MACS 1423-z7p64 is a

galaxy A galaxy is a system of stars, stellar remnants, interstellar gas, dust, dark matter, bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System. ...

listed in the MAssive Cluster Survey (MACS), and announced on 10 April 2017 in the journal ''Nature Astronomy'', as being the most distant source of reionization known at this time, with a

redshift In physics, a redshift is an increase in the wavelength, and corresponding decrease in the frequency and photon energy, of electromagnetic radiation (such as light). The opposite change, a decrease in wavelength and simultaneous increase in f ...

z = 7.640 ± 0.001 (lookback time >13.1 Gyr).

Discovery

MACS 1423-z7p64 was discovered through

gravitational lensing A gravitational lens is a distribution of matter (such as a galaxy cluster, cluster of galaxies) between a distant light source and an observer that is capable of bending the light from the source as the light travels toward the observer. This ...

by MACS J1423.8+2404 (z = 0.545), a cluster that magnified its brightness by a factor of 10. To identify the galaxy, the astronomers used the slitless

grism A grism (also called a grating prism) is a combination of a prism and grating arranged so that light at a chosen central wavelength passes straight through. The advantage of this arrangement is that one and the same camera can be used both for imag ...

spectrograph An optical spectrometer (spectrophotometer, spectrograph or spectroscope) is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify mate ...

of the Wide Field Infrared Survey Telescope on the

Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versa ...

, and to determine its distance the Multi-Object Spectrometer for Infra-Red Exploration (MOSFIRE) detector of the

Keck Observatory The W. M. Keck Observatory is an astronomical observatory with two telescopes at an elevation of 4,145 meters (13,600 ft) near the summit of Mauna Kea in the U.S. state of Hawaii. Both telescopes have aperture primary mirrors, and when comp ...

. Nature received the paper on 27 October 2016.)

Importance

With a redshift z = 7.640 ± 0.001, and being an

order of magnitude An order of magnitude is an approximation of the logarithm of a value relative to some contextually understood reference value, usually 10, interpreted as the base of the logarithm and the representative of values of magnitude one. Logarithmic dis ...

lower in intensity than the four other Lyman-α emitters currently known at z > 7.5, it is probably the most distant representative source of reionization found to date. This is from a time when the universe was around 700 million years old.

References

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External links

Nature article
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doi reference
Boötes Galaxies Big Bang