the heaviest elements in the periodic table.”
(See excerpts from a Harvard University in-
terview of Berger in the online version of the
release).
Leo Singer, of NASA’s Goddard Space Flight
Center, and a collaborator with Kasliwal in the
GROWTH group adds, “Continued monitor-
ing over many subsequent nights at Gemini
allowed us to paint a stunning infrared por-
trait of neutron star mergers.” In agreement
with other researchers, the GROWTH team
concluded that these neutron-neutron star
mergers are primary sites for the production
of elements heavier than iron. According to
Kasliwal, “Each of these events is capable of
forging over ten thousand times the Earth’s
mass in heavy elements such as gold and
platinum — cosmic bling!”
Folding the Gemini data into observations
from radio to X-rays, Eleonora Troja, of the
University of Maryland, joined Berger in pre-
senting her findings at the D.C. press confer-
ence. Troja’s team focused on the time evolu-
tion of the event starting with the very early
Gemini observations in the optical (visible)
part of the spectrum.
“It surprised me very much when I saw how
bright this was in the optical,” says Troja. “The
question we asked is if this really was a so-
called kilonova when a neutron pair merge,
or some kind of exotic transient or super-
nova making fun of us!” Troja and her team
concluded from the optical spectra that this
was not like anything they had seen before.
“We are just beginning our effort to model
and understand these explosions and the
physics behind them,” says team member
Brad Cenko from NASA’s Goddard Space
Flight Center. “We need to add to our mod-
els an outflow of slower and more transpar-
ent material to account for the bright optical
light component. This outflow is likely re-
sponsible for the production of less precious
metals, such as silver and tin.”
October 2017
“The joint detection of light and gravita-
tional waves from cosmic sources is one of
the holy grails of present-day astronomy,”
exclaims Marcelle Soares-Santos (Fermi Na-
tional Accelerator Laboratory), the first au-
thor of the paper from Berger’s team that
reports their discovery of the optical coun-
terpart. Both signals, light and gravitational
waves, contribute unique information about
extreme astrophysical events. As Soares-
Santos explains, “Gravitational waves tell us
about the motions and masses of the neu-
tron stars, and light reveals the astrophys-
ics of the event — what happened exactly
as the stars merged, the mass of heavy ele-
ments produced.”
“This is a game-changer for astrophysics,”
says Andy Howell who also spoke at the D.C.
press conference. Howell leads the super-
nova group at the Las Cumbres Observatory
and is a coauthor on a paper in The Astro-
physical Journal Letters based on the Gem-
ini data. He adds, “One hundred years after
Einstein theorized gravitational waves we’ve
seen them and traced them back to their
source to find an explosion with new physics
of the kind we only dreamed about before.”
“It is tremendously exciting to experience a
rare event that transforms our understand-
ing of the workings of the Universe,” says
France A. Córdova, director of the National
Science Foundation (NSF), which funds LIGO
and a majority of the international Gemini
Observatory. “This discovery realizes a long-
standing goal many of us have had, that is, to
simultaneously observe rare cosmic events
using both traditional as well as gravitation-
al-wave observatories. Only through NSF’s
four-decade investment in gravitational-
wave observatories, coupled with telescopes
that observe from radio to gamma-ray wave-
lengths, are we able to expand our opportu-
nities to detect new cosmic phenomena and
piece together a fresh narrative of the phys-
ics of stars in their death throes.”
GeminiFocus
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