NASA spies bursting supermassive blackholes

Holy belching quasars, Batman

NASA astronomers think they have identified a pair of supermassive black holes, or quasars, that look like they are teetering on the brink of huge explosions.

Using the infrared camera on the Spitzer space telescope, the astronomers have been able to peer through obscuring dust and take a peek at the quasars at work.

Astronomers have suspected for some time that when galaxies collide, the supermassive black holes at their cores consume huge quantities of material; dust, gas and stars. The material is produced by violent periods of star formation, triggered by the galactic collisions.

It is normally very difficult to see the quasars at work on their intergalactic all-you-can-eat sessions because, as you might expect, two galaxies smashing into one another throws out a lot of dust and gas, blocking the view.

However, scientists now think that at some stage, the quasars get full. Once this happens, it will emit a huge burst of energy (NASA is describing this as a cosmic burp...) that could blow away a lot of the obscuring material.

Dr Maria del Carmen Polletta of the University of California at San Diego explains that black holes all emit radiation as they accrete matter. At some point, the amount of energy they emit is sufficient to destroy the surrounding dust.

Polletta used the Spitzer telescope to measure the amount of energy being absorbed by the dust surrounding suspected supermassive black holes. This gave her an indication of how luminous the quasars are, and from that, the research team can calculate how much material is being consumed.

She suggests that two quasars she has identified in a study (published in the May 2006 issue of Astrophysical Journal) are on the verge of just such an expulsion. One of the quasars is three billion times more luminous than our sun, suggesting it is gobbling up matter at a rate of around 68 solar masses per year; more than one of our suns per week.

"Black holes that are this heavily obscured and with this luminosity are very difficult to find and have not been extensively studied," says Polletta. "The belch of a black hole has never been verified with observations, so the explosion may not happen.

"The role that supermassive black holes play in the development of a galaxy is still unclear, there are still a lot of missing pieces. What we are seeing here is a very specific moment in the life of a black hole.

"According to astronomical models, black holes at this luminosity should destroy their surrounding material pretty soon." ®

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