GeminiFocus October 2017 | Page 11

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 9