Using data from NASA's Chandra X-ray Observatory and the National Science Foundation's Jansky Very Large Array, scientists believe that they have revealed the cause of the most recent supernova in the Milky Way.
The team came to its conclusion using a novel technique that could help in the understanding of other type Ia supernovae, a specific type of interstellar explosion that can be used to shed light on the expansion rate of the universe.
The discovery was made by the examination of G1.9+0.3, a supernova remnant that is believed to be the most recent in our galaxy, created 110 years ago in a region of the Milky Way that prevented visible light from making its way to the Earth.
The remnant belongs to the Ia category of supernovae, which possess patterns of brightness that scientists believe will eventually help them reveal the expansion rate of the universe.
"Astronomers use type Ia supernovae as distance markers across the universe, which helped us discover that its expansion was accelerating," said Sayan Chakraborti, lead author of the study. "If there are any differences in how these supernovae explode and the amount of light they produce, that could have an impact on our understanding of this expansion."
Although scientists believe that type Ia supernovae stem from the explosion of white dwarfs, they are torn between the cause of these events: the accumulation of material onto a white dwarf from a companion star or a merger between two of the stellar remnants.
The new study reveals how G1.9+0.3 interacts with the gas and dust surrounding the explosions and shows how an increase in X-ray and radio brightness over time only occurs when a white dwarf merger occurred. The findings provide clues to the cause of the initial explosion.
"We observed that the X-ray and radio brightness increased with time, so the data point strongly to a collision between two white dwarfs as being the trigger for the supernova explosion in G1.9+0.3," said Francesca Childs, co-author of the study.
Based on the recent findings, it seems at though type Ia supernovae are all caused by white dwarf collisions, or a mixture of these collisions and the specific mechanism that caused white dwarfs to attract material from a companion star.
"It is important to identify the trigger mechanism for type Ia supernovae because if there is more than one cause, then the contribution from each may change over time," said Alicia Soderberg, senior author on the study. "This means astronomers might have to recalibrate some of the ways we use them as 'standard candles' in cosmology."
The findings were released on the pre-print server arXiv.
