In a new study, the team has confirmed that the unusual object, known as Hannys Voorwerp (Hannys object in Dutch), is a large cloud of glowing gas illuminated by the light from a quasaran extremely energetic galaxy with a supermassive black hole at its center. The twist, described online in the Astrophysical Journal Letters, is that the quasar lighting up the gas has since burned out almost entirely, even though the light it emitted in the past continues to travel through space, illuminating the gas cloud and producing a sort of light echo of the dead quasar.
This system really is like the Rosetta Stone of quasars, said Yale astronomer Kevin Schawinski, a co-founder of Galaxy Zoo and lead author of the study. The amazing thing is that if it wasnt for the Voorwerp being illuminated nearby, the galaxy never would have piqued anyones interest.
The team calculated that the light from the dead quasar, which is the nearest known galaxy to have hosted a quasar, took up to 70,000 years to travel through space and illuminate the Voorwerpmeaning the quasar must have shut down sometime within the past 70,000 years.
Until now, it was assumed that supermassive black holes took millions of years to die down after reaching their peak energy output. However, the Voorwerp suggests that the supermassive black holes that fuel quasars shut down much more quickly than previously thought. This has huge implications for our understanding of how galaxies and black holes co-evolve, Schawinski said.
The time scale on which quasars shut down their prodigious energy output is almost entirely unknown, said Meg Urry, director of the Yale Center for Astronomy & Astrophysics and a co-author of the paper. That's why the Voorwerp is such an intriguingand potentially criticalcase study for understanding the end of black hole growth in quasars.
Although the galaxy no longer shines brightly in X-ray light as a quasar, it is still radiating at radio wavelengths. Whether this radio jet played a role in shutting down the central black hole is just one of several possibilities Schawinski and the team will investigate next.
Weve solved the mystery of the Voorwerp, he said. But this discovery has raised a whole bunch of new questions.
Explore further:
Chandra finds evidence for quasar ignition
More information:
Kevin Schawinski et al 2010 ApJ 724 L30 DOI:10.1088/2041-8205/724/1/L30
Shino
Slotin
http://en.wikiped...s_Object
SteWe
There's no similarity between "Hoag's Object" and "The Voorwerp":
"Hoag's Object" is a ring galaxy, most likely formed by a small (satellite?) galaxy crashing perpendicular through the disk of a much larger spiral galaxy. (Galaxyzoo has found quite a bunch of those, too, so they're not as rare as once thought!)
"The Voorwerp" is a galaxy-sized gas cloud, in some 70.000 light year distance from the big spiral galaxy (IC 2497, the big dusty spiral just above the green Voorwerp) - and both are roughly at the same distance from us. Its not a "background" galaxy, as it is stated in the article, and the "light" from the Quasar has not gone through the gas cloud to reach us, but has been reflected ~90° to the side)
"The Hanny's Voorwerp." http://www.galaxy...c=3802.0
Tuxford
Our galactic core star could surprise us with a cosmic ray volley at any time. The Hopi indians legends reference a blue star visible during the daytime. And we are worried about asteroids? This could be as bad or worse.