Gravitational lensing shows the galaxy 800 million years after the Big Bang

Although LAP1-B is very poor in heavy matter, it has very high carbon content; its carbon-to-oxygen ratio is higher than that of our Sun. The researchers think the answer may be how the first generation giant stars died.

According to our models, when a massive, Population III star reaches the end of its life, its core collapses into a black hole, but the supernova explosion is not powerful enough to destroy the entire star. “Their gravitational pull is stronger than that of regular massive stars,” Nakajima said.

Instead, the collapse results in a retrograde supernova, in which the heavier material from the star’s core, such as gas, is sucked back through the event and trapped in the black hole below. At the same time, the lighter outer layers, which contain carbon, are released and expelled into the surrounding air. The chemical composition of LAP1-B, with its low oxygen content but high carbon content, looks like the fingerprint of the gas cloud formed by Population III supernovae.

But there was another clue hidden in the gas in LAP1-B, and it was all about its speed.

A dark story

By looking at how the emission lines in the spectrum were amplified by the Doppler effect, Nakajima and his colleagues determined that the gas is rotating inside the galaxy at a speed of about 58 kilometers per second, a value for small galaxies.

Using the laws of gravity, the team calculated how much air would have to be present to keep the air moving at that speed to keep it from flying into space. “We estimated the amount of matter in 10 million suns,” Nakajima said.

Because the stars have less than 3,300 solar masses and only a small accretion of gas, the team concluded that the rest of the galaxy is dark matter.