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Astronomers spot mysterious objects spewing out gas at a quarter the speed of light

Studying the universe in x-ray wavelengths has allowed astronomers to peer inside clouds of gas and probe the edges of a black hole’s event horizon, but there are a few mysteries yet to be solved. In fact, surveying x-ray sources occasionally results in entirely new, unexplained phenomena. For example, a pair of objects recently detected by researchers from the University of Cambridge. These ultra-bright x-ray sources are blasting out gas at more than a quarter the speed of light, far faster than should be possible.

Most of the large x-ray sources in the sky are fairly well understood at this point. They’re either supermassive black holes devouring nearby matter, or binary systems with a stellar remnant (white dwarf, neutron star or black hole) pulling material away from a companion star. The friction from the swirling plasma around these objects results in heat and x-ray emissions. These newly discovered objects are an example of a rare third type of x-ray source. They’re an order of magnitude brighter than regular binary sources, and they could have a lot to teach us about the universe.

Astronomers believe these “ultra-luminous x-ray sources” are a different type of binary system that is consuming gas at a much higher rate. The Cambridge team used the ESA’s XMM-Newton space telescope to detect and study the new pair of ultra-luminous sources in galaxies about 22 million light years away from ours. The ultra-luminous sources are called NGC 131 X-1 and NGC 5408 X-1. The data appears to show x-rays being absorbed by the swirling gas before it was ejected from the object at a quarter the speed of light — about 75,000 meters per second or 167 million miles per hour. This is the first time astronomers have been able to observe the “wind” coming off one (let alone two) of these mysterious ultra-luminous objects.


The team is working to nail down the specific nature of these objects, but they’ve got a good handle on how the gas is being blasted out at such a high speed. As matter is pulled inward by gravity, it’s also being pushed out by the radiation emitted by the object. In this case, the pressure exerted by radiation is so high that it overcomes the force of gravity and pushes the gas away. There’s so much radiation relative to gravity that the gas gets moving very fast. This is an application of a concept called Eddington luminosity, which describes the balance between gravity and radiation.

More research will be needed to figure out what exists inside the envelope of super-fast gas surrounding these objects. Right now, the top contenders are either a neutron star or a smallish black hole, both with very large stellar companions.

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