high enough to escape the Galaxy, once the Galactic rotational velocity and objects of Large Magellanic Cloud origins are considered.

Kinematics of the Galaxy from a Sample of Young Open Star Clusters with Data from the Gaia DR2 Catalogue

We have selected a sample of 326 young $(\log t<8)$ open star clusters with the proper motions and distances calculated by various authors from Gaia DR2 data. The mean values of their line-of-sight velocities have also been taken from various publications. As a result of our kinematic analysis, we have found the following parameters of the angular velocity of Galactic rotation: $\Omega_0=29.34\pm0.31$ km s$^{-1}$ kpc$^{-1}$, $\Omega'_0=-4.012\pm0.074$ km s$^{-1}$ kpc$^{-2}$, and $\Omega''_0=0.779\pm0.062$ km s$^{-1}$ kpc$^{-3}$. The circular rotation velocity of the solar neighborhood around the Galactic center is $V_0=235\pm5$ km s$^{-1}$ for the adopted Galactocentric distance of the Sun $R_0=8.0\pm0.15$ kpc. The amplitudes of the tangential and radial velocity perturbations produced by the spiral density wave are $f_\theta=3.8\pm1.2$ km s$^{-1}$ and $f_R=4.7\pm1.0$ km s$^{-1}$, respectively; the perturbation wavelengths are $\lambda_\theta=2.3\pm0.5$ kpc and $\lambda_R=2.2\pm0.5$ kpc for the adopted four-armed spiral pattern. The Sun's phase in the spiral density wave is close to $-120\pm10^\circ.$

Dark energy density predicted and explained

It has recently been shown that the observed Hubble function for cosmological expansion can be fitted accurately back to redshift unity (7.33 Gyr ago) with only one free constant, while neglecting cosmic curvature and mass density, using the modified Friedmann equation implied by subjecting the Higgs scalar field model to conformal Weyl scaling symmetry. It is shown here that the implied dark energy parameter is produced by dressing the bare scalar field by the neutral gauge boson field induced by weak cosmological time dependence of the conformal Higgs model. Predicted persistent cosmic acceleration is consistent with the nonclassical acceleration parameter inferred by conformal theory from observed excessive galactic rotation velocities and dark galactic halos, all without dark matter.

Median statistics estimate of the galactic rotational velocity

We compile a complete collection of 19 recent (since 2000) measurements of $\Theta_0$, the rotational velocity of the Milky Way at $R_0$ (the radial distance of the Sun from the Galactic center). These measurements use tracers that are believed to more accurately reflect the systematic rotation of the Milky Way. Unlike other recent compilations of $\Theta_0$, our collection includes only independent measurements. We find that these 19 measurements are distributed in a mildly non-Gaussian fashion and a median statistics estimate indicates $\Theta_0 = 220\ \pm 10$ km\,s$^{-1}$ (2$\sigma$ error) as the most reliable summary, at $R_0 = 8.0 \pm 0.3$ kpc (2$\sigma$ error).

Applications of a Particular Four-Dimensional Projective Geometry to Galactic Dynamics

Relativistic localizing systems that extend relativistic positioning systems show that pseudo-Riemannian space-time geometry is somehow encompassed in a particular four-dimensional projective geometry. The resulting geometric structure is then that of a generalized Cartan space (also called Cartan connection space) with projective connection. The result is that locally non-linear actions of projective groups via homographies systematically induce the existence of a particular space-time foliation independent of any space-time dynamics or solutions of Einstein’s equations for example. In this article, we present the consequences of these projective group actions and this foliation. In particular, it is shown that the particular geometric structure due to this foliation is similar from a certain point of view to that of a black hole but not necessarily based on the existence of singularities. We also present a modified Newton’s laws invariant with respect to the homographic transformations induced by this projective geometry. Consequences on galactic dynamics are discussed and fits of galactic rotational velocity curves based on these modifications which are independent of any Modified Newtonian Dynamics (MOND) or dark matter theories are presented.

Kinematics of Stars from the TGAS (Gaia DR1) Catalogue

Based on the stellar proper motions of the TGAS (Gaia DR1) catalogue, we have analyzed the velocity field of main-sequence stars and red giants from the TGAS catalogue with heliocentric distances up to 1.5 kpc. We have obtained four variants of kinematic parameters corresponding to different methods of calculating the distances from the parallaxes of stars measured with large relative errors. We have established that within the Ogorodnikov–Milne model changing the variant of distances affects significantly only the solar velocity components relative to the chosen centroid of stars, provided that the solution is obtained in narrow ranges of distances (0.1 kpc). The estimates of all the remaining kinematic parameters change little. This allows the Oort coefficients and related Galactic rotation parameters as well as all the remaining Ogorodnikov–Milne model parameters (except for the solar terms) to be reliably estimated irrespective of the parallax measurement accuracy. The main results obtained from main-sequence stars in the range of distances from 0.1 to 1.5 kpc are: A = 16.29 ± 0.06 km s−1 kpc−1, B = −11.90 ± 0.05 km s−1 kpc−1, C = −2.99 ± 0.06 km s−1 kpc−1, K = −4.04 ± 0.16 km s−1 kpc−1, and the Galactic rotation period P = 217.41 ± 0.60 Myr. The analogous results obtained from red giants in the range from 0.2 to 1.6 kpc are: the Oort constants A = 13.32 ± 0.09 km s−1 kpc−1, B = −12.71 ± 0.06 km s−1 kpc−1, C = −2.04 ± 0.08 km s−1 kpc−1, K = −2.72 ± 0.19 km s−1 kpc−1, and the Galactic rotation period P = 236.03 ± 0.98 Myr. The Galactic rotation velocity gradient along the radius vector (the slope of the Galactic rotation curve) is −4.32 ± 0.08 km s−1 kpc−1 for main-sequence stars and −0.61 ± 0.11 km s−1 kpc−1 for red giants. This suggests that the Galactic rotation velocity determined from main-sequence stars decreases with increasing distance from the Galactic center faster than it does for red giants.

Many-Body-Gravitational Solutions for Galactic Rotational Velocities, Including Possible Negative Mass

The necessary derivation of negative mass in dispersion dynamics suggests cosmic applications. The method analyzes functional relationships between particle angular frequency, wave vector, rest mass and electromagnetic or nuclear potential, f(ω, k, m0, V) = 0. A summary of consequential predictions of the dynamics leads to a calculation of ways in which negative mass might influence such phenomena as the rotational velocities that are observed in spiral galaxies. The velocities are found to be not Newtonian in the simple two body approximations for our solar system; but nearly constant with increasing orbital radii. It has moreover been suggested that the motion is due to halo structures of dark matter or dark energy. However, the motion is simply described by many-body gravitation that is transmitted along elastic spiral arms. In this context, we calculate possible effects of negative mass, but without observational confirmation.

How to Reconcile the Observed Velocity Function of Galaxies with Theory

Abstract Within a Λ cold dark matter (ΛCDM) scenario, we use high-resolution cosmological simulations spanning over four orders of magnitude in galaxy mass to understand the deficit of dwarf galaxies in observed velocity functions (VFs). We measure velocities in as similar a way as possible to observations, including generating mock H i data cubes for our simulated galaxies. We demonstrate that this apples-to-apples comparison yields an “observed” VF in agreement with observations, reconciling the large number of low-mass halos expected in a ΛCDM cosmological model with the low number of observed dwarfs at a given velocity. We then explore the source of the discrepancy between observations and theory and conclude that the dearth of observed dwarf galaxies is primarily explained by two effects. The first effect is that galactic rotational velocities derived from the H i linewidth severely underestimate the maximum halo velocity. The second effect is that a large fraction of halos at the lowest masses are too faint to be detected by current galaxy surveys. We find that cored DM density profiles can contribute to the lower observed velocity of galaxies but only for galaxies in which the velocity is measured interior to the size of the core (∼3 kpc).

Properties of the Tycho-2 catalogue from Gaia data release

Based on the measurements performed in the first 14 months of Gaia operation, we have solved the problem of obtaining the systematic differences between the stellar positions and proper motions of the TGAS (Tycho–Gaia Astrometric Solution) and Tycho-2 catalogues. By dividing the common stars from the TGAS and Tycho-2 catalogues into three G-magnitude groups for mean values of $$10\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\cdot}$}}{m} 5,11\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\cdot}$}}{m} 5,and13\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\cdot}$}}{m} 0,$$ we have obtained the systematic differences between the stellar equatorial coordinates and proper motions of both catalogues in the form of a decomposition into vector spherical harmonics by taking into account the magnitude equation. The systematic components have been extracted from the individual differences with a probability of 0.977–0.999. The constructed model of systematic differences allows any position measurements performed using Tycho-2 as a reference catalogue to be transformed to the TGAS frame. An important fact is the existence of a magnitude equation in the systematic differences: when passing from bright (G = 10 m ) to faint (G = 13 m ) stars, the systematic position differences change within the range from approximately −40 to 15 mas, while the systematic proper motion differences change from −3 to 3 mas yr−1. The orientation and mutual rotation parameters of the Tycho-2 and TGAS frames have also been found to be different for stars of different magnitudes: when passing from bright to faint stars, the rotation angle of the Tycho-2 frame relative to TGAS changes from 3.51 to 5.63 mas, while the angular velocity of rotation changes from 0.35 to 1.22 mas yr−1. Based on the developed method that allows the extent to which the systematic errors in the equatorial propermotions of stars affect the results of a kinematic analysis of the Galactic proper motions to be estimated within the Ogorodnikov–Milne model, we have shown that the slope of the Galactic rotation curve and the Oort parameter C are most sensitive to the transition from the Tycho-2 frame to the TGAS one. Their relative changes after the transformation to the TGAS frame reach 56 and 100%, respectively. At the same time, the changes in the estimates of the Oort parameters A and B as well as the linear velocity of the Sun relative to the Galactic center, the Galactic rotation period, the ratio of the epicyclic frequency to the angular velocity of Galactic rotation, and the mass of the Galaxy within the Galactocentric distance of the Sun are not so large, being 2−10%.