Testing modified gravity at large distances with the HI Nearby Galaxy Survey’s rotation curves

Recently a new—quantum motivated—theory of gravity has been proposed that modifies the standard Newtonian potential at large distances when spherical symmetry is considered. Accordingly, Newtonian gravity is altered by adding an extra Rindler acceleration term that has to be phenomenologically determined. Here we consider a standard and a power-law generalization of the Rindler modified Newtonian potential. The new terms in the gravitational potential are hypothesized to play the role of dark matter in galaxies. Our galactic model includes the mass of the integrated gas, and stars for which we consider three stellar mass functions (Kroupa, diet-Salpeter, and free mass model). We test this idea by fitting rotation curves of seventeen low surface brightness galaxies from the HI Nearby Galaxy Survey (THINGS). We find that the Rindler parameters do not perform a suitable fit to the rotation curves in comparison to standard dark matter profiles (Navarro-Frenk-White and Burkert) and, in addition, the computed parameters of the Rindler gravity show a high spread, posing the model as a nonacceptable alternative to dark matter.

Figure 1

2D likelihood contours between the $a$ and $n$, corresponding to $1\sigma$ and $2\sigma$, for the Kroupa IMF model.

Figure 2

2D likelihood contours between the $a$ and $n$, corresponding to $1\sigma$ and $2\sigma$, for the diet-Salpeter IMF model.

Figure 3

2D likelihood contours between the $a$ and $n$, corresponding to $1\sigma$ and $2\sigma$, for the free mass model.

Figure 4

Rotation curve for the galaxies (a) N 2841, (b) N 3621, and (c) N 6946. We explicitly plot the contribution of the gas (dotted, black), the Kroupa star model (dashed, black), the red/green plots are the NFW/Burkert DM halo profile and its total contribution (dashed and thick lines, respectively), and finally the blue line is the total rotation curve of the standard ($n=1$) Rindler acceleration model.