CDF-S XT1

CDF-S XT1 was first observed by the Chandra telescope on October 1, 2014 in the Deep-Field South Survey (CDF-S).^[5] The first photon arrived 1.68x10^4 seconds into the observation period with the following ~100 seconds swing displaying a sharp increase in the count of photons. Then over the next 10^5 seconds, the number of photons would decrease. However there is some debate over whether the first photon to arrive was from CDF-S XT1, with some arguing that it is consistent with the background rate.^[2]

The origin of CDF-S XT1 remains unclear despite numerous hypotheses being put forth about its origins, and most scientist’s agree that it involved a destructive event and the occurrence of a gamma-ray burst (GRB) with an off-set axis. Many ideas involve the merger of two objects, such as a neutron star merging with another neutron star or a neutron star merging with a black hole. Another idea is the collapse of a massive star or a white dwarf star being shredded by a medium sized black hole.^[1][3]

In this scenario, a binary system of two neutron stars merged producing a gamma-ray burst that was off-set. If this scenario is true, this would be potentially one of the most distant observed neutron star merger event. This would have implications for the star formation and nucleosynthesis of heavy elements in the early universe. The potential existence of neutron star mergers this early in the universe history implies that stellar evolution has been occurring before the peak of star formation in the universe. This also implies that the synthesis of heavy elements has been occurring in the early universe.^[2]

In this scenario, a massive star had its core collapse resulting in an event called a core-collapse supernova. While the time scales observed from CDF-S XT1 is consistent with a supernova, the observed spectra is not. They are thermal transients and the radiation they produce is typically soft X-ray or ultra-violet depending on the temperature of the system.^[2]