[P-EM11] Exoplanet

[PEM11-10] PRime-focus Infrared Microlensing Experiment (PRIME)

*Hibiki Yama¹, Daisuke Suzuki¹, Shota Miyazaki², Rintaro Kirikawa¹, Iona Kondo¹, Yuki Hirao¹, Naoki Koshimoto^3,4, Takahiro Sumi¹ (1.Department of Earth and Space Science, Osaka University, 2.Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3.Laboratory for Exoplanets and Stellar Astrophycis, NASA Goddard Space Flight Center, 4.Department of Astronomy, University of Maryland)

Keywords:The PRIME telescope, Near-infrared, Optical alignment

A lot of exoplanets discovered by transit and doppler surveys have difference character from planets of our solar system. These planets are orbiting inner snow line at which liquid water become ice and we don't know character and distribution of cool exoplanets orbiting outer snow line. The characterization and distribution of cool planets should be clarified in order to reveal planetary formation, and only then we can know that our solar system is general or not. The gravitational microlensing method is only method to detect cool and low-mass exoplanets orbiting outer snow line. MOA, OGLE and KMTNet have discovered ~100 exoplanets by the gravitational microlensing method.
The PRime-focus Infrared Microlensing Experiment (PRIME) telescope is a prime focus near infrared (NIR) telescope with a wide field of view (FOV). NIR can mitigate the dust extinction so that the PRIME telescope can observe toward the galactic bulge and center which are not accessible with MOA and other groups. For the first time in the world, the PRIME telescope will conduct the survey by the gravitational microlensing method toward the galactic bulge and center at NIR, with the wide FOV and in high cadence. The galactic bulge surveys by the PRIME telescope is expected to discover ~10 times more exoplanets than the surveys by MOA, to put further constraint on the cool exoplanet mass function of bound and unbound exoplanets, to optimize the Roman Galactic Bulge Time Domain Survey field by providing the microlensing event rate toward the inner bulge, to find the isolated black hole candidates, to study variable stars in the bulge, to give a new constraint on the structure of the galactic center and so on. In addition, when the bulge is below the horizon, the PRIME telescope will be used to observe transient objects, such as gravitational wave events, super novae, transiting planets, etc. In the future, the South Africa Near-infrared Doppler (SAND) will be installed to the PRIME telescope so that the PRIME telescope will also surveys exoplanets by the radial velocity method.
The PRIME telescope was installed at Sutherland observatory, SAAO in August, 2022. PRIME-Cam which is the primary imaging instrument of the PRIME telescope was installed to the PRIME telescope in October, 2022. We conducted some optical alignments during the installation of telescope and PRIME-Cam. We achieved the FOV average Hartmann constant of 0.295". The PRIME telescope is currently in commissioning phase and the galactic bulge time domain survey is expected to start in 2023. In this presentation, the optical alignment for the PRIME telescope and progress of PRIME will be made.