scholarly journals Halo acceleration relation

2019 ◽  
Vol 488 (1) ◽  
pp. L41-L46 ◽  
Author(s):  
Yong Tian (田雍) ◽  
Chung-Ming Ko (高仲明)
Keyword(s):  
Dark Matter ◽  
Spiral Galaxies ◽  
Rotation Curves ◽  
Radial Acceleration ◽  
Modified Newtonian Dynamics ◽  
Newtonian Dynamics ◽  
Total Acceleration

ABSTRACT Recently, from the new Spitzer Photometry and Accurate Rotation Curves data, McGaugh, Lelli & Schombert reported a tight radial acceleration relation between the observed total acceleration and the acceleration produced by baryons in spiral galaxies. The relation can be fitted by different functions. However, these functions can be discerned if we express the data in the form of a halo acceleration relation. The data reveals a maximum in the halo acceleration. We examined the NFW (cusp) and Burkert (core) profiles in the context of dark matter and different parameter families of the interpolating function in the framework of modified Newtonian dynamics.

scholarly journals Newtonian and modified newtonian gravitational simulation of spiral galaxies

2019 ◽  
Vol 11 (21) ◽  
pp. 20-27
Author(s):  
Bushra A. Ahmed
Keyword(s):  
Dark Matter ◽  
Rotation Curve ◽  
Spiral Galaxies ◽  
Stellar Dynamics ◽  
Gravitational Attraction ◽  
Rotation Curves ◽  
Modified Newtonian Dynamics ◽  
Newtonian Dynamics ◽  
Rotational Curve ◽  
Good Agreement

One of the most powerful tools for any stellar dynamics is the N-body simulation. In an N-body simulation the motion of N particles is followed under their mutual gravitational attraction. In this paper the gravitational N-body simulation is described to investigate Newtonian and non- Newtonian (modified Newtonian dynamics) interaction between the stars of spiral galaxies. It is shown that standard Newtonian interaction requires dark matter to produce the flat rotational curves of the systems under consideration, while modified Newtonian dynamics (MOND) theorem provides a flat rotational curve and gives a good agreement with the observed rotation curve; MOND was tested as an alternative to the dark matter hypothesis. So that MOND hypothesis has generated better rotation curves than Newtonian theorem.

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.

Modified Newtonian Dynamics Rotation Curves of Very Low Mass Spiral Galaxies

2007 ◽  
Vol 658 (1) ◽  
pp. L17-L20 ◽  
Author(s):  
Mordehai Milgrom ◽  
Robert H. Sanders
Keyword(s):  
Spiral Galaxies ◽  
Rotation Curves ◽  
Modified Newtonian Dynamics ◽  
Newtonian Dynamics ◽  
Low Mass

scholarly journals A method for discriminating between dark matter models and MOND modified inertia via galactic rotation curves

2020 ◽  
Vol 496 (2) ◽  
pp. 1077-1091
Author(s):  
Jonas Petersen ◽  
Mads T Frandsen
Keyword(s):  
Dark Matter ◽  
Galactic Centre ◽  
Galactic Rotation ◽  
Baryonic Matter ◽  
Rotation Curves ◽  
Density Profiles ◽  
Closed Curves ◽  
Modified Newtonian Dynamics ◽  
Newtonian Dynamics ◽  
Systematic Uncertainties

ABSTRACT Dark matter (DM) and modified Newtonian dynamics (MOND) models of rotationally supported galaxies lead to curves with different geometries in (gN, gtot)-space (g2-space). Here, gtot is the total acceleration and gN is the acceleration as obtained from the baryonic matter via Newtonian dynamics. In MOND modified inertia (MI) models, the curves in g2-space are closed with zero area and so curve segments at radii r ≥ rN (large radii) and r < rN (small radii) coincide, where rN is the radius where gN is greatest. In DM models with cored density profiles where gtot is also zero at the Galactic Centre, the curves are again closed, but the area of the closed curves are in general non-zero because the curve segments at radii r ≥ rN and r < rN do not coincide. Finally in DM models with cuspy density profiles such as the NFW profile where gtot is formally non-zero at the galactic origin the curves are open, and again the curve segments at radii r ≥ rN and r < rN do not coincide. We develop a test of whether data at small and large radii coincide and investigate rotation curves from the SPARC data base in order to discriminate between the above geometries. Due to loosely quantified systematic uncertainties, we do not underline the result of the test, but instead conclude that the test illustrates the relevance of this type of analysis and demonstrate the ability to discriminate between the considered DM and MI models in this way.

scholarly journals Modified Newtonian Dynamics: A Falsification of Cold Dark Matter

2009 ◽  
Vol 2009 ◽  
pp. 1-9 ◽  
Author(s):  
R. H. Sanders
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Spiral Galaxies ◽  
Elliptical Galaxies ◽  
Additional Parameter ◽  
Baryonic Matter ◽  
Critical Acceleration ◽  
Modified Newtonian Dynamics ◽  
Newtonian Dynamics ◽  
Astronomical Object

The only viable alternative to dark matter is one in which Newtonian dynamics or gravity breaks down in the limit of low accelerations, as in modified Newtonian dynamics (MONDs). This hypothesis, suggested by Milgrom, has been successful in explaining systematic properties of spiral and elliptical galaxies and predicting in detail the observed rotation curves of spiral galaxies with only one additional parameter—a critical acceleration which is on the order of the cosmologically interesting value of . MOND may be viewed as an algorithm for calculating the distribution of force in an astronomical object from the observed distribution of baryonic matter. The fact that it works very well on the scale of galaxies is problematic for cold dark matter (CDM). Here I present evidence in favor of this assertion and claim that this is, in effect, a falsification of CDM on the scale of galaxies.

An alternative classical force of gravitation in order to explain the velocity curve of spiral galaxies

2015 ◽  
Vol 24 (05) ◽  
pp. 1550036 ◽  
Author(s):  
E. Guiot
Keyword(s):  
Dark Matter ◽  
Observational Data ◽  
Rotation Curve ◽  
Spiral Galaxies ◽  
Tangential Component ◽  
Velocity Curve ◽  
Classical Physics ◽  
Modified Newtonian Dynamics ◽  
Newtonian Dynamics

The purpose of this work is to investigate an alternative to modified Newtonian dynamics (MOND), in order to explain the rotation curve of galaxies without dark matter hypothesis, and with respect for classical physics. Our hypothesis is that the force of gravitation, in the case of large distances and under certain conditions, possesses a tangential component. We show that the force of gravitation we obtain is compatible with observational data, such as "flat" curve of rotation and the conic trajectories of the stars.

Missing Mass as Evidence for Modified Newtonian Dynamics at Low Accelerations

2003 ◽  
Vol 18 (27) ◽  
pp. 1861-1875 ◽  
Author(s):  
R. H. Sanders
Keyword(s):  
Structure Formation ◽  
Spiral Galaxies ◽  
Elliptical Galaxies ◽  
Additional Parameter ◽  
Rotation Curves ◽  
Dynamical Mass ◽  
Missing Mass ◽  
Critical Acceleration ◽  
Modified Newtonian Dynamics ◽  
Newtonian Dynamics

Milgrom has proposed that the appearance of discrepancies between the Newtonian dynamical mass and the directly observable mass in astronomical systems could be due to a breakdown of Newtonian dynamics in the limit of low accelerations rather than the presence of unseen matter. Milgrom's hypothesis, modified Newtonian dynamics or MOND, has been remarkably successful in explaining systematic properties of spiral and elliptical galaxies and predicting in detail the observed rotation curves of spiral galaxies with only one additional parameter — a critical acceleration which is on the order of the cosmologically interesting value of cH0. Here we review the empirical successes of this idea and discuss its possible extension to cosmology and structure formation.

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

2020 ◽  
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. The UEG theory may similarly be extended to emulate the hypothetical dark matter in galaxy clusters as well as in cosmology.

scholarly journals A fundamental test for MOND

2020 ◽  
Vol 494 (2) ◽  
pp. 2875-2885 ◽  
Author(s):  
Valerio Marra ◽  
Davi C Rodrigues ◽  
Álefe O F de Almeida
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Basic Assumption ◽  
Robust Method ◽  
Rotation Curves ◽  
Radial Acceleration ◽  
Modified Newtonian Dynamics ◽  
Newtonian Dynamics ◽  
Credible Intervals ◽  
Galaxy Rotation Curves

ABSTRACT The radial acceleration relation (RAR) shows a strong correlation between two accelerations associated with galaxy rotation curves. The relation between these accelerations is given by a non-linear function that depends on an acceleration scale a†. Some have interpreted this as an evidence for a gravity model, such as modified Newtonian dynamics (MOND), which posits a fundamental acceleration scale a0 common to all the galaxies. However, it was later shown, using Bayesian inference, that this seems not to be the case: the a0 credible intervals for individual galaxies were not found to be compatible among themselves. A test like the latter is a fundamental test for MOND as a theory for gravity, since it directly evaluates its basic assumption and this using the data that most favour MOND: galaxy rotation curves. Here we improve upon the previous analyses by introducing a more robust method to assess the compatibility between the credible intervals, in particular without Gaussian approximations. We directly estimate, using a Monte Carlo simulation, that the existence of a fundamental acceleration is incompatible with the data at more than 5σ. We also consider quality cuts in order to show that our results are robust against outliers. In conclusion, the new analysis further supports the claim that the acceleration scale found in the RAR is an emergent quantity.

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