For the first time, scientists may have observed the merging of a black hole and a neutron star.
This discovery could soon answer questions related to the understanding of an invisible universe and the afterlife of dead stars.
A series of significant observations using gravitational waves or ripples in space and time helped scientists from LIGO and Virgo collaboration project document several candidates of merging of black holes and merging of neutron stars.
LIGO-Virgo Collaboration
The National Science Foundation's Laser Interferometer Gravitational-wave Observatory in Hanford, Washington, and the Virgo Observatory at the European Gravitational Observatory in Italy, started their joint observation run on April 1. Soon thereafter, the observatories were rewarded with new data and discoveries — a total of five gravitational wave events in just a month.
The latest shockwave event on April 26, estimated to be around 1.2 billion light-years away, turned out to be something different — a black hole devoured a neutron star. All three detectors of the LIGO-Virgo facilities were online that day, and it helped better narrow the location of the event to regions covering about 1,100 square degrees, or about 3 percent of the total sky.
The said event provisionally named S190426c, is nothing like previous observations by the collaboration.
"The fact that we haven't found a counterpart yet would mean that it's farther away, which is more consistent with a neutron star-black hole system," said Gabriela González, a LIGO team member.
"The latest LIGO-Virgo observing run is proving to be the most exciting one so far," said David H. Reitze of Caltech, executive director of LIGO. "We're already seeing hints of the first observation of a black hole swallowing a neutron star. If it holds up, this would be a trifecta for LIGO and Virgo — in three years, we'll have observed every type of black hole and neutron star collision. But we've learned that claims of detections require a tremendous amount of painstaking work — checking and rechecking — so we'll have to see where the data takes us."
According to LIGO, when two black holes collide, they warp the fabric of space and time, producing gravitational waves. When two neutron stars collide, they not only send out gravitational waves but also light. All events will be tested with follow-up observations in the coming weeks and months.
How Does Gravitational Wave Detectors Work?
Gravitational wave detectors are a series of tubes that can track minuscule distortions in space-time. They can survey larger volumes of the universe in search of extreme events.
Each of the LIGO detectors is able to sense massive collisions happening millions or even billions of light-years away from Earth. Scientists are able to triangulate potential sources of the events by combining measurements and adding detections from the observatories.
Scientists observe the source in different wavelengths such as optical, X-ray, ultraviolet, and radio to further probe what causes the events and their dynamics. They analyze the data in almost real-time by comparing the data to volumes of different possible gravitational waves and upload any significant candidates to a database as soon as possible.
Battle Between Dead Stars
Both black holes and neutron stars come from dying stars. When a star dies or explodes, it uses all its energy and then undergoes an extreme gravitational collapse.
If a dying parent star has a mass that is similar to that of the Earth's Sun, it will form a white dwarf. When the star's mass is below three times that of the Sun, it will form a neutron star. If the dying star's mass is at least three times greater than the Sun's mass, a black hole is formed.
