shift z = 6.3, only about 875 million years after
the Big Bang.
This result requires extremely rapid growth
of the black hole. While black holes of comparable mass have been observed — after
they have had billions of years to gradually
gain mass over cosmic history — this quasar
challenges astronomers to determine how
such a huge object could exist so early in
the history of the Universe. Mass accretion
at the Eddington limit, over most of cosmic
time, is required to reach the large mass at
this early epoch.
Color selection in optical and infrared imaging surveys identified the target as a candidate high-redshift quasar, which the team,
led by Xue-Bing Wu (Peking University, China), followed with multi-wavelength spec-
troscopic observations. The near-infrared
observations from both the Gemini NearInfrared Spectrograph (GNIRS) on Gemini
North, and the Magellan Telescope, show
the emission of ionized magnesium (Mg II),
which was used to estimate the black hole
mass from scaling relationships applicable
to quasars (Figure 13). In addition to standing out for its extreme black hole mass, this
quasar, SDSS J010013.02 + 280225.8, is exceptionally luminous, having a bolometric
luminosity greater than 1048 ergs per second;
it is in fact the most luminous one known at
z > 6. This work is published in Nature (Vol.
518, p 512).
Nancy A. Levenson is Deputy Director and Head
of Science at Gemini Observatory. Her office is at
Gemini South headquarters in La Serena, Chile.
She can be reached at: [email protected]
Figure 13.
The spectrum of quasar
SDSS J010013.02 +
280225.8, obtained
using the Gemini NearInfrared Spectrograph
combined with
observations from the
Magellan Telescope,
appears in red; gaps
are regions of low sky
transparency. The
optical spectrum (from
the Large Binocular
Telescope; black) and
noise (magenta) are also
plotted. The inset shows
the three components of
the fit to a portion of the
near-infrared emission.
The ionized magnesium
(Mg II; blue) emission
is used to estimate the
extremely large black
hole mass of 12 billion
times the mass of
the Sun.
Figure credit: Nature.
January 2016
2015 Year in Review
GeminiFocus
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