Scientists find dormant black hole born without explosion of a dying star

Astronomers have found a black hole that appears to have been born without the explosion of a dying star. Spotted in a galaxy adjacent to our Milky Way and what they are calling a cosmic “needle in a haystack”, the black hole is classified as dormant.

On Monday, researchers said that this black hole differs from all other known black holes in that it is “X-ray quiet” – not emitting powerful X-ray radiation indicative of gobbling up nearby material with its strong gravitational pull. They also said that it was not born in a stellar blast called a supernova.

What is a black hole?

A black hole is an extraordinarily dense object with gravity so intense not even light can escape.

They are formed when massive stars collapse in on themselves.

The gravity is so intense because the matter involved has compressed down to a singularity, or zero volume and infinite density.

According to study co-author Julia Bodensteiner, a postdoctoral research fellow at the European Southern Observatory in Munich, black holes are intrinsically dark objects. They do not emit any light. Therefore, in order to detect a black hole, “we usually look at binary systems in which we see one luminous star moving around a second, not-detected object”.

The term black hole itself was coined in 1967 by theoretical physicist John Wheeler after a suggestion from Einstein student J Robert Oppenheimer. “Black” was used to describe how these objects absorb all the light around them.

Types of black holes

There are different types of black holes. The smallest, like the newly detected one, are so-called stellar-mass black holes formed by the collapse of massive individual stars at the ends of their life cycles. There also are intermediate-mass black holes as well as the enormous supermassive black holes residing at the center of most galaxies.

How is the newly found black hole?

This newly found black hole has a mass at least nine times greater than our sun. It was detected in the Tarantula Nebula region of the Large Magellanic Cloud galaxy and is located about 160,000 light years from Earth. A light year is the distance light travels in a year, 5.9 trillion miles (9.5 trillion km).

An extremely luminous and hot blue star with a mass about 25 times that of the sun orbits with this black hole in a stellar marriage. This so-called binary system is named VFTS 243. The scientists say the companion star eventually also will become a black hole and could merge with the other one.

Astronomer say Dormant black holes are relatively common and are hard to detect because they interact very little with their surroundings. Numerous prior proposed candidates have been debunked with further study, including by members of the team that uncovered this one.

Stating that the challenge is finding those objects, Reuters quotes Tomer Shenar, a research fellow in astronomy at Amsterdam University, lead author of the study published in the journal Nature Astronomy, as further saying, “We identified a needle in a haystack”.

Astronomer and study co-author Kareem El-Badry of the Harvard & Smithsonian Center for Astrophysics said that it was the first object of its kind discovered after astronomers had been searching for decades.

The researchers used six years of observations from the European Southern Observatory’s Chile-based Very Large Telescope.

How was this black hole formed without explosion?

It is typically assumed that the collapse of massive stars into black holes is associated with a powerful supernova explosion. In this case, a star perhaps 20 times our sun’s mass blew some of its material into space in its death throes, then collapsed in on itself without an explosion.

The shape of its orbit with its companion offers evidence for the lack of an explosion.

Shenar says the orbit of the system is almost perfectly circular. If a supernova had occured, the blast’s force would have kicked the newly formed black hole in a random direction and yielded an elliptical rather than circular orbit, according to Shenar.

Read: Huge, Spectacular Rings around a Black Hole Captured

Black holes can be mercilessly ravenous, guzzling any material – gas, dust and stars – wandering within their gravitational pull.

Bodensteiner says black holes can only be mercilessly ravenous if there is something close enough to them that they can devour. Usually, we detect them if they are receiving material from a companion star, a process we call accretion

In so-called dormant black hole systems, as astronomers say, the companion is far enough away that the material does not accumulate around the black hole to heat up and emit X-rays. Instead, it is immediately swallowed by the black hole.

Scientists say this finding is not only a precedent for identifying other black holes without supernovae explosions, it is also an indication that dormant black holes may exist in a higher number than supermassive black holes.