Nuclear transient event discovered by international team of astronomers using NASA’s Swift spacecraft
An international team of astronomers has made an exciting discovery using NASA’s Swift spacecraft. They have detected a luminous and slowly-evolving nuclear transient event, named Swift J221951-484240. The origin of this newly detected event is still unknown, but its discovery could provide valuable insights into supernova explosions and the synthesis of chemical elements after the Big Bang.
Led by Sam Oates from the University of Birmingham in the U.K., the team conducted follow-up observations of a gravitational wave alert known as S190930t using Swift’s Ultra-Violet/Optical Telescope (UVOT). Through these observations, they were able to identify the nuclear transient event, Swift J221951.
Comparing imagery from the Hubble Space Telescope’s Advanced Camera for Surveys and the Dark Energy Survey, the researchers determined that J221951 appeared nuclear in nature. It was found at a spectroscopic redshift of 0.52, ruling out any association with the gravitational event S190930t.
At its peak, J221951 was brighter than previous archival values across ultraviolet, optical, and infrared wavelengths. It reached a peak absolute magnitude of -23 mag and a peak bolometric luminosity of 1.1 quattuordecillion erg/s. The total radiated energy from J221951 was estimated to be about 26 sexdecillion erg. Importantly, the lack of broad absorption lines in the optical spectrum ruled out the possibility of a supernova explosion.
Data from J221951 showed a slow rise in brightness before reaching its peak, and its new optical spectra had a blue and featureless appearance. Based on these observations, the team classified J221951 as a luminous and slow-evolving blue transient.
When it comes to determining the origin of J221951, the researchers considered two plausible hypotheses. The transient’s properties resemble both a tidal disruption event (TDE) and the turn-on of an active galactic nucleus (AGN). Further observations of J221951’s late-time evolution will be crucial in order to determine which hypothesis is true.
This discovery, along with the increasing population of similar ambiguous nuclear transients, highlights the need for further research in this area. By studying these events, scientists hope to gain a better understanding of the processes involved in supernova explosions and the evolution of chemical elements in the universe.
The findings of this study were reported on the preprint server arXiv and were published by the journal arXiv.