Jan 10 2019
A crucial fingerprint of an extremely distant quasar, observed from Gemini Observatory, will now enable astronomers to sample light produced from the dawn of time.
A number of large telescopes were used to observe quasar J0439+1634 in the optical and infrared light. The 6.5 m MMT Telescope was used to discovery this distant quasar. It and the 10 m Keck-I Telescope obtained a sensitive spectrum of the quasar in optical light. The 8.1 m Gemini Telescope obtained an infrared spectrum that accurately determined the quasar distance and the mass of its powerful black hole. The 2x8.4 m Large Binocular Telescope captured an adaptive optics corrected image that suggests the quasar is lensed, later confirmed by the sharper Hubble image. (Image credit: Feige Wang (UCSB), Xiaohui Fan (University of Arizona)
This intensive glimpse into time and space was experienced by astronomers due to an inconspicuous foreground galaxy acting as a gravitational lens, which enlarged the ancient light of quasar. The observations from Gemini Observatory provide the crucial pieces of the puzzle in establishing this object as the brightest appearing quasar that emerged relatively early in the Universe’s history. The discovery raises hopes that more similar sources will be identified.
Some of the very first cosmic light started a long voyage via the expanding Universe, much before the cosmos reached its billionth birthday. One specific light beam, from an energetic source known as a quasar, serendipitously passed close to an intervening galaxy, the gravity of which bent and enlarged the light from quasar and refocused it in the direction, enabling telescopes like Gemini North to explore the quasar in a more detailed manner.
“If it weren’t for this makeshift cosmic telescope, the quasar’s light would appear about 50 times dimmer,” stated Xiaohui Fan of the University of Arizona who headed the research. “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.”
By filling a crucial hole in the data, the Gemini observations were able to offer important pieces of the puzzle. The Gemini Near-InfraRed Spectrograph (GNIRS) was utilized by the Gemini North telescope on Maunakea, Hawaii to dissect a considerable swath of the infrared portion of the light’s spectrum. Tell-tale signature of magnesium present in the Gemini data is important for establishing how far humans are looking back in time. In addition, the Gemini observations made it possible to determine the mass of the black hole that powers the quasar.
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.
Feige Wang, University of California, Santa Barbara
Wang is also a member of the discovery team.
That picture showed that the quasar is situated quite far back in space and time—shortly after the so-called Epoch of Reionization—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. Prior to this, no stars, quasars, or galaxies had been formed, until objects like this appeared like candles in the dark.
Jinyi Yang, University of Arizona
Yang is another member of the discovery team.
The foreground galaxy that improves the humans’ view of the quasar is particularly dim, which is rather unexpected. “If this galaxy were much brighter, we wouldn’t have been able to differentiate it from the quasar,” explained Fan and further added that this discovery will transform the way astronomers search for lensed quasars in the coming days and may considerably boost the number of lensed quasar discoveries. Conversely, as Fan proposed, “We don’t expect to find many quasars brighter than this one in the whole observable Universe.”
Moreover, the strong brilliance of the quasar, called J0439+1634 (J0439+1634 for short), indicates that it is driven by a supermassive black hole at the core of a young forming galaxy. Through the wide appearance of the crucial magnesium fingerprint captured by Gemini, astronomers were able to determine the supermassive black hole of the quasar mass at 700 million times that of the Sun. Most probably, a sizable flattened disk of gas and dust surrounds the supermassive black hole. It is believed that this torus of matter—called an accretion disk— feeds the black hole powerhouse by continually spiraling inward. Observations made at submillimeter wavelengths using the James Clerk Maxwell Telescope on Maunakea, indicate that the black hole is accreting gas and may also be triggering the birth of stars at an extraordinary rate—which seems to be around 10,000 stars every year; in contrast, the Milky Way Galaxy forms one star every year. Yet, the exact rate of the formation of stars could be considerably lower due to the boosting effect of gravitational lensing.
Quasars are quite energetic sources fueled by massive black holes believed to have existed in the very first galaxies to occur in the Universe. Quasars, due to their distance and brightness, offer an extraordinary view into the conditions in the early Universe. A redshift of 6.51 in this quasar translates to a distance of 12.8 billion light years, and the quasar also seems to shine with an integrated light of approximately 600 trillion Suns, increased by the gravitational lensing magnification. The foreground galaxy, which bent the light of the quasar, is roughly half that distance away, at just 6 billion light years from the earth.
Fan’s group chose J0439+1634 as an extremely distant quasar candidate depending on optical data from a number of sources: the United Kingdom Infra-Red Telescope Hemisphere Survey (performed on Maunakea, Hawaii), the Panoramic Survey Telescope and Rapid Response System1 (Pan-STARRS1; operated by the University of Hawaii’s Institute for Astronomy), and the Wide-field Infrared Survey Explorer (WISE) space telescope archive of NASA.
The initial follow-up spectroscopic observations, which were performed at the Multi-Mirror Telescope in Arizona, demonstrated the object as a high-redshift quasar. The MMT’s finding was confirmed by subsequent observations with the Gemini North and Keck I telescopes in Hawaii, leading to Gemini’s detection of the vital magnesium fingerprint—the key to solving the incredible distance of the quasar. Conversely, the quasar and the foreground lensing galaxy seemed to be so close that it became impossible to isolate them with images captured from the ground owing to a blurring of the atmosphere on Earth. The exquisitely vivid images taken by the Hubble Space Telescope revealed that a faint lensing galaxy splits the quasar image into three parts.
The quasar is ready for future inspection. Furthermore, astronomers intend to apply the Atacama Large Millimeter/submillimeter Array, and then NASA’s James Webb Space Telescope, to peer within 150 light-years of the black hole and directly identify the effect of the black hole’s gravity on gas motion and on the formation of stars in its vicinity. Any upcoming discoveries of very distant quasars, for example, J0439+1634 will continue to provide knowledge to astronomers about the growth and the chemical environment of large black holes in the early Universe.