Rerun of a supernova blast expected 2037

Rerun of a supernova blast: Two images, side by side, of arcs of light in starry space with small dots circled.
View larger. | In the 2016 image on the left, you see 3 images of one supernova (inside circles). The supernova appears triple due to gravitational lensing, whereby space curves around a massive object lying between us and the supernova. The supernova’s light splits as it travels along this curved space. Now look inside the circles in the 2019 image. The 3 supernova images are gone. That’s not surprising. But now astronomers predict a rerun of a supernova blast in the year 2037. The predicted location of that 4th image is highlighted by the yellow circle at top left. Image via Hubble Space Telescope Wide Field Camera 3.

Rerun of a supernova blast

HubbleSite said on September 13, 2021, that astronomers expect a rerun of a faraway supernova. Researchers have seen multiple images of this supernova already, as the light of this distant blast has traveled for 10 billion years to reach our eyes. Now, astronomers say, they expect to see the supernova again in the year 2037. Will it appear to the eye? No. But it’ll appear to all of us thanks to telescopes and advanced imaging. And it’ll appear thanks to the phenomenon of curved space, which was predicted by Albert Einstein in the early 1900s. Astronomers are calling it the REQUIEM Supernova, named for an ongoing Hubble Space Telescope galaxies program.

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Between us and this distant supernova is a massive galaxy cluster, called MACS J0138.0-2155. And, as you may know, mass causes space to curve. When starlight (including supernova light) passes a massive galaxy cluster on its way to our eyes, the light has to travel on the deeply curved space around the cluster. This bending of starlight creates what astronomers call gravitational lensing. HubbleSite explained:

The massive cluster’s powerful gravity acts like an oversized celestial zoom lens, magnifying and distorting the light from the supernova and splitting it into multiple copies. Three mirror images of Supernova REQUIEM were spotted by the Hubble Space Telescope scattered in an arc-like pattern across the cluster. Each image is a snapshot of the supernova’s light at different times after the explosive event.

Now, if these scientists are patient, they can see a fourth image of the supernova about 16 years from now. Or at least that’s their prediction. It appeared on September 13, 2021, in the peer-reviewed journal Nature Astronomy. Read the entire article here.

A delay in light-arrival time

HubbleSite explained:

The three lensed supernova images, seen as tiny dots captured in [the 2016] Hubble snapshot, represent light from the explosive aftermath. The dots vary in brightness and color, which signify three different phases of the fading blast as it cooled over time.

Lead researcher Steve Rodney of the University of South Carolina in Columbia added:

This new discovery is the third example of a multiply imaged supernova for which we can actually measure the delay in arrival times. It is the most distant of the three, and the predicted delay is extraordinarily long. We will be able to come back and see the final arrival, which we predict will be in 2037, plus or minus a couple of years.

NASA said the light that Hubble captured from the MACS J0138.0-2155 cluster took about 4 billion years to reach Earth. Meanwhile, the light from Supernova REQUIEM needed an estimated 10 billion years for its journey.

A maze of dark matter

The team’s prediction of the supernova’s return appearance is based on computer models of the cluster, which, HubbleSite explained:

… describe the various paths the supernova light is taking through the maze of clumpy dark matter in the galactic grouping. Dark matter is an invisible material that comprises the bulk of the universe’s matter and is the scaffolding upon which galaxies and galaxy clusters are built.

Each magnified image takes a different route through the cluster and arrives at Earth at a different time, due, in part, to differences in the length of the pathways the supernova light followed.

Rodney compared the supernova’s various light paths to several trains:

… that leave a station at the same time, all traveling at the same speed and bound for the same location. But each train takes a different route, and the distance for each route is not the same. Because the trains travel over different track lengths across different terrain, they do not arrive at their destination at the same time.

The lensed supernova image predicted to appear in 2037, HubbleSite said, lags behind the other images of the same supernova because its light travels directly through the middle of the cluster, where the densest amount of dark matter resides. The immense mass of the cluster bends the light, producing the longer time delay. Rodney said:

This is the last one to arrive because it’s like the train that has to go deep down into a valley and climb back out again. That’s the slowest kind of trip for light.

Catching the 2037 rerun

Astronomers of course want to catch the supernova rerun 16 years from now. They said it’ll help them measure the time delays between all four supernova images. And that information will offer clues to the type of warped-space terrain the exploded star’s light had to cover. They explained:

Armed with those measurements, researchers can fine-tune the models that map out the cluster’s mass. Developing precise dark-matter maps of massive galaxy clusters is another way for astronomers to measure the universe’s expansion rate and investigate the nature of dark energy, a mysterious form of energy that works against gravity and causes the cosmos to expand at a faster rate.

The astronomers also said that spotting lensed images of supernovae will become increasingly common in the next 20 years with the launch of NASA’s Nancy Grace Roman Space Telescope and the start of operations at the Vera C. Rubin Observatory. Both telescopes will observe large swaths of the sky, which will allow them to spot dozens more multiply imaged supernovae.

Bottom line: In about the year 2037, astronomers expect to see a rerun of a supernova blast whose light traveled 10 billion years to reach us.

Source: A Gravitationally Lensed Supernova with an Observable Two-Decade Time Delay

Via HubbleSite

September 15, 2021

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