Hayadan > Echoes of the Big Bang: The Roman Space Telescope's Search for Black Holes with Masses of approx

Echoes of the Big Bang: The Roman Space Telescope's Search for Black Holes with Masses of approx

A soon-to-be-launched novel space telescope may reveal a new type of "featherweight" black hole that will challenge existing theories about the formation of black holes

A soon-to-be-launched novel space telescope may reveal a new type of "featherweight" black hole that will challenge existing theories of black hole formation. Credit: NASA's Goddard Space Flight Center — A soon-to-be-launched novel space telescope may reveal a new type of "featherweight" black holes that will challenge the existing theories on the formation of black holes. Credit: NASA's Goddard Space Flight Center

Astronomers have discovered black holes with a mass ranging from several times to tens of billions of the mass of the Sun. A group of scientists has now predicted that NASA's Nancy Grace Roman space telescope could find a type of "featherweight" black hole that has so far eluded detection.

Today, black holes are formed when a massive star collapses or when massive objects merge. But scientists suspect smaller "Juliar" black holes, including some with a mass similar to that of Earth, could have formed in the first chaotic moments of the early universe.

"Discovering a population of Earth-mass Julian black holes would be an incredible step forward for astronomy and particle physics," said William DiRocco, who led research into how Roman could discover them. "If we find them, it will shake up the field of theoretical physics."

The discovery of Earth-mass Julian black holes using the Roman Space Telescope could change our understanding of the universe and dark matter. Credit: NASA's Goddard Space Flight Center

The smallest black holes forming today are born when a massive star runs out of fuel. The outward pressure weakens as nuclear fusion subsides, so inward gravity wins the tug of war. The star contracts and may become so dense that it becomes a black hole.

But there is a minimum mass that is needed: at least eight times the mass of our sun. Lighter stars will become white dwarfs or neutron stars.

But conditions in the very early universe may have allowed the formation of black holes much easier. A black hole weighing the mass of the Earth would have an event horizon - the point of no return for objects falling in - of about 9 mm.

Right when the universe was forming, scientists think it went through a brief but intense phase known as inflation where space expanded faster than the speed of light. Under these special conditions, regions that were denser than their surroundings may have collapsed to form low-mass Julian black holes.

The theory predicts that the smallest black holes evaporated before the universe reached its current age, but those with a mass similar to Earth could survive.

Stephen Hawking hypothesized that black holes can slowly shrink as radiation is emitted from them. The slow leakage of what is now known as Hawking radiation will, over time, cause the black hole to simply evaporate. This infographic shows the estimates of the lifetime and diameter of the event horizon—the point beyond which objects cannot fall into the black hole and escape its gravity—for black holes of various small masses. Credit: NASA Goddard Space Flight Center. — Stephen Hawking hypothesized that black holes can slowly shrink as radiation is emitted from them. The slow leakage of what is now known as Hawking radiation will, over time, cause the black hole to simply evaporate. This infographic shows the estimates of the lifetime and the diameter of the event horizon – the point beyond which objects cannot fall into the black hole and escape its gravity – for black holes of various small masses. Credit: NASA Goddard Space Flight Center.

The discovery of these small objects will have a huge impact on physics and astronomy.

"The discovery will affect all things, such as the formation of galaxies, the dark matter content of the universe and cosmic history," said Kaliash Sahu, an astronomer who was not involved in the research. "Verifying their identities will be hard work and astronomers will need a lot of persuasion, but the effort will pay off."

Observations have already revealed hints that such objects may be lurking in our galaxy. Julian black holes would be invisible, but wrinkles in space-time helped gather as possible suspects.

Microdistortion is an observational effect that occurs because the presence of mass distorts the fabric of space-time. Whenever an intervening object appears to us from our vantage point to be drifting near a background star, the star's light must cross the warped space-time around the object. If the alignment is particularly close, the object can act as a natural lens, focusing and amplifying the light of the background star.