The emergence of quasars at the end of the astronomical 鈥渄ark age鈥� that enshrouded the early Universe has been identified by astronomers.
Researchers at Arizona State University in Phoenix, US, used the Hubble Space Telescope to obtain the image, which shows about 30 of the oldest quasars ever spotted. Quasars are extremely bright galaxies that are thought to draw their power from supermassive black holes at their core.
鈥淲ith the Hubble Telescope, we can now see back to the epoch when stars in young galaxies began to shine in significant numbers, concluding the cosmic 鈥榙ark ages鈥� about 13 billion years ago,鈥� said Haojing Yan, of Arizona State University.
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Another team at Arizona University in Tucson, US, led by Xiaohui Fan, has also found the most distant quasar yet discovered. The quasar has a redshift of 6.4, beating the previous record of 6.28. The researchers used the Sloan Digital Sky Survey, an international collaboration of telescopes with headquarters in New Mexico.
First light
Cosmologists think that by about 300,000 years after the Big Bang, the Universe had cooled sufficiently for protons and electrons to combine into neutral hydrogen atoms. In sufficient quantity, this atomic hydrogen would have blocked the light in the early Universe, causing an astronomical dark age.
But as the number of new stars grew, their ultraviolet light would have re-ionised the neutral hydrogen clouds, allowing light pass. The new found quasars are some of the first objects to be seen emerging from the early Universe鈥檚 dark age, which ended roughly one million years after the Big Bang.
Patrick Leahy, at the UK鈥檚 Jodrell Bank Observatory, says it is currently unclear whether quasars or normal galaxies caused this re-ionisation. 鈥淏ut this kind of research is going to help answer that question and that feeds right back into fundamental cosmology,鈥� Leahy told 快猫短视频.
The two research teams presented their work at the American Astronomical Society Meeting in Seattle, US.