Ghosts in space

Posted on November 30, 2011

Galaxy ZooThey glow out there in space like a couple of dozen phantoms wandering the starways with no apparent source for the light they glow by. Now it seems like nearby black holes that have recently ended a feeding frenzy may be the cause.

Hanny's Voorwerp

Hannay's Voorwerp

Like ourselves here at Changed Times, their discoverer Hanny van Arkel had been classifying galaxies on the community science project Galaxy Zoo. As must have happened to other participants in this great citizen science project, we have seen and reported several odd things in the pictures on the Galaxy Zoo, but so far nothing of such importance as the strange glowing object spotted by van Arkel and later named Hanny’s Voorwerp – in her native Dutch a name meaning Hanny’s “Thing”.

Jealousy apart, it was soon discovered that the energy driving the Thing was X-rays, which are created in plenitude when matter falls towards the giant black holes in the cores of many galaxies. A galaxy called IC 2497 lies less than 70,000 light years from the glowing cloud – near neighbours in intergalactic terms – but its core shows no sign of emitting X-rays. It was suggested that when the Thing emitted its light, IC 2497’s core black hole had finished swallowing a big meal just 100,000 years earlier and that X-rays from that were still arriving at the cloud to make it glow.

English: Astronomers found that Hanny's Voorwe...

Now, a team of volunteer astronomers from the Galaxy Zoo – which may, of course, include ourselves – led by William Keel of the University of Alabama in Tuscaloosa have found 19 similar clouds near other galaxies whose black holes appear to be quiet but which may have blasted the Things with X-rays in the past. We volunteers, obviously, do not figure in the contributors to the published paper detailing these findings – which rather strangely appears under the aegis of the Cornell University Library rather than Keel’s own university.

These strange objects could give us a new way to examine in detail the growth and feeding habits of galactic core black holes, whose consumption of matter has have an enormous effect on the galaxies they reside in. They can shut off the growth of galaxies by heating and expelling the gas inside the galaxy normally used as feedstock for new stars born within the galaxy and leading to the growth of the galaxy.

Perhaps even more importantly, the results also demonstrate in concrete terms the value of citizen science projects such as the Galaxy Zoo. By using large numbers of amateur observers and volunteer scientists around the world to achieve in a much shorter time what would otherwise take huge amounts of time – and vast cost – simply by making science more accessible to the man or woman in the street.

But what do you think? Is the value of this discovery greater in the new science it has indicated and the step forward it has generated in astronomy or is it in the importance of making science available directly to the public for public help? Either way, the importance of this new finding is hard to underestimate. Now if they could just explain the strange green “beams” we here at Changed Times have spotted on the Galaxy Zoo…