A large portion of the universe has gone missing, claims university research

November 14th, 2007 - 8:19 am ICT by admin  
The discovery was made in 2002 while trying to analyze the makeup of warm, x-ray emitting gas at the center of galaxy clusters - the largest cosmological structures in the universe.

The UAH team reported finding large amounts of extra “soft” (relatively low-energy) x-rays coming from the vast space in the middle of galaxy clusters. This was in addition to previously discovered “hot” gas in that space, which emits higher energy “hard” x-rays.

Although the soft x-ray-emitting atoms were thought to be spread thinly through space (less than one atom per cubit meter), they would have filled billions of billions of cubic light years. Their cumulative mass was thought to account for as much as ten percent of the mass and gravity needed to hold together galaxies, galaxy clusters and perhaps the universe itself. This was thought of as a major portion of the universe.

But the latest research by the same UAH group that had come out with the earlier theory, proved otherwise. They found out that some x-rays thought to come from intergalactic clouds of “warm” gas are instead probably caused by lightweight electrons.

“This means the mass of these x-ray emitting clouds is much less than we initially thought it was,” said Dr. Max Bonamente, an assistant professor in UAH’s Physics Department. “A significant portion of what we thought was missing mass turns out to be these ‘relativistic’ electrons,” he added.

Traveling at almost the speed of light (and therefore ‘relativistic’), these feather weight electrons collide with photons from the cosmic microwave background. Energy from the collisions converts the photons from low-energy microwaves to high-energy x-rays.

“Finding these electrons, however, is like finding the tip of the iceberg, as they would not be limited to emitting only the soft x-ray signal,” said Bonamente. “The signal from these electrons would also make up part of the previously observed harder X-rays, which would reduce the amount of mass thought to make up the hot gas at the center of galaxy clusters,” he added.

According to Bonamente, “If a significant portion of the total x-ray energy comes from fast electrons, that could trick us into thinking there is more gas than is actually there. It means we need to revise how we calculate both the gas mass and the total mass.”

The new calculations might leave the mass of the universe as much as ten to 20 percent lighter than previously calculated. (ANI)

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