How Merging Black Holes Devour Stars

Astronomers propose a new way of monitoring merging black holes as they shred apart and consume new stars. They say that using an upcoming telescope mission could provide them with the ability to survey gravitational waves that are produced as these events unfold.

Studies have revealed that black holes can be found at the core of all large galaxies. These objects tend to rip apart stars that stray too close, by using tidal forces. They then consume the material the previous star was made of.

Generally, a single black hole sitting at the core of its galaxy “eats” a star every 100,000 years or so. But that rate goes through the roof when the dark behemoth is disturbed from its tranquility.

This happens when the galaxy hosting it collides with another galaxy, which also features a similar galaxy at its core. Eventually, the two black holes meet , and they begin interacting.

And this is where things really get out of hand, say investigators from the Harvard-Smithsonian Center for Astrophysics (CfA). The two objects begin to circle each other, spiraling ever inwards until they merge with each other.

As this happens, the object is cast out of its previous location, and into the surrounding, star-rich regions of the galactic core. There, it starts wrecking havoc, tearing apart stars at very high rates.

CfA experts Nick Stone and Avi Loeb say that these events could be observed by analyzing the gravitational waves they produce. These are ripples in spacetime that are generated during mergers.

The Laser Interferometer Space Antenna (LISA), a satellite constellation currently being built by the European Space Agency (ESA) could finally allow investigators to see these gravitational ripples.

In addition to gaining the ability to detect black hole collisions, certify that the objects exist, and gain a deeper understanding of galactic collisions, physicists will also have a new tool at their disposal for testing existing theories.

"We could test general relativity in the regime of strong gravity with unprecedented precision,” Loeb explains. The team published the details of its new proposal in the March 2011 issue of the esteemed journal Monthly Notices of the Royal Astronomical Society.

Using data supplied by LISA together with measurements of the redshift exhibited by very distant galaxies, astrophysicists will be able to study dark energy in more detail than ever before.

This force is widely believed to be responsible for the ever-accelerating expansion of the Universe.

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