time for the two SMBHs to lose
orbital energy as a result of gravi-
tational radiation and collide
could be anywhere from about
350 years to more than 350,000
years, depending on the exact
masses involved.
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.
ground. In order to determine the true na-
ture of J0045+41, the team submitted a
Fast Turnaround proposal to use the Gemini
Multi-Object Spectrograph (GMOS) on Gem-
ini North.
As reported in The Astrophysical Journal,
the GMOS spectrum conclusively showed
that J0045+41 is an AGN in a galaxy at a dis-
tance of 2.6 billion light years, more than a
thousand times farther away than the Milky
Way’s majestic neighbor (Figure 2). And
careful modeling of the broad hydrogen
emission lines seen in the object’s spectrum
turned up something even more surprising:
evidence for two distinct massive objects
orbiting each other with an extraordinary
velocity of at least 4,800 km/s. In addition,
photometry from the Palomar Transient Fac-
tory — a fully-automated, wide-field survey
of the optical transient sky — indicated mul-
tiple periodic variations on time scales with
ratios consistent 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
10
GeminiFocus
Gravitational waves from merging
supermassive black holes have
frequencies too low for detection
by facilities such as LIGO and Vir-
go. However, they should be detectable by a
different technique that involves monitoring
pulsars for correlated signals in their pulse
arrival times. Objects such as J0045 + 41 pro-
vide confidence that such pulsar timing ex-
periments 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
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
January 2018