Friday, January 24, 2014

NASA Chandra RX J1532.9+3021: Extreme power of black hole revealed


Credit: X-ray: NASA/CXC/Stanford/J.Hlavacek-Larrondo et al, Optical: NASA/ESA/STScI/M.Postman & CLASH team

Astronomers have used NASA's Chandra X-ray Observatory and a suite of other telescopes to reveal one of the most powerful black holes known.

The black hole has created enormous structures in the hot gas surrounding it and prevented trillions of stars from forming.

The black hole is in a galaxy cluster named RX J1532.9+3021 (RX J1532 for short), located about 3.9 billion light-years from Earth.

The image here is a composite of X-ray data from Chandra revealing hot gas in the cluster in purple and optical data from the Hubble Space Telescope showing galaxies in yellow.

The cluster is very bright in X-rays implying that it is extremely massive, with a mass about a quadrillion—a thousand trillion—times that of the Sun.

At the center of the cluster is a large elliptical galaxy containing the supermassive black hole.

The large amount of hot gas near the center of the cluster presents a puzzle. Hot gas glowing with X-rays should cool, and the dense gas in the center of the cluster should cool the fastest.

The Phoenix Cluster
The pressure in this cool central gas is then expected to drop, causing gas further out to sink in towards the galaxy, forming trillions of stars along the way.

However, astronomers have found no such evidence for this burst of stars forming at the center of this cluster.

This problem has been noted in many galaxy clusters but RX J1532 is an extreme case, where the cooling of gas should be especially dramatic because of the high density of gas near the center.

Out of the thousands of clusters known to date, less than a dozen are as extreme as RX J1532. The Phoenix Cluster is the most extreme, where, conversely, large numbers of stars have been observed to be forming.

What is stopping large numbers of stars from forming in RX J1532? 
Images from the Chandra X-ray Observatory and the NSF's Karl G. Jansky Very Large Array (VLA) have provided an answer to this question.

The X-ray image shows two large cavities in the hot gas on either side of the central galaxy (mouse over the image for a labeled version).

The Chandra image has been specially processed to emphasize the cavities. Both cavities are aligned with jets seen in radio images from the VLA.

The location of the supermassive black hole between the cavities is strong evidence that the supersonic jets generated by the black hole have drilled into the hot gas and pushed it aside, forming the cavities.

More information: A paper describing this work was published in the 10 November 2013 issue of The Astrophysical Journal and is available online: dx.doi.org/10.1088/0004-637X/777/2/163 . Preprint: arxiv.org/abs/1306.0907

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