Fitting galactic rotation curves with conformal gravity and a global quadratic potential

Abstract

We apply the conformal gravity theory to a sample of 111 spiral galaxies whose rotation curve data points extend well beyond the optical disk. With no free parameters other than galactic mass to light ratios, the theory is able to account for the systematics that is observed in this entire set of rotation curves without the need for any dark matter at all. In previous applications of the theory a central role was played by a universal linear potential term V (r) = γ 0 c 2 r/2 that is generated through the effect of cosmology on individual galaxies, with the coefficient γ 0 = 3.06 × 10 −30 cm −1 being of cosmological magnitude. Because the current sample is so big and encompasses some specific galaxies whose data points go out to quite substantial distances from galactic centers, we are able to identify an additional globally induced universal term in the data, a quadratic V (r) = −κc 2 r 2 /2 term that is induced by inhomogeneities in the cosmic background. With κ being found to be of magnitude κ = 9.54 × 10 −54 cm −2 , through study of the motions of particles contained within galaxies we are thus able to both detect the presence of a global de Sitter-like component and provide a specific value for its strength. Our study suggests that invoking dark matter may be nothing more than an attempt to describe global physics effects such as these in purely local galactic terms.

The variation of rotation curve shapes as a signature of the effects of baryons on dark matter density profiles

“…We compiled 110 observed galaxies (de Blok & Bosma 2002;Swaters et al 2003;de Blok et al 2004;Kuzio de Naray et al 2008;de Blok et al 2008;Swaters et al 2009;Oh et al 2011;Mannheim & O'Brien 2012;Oh et al 2015, and references therein) with Vmax<150kms −1 that have rotation curves that allow us to compare Vrot(1kpc) with Vmax.…”

Conformal Gravity Solutions to Standard Gravity Problems

“…) last seems to be of order one, for now over 200 galaxies [3][4][5][6] fit by the theory. This universality found in the last data point of each galaxies centripetal acceleration (scaled here to 1 c 2 ) provides argument for the recent work of McGaugh 7 et al, and this phenomena will be explored in more detail below.…”

“…In recent years, Mannheim and O'Brien have shown that conformal gravity can be used to accurately describe the rotation curves of a diverse set of galaxies without the need to invoke dark matter. [3][4][5][6] Since all attempts to find any direct evidence of dark matter have been unsuccessful so far, alternative theories of gravity have become increasingly worth considering as an explanation for phenomena ascribed to dark matter. Its success in fitting galactic rotations makes conformal gravity an ideal candidate to explore in an effort to theoretically describe these additional effects.…”

“…While the rotation curve fitting provides direct data that can be tested against the predictions of an alternative model of gravity, there are other observational motivations for the existence of dark matter, such as the motion of galaxies in clusters and gravitational lensing. The goal of this paper is to summarize some recent conformal gravity fits to rotation [3][4][5][6] curves, to show how conformal gravity can address the cluster motion problem without invoking dark matter, and develop the initial framework for gravitational lensing formalism in conformal gravity. Since the actual IWARA meeting, recent work was published in Physical Review Letters 7 (PRL), which generalizes rotation curve data to instead encapsulate what appears to be universality in the centripetal accelerations of the rotation curve data.…”

Spectral action with zeta function regularization

“…It would be fascinating to put a full-fledged quantization of gravity in this scheme, and even if this is still far in the future, we note that possible stating points could be conformal gravity, especially in the Bender-Mannhiem formalism [47][48][49], which leads to unitary and renormalizable theory of gravity [50] and has interesting astrophysical consequences [51,52]. Interesting connections between conformal and Einstein gravities are discussed in Ref.…”