Einstein Cross: Unusual discovery may explain the end of the world

Astronomers use a variety of techniques and instruments — collectively referred to as the "cosmic distance ladder" — to measure cosmic distances because it is a difficult task.

Type Ia supernovae, which occurs in binary systems where one star, a white dwarf, consumes matter from a companion star, frequently a red giant, until it reaches the Chandrasekhar limit and collapses under its own mass, are a particularly important tool.

These stars briefly overwhelm the background as they blow off their outer layers in a great explosion.

Ariel Goobar of the Oskar Klein Centre at Stockholm University, along with a team of researchers from around the world, recently discovered the unusual type Ia supernova, SN Zwicky (SN 2022qmx), as stated in a study published in the journal  Nature Astronomy.

In an unexpected turn of events, the team discovered what is known as an "Einstein ring," a strange phenomenon predicted by Einstein's theory of general relativity in which the presence of a gravitational lens in the foreground amplifies light from a distant object.

The team's success in observing two extremely rare astronomical events that just so happened to coincide was significant.

Researchers from various institutions, including the Oskar Klein Centre, the Kavli Institute for Cosmology, the Cahill Centre for Astrophysics, and more, collaborated to create a team studying various astronomical phenomena, including cosmology, astrophysics, and various universities.

According to Science Alert, the initial detection was made using the Zwicky Transient Facility at the Palomar Observatory in California. This facility is named in honour of Fritz Zwicky, the astronomer who first theorised the existence of dark matter in the 1930s.

A few weeks later, the team observed it with the adaptive optics (AO) at the W.M. Keck Observatory atop Maunakea, Hawaii, and the Very Large Telescope (VLT) at the Paranal Observatory in Chile. Based on the observed brightness, Goobar and his colleagues hypothesised that they were observing a strong lensing effect.

These follow-up observations and images acquired by the Hubble Space Telescope confirmed this theory, showing that the multiple-image lensing effect resulted from a galaxy in the foreground that magnified the supernova 25 times!

This fortuitous discovery presents numerous opportunities for astronomers, including the ability to study SN Zwicky in greater detail and further investigate the mysteries of gravitational lenses.

As Goobar explained in a Stockholm University press release: "The discovery of SN Zwicky not only showcases the remarkable capabilities of modern astronomical instruments but also represents a significant step forward in our quest to understand the fundamental forces shaping our Universe."

The implications of this go beyond these two phenomena, however. The study of type Ia supernovae led astronomers to the realisation that the cosmos is expanding at an accelerating rate.

This discovery earned the discovery team the 2011 Nobel Prize in Physics, which was split between Saul Perlmutter (The Supernova Cosmology Project) and jointly between Brian P. Schmidt and Adam G. Reiss (The High-z Supernova Search Team).

Therefore, observations of SN Zwicky could help astronomers address the mystery of what is driving this accelerated expansion.

"The extreme magnification of SN Zwicky gives us an unprecedented chance to study the properties of distant type Ia supernova explosions, which we need when we use them to explore the nature of dark energy," said Joel Johansson, a postdoctoral fellow at Stockholm University and a co-author on the study.

Beyond that, it could also help astronomers pull back the veil on dark matter and inform theories about how the universe will end (Big Crunch, Big Rip, Heat Death, etc.).