Dark Matter Mystery Stays Unsolved

A new study deepened the mystery of dark matter, as finding the dark matter in galaxies is spread out smoothly, according to media reports.The study was published Monday in the American scientific journal Astrophysical.Having analyzed the observations of two dwarf galaxies, Fornax and Sculptor, researchers from the Harvard-Smithsonian Center for Astrophysics found that there was no higher concentration in the center of the galaxy than anywhere else.

The finding goes completely against the current cosmological models, which suggest that dark matter should be clustered at the centers of galaxies."After completing this study, we know less about dark matter than we did before. Our measurements contradict a basic prediction about the structure of cold dark matter in dwarf galaxies," said Matt Walker, the study's lead author.Astronomers have one more reason to scratch their heads over the unseen material known as dark matter. Observations of two dwarf galaxies, Fornax and Sculptor, show the dark matter within them is spread out smoothly rather than heaped into a central bulge, contradicting cosmological models.

Researchers know dark matter comprises a far greater percentage of the universe than the ordinary matter making up things like people and stars. Because of this, the distribution of dark matter determines the structure of the cosmos. Galaxies form when they are attracted to and anchored by large clumps of dark matter.The dwarf galaxies Fornax and Sculptor are themselves made of 99 percent dark matter and only 1 percent normal matter. It is impossible to directly see the dark matter but, by observing the rotation of stars around each galactic center, researchers can detect its influence and map out its distribution.According to the current cosmological models, dark matter almost certainly exists, otherwise, galaxy clusters would have no sufficient gravity to hold themselves together.

While simulations suggest that the dark-matter density should increase sharply near the galactic centers, the recent observations found the dark matter spread relatively uniform throughout. Yet if these dwarf galaxies have no “clump” in their center, then what is pinning them in place?Scientists hoped the study on dwarf galaxies could make some breakthrough in dark matter hunting, because calculations suggest dwarf galaxies consisted of 99 percent dark matter.However, the new study has disappointed the researchers, as it has "drawn a big, frustrating blank", Dr. Alastair Wilkins from University of Bristol in Britain remarked in his blog.

Observations of other small galaxies have similarly failed to find a dense central dark matter core, a difficulty that has prompted astronomers to begin expanding their ideas on the mysterious substance.It is possible that dark matter might interact more with ordinary matter than currently thought, allowing the regular matter to stir up the dark matter and spread it out. Alternatively, dark matter might move faster than expected and therefore be less prone to clumping in galactic centers. Either case creates many further mysteries and problems for astronomers to keep mulling over.