Astronomers using NASA's NASA / ESA Hubble Space Telescope have observed a galaxy in the distant regions of the universe that appears to be duplicated at least twelve times in the night sky. This unique sight, created by strong gravitational lenses, helps astronomers better understand the cosmic era known as the epoch of reionization.
This new NASA / ESA Hubble Space Telescope image shows an astronomical object whose image is multiplied by the action of strong gravitational lenses. Nicknamed Sunburst Arc, the galaxy is nearly 11 billion light-years from Earth, and has been bundled into multiple images by a huge galaxy cluster 4.6 billion light-years away.
The mass of the galaxy cluster is large enough to bend and magnify the light from the galaxy further afield. This process not only leads to a deformation of the light from the object, but also to a multiplication of the image of the lens galaxy.
In the Sunburst Arc, the lens effect resulted in at least 12 images of the galaxy, spread over four main arcs. Three of these arches can be seen in the upper right corner of the picture, while a counterarc can be seen in the lower left – partially obscured by a bright foreground star in the Milky Way.
Hubble uses these cosmic loupes to study objects in a different way, weak and too small for his extraordinarily sensitive instruments. The Sunburst Arc is no exception, though it is one of the brightest known galaxies with gravitational lenses. Hubble intercepts a dozen Sunburst Arc doppelgangers of light from the galaxy nicknamed Sunburst Arc. This bright arc is created by strong gravitational lenses and consists of at least four copies of the image of a single galaxy. The galaxy with lenses is about 11 billion light-years away. Photo credits: ESA / Hubble, NASA, Rivera-Thorsen et al.
The lens makes different images of the Sunburst Arc between 10 and 30 times brighter. In this way, Hubble can view structures as small as 520 light years – a rare detail observation for a distant object. This is somewhat comparable to star forming regions in galaxies in the local universe that allow astronomers to study the galaxy and its surroundings in detail.
Hubble's observations showed that the Sunburst Arc is analogous to galaxies that existed at a much earlier time in the history of the Universe: a period known as the epoch of Reionization – an era only 150 million years after The big bang started.
The epoch of reionization was a key era in the early universe that filled the "dark age," the epoch of the first stars, when the universe was dark and filled with neutral hydrogen. As soon as the first stars formed, they emitted light and generated the energetic photons required to ionize the neutral hydrogen.
This transformed intergalactic matter into the most ionized form in which it exists today. However, to ionize intergalactic hydrogen, the energetic radiation of these early stars would have to escape their host galaxies without first being absorbed by interstellar matter. So far, only a small number of galaxies have been found that "lick" high-energy photons into space. How this light escaped from the early galaxies remains a mystery.
The analysis of the sunburst arc helps astronomers expand the puzzle. It seems that at least some photons can leave the galaxy in a gas-rich, neutral medium through narrow channels. This is the first observation of a long theorized process. It is unlikely that this process is the main mechanism for the reionization of the universe, but it could well have been a decisive boost.
The paper in which these observations are sketched appears on November 8, 2019 in Science .
Image: Hubble's distorted view of the universe
T. E. Rivera-Thorsen el al., "Gravitational lenses reveal ionizing ultraviolet photons escaping from a distant galaxy," Science (2019). science.sciencemag.org/cgi/doi… 1126 / science.aaw0978
Hubble captures a dozen Sunburst Arc lookalikes (2019, November 7)
retrieved on November 8, 2019
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