Feeds

Homeless quasar poses intergalactic mystery

Paging Mr. Holmes

Application security programs and practises

European astronomers have discovered a true space oddity: a quasar without a detectable home galaxy. The discovery has led to speculation that the host galaxy could be made up entirely of dark matter, or that a normal galaxy collided with another object that happened to contain a quasar.

The research team studied 20 relatively close quasars (a mere five billion light years away) drawing on data from both the Hubble Space Telescope and the ESO Very Large Telescope (VLT). In 19 of the 20 cases, they found that the quasar was, as expected, sited at the centre of a massive galaxy.

Normal quasar (on the right) compared with the no-host quasar

The researchers note that observing the host galaxy of a quasar is often challenging work because the quasar completely outshines the host, masking the galaxy’s underlying structure.

By combining observation data from Hubble and the ESO VLT, and making observations of a reference star at the same time, the astronomers were able to disentangle the quasar light from any possible light from an underlying galaxy.

But in the case of quasar HE0450-2958, no host galaxy could be found. This means the galaxy must be six times fainter than normal, or as much as 170 times smaller than normal. A quasar's host galaxy's radius is typically between 6,000 and 50,000 light-years, but this one can be no bigger than 300 light-years from end to end.

Nearby, astronomers observed a star-forming galaxy showing signs of a recent collision, and a strange blob - a cloud of gas about 2,500 light-years wide - just next to the quasar.

"The absence of a massive host galaxy, combined with the existence of the blob and the star-forming galaxy, lead us to believe that we have uncovered a really exotic quasar", says Frédéric Courbin from the Ecole Polytechnique Federale de Lausanne, Switzerland.

"There is little doubt that an increase in the formation of stars in the companion galaxy and the quasar itself have been ignited by a collision that must have taken place about 100 million years ago. What happened to the putative quasar host remains unknown," he said.

A quasar is a very distant source of vast quantities of radiation. Originally, astronomers thought they were nearby stars, but it turned out that they were much more distant, and so much brighter, than anyone had thought. Hence the name: quasi-stellar objects.

Quasars are thought to form when a galaxy's central super massive black hole gobbles up matter at a particularly fast rate. The galactic dust and gas fall into the black hole's accretion disk producing some very hot regions where huge quantities of energy are released.

The researchers say that the case of HE0450-2958, published in the 15 September issue of Nature, will need more study before the mystery can be unravelled. ®

Build a business case: developing custom apps

More from The Register

next story
Asteroid's DINO KILLING SPREE just bad luck – boffins
Sauricide WASN'T inevitable, reckon scientists
BEST BATTERY EVER: All lithium, all the time, plus a dash of carbon nano-stuff
We have found the Holy Grail (of batteries) - boffins
The Sun took a day off last week and made NO sunspots
Someone needs to get that lazy star cooking again before things get cold around here
Boffins discuss AI space program at hush-hush IARPA confab
IBM, MIT, plenty of others invited to fill Uncle Sam's spy toolchest, but where's Google?
Famous 'Dish' radio telescope to be emptied in budget crisis: CSIRO
Radio astronomy suffering to protect Square Kilometre Array
Bad back? Show some spine and stop popping paracetamol
Study finds common pain-killer doesn't reduce pain or shorten recovery
Forty-five years ago: FOOTPRINTS FOUND ON MOON
NASA won't be back any time soon, sadly
prev story

Whitepapers

Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Consolidation: The Foundation for IT Business Transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.
Application security programs and practises
Follow a few strategies and your organization can gain the full benefits of open source and the cloud without compromising the security of your applications.
How modern custom applications can spur business growth
Learn how to create, deploy and manage custom applications without consuming or expanding the need for scarce, expensive IT resources.
Securing Web Applications Made Simple and Scalable
Learn how automated security testing can provide a simple and scalable way to protect your web applications.