Since the first direct detection of space-time ripples known as gravitational waves was announced in 2016, astronomers have regularly heard black holes ring across the universe. Projects such as the Gravitational-Wave Laser Interferometer Observatory (known as LIGO) they discovered nearly 100 Collision of black holes (and sometimes neutron stars), which shake the fabric of the universe and send invisible waves rippling through space.
But new research shows that LIGO may soon hear another kind of vibration in space: cocoons of volatile gas emitted from dying stars. Northwestern University researchers used sophisticated computer simulations of massive stars to show how these cocoons might produce gravitational waves that are “impossible to ignore,” according to research presented this week at the 242nd meeting. American Astronomical Society. Studying these ripples in real life can provide insight into the violent deaths of giant stars.
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As massive stars run out of fuel, they collapse black holes, throws out huge jets of ultra-fast particles at the same time. The team of astronomers simulated these final stages in a star’s life, thinking the jets might trigger gravitational waves — but something else took center stage.
“When I calculated the gravitational waves from the vicinity of the black hole, I found another source that disrupted my calculations – the cocoon,” says the principal investigator. Ore Gottliebsaid astronomer at the Northwestern Interdisciplinary Research and Exploration Center in Astrophysics, V.I statement. The cocoon is a turbulent mass of gas, formed when the outer layers of a collapsing star interact with the high-energy jets emanating from within. To produce gravitational waves, we need something massive that moves asymmetrically, just like the matter of a cocoon.
“A deep jet inside a star shoots and then makes its way to escape,” Gottlieb said. “It’s like when you drill a hole in the wall. The rotating drill bit hits the wall and debris spills out of the wall. The drill bit gives that material energy. Likewise, the jet pierces the star, causing the star’s material to heat up and spill out. This debris forms the hot layers of a cocoon.”
According to Gottlieb’s calculations, the ripples generated by the cocoon should be easy to detect by LIGO during the next set of observations. In addition, the cocoons emit light, so astronomers can obtain information about them using gravitational waves and telescopes at the same time – an exciting feat known as multiple-messenger astronomy.
If LIGO does notice a cocoon in the near future, it’s sure to be an interesting new look at the insides of stars and the ends of their lives. This may be the first time that LIGO has been able to detect gravitational waves from a single object, rather than interactions between two binary objects orbiting each other.
“As of today, LIGO has only detected gravitational waves from binary systems, but one day it will discover the first non-binary source of gravitational waves,” Gottlieb said. “Cocoons are one of the first places we have to look for this kind of source.”
The team’s research has not yet been published in a peer-reviewed journal.
