Near Infrared, High Resolution Observations Using Laser Guide Adaptive Optics System

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This project research aimed at developing newly a "laser guided adaptive optics system" for the 8.2m Subaru Telescope at Mauna Kea, Hawaii Island, operated by National Astronomical Observatory of Japan to promote high resolution, near infrared observations of distant galaxies.The new adaptive optics system developed comprises of a 188-element wavefront sensor, a 188-driving element deformable mirror, and the control system. The system measures a bright guide star in real time to evaluate variation of the wavefront error produced by the turbulent atmosphere and drives the deformable mirror to compensate those errors in real time to achieve diffraction limited imaging capability of the Subaru Telescope. The first light experiment conducted in October 2006 has shown that a stellar image of 0.6 arcsec under the atmospheric turbulence can be squeezed into a 0.06 arcsec image size, 10times smaller than that obtained without using the current system. This helps much in improving the spatial r … More esolution and the sensitivity of observations.Another key system developed is a laser guide star generating system. It comprises of an all solid-state 4W sum-frequency laser developed in collaboration with the RIKEN, a photonic crystal optical fiber to transmit the high power laser to the 50cm diameter laser launching telescope mounted at the top end of the Subaru Telescope. First laser launching experiment carried out in October 2006 also proved successful in generating an artificial laser guide star in the sodium layer at 90km above the ground where the laser beam tuned at 589nm sodium D2 line excites the sodium atoms and causes emission of sodium light bright enough to measure the atmospheric turbulence.In the meantime the current PI found a galaxy at redshift 7.0, which turned out to be the most distant (and hence the earliest in the cosmic history) galaxy. The project team aims to make high resolution imaging observations of these galaxies to unrabel the formation and evolution of galaxies in the early universe. Less