New Insights on Cosmic Explosions as Researchers Monitor GRB from Just One Billion Light Years Away
In a groundbreaking observation, scientists in Namibia captured a colossal gamma-ray burst (GRB) from a collapsing star on August 29, 2019, using the High Energy Stereoscopic System (H.E.S.S). First detected by the Fermi and Swift satellites in the Eridanus constellation, the burst provided researchers an unprecedented “front row” view of a GRB, as it occurred only a billion light years away, far closer than the usual 20 billion light-year distance.
Gamma-ray bursts, known as the universe’s most powerful explosions, result from the collapse of massive, rotating stars into black holes. “They are bright X-ray and gamma-ray flashes from distant extragalactic sources,” explained Sylvia Zhu from Germany’s DESY research center. These explosions release vast gravitational energy, forming an ultrarelativistic blast wave with two phases: a brief, intense “prompt” phase followed by a prolonged afterglow.
H.E.S.S. detected very-high-energy gamma rays, allowing scientists to analyze the afterglow for several days and measure energies up to 3.3 tera-electronvolts—about one trillion times more powerful than visible light photons. Findings challenge existing theories on radiation, suggesting that X-rays and gamma rays could share a common origin, contrasting previous assumptions that X-rays result from ultra-fast electrons deflected in the magnetic field of the burst.
