Birth of black hole kills the radio star

Dec 20, 2013
If matter and antimatter repel each other, the quick conversion of one into the other inside a supermassive black hole may look like a Big Bang. Image credit: NASA

Astronomers led by a Curtin University researcher have discovered a new population of exploding stars that "switch off" their radio transmissions before collapsing into a Black Hole.

These exploding stars use all of their energy to emit one last strong beam of highly energetic radiation – known as a – before they die.

Up until now, it was thought all gamma-ray bursts were followed by a radio afterglow – a premise that a team of Australian astronomers of the Centre for All-sky Astrophysics (CAASTRO) at Curtin University and the University of Sydney originally set out to prove correct.

"But we were wrong. After studying an ultra-sensitive image of gamma-ray bursts with no afterglow, we can now say the theory was incorrect and our telescopes have not failed us," lead researcher and Curtin research fellow Dr Paul Hancock said.

The technique used to create the ultra-sensitive image was recently published in The Astrophysical Journal.

It allowed for the stacking of 200 separate observations on top of each other to re-create the image of a gamma-ray burst in much better quality – yet, no trace of a radio afterglow was found.

"In our research paper we argue that there must be two distinct types of gamma-ray burst, likely linked to differences in the magnetic field of the exploding star," Dr Hancock said.

"Gamma-ray bursts are thought to mark the birth of a Black Hole or Neutron Star – both of which have super-dense cores. But Neutron Stars have such strong magnetic fields (a million times stronger than those of Black Holes) that producing gamma-rays are more difficult.

"We think that those stars that collapse to form a Neutron Star have energy left over to produce the radio afterglow whereas those that become Black Holes put all their energy into one final powerful gamma-ray flash."

New work is underway to test the team's theory and to see if there are other subtle ways in which the two types of bursts differ.

"We now have to take a whole new look at gamma-ray bursts – so far this work has shown that being wrong is sometimes more interesting than being right," Dr Hancock said.

Telescope facilities such as the Australia Telescope Compact Array in northern New South Wales and the Karl Jansky Very Large Array in the US both have observing programs to search for gamma-ray burst afterglows and have been recently upgraded to increase their sensitivity.

Explore further: Glimpsing the infrastructure of a gamma-ray burst jet

More information: The research report can be found at arxiv.org/abs/1308.4766

Related Stories

Glimpsing the infrastructure of a gamma-ray burst jet

Dec 04, 2013

(Phys.org) —A new study using observations from a novel instrument provides the best look to date at magnetic fields at the heart of gamma-ray bursts, the most energetic explosions in the universe. An international ...

Fast radio bursts might come from nearby stars

Dec 12, 2013

First discovered in 2007, "fast radio bursts" continue to defy explanation. These cosmic chirps last for only a thousandth of a second. The characteristics of the radio pulses suggested that they came from ...

NASA sees 'watershed' cosmic blast in unique detail

Nov 21, 2013

(Phys.org) —On April 27, a blast of light from a dying star in a distant galaxy became the focus of astronomers around the world. The explosion, known as a gamma-ray burst and designated GRB 130427A, tops ...

Earth's gold came from colliding dead stars

Jul 17, 2013

We value gold for many reasons: its beauty, its usefulness as jewelry, and its rarity. Gold is rare on Earth in part because it's also rare in the universe. Unlike elements like carbon or iron, it cannot ...

Recommended for you

The entropy of black holes

Sep 12, 2014

Yesterday I talked about black hole thermodynamics, specifically how you can write the laws of thermodynamics as laws about black holes. Central to the idea of thermodynamics is the property of entropy, which c ...

Modified theory of dark matter

Sep 12, 2014

Dark matter is an aspect of the universe we still don't fully understand. We have lots of evidence pointing to its existence (as I outlined in a series of posts a while back), and the best evidence we have point ...

Gaia discovers its first supernova

Sep 12, 2014

(Phys.org) —While scanning the sky to measure the positions and movements of stars in our Galaxy, Gaia has discovered its first stellar explosion in another galaxy far, far away.

Astronomers unveil secrets of giant elliptical galaxies

Sep 12, 2014

New findings of how giant elliptical galaxies move have been discovered by an international team of astronomers using the newly installed Multi Unit Spectroscopic Explorer (MUSE) at the European Southern Observatory's (ESO) ...

User comments : 6

Adjust slider to filter visible comments by rank

Display comments: newest first

katesisco
2 / 5 (5) Dec 20, 2013
I am wondering if we will discover that there are many kinds of magnatars like we now understand stars to be many different kinds.
Zephir_fan
Dec 20, 2013
This comment has been removed by a moderator.
cantdrive85
1 / 5 (6) Dec 20, 2013
Pseudo-scientific metaphysical mumbo jumbo!
davidivad
4.6 / 5 (7) Dec 20, 2013
magnatars are strange beasts. I am sure that with time we will begin to distinguish differences in the details.
goracle
5 / 5 (2) Dec 22, 2013
Pseudo-scientific metaphysical mumbo jumbo!

Thanks, but we already know what you have to peddle.
bredmond
not rated yet Dec 26, 2013
"...In my mind and in my car, we can't rewind we've gone to far.
Pictures came and broke your heart, put the blame on VTR. ..."

am I the only one?
Widdekind
2 / 5 (1) Jan 12, 2014
"We think that those stars that collapse to form a Neutron Star ... produce the radio afterglow, whereas those that become Black Holes [do not]."

------------

Perhaps those that become Black Holes do produce radio afterglows... BUT their radio afterglows are even MORE gravitationally red-shifted, than those from Neutron Stars... and so the signals are both weakened, and also red-shifted, beyond the wave-band investigated ?