dark matter tagged posts

Dark matter is a hypothetical form of matter that is implied by gravitational effects that can’t be explained by general relativity unless more matter is present in the universe than can be seen. It remains virtually as mysterious as it was nearly a century ago when first suggested by Dutch astronomer Jan Oort in 1932 to explain the so-called “missing mass” necessary for things like galaxies to clump together.

Now Dr. Richard Lieu at The University of Alabama in Huntsville (UAH) has published a paper in the Monthly Notices of the Royal Astronomical Society that shows, for the first time, how gravity can exist without mass, providing an alternative theory that could potentially mitigate the need for dark matter.

“My own inspiration came from my pursuit fo...

Stars near the center of our galaxy are acting kind of weird. Dark matter may be the explanation. A team of scientific detectives (so to speak) have discovered a potential new class of stars that could exist within a light-year of the Milky Way’s center that could be operating according to an unusual mechanism: dark matter annihilation. This process would produce an outward pressure on the stars other than hydrogen fusion, keeping them from gravitationally collapsing—and making them essentially immortal, their youth being refreshed constantly...

Dark matter is a ghostly substance that astronomers have failed to detect for decades, yet which we know has an enormous influence on normal matter in the universe, such as stars and galaxies. Through the massive gravitational pull it exerts on galaxies, it spins them up, gives them an extra push along their orbits, or even rips them apart.

Like a cosmic carnival mirror, it also bends the light from distant objects to create distorted or multiple images, a process which is called gravitational lensing.

And recent research suggests it may create even more drama than this, by producing stars that explode.

For all the havoc it plays with galaxies, not much is known about whet...

Astronomers have charted the largest-ever volume of the universe with a new map of active supermassive black holes living at the centers of galaxies. Called quasars, the gas-gobbling black holes are, ironically, some of the universe’s brightest objects.

The new map logs the location of about 1.3 million quasars in space and time, the furthest of which shone bright when the universe was only 1.5 billion years old. (For comparison, the universe is now 13.7 billion years old.)

“This quasar catalog is different from all previous catalogs in that it gives us a three-dimensional ma...