A team of astronomers from the UK, the USA, and Chile have found that a fairly run-of-the-mill galaxy is much more energetic than previously believed. The discovery, which was made using the Very Large Array (VLA) radio telescope, in New Mexico, could have large implications over what was previously believed to be happening in galactic nuclei.
Most galaxies have a supermassive black hole at their centre, but the effect that they have on their host galaxy as a whole has thus far appeared to have been relatively benign, with their presence usually only inferred from gravitational interactions.
The team of astronomers, led by Durham University’s Chris Harrison, have discovered that these black holes may be causing some dramatic complications, and inhibiting new star formation. Using the VLA, the team studied the distant galaxy J1430+1339, nicknamed the Teacup, which lies 1.1 billion light years away.
Far from being the normal, “boring” galaxy that would have perhaps been expected, the supermassive black hole in the centre of the Teacup appears to be consuming material, whipping up a storm which is stripping the galaxy of much of the gas it has available to form new stars.
Among the multitudes of galaxies, there are a very small minority which have long been known to produce vast jets of material. These rarities, known as active or radio galaxies, spew out plasma from their nucleus at phenomenal speeds, producing jets thousands of light years long.
The Teacup is not an active galaxy; however the astronomers found that not only are there radio-bright lobes of gas stretching 30,000 to 40,000 light years from the centre, but also that the supermassive black hole at the centre was producing jets. Material in these 2,000 light year long jets is being flung out of the galaxy at the astonishing speed of 1,000 km per second.
“For many years, we’ve seen direct evidence of this happening in galaxies that are extremely bright when viewed through radio telescopes. These, rare, radio-bright galaxies harbour powerful jets, launched at the black hole, that plough into the surrounding gas”, says Dr Harrison. “However, to understand how all of galaxies in our Universe formed, we needed to know if these same processes occur in less extreme galaxies that better represent the majority. This was the focus of our study.”
The majority of galaxies in the Universe are either spirals like our own, actively producing new stars, or elliptical galaxies; vast collections of aged stars, with little or no raw materials remaining from which to form new generations. Based on follow-up visual observations, the Teacup appears to belong to the latter of these groups.
As explained by Dr Harrison, “It appears that a supermassive black hole is explosively heating and blasting around the gas in this galaxy and, as a result, is transforming it from an actively star-forming galaxy into one devoid of gas that can no longer form stars.”
Following on from this discovery, the team are now investigating an additional eight galaxies in the hopes of determining if this storm in a teacup is just a needle in a haystack.