The Discrepancy in Galaxy Rotation Curves

Version 1

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.

The Effects of Inertial Forces on the Dynamics of Disk Galaxies

Version 2

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 galaxy. Recent observations suggest that the validity of this assumption might be limited: an unexpected coherence between intrinsic galaxy rotation and the motions of neighbor galaxies up to 12 Mpc has been found. Generally speaking, the background of a given galaxy was found to rotate relative to the galaxy's observational frame. Such a rotation, however, is not expected to be measured relative to local inertial frames. Motivated by this discovery, we study the possible non-inertial effects on galactic dynamics. We derive a model for spiral galaxies, that takes into account the influence of fictitious forces. Using the model, a surprising result is revealed:

the "gravitational field" produced by the fictitious forces resembles the gravitational field of a dark halo; that is, the contribution to the rotational velocities is similar in both cases. 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 model reproduces the structures of the rotation curves in the vast majority of the galaxies, providing very good fittings to the data.