Detecting Gravitational Waves on the Cheap

Forget building gravitational wave detectors costing hundreds of millions of dollars (I’m looking at you, LIGO), make use of the most accurate cosmic timekeepers instead and save a bundle.

The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) is a proposal that involves closely monitoring the regular flashes of spinning neutron stars (or pulsars) to detect very slight “shimmers” in their signal. Although the physics is crazy-complex, by tracking these shimmers over a suitably distributed number of pulsars could reveal the passage of gravitational waves.

However, there’s a problem with this plan; pulsars are notoriously tricky stellar objects, as my colleague Jennifer Ouellette points out:

The problem is that you need to closely monitor rapidly-spinning millisecond pulsars, which are (a) tough to find (only 150 have been found over nearly three decades since pulsars were first discovered), and (b) not very plentiful in the part of the night sky of interest to scientists (northern hemisphere). They tend to clump together in globular star clusters, which makes them useless for detecting gravitational waves.

However, according to results announced by the National Radio Astronomy Observatory (NRAO) at this week’s American Astronomical Society (AAS) meeting in Washington D.C., they’ve discovered 17 new pulsars with the help of NASA’s Fermi Gamma-Ray Space Telescope.

In addition to recent Fermi telescope pulsar discoveries, it would appear that the number of potential targets for NANOGrav are increasing, making a stronger case for the 10 year, $65 million project…

You have to wonder whether building the Laser Interferometer Gravitational-Wave Observatory (LIGO) was worth it (but you can’t be too careful, some terrorist organizations might want to use gravitational waves for evil, so it would be good if we detected them first).

Source: Discovery News

Magnetars Born Through Quark Star Switch?

Could quark stars be magnetar progenitors? (© Mark Garlick)
Could quark stars be magnetar progenitors? (© Mark Garlick*)

If you thought neutron stars and magnetars were exotic, think again. In studies of magnetars that occasionally blink to life, generating an intense blast of X-rays and gamma-rays, astronomers have been at a loss to explain why these objects have such strong magnetic fields. After all, after a supernova, a neutron star remnant conserves the angular momentum and magnetic field of the parent massive star; it is therefore a rapidly spinning, magnetically dominant entity, often observed emitting intense radiation from its poles (a.k.a. a pulsar).

However, magnetars (the most magnetically powerful objects observed in the Universe) do not have such a reasonable explanation for their magnetic field, it is simply too strong.

During the AAS conference last week, one scientist presented his research, possibly indicating another state of matter may be at play. A massive neutron star may pass through a “quark star phase”, kick starting a mechanism known as colour ferromagnetism

*This image is copyright Mark A. Garlick and has been used with permission. Please do not use this image in any way whatsoever without first contacting the artist.
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