Current Science at NOAO
The Most Distant Quasar Known
Daniel Stern, NASA/JPL
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The image shows the area of sky where the quasar was detected in red and near-infrared light. |
March, 2000 | Astronomer Daniel Stern and collaborators discovered the most distant quasar known in the Universe, a quasar at a redshift
of z=5.5. The discovery was made using the National Science Foundation's 4-m Mayall Telescope at Kitt Peak , as well as the Palomar 200" and the 10-m Keck Telescope.
The quasar was discovered as part of a deep imaging survey to probe
the first billion years of galaxy formation in the Universe.
Imaging surveys are among the most useful tools for probing the
evolution of galaxies and quasars. Wide-field, "shallow'' surveys
such as the Palomar Digital Sky Surveys and Sloan Digital Sky Survey
have been very successful at identifying bright, high-redshift
quasars at redshifts between z=4 and z=5. Deep, smaller field surveys
probe star-forming galaxies at earlier cosmic epoch.
The newly discovered quasar, named RD300, was the brightest candidate
from their current survey area covering 74 square arcminutes of sky.
The quasar is not seen in images taken in red light, but is faintly
detected at longer wavelengths in the near-infrared.
The image shows the area of sky where the quasar was detected in
red and near-infrared light.
A spectrum obtained on the Keck II Telescope confirmed that the
object is an extremely high-redshift quasar. The spectrum shows
broad emission from hydrogen Lyman-alpha and ionized nitrogen,
as well as absorptions from intervening material at lower redshift.
Surprisingly, RD300, is not one of the intrinsically brightest
quasars known. Its actuall luminosity is comparble to lower
luminosity quasars in the more-nearby Universe. If the distribution
of quasar luminosities is the same at the high redshift of RD300
as it is at lower redshift, then faint, distant quasars may be
more common than expected.
For more information see:
NOAO Newsletter
JPL Press Release
JPL Press Release Images
Redshifts of Quasi-Stellar Objects
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