The upcoming Rome Space Telescope may reveal a new class of “featherweight” black holes, challenging existing theories of black hole formation. These Earth-mass black holes, if found, could have significant implications for our knowledge of the early universe and the nature of dark matter. Credit: NASA’s Goddard Space Flight Center
NASAis Nancy Grace Roman space telescope could reveal previously undetected “feather” black holes with masses similar to Earth’s. These primordial black holes, which formed in the early universe, could significantly influence our understanding of astronomy and particle physics and potentially explain some of the dark matter in the universe.
Astronomers have discovered black holes with masses several times the mass of the Sun up to tens of billions. Now, a team of scientists has predicted that NASA’s Nancy Grace Rome Space Telescope could find a class of “featherweight” black holes that has so far eluded detection.
Today, black holes are formed either by the collapse of a massive star or by the merger of heavy objects. However, scientists believe that smaller “primordial” black holes, including some with mass similar to Earth, may have formed in the first chaotic moments of the early universe.
“The detection of a population of Earth-mass primordial black holes would be an incredible step for both astronomy and particle physics, because these objects cannot be formed by any known physical process,” said William DeRocco, a postdoctoral fellow at the University of California Santa. Cruz, who led a study on how Roman could detect them. An article describing the results was published in the journal Physical overview D. “If we find them, it will shake up the field of theoretical physics.”
The discovery of Earth-mass primordial black holes by NASA’s Rome Space Telescope could change our understanding of the universe and dark matter. Credit: NASA’s Goddard Space Flight Center
Primordial Black Hole Recipe
The smallest black holes that form today are born when a massive star runs out of fuel. Its outward pressure decreases as nuclear fusion subsides, so the inward gravitational pull wins the tug-of-war. A star contracts and can become so dense that it becomes a Black hole.
However, a minimum mass is required: at least eight times that of our Sun. Lighter stars become either white dwarfs or neutron stars.
However, conditions in the very early universe may have allowed much lighter black holes to form. One weighing the mass of Earth would have an event horizon—the point of no return for falling objects—about as wide as a US dime.
Just as the universe was being born, scientists believe it experienced a brief but intense phase known as inflation, when the universe expanded faster than the speed of light. Under these special conditions, regions that were denser than their surroundings could collapse to form low-mass primordial black holes.
While theory predicts that the smallest ones should evaporate before the universe reaches its current age, those with Earth-like masses may have survived.
The discovery of these tiny objects would have a huge impact on physics and astronomy.
“It would affect everything from galaxy formation to the dark matter content of the universe to cosmic history,” said Kailash Sahu, an astronomer at the Space Telescope Science Institute in Baltimore, who was not involved in the study. “Confirming their identity will be hard work and astronomers will need a lot of convincing, but it would be worth it.”
Stephen Hawking theorized that black holes may slowly shrink as radiation escapes. The slow escape of what is now known as Hawking radiation would over time cause the black hole to simply evaporate. This infographic shows the estimated lifetime and event horizon—the point beyond which infalling objects cannot escape the gravitational grip of a black hole—the diameters of black holes of various small masses. Credit: NASA’s Goddard Space Flight Center
Hidden Homestead Tips
Observations have already revealed clues that such objects may be lurking in our galaxy. Primordial black holes would be invisible, but the wrinkles in spacetime helped gather some possible suspects.
Microlensing is an observational effect that occurs because the presence of matter distorts the fabric of spacetime, like the imprint of a bowling ball when placed on a trampoline. Whenever an intervening object appears to be moving near a background star from our point of view, the starlight must travel through warped space-time around the object. If the alignment is particularly close, the object can act like a natural lens, focusing and amplifying the background starlight.
Separate groups of astronomers using data from MOA (Microlensing Observations in Astrophysics) – a collaboration that makes microlensing observations using the Mount John University Observatory in New Zealand – and OGLE (The Optical Gravitational Lensing Experiment) have found an unexpectedly large population of isolated Earths. – bulk items.
Theories of planet formation and evolution predict certain masses and abundances of rogue planets—worlds of wandering galaxies not tethered to a star. MOA and OGLE observations suggest that there are more Earth-mass objects moving through the galaxy than models predict.
This artist’s concept takes a fantastic approach to imagining tiny primordial black holes. In reality, such small black holes would have difficulty forming the accretion disks that make them visible here. Credit: NASA’s Goddard Space Flight Center
“There is no way to distinguish between Earth-mass black holes and rogue planets on a case-by-case basis,” DeRocco said. However, scientists expect Roman to find 10 times more objects in this mass range than ground-based telescopes. “Roman will be extremely powerful in distinguishing between the two statistically.
DeRocco led the effort to determine how many rogue planets there should be in this mass range and how many primordial black holes Roman could discern between them.
Finding primordial black holes would reveal new information about the very early universe and strongly suggest that an early period of inflation did indeed occur. It could also explain the small percentage of mysterious dark matter that scientists say makes up most of the matter in our universe but have not yet been able to identify.
“This is an exciting example of something scientists could do in addition to the data that Roman is already getting from searching for planets,” Sahu said. “And the results are interesting whether scientists find evidence that Earth-mass black holes exist or not.” Either way, it would enhance our understanding of the universe.”
Reference: “Revealing primordial Earth-mass black holes with the Nancy Grace Rome Space Telescope” by William DeRocco, Evan Frangipano, Nick Hamer, Stefan Profum, and Nolan Smyth, 08 Jan 2024, Physical overview D.
DOI: 10.1103/PhysRevD.109.023013
The Nancy Grace Rome Space Telescope is managed at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, with participation from NASA’s Jet Propulsion Laboratory and Caltech/IPAC in Southern California, the Space Telescope Science Institute in Baltimore, and a science team composed of scientists from various research institutions. Primary industry partners are BAE Systems, Inc in Boulder, Colorado; L3Harris Technologies in Rochester, New York; and Teledyne Scientific & Imaging in Thousand Oaks, California.