1.4 gigahertz. Searches for a counterpart at
the location of the radio source in publicly
available optical and infrared sky surveys re-
vealed nothing. Consequently, the source
was targeted, blindly, for deep spectroscopy
at Gemini.
The study was led by graduate students Aa-
yush Saxena (Leiden Observatory, the Neth-
erlands) and Murilo Marinello (Observatório
Nacional, Brazil), and the observations were
obtained through Brazil’s participation in
Gemini. The relatively small size of the radio
emission region in TGSS J1530 + 1049 indi-
cates that it is quite young, as expected at
such early times. Thus, the galaxy is still in
the process of assembling. Because the ra-
dio emission is believed to be powered by
a supermassive black hole, this discovery
indicates that black holes can grow to enor-
mous masses very quickly in the early Uni-
verse, since the black hole must have been
in place long enough for the jet to grow to
its observed size.
The measured redshift of TGSS J1530 + 1049
places this galaxy near the end of the Epoch
of Reionization, when the majority of the
neutral hydrogen in the Universe was ion-
ized by high-energy photons from young
stars and perhaps other sources of radia-
tion. The question of whether or not active
galactic nuclei, including quasars and radio
galaxies, may have contributed to the reion-
ization remains controversial. “The Epoch
of Reionization is very important in cos-
mology, but it is still not well understood,”
said Roderik Overzier, also of Brazil’s Obser-
vatório Nacional, and the Principal Investi-
gator of the Gemini program. “Distant radio
galaxies can be used as tools to find out
more about this period.”
The research has been published in Monthly
Notices of the Royal Astronomical Society.
JULY 2018
Hydrogen Sulfide in the Cloud
Tops of Uranus
Despite decades of observations, including
the landmark visit by Voyager 2 in 1986, the
question of whether ammonia (NH 3 ) or hy-
drogen sulfide (H 2 S) dominates the visible
cloud deck on Uranus has remained unre-
solved. However, recent observations ob-
tained with the Near-infrared Integral Field
Spectrometer (NIFS) on Gemini North con-
firm that hydrogen sulfide, a colorless gas
with the distinctive odor of rotten eggs, is a
key component of those clouds. The study
reporting the long-sought evidence is led
by Patrick Irwin of Oxford University and
appears in the April 23rd issue of Nature As-
tronomy.
The visible cloud deck, which forms by con-
densation of the gases within the atmo-
sphere of a planet, provides information on
the composition of the overall atmospheric
reservoir. The NIFS observations, illustrated
in Figure 8, sample reflected sunlight from
the region immediately above the main
visible cloud layer in Uranus’s atmosphere.
“The lines we were trying to detect were just
barely there, but thanks to the sensitivity
of NIFS on Gemini, we have the fingerprint
which caught the culprit,” said Irwin.
The detection of hydrogen sulfide in the
clouds of Uranus contrasts with the inner
gas giants, Jupiter and Saturn, where the
bulk of the upper clouds are comprised of
ammonia ice, and no hydrogen sulfide is
detectable. These differences were likely im-
printed within the proto-solar nebula, where
the balance between the amounts of nitro-
gen and sulphur was determined by the
temperature, and therefore the location, of
a given planet’s formation.
As reported widely in the media, in establish-
ing a lower limit to the amount of H 2 S in the
30
GeminiFocus
January 2019 / 2018 Year in Review