NASA’s Rome Space Telescope will search for the universe’s first star, or at least its fragmented stars.

A powerful and frightening phenomenon known as tidal disruption could hold the key to discovering the universe’s elusive first stars. NASA’s upcoming Nancy Grace Roman Telescope could exploit the tragic deaths of stars torn apart by black holes to track the universe’s first stellar population. These early stars were (somewhat confusingly) called Population III (Pop III) stars, and they were very different from the Sun and other stars seen in the universe today. This is because the universe was not yet filled with “metals.” Astronomers use this term to describe elements heavier than hydrogen or helium. Pop III stars formed just a few hundred million years after the Big Bang and were “metal-poor” stars composed mostly of hydrogen and helium. They were also believed to be much larger and hotter than the sun. This means Pop III ran out of fusion fuel faster than smaller stars, and its short lifespan makes it an elusive target for astronomers. Studying these early stars is key to understanding the evolution of the universe, as they are responsible for forming the metals that are the building blocks of the next generation of metal-poor stars. New research suggests that the Nancy Grace Roman Telescope (Rohman for short), scheduled to launch in 2027, may have a unique way to accomplish this. Instead of looking for an intact Pop III star, Roman will be looking for the remains of a star that flew too close to a black hole and was destroyed in what astronomers call a tidal disruption event (TDE). “We know that black holes are likely to exist during these early epochs, so capturing them engulfing these first stars is a great way to capture them,” said study team member Priyamvada Natarajan, a Yale University scientist. “If we can do this, we may have the best chance of detecting Pop III stars indirectly.” The university issued a statement.

Roman will observe the destruction of the first star When a star passes close to a black hole, the huge gravitational influence it experiences creates huge tidal forces within it. This compresses the star horizontally and stretches it vertically. The material that makes up stars is converted into “noodles” of stellar material in a process called “spaghettification.” However, the material that once made up the destined star cannot fall into the black hole right away. Instead, they collect in a flat cloud around the black hole called an accretion disk. As this material swirls around and toward the black hole, it heats up and glows, sometimes visible over billions of light-years away. TDE itself is a temporary event. This means that when a star is destroyed, it causes a brief but intense flare of light at X-ray, radio, ultraviolet, and optical wavelengths. This is how a TDE occurs in a local universe where Pop III stars no longer exist. But these violent events look very different when viewed from a vast distance of about 13 billion light years. That’s because as the universe expands, the wavelengths of the light from these events become longer and enter the infrared part of the spectrum. This is a phenomenon called “redshift.” Furthermore, the temporal nature of TDE changes as its light travels through space. This is because redshift causes the TDE that destroys Pop III to brighten for hundreds to thousands of days and then dim for periods of up to 10 years. “The evolutionary time scale of Pop III TDEs is very long, a feature that distinguishes Pop III TDEs from other transient phenomena, including supernovae and TDEs from current-generation stars like the Sun,” said the research team leader. Rudrani Kar Chowdhury said. Postdoctoral researcher at the University of Hong Kong.

Providing a panoramic view of the universe 200 times greater than the Hubble Space Telescope and surveying the sky 1,000 times faster than this ion telescope, Roman becomes the ideal instrument for discovering these early TDEs. Team members say it should. NASA’s James Webb Space Telescope (JWST) has the capabilities needed to observe these distant early TDEs, but its field of view is also much smaller than the Roman Space Telescope. That means TDE Hunter won’t be as effective as future space telescopes. Particularly promising in the search for the destroyed Pop III star is Roman’s high-latitude, wide-area survey, which will provide views of the sky 2,000 square degrees beyond the plane of the Milky Way. “Roman can reach very deep and still cover a very large area of ​​the sky,” said team member Jane Dai, a professor of astrophysics at the University of Hong Kong. “This is necessary to detect meaningful samples of these TDEs.”

That doesn’t mean JWST won’t play a role in finding TDE for Pop III stars. If Roman discovers such a deposit, JWST’s powerful infrared vision will allow it to magnify it and use spectroscopic instruments to determine the presence of metals. This will determine whether TDE actually involves the destruction of the Pop III star. “These stars are composed only of hydrogen and helium, so no metal lines are visible in the spectra of astronomical objects, but various metal lines are visible in the TDE spectra of normal stars,” said Kar Cho. Mr. Dolly said. This tag team of Roman and JWST may therefore unlock the secrets of the universe’s oldest stars and how they influenced the evolution of future generations of stars and the galaxies that host them.