Upgrades to improve the sensitivity of gravitational wave detectors enable more frequent detections and more precise source parameter estimation. Unlike other advanced interferometric detectors such as Advanced LIGO and Advanced Virgo, KAGRA requires different approach for the upgrade since it is the only detector which employs cryogenic cooling of the test masses. In this paper, we describe possible KAGRA upgrades with technologies focusing on different detector bands, and compare the impacts on the detection of compact binary coalescences. We show that either fivefold improvement in the 100M⊙--100M⊙ binary black hole range, a factor of 1.3 improvement in the binary neutron star range, or a factor of 1.7 improvement in the sky localization of binary neutron stars is well feasible with upgrades that do not require changes in the existing cryogenic or vacuum infrastructure. We also show that twofold broadband sensitivity improvement is possible by applying multiple upgrades to the detector.
@article{arxiv.2006.08970,
title = {Prospects for improving the sensitivity of the cryogenic gravitational wave detector KAGRA},
author = {Yuta Michimura and Kentaro Komori and Yutaro Enomoto and Koji Nagano and Atsushi Nishizawa and Eiichi Hirose and Matteo Leonardi and Eleonora Capocasa and Naoki Aritomi and Yuhang Zhao and Raffaele Flaminio and Takafumi Ushiba and Tomohiro Yamada and Li-Wei Wei and Hiroki Takeda and Satoshi Tanioka and Masaki Ando and Kazuhiro Yamamoto and Kazuhiro Hayama and Sadakazu Haino and Kentaro Somiya},
journal= {arXiv preprint arXiv:2006.08970},
year = {2020}
}