By Chris Skeldon 
NASA, ESA, STScI, Wenley Chen, Patrick Kelly
Over the past few decades, we have greatly improved monitoring of supernovae as they occur. Orbiting telescopes can now capture the high-energy photons emitted and know their source, allowing other telescopes to make quick observations. Some automated scanning telescopes image the same parts of the sky night after night, allowing image-analysis programs to identify new light sources.
NASA, ESA, STScI, Wenley Chen, Patrick Kelly
But sometimes, luck still plays a role. Such is the case with the 2010 Hubble image, in which the image also captured a supernova. But due to the gravitational lensing, the single event appeared at three different locations within Hubble’s field of view. Thanks to quirks about how this lens works, all three locations were captured differently. times After the star exploded, it allowed researchers to reconstruct the time course after the supernova, even though it was observed more than a decade ago.
I will need it in three copies
The new work is based on searching Hubble’s archives for old images that capture fleeting events: something found in some images on a website but not others. In this case, the researchers were looking specifically for events that were modified by gravity. This occurs when a massive frontal object distorts space in such a way that it creates a lens effect, bending the path of light that originates behind the lens from Earth’s perspective.
Because gravitational lenses aren’t nearly as fine-tuned as the ones we make, they often create strange distortions of background objects, or in many cases, magnify them in multiple locations. This appears to be what happened here, as there are three distinct images of a transient event within Hubble’s field of view. Other images of this region indicate that the site coincides with a galaxy; Analysis of the light from this galaxy indicates a redshift indicating that we are looking at it as it was more than 11 billion years ago.
Given the relative brightness, sudden appearance, and location within the galaxy, this event is likely to be a supernova. At this distance, many of the high-energy photons produced in a supernova were shifted to the visible region of the spectrum, allowing Hubble to visualize them.
To understand more about the background supernova, the team discovered how the lens works. It was created by a group of galaxies called Abell 370, and assigning the mass of this cluster has allowed us to estimate the properties of the lens that created it. The resulting lens model indicated that there were already four images of the galaxy, but no image was enlarged enough to be visible; The three that were visible were magnified by factors of four, six and eight.
But the model further indicated that the lens also affected the timing of the light’s arrival. Gravitational lenses push light along paths between the source and the observer of varying lengths. Because light moves at a constant speed, these different lengths mean that light takes a different time to get here. Under the conditions we are familiar with, this is an imperceptibly small difference. But on cosmic scales, it makes a big difference.
Again, using a lens model, the researchers estimated potential delays. Compared to the older image, the first and second images were delayed by 2.4 days and the third by 7.7 days, with an uncertainty of about 1 day in all estimates. In other words, a single image of the area produced what was essentially a period of time of a few days.
what was that
When comparing the Hubble data with the different classes of supernovae we have imaged in the modern universe, they are likely caused by the explosion of a red or blue giant star. The detailed features of the event were best suited to a red giant, which was about 500 times the size of the Sun at the time of its explosion.
The intensity of light at different wavelengths provides an indication of the temperature of the explosion. The first image indicates that it was about 100,000 K, indicating that we were looking at it just six hours after it exploded. The last image of the lens shows that the debris has already cooled to 10,000 K during the eight days between the two different images.
Of course, there is a newer and closer supernova that we can study in more detail if we want to understand the processes that lead to the explosion of a massive star. If we can find more supernovae of this type in the distant past, we will be able to infer things about how many stars there were earlier in the history of the universe. But for now, this is the second time we’ve found it. The authors of the paper they describe make an effort to draw some conclusions, but it is clear that those conclusions would involve a high degree of uncertainty.
So in many ways, this doesn’t help us make much progress in understanding the universe. But as an example of the strange consequences of the forces that govern the behavior of the universe, this is astounding.
nature of mood2022. DOI: 10.1038 / s41586-022-05252-5 🇧🇷About DOIs🇧🇷