Improvement of the Target Sensitivity in DECIGO by Optimizing its Parameters for Quantum Noise Including the Effect of Diffraction Loss

Galaxies

Izumi Watanabe¹  Seiji Kawamura¹  Taigen Morimoto¹  Takeo Naito¹  Tomohiro Ishikawa¹  Rika Yamada¹  Shoki Iwaguchi¹  Masaki Ando²  Yuta Michimura²  Tomotada Akutsu³  Mitsuru Musha⁴  Koji Nagano⁵  Kentaro Komori⁵ 

[1] Department of Physics, Nagoya University, Nagoya, Aichi 464-8602, Japan;Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan;Gravitational Wave Science Project, National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588, Japan;Institute for Laser Science, The University of Electro-Communications, Chofu, Tokyo 182-8585, Japan;Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa 252-5210, Japan;

关键词: gravitational waves;    DECIGO;    quantum noise;    diffraction loss;   

DOI  :  10.3390/galaxies9010014

来源: DOAJ

【 摘 要 】

The DECi-hertz Interferometer Gravitational-wave Observatory (DECIGO) is the future Japanese, outer space gravitational wave detector. We previously set the default design parameters to provide a good target sensitivity to detect the primordial gravitational waves (GWs). However, the updated upper limit of the primordial GWs by the Planck observations motivated us toward further optimization of the target sensitivity. Previously, we had not considered optical diffraction loss due to the very long cavity length. In this paper, we optimize various DECIGO parameters by maximizing the signal-to-noise ratio (SNR) of the primordial GWs to quantum noise, including the effects of diffraction loss. We evaluated the power spectrum density for one cluster in DECIGO utilizing the quantum noise of one differential Fabry–Perot interferometer. Then we calculated the SNR by correlating two clusters in the same position. We performed the optimization for two cases: the constant mirror-thickness case and the constant mirror-mass case. As a result, we obtained the SNR dependence on the mirror radius, which also determines various DECIGO parameters. This result is the first step toward optimizing the DECIGO design by considering the practical constraints on the mirror dimensions and implementing other noise sources.

【 授权许可】

Unknown