HKU scientists develop new method to detect universe's earliest stars

HKU scientists develop new method to detect universe's earliest stars
by Simon Mansfield
Sydney, Australia (SPX) May 10, 2024

Astrophysicists from The University of Hong Kong have unveiled a new technique to detect the universe's first stars, known as Population III stars. These stars, primarily composed of hydrogen and helium, differ significantly from modern stars like our Sun and those forming today. Despite their massive size and high temperature, Population III stars were ephemeral and critical in the synthesis of heavier elements and the formation of subsequent star generations.

Until now, direct detection of these ancient stars has been elusive due to their faintness and vast distance from Earth. The new method involves observing the remnants of Population III stars that have been disrupted by massive black holes' tidal forces. This process results in tidal disruption events (TDEs), during which the black hole consumes the stellar debris, emitting exceptionally bright flares detectable from Earth.

Professor Jane Lixin Dai, the project's principal investigator, explained, "As the energetic photons travel from a very faraway distance, the timescale of the flare will be stretched due to the expansion of the Universe. These TDE flares will rise and decay over a very long period of time, which sets them apart from the TDEs of solar-type stars in the nearby Universe." Further insights were provided by Dr. Rudrani Kar Chowdhury, stating, "Interestingly, not only are the timescales of the flares are stretched, so is their wavelength. The optical and ultraviolet light emitted by the TDE will be transferred to infrared emissions when reaching the Earth."

This discovery is timely as NASA's James Webb Space Telescope (JWST) and the forthcoming Nancy Grace Roman Space Telescope are well-equipped to observe these infrared emissions. Professor Priya Natarajan highlighted the Roman telescope's capabilities, noting its potential to significantly advance our understanding of the early universe through the detection of Pop III TDE flares. Janet Chang, a PhD student involved in the research, anticipates the detection of numerous such events annually with the proper observational strategies.

This breakthrough sets the stage for significant discoveries about the universe's first stars and the mysteries surrounding its origins.

Research Report:Detecting Population III Stars through Tidal Disruption Events in the Era of JWST and Roman