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Fraser
2006-Jul-27, 01:36 AM
Look into the sky with X-ray instruments, and you'll see a background radiation in all directions. Astronomers think these X-rays are produced by the supermassive black holes at the centres of most galaxies. But astronomers can't find these black holes, which should be bright in the most energetic range of the electromagnetic spectrum. Maybe they're hiding; shrouded in thick clouds of gas and dust. Or maybe something else is generating all the X-ray background radiation.

Read the full blog entry (http://www.universetoday.com/2006/07/26/the-search-for-hidden-black-holes/)

Jerry
2006-Aug-01, 09:05 PM
The hidden black holes we have found so far can contribute only a few percent of the power to the cosmic X-ray background, says Bassani. This implies that if hidden black holes make up the bulk of the X-ray background, they must be located much further away in the more distant universe. Why would this be? One reason could be that in the local universe most super-massive black holes have had time to eat or blow away all the gas and dust that once enshrouded them, leaving them revealed.

...Or another possibility is that the universe is much more massive than prevailing theories imagine...