A cosmic question mark

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A cosmic question mark
DR EMILY BALDWIN
ASTRONOMY NOW
Posted: 12 August 2010

Things are not as serene as they may first seem in this elliptical galaxy, for behind its dark dust lane lies hidden turmoil.

NGC 4696 as seen by Hubble's Advanced Camera for Surveys. Image: ESA/Hubble/NASA.

NGC 4696 is the largest galaxy in the Centaurus Cluster and is an elliptical galaxy with a difference. In this Hubble Space Telescope image, as well as its incomplete dust band that spans some 30,000 light years across and appears to curl around itself like a question mark, capillary-like filaments of ionized hydrogen hang above and below it, giving the galaxy's bright centre a subtle marbling effect.

Chandra's X-ray eyes reveal a vast cloud of hot gas (red) surrounding high-energy bubbles 10,000 light years across (blue) on either side of the area surrounding the black hole.

Elliptical galaxies most likely form by collisions between spiral galaxies, suffering a burst of star formation that quickly subsides to leave a population of ageing stars. NGC 4696 has hidden depths, however. Lurking deep within the galaxy's centre is a supermassive black hole ejecting matter at nearly the speed of light. Probing the galaxy at X-ray wavelengths with the Chandra X-ray Observatory shows huge voids in the galaxy's material, testament to the jets' incredible power.

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