GeminiFocus January 2018 | Page 12

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