Why should baryons define where the dark matter is? Another dark matter problem

A research paper1 recently accepted for publication in Physical Review Letters titled “The radial acceleration relation in rotationally supported galaxies”2 highlights a discovery that is bad news for dark matter. It certainly does not strengthen the case for halo dark matter around spiral galaxies.

The research team, McGaugh et al, took data for 153 spiral disk galaxies from the Spitzer Photometry and Accurate Rotation Curves (SPARC) database that represents spiral galaxies of all types and morphologies, from very bright to very low surface brightness disks. It included representative spiral galaxies that would be assumed to contain a very high fraction of dark matter at very low orbital accelerations to those with very little dark matter at high orbital accelerations. These galaxies are all assumed to be rotationally supported, which means their disks are assumed to be gravitationally bound by the included matter inside any radial distance (R) from the centre of the galaxy. The speeds of the stars and gases (V) as a function of their measured radial distance (R) determines what is known as a rotation curve V(R). See Fig. 1.

In this paper the observed acceleration, gobs, at each radial distance R from the centre of the chosen galaxies, was calculated from the measured values of V(R) and R for each galaxy, totalling 2693 data points over the 153 galaxies. Also using infrared data the mass density was accurately measured at these same radial points, which permitted, via the Poisson equation, a direct calculation of the expected acceleration, gbar, due to the baryonic matter (protons and neutrons, i.e. normal matter) content within the same galaxies. No free fit parameters were used in these estimations, except a single fixed Mass-to-Light ratio of 0.5 was used across all galaxies.


Figure 1: Examples of mass models and rotation curves for individual galaxies. The points with error bars in the upper panels are the observed rotation curves V (R). The errors represent both random errors and systematic uncertainty in the circular velocity due to asymmetry in the velocity field. Each baryonic component is represented: dotted lines for the gas, dashed lines for the stellar disk, and dash-dotted lines for the bulge, when present. The sum of these components is the baryonic mass model (solid line). The lower panels illustrate the run of gbar and gobs for each galaxy, with the dashed line being the line of unity. Note that higher accelerations occur at smaller radii. From left to right each line is replotted in gray to illustrate how progressively fainter galaxies probe progressively lower regimes of acceleration.

Assuming standard Newtonian (or Keplerian) physics the acceleration due to the baryonic matter, gbar, is all we should need to correctly calculate the rotation curve of any galaxy. See Fig. 1 (which reproduces their Fig. 2). Some representative rotation curves are shown by the upper-most black circles with error bars. Quite obviously the solid blue lines—the expect rotation velocities due to the observed baryonic matter—do not follow the observed rotation curves, but fall well below, in most galaxies. This is the reason halo dark matter is invoked. See Fig. 2. Continue reading

Dark energy and the elusive chameleon—more darkness from the dark side

If you thought Dark Matter was strange enough—the new ‘god of the gaps’ in cosmology—the ‘unknown god’ used to force the ‘square peg’ of observational evidence into the ‘round hole’ of the standard big bang theory, then I say you have good reason to think again.

Dark energy is even stranger still. It is allegedly some form of ‘anti-gravity’ energy forcing the Universe apart at an ever faster rate as the Universe gets older. It has arisen from the need to fit theory to observational data that purportedly gives the distance to very distant galaxies as a function of their redshifts.1 Those redshifts are believed to mean that the Universe is expanding, a claim I believe there is sufficient reason to doubt.2-5


Figure 1: Type Ia supernova 1994D in Galaxy NGC 4526 (bottom left bright spot) Credit: NASA/ESA, The Hubble Key Project Team and The High-Z Supernova Search Team

However when two independent teams of astronomers used the Type Ia supernovae as a means of determining the distances of galaxies independently of their redshifts, they both discovered the same thing, that you had to add something else—Dark Energy—to make the big bang theory fit the observational data. I have previously pointed out the implicit circular reasoning in their methods, that is, assume the cosmology you want to prove, use that to select the supernovae you will use in your analysis, then use those supernovae to test your cosmology.4

Dark Energy, I say is just another fudge factor, because the theory is wrong and should have been rejected a long time ago. You might ask, what evidence do I have for such a claim? The actual non-existence of Dark Energy in laboratory physics is evidence for its fudge factor status. As it currently stands it is stuff stranger than fiction—it needs to have physical properties unknown to physics, as we’ll see below. Though that in itself is not necessarily grounds for its rejection, we must remember the origin of the idea—it has only been proposed because of the a priori assumption that the big bang cosmology and history of the Universe is true.6 Continue reading