The Leo Ring
Sep 17, 2009

The Leo Ring is about 35 million light-years away, 620,000 light-years wide, and is apparently orbiting a pair of galaxies in the Leo Group, M105 and NGC 3384. It is fairly evenly spread but exhibits some clumpiness as shown in the figure above. The Ring has been mapped most thoroughly in its southern portions close to the bright M96 galaxy (bottom right of the picture above).

The Leo Ring is clear evidence of extensive intergalactic matter, which in itself is relatively controversial. Additionally, it is intergalactic matter which in its clumpier regions approaches densities equivalent to interstellar matter within galaxies. This is highly unusual indeed and indicates there is likely more of this type of intergalactic matter if we look for it correctly.

In the numerous journal articles written about this structure (mostly contributed by Stephen Schneider, who discovered the Leo Ring), there has evolved an accepted view that the Leo Ring is composed of “pristine” gas from the early days of the Universe after the Big Bang. This assumption derives from an as yet untested hypothesis that the matter comprising the Leo Ring is low in metallicity (elements heavier than hydrogen or helium).

Observations over the years have revealed no star formation in the Leo Ring, except for a small, very dim dwarf galaxy (Leo Dwarf A). However, a recent study (Thilker et al., 2009) observed the Leo Ring in ultraviolet light (UV) using the NASA Galaxy Evolution Explorer (GALEX). The investigators detected UV emissions within distinct substructures in the Leo Ring, indicating recent star formation. However, the star formation appears to be confined to small dim dwarf galaxies. The confusing part for the investigators is that such dwarf galaxies (often observed as satellite galaxies around larger galaxies) are usually dominated by dark matter. In this case, there is no evidence for dark matter.

Elsewhere we’ve discussed how dark matter is inferred from galactic dynamics. If the rotational velocity of a galaxy is greater than can be explained by its observable mass, then dark matter is assumed to contribute the missing mass. However, in the case of the dwarf galaxies in the Leo Ring, their dynamical masses seem to agree relatively well with the mass estimated from luminosity.

There is one other confusing attribute of the Leo Ring. The rotational velocity of the Leo Ring itself is estimated at about 80 km/s, which means it orbits the two central galaxies about once every 4 billion years. That means if only 13.7 billion years has elapsed since the Big Bang, then the Leo Ring has orbited at most about three times. How could gravitational forces have smoothed the matter in the Ring in only three (or less) revolutions?

Interestingly, this issue is rarely mentioned in the various articles about the Leo Ring. To Schneider’s credit in his 1989 paper, he mentions this as a key puzzle about the structure: “It is difficult to imagine a way of spreading it around the ellipse via differential rotation in less than a few orbital periods.” In the same paper, Schneider speculates that M96 might be shaping the ring by orbiting around the outside, cleaning up gas. But the orbital period of M96 is on the order of 10 billion years, so that leaves a conundrum as well.

One of the other investigators of the Thilker et al. paper above, Schiminovich, had this to say about the Leo Ring: “The ring spins just once every 4 billion years or so and the gas may have had to take several orbits to become so evenly spread”. This is confusing, since Schiminovich would probably support the theory of a Big Bang occurring about 13 billion years ago. We can only infer that by “several” Schiminovich means twice.

The Electric Universe model would take a different view of the Leo Ring and the newly discovered dwarf galaxy formation: The “gas” in the Leo Ring is actually plasma, though in dark mode with very low current density. The plasma is not “primordial” and could of a similar metallicity as other interstellar matter, unless Marklund Convection has "sorted" it into relatively pure hydrogen and helium.

The Leo Ring plasma is under very low electrical stress, resulting in very low rotational velocity for the dwarf galaxies (e.g. the Leo Dwarf A has a rotational velocity less than one tenth of the much brighter M105 galaxy).

The low electrical stress also produces low rates of star formation and a notable lack of X-ray emission. The Leo Ring plasma might have organized over billions of years through mostly electromagnetic forces, possibly through weak magnetic fields permeating the unusually closely packed cluster of galaxies in the Leo Group.

The study by Thilker et al. has prompted discussions about different types of galaxies, some with dark matter and others without dark matter. However, a different view is that there are galaxies under more or less electrical stress. Those under higher electrical stress will exhibit higher rotational velocities than can be explained with gravity alone.

Interestingly, those galaxies under higher electrical stress will show brighter X-ray sources in the region outside of the visible matter in the galactic ring. Note that X-ray emissions in outer galactic rings (where rotational velocities are higher than gravity can support) tend to be used for dark matter computations.

The dark matter model will not die easily though. As Thilker says, “I think the bulk of evidence from previous studies still strongly supports the role of dark matter in shaping the well-known galaxy population.”

Understand the logic here. Thilker has just reported on galaxy formation completely contradicting the dark matter halo model and yet concedes his findings do not really impact the conventional wisdom about dark matter. One wonders where the clear thinkers and scientific rebels have disappeared to in the astronomy community. Let us hope there are more Halton Arps out there somewhere.

By Tom Wilson