Scientists from the pioneer research cluster of the Japanese Institute of physics and chemistry used computer modeling to show how a hypothetical supernova type will evolve over thousands of years, providing researchers with a way to find examples of supernovae (known as "D6") of this model.
Supernovae are important to cosmology because one type, IA, is used as a "standard candle" so that distance can be measured. In fact, they were used to measure and reveal that the expansion of the universe was accelerating, which was surprising to the first observers. Although it is generally believed that type Ia supernovae are produced by the explosion of degenerate stars called White Dwarfs - which have burned out their hydrogen and shrunk into compact objects - the process of initiating the explosion is unknown.
Recently, the discovery of extremely fast-moving white dwarfs has added credibility to a proposed mechanism for the origin of these supernovae, namely "D6". In this case, one of the two white dwarfs in the binary system experienced a so-called "double explosion", that is, the helium gas layer on the surface exploded first, and then ignited a larger explosion in the carbon and oxygen core of the star. This leads to the destruction of the star, and the companion is suddenly released from the gravity of the exploding star and thrown out at a huge speed.
However, little is known about the shape of the consequences of such events long after the initial explosion. To study this problem, the researchers chose to simulate the long-term evolution of a supernova remnant that lasted thousands of years after the explosion. In fact, scientists can detect several characteristics unique to this situation in the primary system, which provides a means to explore the physics of supernovae, such as a "shadow" or dark spot surrounded by a bright ring. They also found that, contrary to popular belief, the remnants of type Ia explosions were not always symmetrical.
According to Gilles Ferrand, the study's lead author, "the D6 supernova explosion has a specific shape. We are not confident to see it in the residue long after the initial event, but in fact we found a specific 'signature' that we can still see thousands of years after the explosion."
Shigehiro nagataki, head of the astrophysical big bang laboratory at the Institute of physics and chemistry, said: "this is a very important discovery because it may have an impact on the use of Ia supernovae as the ruler of the universe. They were once considered to originate from a single phenomenon, but if they are diverse, it may need to reassess how we use them.".
"In the future, we plan to learn how to calculate X-ray emission more accurately, taking into account the composition and state of the impacted plasma, so as to directly compare with the observation results. We hope that our paper will bring new ideas to observers, that is, what to look for in supernova remnants," Ferrand continued
The study was completed with an international team including researchers from the University of Manitoba and was published in the Journal of astrophysics on May 6, 2022.