photometry from the Palomar
Transient Factory — a fully-auto-
mated, wide-field survey of the
optical transient sky — indicat-
ed multiple periodic variations
on time scales with ratios consis-
tent with theoretical models of
binary supermassive black hole
(SMBH) systems. Although other
possibilities exist, if this is the
correct explanation, each black
hole would have a mass of about
100 million times that of the Sun.
If the extreme velocities revealed by the
Gemini spectra and the observed photomet-
ric variability arise from the orbital motions
of two SMBHs with their associated accretion
disks, then J0045+41 must be radiating grav-
itational waves. The researchers estimate the
time for the two SMBHs to lose orbital energy
as a result of gravitational radiation and col-
lide could be anywhere from about 350 years
to more than 350,000 years, depending on
the exact masses involved.
Gravitational waves from merging super-
massive black holes have frequencies too
low for detection by facilities such as LIGO
and Virgo. However, they should be detect-
able by a different technique that involves
monitoring pulsars for correlated signals
in their pulse arrival times. Objects such as
J0045 + 41 provide confidence that such
pulsar timing experiments will eventually
succeed.
A Quasar in the Epoch of
Reionization
Quasars are among the most energetic phe-
nomena observed in the Universe. They are
believed to be powered by the accretion of
material by supermassive black holes during
the active phase of their growth. The epoch
of peak quasar activity, and therefore the
time of the most rapid supermassive black
January 2018 / 2017 Year in Review
hole growth, occurred about 10 billion years
ago. However, quasars have been observed
at earlier cosmic times, and a new record
holder has now been established using data
from Gemini and several other observatories.
A team of astronomers led by Eduardo Ba-
ñados at the Carnegie Institution for Sci-
ence discovered the record-breaking quasar,
known as J1342+0928, in observations from
the Dark Energy Camera on the Blanco 4-m
telescope at Cerro Tololo, NASA’s Wide-field
Infrared Survey Explorer (AllWISE), and the
United Kingdom Infrared Telescope on Mau-
nakea. The quasar is more than 13 billion
light years from the Milky Way and is pow-
ered by a supermassive black hole with an
estimated mass 800 million times greater
than that of our Sun. At this distance, the
Universe was only about 5% of its current
age, or about 690 million years old. “That’s
not a lot of time for stuff to happen,” com-
mented Gemini’s Peter Michaud. “That’s why
it’s such a mystery.”
Figure 2.
GMOS optical spectrum
of J0045+41, a distant
AGN previously thought
to be a binary star
system in the disk of
the Andromeda Galaxy.
Emission lines from
various elements are
identified, including the
very strong Hα emission
due to atomic hydrogen.
The broad range of
wavelengths spanned
by this emission “line”
indicates an enormous
spread in velocity that
may be caused by a pair
of supermassive black
holes orbiting each other
in a binary system.
According to Bañados, spectroscopic data
from the Gemini Near-InfraRed Spectrom-
eter (GNIRS) on Gemini North were key in
determining the mass for the supermassive
black hole. “We dove deep into the infrared
light spectrum at Gemini and probed the
magnesium lines,” said Bañados. These mag-
nesium lines are emitted at ultraviolet wave-
lengths, but at such large distances, they
GeminiFocus
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