black hole at redshift 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.
Figure 3.
The spectrum
of quasar
SDSSJ010013.02 +
280225.8, obtained
using the Gemini
Near-Infrared
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.
10
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-
GeminiFocus
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. In addition to standing out for its
extreme black hole mass, this quasar, SDSS
J010013.02 280225.8, is exceptionally lu+
minous, 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]
April 2015