Two "Black Holes?"
It seems that Abell 400, a galaxy
cluster that has long enchanted astronomers, is provoking a
new round of speculations, with little regard for the
separation of fact and fiction.
The picture above combines X-ray
and radio images of the galaxy cluster Abell 400. According
to the press release from the Chandra X-Ray Observatory, the
composite "shows radio jets immersed in a vast cloud of
multimillion degree X-ray emitting gas that pervades the
"The jets emanate from the vicinity of two supermassive
black holes (bright spots in the image)…. The peculiar
dumbbell structure of this galaxy is thought to be due to
two large galaxies that are in the process of merging."
Any substance with a temperature of "multimillion" degrees
cannot possibly be a gas: It will be a completely ionized
plasma. What the press release doesn’t say is
that the X-rays in such cases are almost exclusively
synchrotron radiation, not thermal radiation. That means the
X-rays are emitted by very fast electrons spiraling in a
strong magnetic field. The Abell 400 galaxies are under
extreme electrical stress.
But electricity is not something astronomers are eager to
hear about. They are not fond of electrical currents in
space, because the possibility that electricity generates
large scale structure is alien to their theoretical models.
To generate the observed levels of energy seen in Abell
400—using nothing but the puny force of gravity—more matter
would have to be squeezed into a galaxy than a galaxy could
hold. But the theorists are mathematicians, and they work
with equations, not with real objects. This permits them to
ignore empirical limits on density and let the amount of
matter per unit volume increase without limit: The "neutron
stars" and "black holes" conjured through this mathematical
license can be placed wherever needed to explain away the
stunning and potentially embarrassing energy excesses.
The galaxies would still have to be large. But because of
the two "close" bright spots, astronomers now speculate
about "colliding black holes" that could form a "single
super-supermassive black hole" in a few million years—a
mathematicians delight whether or not anything of this sort
actually occurs in the natural world.
But photographs of Abell clusters — there are over 4000 such
clusters — point to a different conclusion. Halton Arp, the
Galileo of the twentieth century, has shown that
several are aligned along the spine of the Virgo
Cluster. Their x-ray contours are elongated toward nearby
active galaxies, and these galaxies often have jets
directed toward the Abell clusters.
Some members of the Abell clusters are paired with a quasar
or a BL Lac (a kind of fragmented quasar) across an active
galaxy, presenting astronomers with a now-familiar paradox.
Because quasars and their kin are small and faint and have
rather larger redshifts than the active galaxies, convention
assumes they are large and bright but far away. But as Arp
points out, Hubble diagrams for Abell clusters have enormous
dispersion, placing the astronomers' assumptions about
redshift in doubt: "[T]here is no redshift-apparent
magnitude relation for these clusters like that which is
claimed to demonstrate a redshift-distance relation."
[Seeing Red, p. 154] And their association with active
galaxies suggests that they are "grown up" BL Lacs — that
they are not far away, but actually small and faint and
close to the nearby active galaxy. Arp discusses this
issue at length in his book, Seeing Red.
Abell 400 is particularly interesting because it lies along
the line of
Local Group objects extending from the minor axis
of M31 (the Andromeda galaxy), through M33, to 3C120 (the
active galaxy with the "faster-than-light" jet). Along that
line are also nebulous clouds "obviously interacting" with
higher-redshift dwarf and low-luminosity spiral galaxies,
strong radio and x-ray sources, and quasar groupings. Arp
suggests that the objects in this line have been ejected
from M31, as may have been our own galaxy.
The Abell 400 cluster would be a part of the "umbilicus" that
still connects us with our "mother," M31.
Submitted by Mel Acheson