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Gravitational Lensing Magnifies Light of Quasar from Extremely Distant Space and Time

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Observations from Gemini Observatory have identified a key fingerprint of an extremely distant quasar, allowing astronomers to sample light emitted from the beginning of time. Astronomers happened upon this deep glimpse into space and time thanks to a foreground galaxy acting as a gravitational lens, which magnified the quasar’s ancient light. The Gemini observations provide critical pieces of the puzzle in confirming this object as the brightest appearing quasar so early in the history of the universe.

Far distant quasar, Gemini Observatory.

This is a Hubble Space Telescope image of a very distant quasar (at right) that has been brightened and split into three images by the effects of the gravitational field of a foreground galaxy (left). The crosses mark the centers of each quasar image. The quasar would have gone undetected if not for the power of gravitational lensing. The image shows the quasar as it looked 12.8 billion years ago — only about 1 billion years after the Big Bang. The quasar appears red because its blue light has been absorbed by diffuse gas in intergalactic space. By comparison, the foreground galaxy has bluer starlight light. Courtesy of NASA, ESA, Xiaohui Fan (University of Arizona).

“If it weren’t for this makeshift cosmic telescope, the quasar’s light would appear about 50 times dimmer,” said Xiaohui Fan of the University of Arizona, who led the study. “This discovery demonstrates that strongly gravitationally lensed quasars do exist despite the fact that we’ve been looking for over 20 years and not found any others this far back in time.”

The Gemini North telescope on Maunakea, Hawaii, utilized the Gemini Near-InfraRed Spectrograph (GNIRS) to dissect a significant swath of the IR part of the light’s spectrum. “When we combined the Gemini data with observations from multiple observatories on Maunakea, the Hubble Space Telescope, and other observatories around the world, we were able to paint a complete picture of the quasar and the intervening galaxy,” said Feige Wang of the University of California, Santa Barbara.

That picture reveals that the quasar is located extremely far back in time and space, when the very first light emerged from the Big Bang. “This is one of the first sources to shine as the universe emerged from the cosmic dark ages,” said Jinyi Yang of the University of Arizona. “Prior to this, no stars, quasars, or galaxies had been formed, until objects like this appeared like candles in the dark.”

Far distant quasar, Gemini Observatory.

The light from quasar J0439+1634, some 12.8 billion light years away, passes close to a faint galaxy that is about 6 billion light years away. The gravity of this foreground galaxy warps the space around it, according Einstein’s theory of general relativity. This bends the light like an optical lens, magnifies the quasar image by a factor of 50, while at the same time splits the quasar image in three. Both the foreground galaxy and the multiple-imaged quasar are captured by the high-resolution image of the Hubble Space Telescope. Ground-based telescopes, including the MMT, Keck, Gemini, LBT, and JCMT, are used to observe this object in optical, IR, and sub-millimeter wavelengths to measure its distance, and to characterize its central black hole and host galaxy. Courtesy of NASA, ESA, Xiaohui Fan (University of Arizona).

Fan’s team selected the quasar known as J0439+1634 as a very distant quasar candidate based on optical data from several sources: the Panoramic Survey Telescope and Rapid Response System operated by the University of Hawaii’s Institute for Astronomy, the United Kingdom Infra-Red Telescope Hemisphere Survey (conducted on Maunakea, Hawaii), and NASA’s Wide-Field Infrared Survey Explorer (WISE) space telescope archive.

The first follow-up spectroscopic observations, conducted at the Multi-Mirror Telescope (MMT) in Arizona, confirmed the object as a high-redshift quasar. Subsequent observations with the Gemini North and Keck I telescopes in Hawaii confirmed the MMT’s finding and led to Gemini’s detection of the crucial magnesium fingerprint — the key to nailing down the quasar’s fantastic distance.

Fan said that this finding will change the way astronomers look for lensed quasars in the future and could significantly increase the number of lensed quasar discoveries. However, he said, “We don’t expect to find many quasars brighter than this one in the whole observable universe.”

The research was published in The Astrophysical Journal Letters (https://doi.org/10.3847/2041-8213/aaeffe). For more information on this discovery also visit the Gemini Observatory website


This artist's impression shows how the quasar, cataloged as J043947.08+163415.7 (J0439+1634 for short), may look close up. This object could hold the record of being the brightest in the early universe for some time, making it a unique object for follow-up studies. Courtesy of ESA/Hubble, NASA, M. Kornmesser.

 


Photonics Handbook
GLOSSARY
astronomy
The scientific observation of celestial radiation that has reached the vicinity of Earth, and the interpretation of these observations to determine the characteristics of the extraterrestrial bodies and phenomena that have emitted the radiation.
telescope
An afocal optical device made up of lenses or mirrors, usually with a magnification greater than unity, that renders distant objects more distinct, by enlarging their images on the retina.
spectrograph
An optical instrument for forming the spectrum of a light source and recording it on a film. The dispersing medium may be a prism or a diffraction grating. A concave grating requires no other means to form a sharp image of the slit on the film, but a plane grating or a prism requires auxiliary lenses or concave mirrors to act as image-forming means in addition to the dispersing element. Refracting prisms can be used only in parallel light, so a collimating lens is required before the prism and...
quasar
A contraction of quasi stellar. An astronomical object that appears to be a star but has a different, larger redshift.
Research & Technologyeducationastronomyimagingtelescopegravitational lensingGemini ObservatoryspectrographQuasarvery distant quasarHubble Space TelescopeNASAopticsmirrors

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