scholarly journals The Effects of Inertial Forces on the Dynamics of Disk Galaxies

2021 ◽  
Author(s):  
Tomer Zimmerman ◽  
Roy Gomel
Keyword(s):  
Basic Assumption ◽  
Large Range ◽  
Galactic Rotation ◽  
Disk Galaxies ◽  
Dark Halo ◽  
Inertial Forces ◽  
Inertial Effects ◽  
Rotation Curves ◽  
New Model ◽  
Galaxy Rotation Curves

When dealing with galactic dynamics, or more specifically, with galactic rotation curves, one basic assumption is always taken: the frame of reference relative to which the rotational velocities are given is assumed to be inertial. In other words, fictitious forces are assumed to vanish relative to the observational frame of a given galaxy. It might be interesting, however, to explore the outcomes of dropping that assumption; that is, to search for signatures of non-inertial behavior in the observed data. In this work, we show that the very discrepancy in galaxy rotation curves could be attributed to non-inertial effects. We derive a model for spiral galaxies that takes into account the possible influence of fictitious forces and find that the additional terms in the new model, due to fictitious forces, closely resemble dark halo profiles. Following this result, we apply the new model to a wide sample of galaxies, spanning a large range of luminosities and radii. It turns out that the new model accurately reproduces the structures of the rotation curves and provides very good fittings to the data.

scholarly journals The Effects of Inertial Forces on the Dynamics of Disk Galaxies

2020 ◽  
Author(s):  
Tomer Zimmerman ◽  
Roy Gomel
Keyword(s):  
Basic Assumption ◽  
Large Range ◽  
Galactic Rotation ◽  
Disk Galaxies ◽  
Dark Halo ◽  
Inertial Forces ◽  
Inertial Effects ◽  
Rotation Curves ◽  
New Model ◽  
Galaxy Rotation Curves

When dealing with galactic dynamics, or more specifically, with galactic rotation curves, one basic assumption is always taken: the frame of reference relative to which the rotational velocities are given is assumed to be inertial. In other words, fictitious forces are assumed to vanish relative to the observational frame of a given galaxy. It might be interesting, however, to explore the outcomes of dropping that assumption; that is, to search for signatures of non-inertial behavior in the observed data. In this work, we show that the very discrepancy in galaxy rotation curves could be attributed to non-inertial effects. We derive a model for spiral galaxies that takes into account the possible influence of fictitious forces and find that the additional terms in the new model, due to fictitious forces, closely resemble dark halo profiles. Following this result, we apply the new model to a wide sample of galaxies, spanning a large range of luminosities and radii. It turns out that the new model accurately reproduces the structures of the rotation curves and provides very good fittings to the data.

scholarly journals The Effects of Inertial Forces on the Dynamics of Disk Galaxies

Galaxies ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 34
Author(s):  
Roy Gomel ◽  
Tomer Zimmerman
Keyword(s):  
Basic Assumption ◽  
Large Range ◽  
Galactic Rotation ◽  
Disk Galaxies ◽  
Dark Halo ◽  
Inertial Forces ◽  
Inertial Effects ◽  
Rotation Curves ◽  
New Model ◽  
Galaxy Rotation Curves

When dealing with galactic dynamics, or more specifically, with galactic rotation curves, one basic assumption is always taken: the frame of reference relative to which the rotational velocities are given is assumed to be inertial. In other words, fictitious forces are assumed to vanish relative to the observational frame of a given galaxy. It might be interesting, however, to explore the outcomes of dropping that assumption; that is, to search for signatures of non-inertial behavior in the observed data. In this work, we show that the very discrepancy in galaxy rotation curves could be attributed to non-inertial effects. We derive a model for spiral galaxies that takes into account the possible influence of fictitious forces and find that the additional terms in the new model, due to fictitious forces, closely resemble dark halo profiles. Following this result, we apply the new model to a wide sample of galaxies, spanning a large range of luminosities and radii. It turns out that the new model accurately reproduces the structures of the rotation curves and provides very good fittings to the data.

scholarly journals On galaxy rotation curves from a continuum mechanics approach to modified gravity

2018 ◽  
Vol 27 (02) ◽  
pp. 1850007 ◽  
Author(s):  
Christian G. Böhmer ◽  
Nicola Tamanini ◽  
Matthew Wright
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
Continuum Mechanics ◽  
Modified Gravity ◽  
Galactic Rotation ◽  
Dark Matter Halos ◽  
Additional Structure ◽  
Rotation Curves ◽  
Small Deviations ◽  
Galaxy Rotation Curves

We consider a modification of General Relativity motivated by the treatment of anisotropies in Continuum Mechanics. The Newtonian limit of the theory is formulated and applied to galactic rotation curves. By assuming that the additional structure of spacetime behaves like a Newtonian gravitational potential for small deviations from isotropy, we are able to recover the Navarro–Frenk–White profile of dark matter halos by a suitable identification of constants. We consider the Burkert profile in the context of our model and also discuss rotation curves more generally.

Parameters for Dark Halos

1987 ◽  
Vol 117 ◽  
pp. 119-132 ◽  
Author(s):  
K. C. Freeman
Keyword(s):  
Elliptical Galaxies ◽  
Disk Galaxies ◽  
Dark Halo ◽  
Characteristic Scale ◽  
Rotation Curves ◽  
X Ray ◽  
Unique Information ◽  
Best Estimates

What are the characteristic scale lengths and densities for the dark halos of galaxies, and the typical ratios of dark to luminous mass? For elliptical galaxies, the best estimates come from X-ray data which will be discussed in a later session. For spirals, the best estimates come from rotation curves. I will concentrate on the halo parameters for disk galaxies. At the end, there will be a few comments on stellar dynamical data for ellipticals, and on the unique information available for the dark halo of our Galaxy.

scholarly journals The Discrepancy in Galaxy Rotation Curves

2019 ◽  
Author(s):  
Roy Gomel ◽  
Tomer Zimmerman
Keyword(s):  
Rotation Curve ◽  
Laws Of Nature ◽  
Not Given ◽  
Rotation Curves ◽  
New Approach ◽  
New Model ◽  
Robust Model ◽  
Inertial Frames ◽  
Theoretical Predictions ◽  
Galaxy Rotation Curves

In this work we try a new approach for dealing with the discrepancy between observed galaxy rotation curves and theoretical predictions. This new approach does not involve any changes in the current fundamental laws of nature or the addition of dark halos. Rather, it is based on the following single assumption: the observed velocities presented in rotation curves are not given relative to the galaxies' local inertial frames. Another way of putting it down: fictitious forces, which arise in non-inertial frames, should be taken into account when constructing a theoretical rotation curve. It turns out that this single assumption is sufficient in order to establish a robust model for fitting rotation curves. Applying the new model on a sample of more than 30 galaxies provides very promising results.

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.

scholarly journals Galaxy Rotation Curves in Covariant Hořava-Lifshitz Gravity

Galaxies ◽  
2013 ◽  
Vol 2 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Jean Alexandre ◽  
Martyna Kostacinska
Keyword(s):  
Rotation Curves ◽  
Galaxy Rotation Curves

scholarly journals MODIFIED GRAVITY AS A COMMON CAUSE FOR COSMIC ACCELERATION AND FLAT GALAXY ROTATION CURVES

2012 ◽  
Vol 21 (11) ◽  
pp. 1242002 ◽  
Author(s):  
PRITI MISHRA ◽  
TEJINDER P. SINGH
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Cosmic Acceleration ◽  
Accelerating Universe ◽  
Rotation Curves ◽  
Common Cause ◽  
Order Of Magnitude ◽  
Flat Rotation Curves ◽  
Acceleration Of The Universe ◽  
Galaxy Rotation Curves

Flat galaxy rotation curves and the accelerating Universe both imply the existence of a critical acceleration, which is of the same order of magnitude in both the cases, in spite of the galactic and cosmic length scales being vastly different. Yet, it is customary to explain galactic acceleration by invoking gravitationally bound dark matter, and cosmic acceleration by invoking a "repulsive" dark energy. Instead, might it not be the case that the flatness of rotation curves and the acceleration of the Universe have a common cause? In this essay we propose a modified theory of gravity. By applying the theory on galactic scales we demonstrate flat rotation curves without dark matter, and by applying it on cosmological scales we demonstrate cosmic acceleration without dark energy.

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