Lyman Alpha Blobs May Contain Galactic Mergers

In 2005, astronomers using visible-light telescopes to analyze the night sky identified a new class of cosmic objects, that they called blobs. They resembled spherical patches of light, usually found inside large-scale structures such as galactic filaments and clusters.

The closest such blob that astronomers were able to identify since then is located billions of light-years away. Therefore, all these structures appear very fuzzy in the data of even the most advanced observatories available to scientists today.

Scientists have classified these structures, now called Lyman Alpha blobs, as large galactic halos, that are made up primarily of hydrogen gas. It was also determined that they are about 10 times larger than the galaxies they contain.

This was all well and good, until it came time for experts to determine what was causing the blobs to glow so brightly from within. Given their sheer size, it would take a massive light source to cause this effect, and its doubtful that a single galaxy, regardless how massive, could be responsible.

“It is possible that extremely bright galactic mergers lie at the center of all the mysterious blobs, but we still don't know how they fuel the blobs themselves,” explains Dr. Harry Teplitz.

“It's like seeing smoke in the distance and now discovering that it's a forest fire, not a house or car fire, but still not knowing whether it was caused by lightning or arson,” adds the expert, who holds an appointment at the California Institute of Technology's Spitzer Science Center (SSC).

“The findings will ultimately provide a better understanding of how galaxies, including ones like our own Milky Way, form,” the investigator goes on to say, quoted by Daily Galaxy.

In one of its latest studies, the NASA Spitzer Space Telescope managed to discover three tremendously-bright galaxies in a Lyman Alpha blob located some 11 billion light-years ago. The three components were in the process of merging with each other.

When galaxies merge, excess hydrogen that can no longer form stars gets stirred up in each of them, and a tumultuous period of intense stellar formation begins. This makes the objects very luminous.

“To figure out what's going on, we need to better characterize the galaxies at the center of the blobs,” adds SSC investigator Dr. James Colbert.

“Far from solving the mystery of the blobs, these observations only deepen it. Not only are the gas clouds bizarre, we now know that they contain some of the brightest and most violent galaxies in the Universe,” Teplitz concludes.