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Principale » Discovering gravitational waves from big black hole crash using pulsars

Discovering gravitational waves from big black hole crash using pulsars

14 Novembre 2017

But the method to detect the merger of supermassive black holes will rely on pulsars.

The Laser Interferometer Gravitational-Wave Observatory (LIGO), which first detected gravitational waves from colliding black holes in 2016, and the European Virgo gravitational-wave detector, which observed the neutron star merger-produced waves in October, both detect objects in the moments right before they merge. These observatories assemble their perception by disseminating lasers down long tunnels and exactly calculating minute deformities in the beam. This is due to ripples created at a much lower frequency, and a novel research has demarcated where and how to start looking.

"Observing low-frequency gravitational waves would be akin to being able to hear bass singers, not just sopranos", said Joseph Lazio, chief scientist of Nasa's Deep Space Network and co-author of the study.

The researchers say pulsars are key to tapping into the songs of these intergalactic Barry Whites. Pulsars are dense neutron stars that rapidly rotate, emitting electromagnetic signals like clockwork. Essentially, if enough is known about each pulsar, then their signals can be predicted incredibly precisely, so if those signals are delayed by even the tiniest fraction of time, then that could indicate that a gravitational wave has rolled through.

"If you take into account the positions of the pulsars in the sky, you basically have a 100 percent chance of detecting something in 10 years", Chiara Mingarelli, a research fellow at the Center for Computational Astrophysics at the Flatiron Institute in New York City, and lead author of the study, said in another statement. "And since the pulsars we study are about 3,000 light-years away, they act as a galactic-scale gravitational-wave detector", she added. According to a new paper published in the journal Nature Astronomy, it's quite possible to detect gravitational waves from merging supermassive black holes by studying the subtle anomalies in pulsars.

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For instance, black holes merging in the massive M87 galaxy would have a four-million-year window of detection. To figure all this out, the team used data from the 2 Micron All-Sky Survey (2MASS), and combined it with galaxy merger rates pulled from the Illustris simulation project.

Of the 5,000 galaxies they studied, the astronomers narrowed in on about 90 that probably have pairs of supermassive black holes in the process of merging.

In just a year, scientists have confirmed not one but five gravitational waves. Thus the merger of the blackholes happens for a short time.

The researchers hope that the array can also teach us about how galaxies are formed and what happens when they merge - which could be useful information, considering we're now on-course for a collision with our neighboring Andromeda galaxy.

Mingarelli and colleagues are confident that by expanding the "pulsar timing array over the next 10 years or so, there is a high likelihood of detecting gravitational waves from at least one supermassive black hole binary".

Discovering gravitational waves from big black hole crash using pulsars