High-z gamma-ray bursts unraveling the dark ages and extreme space-time mission - HiZ-GUNDAM

HiZ-GUNDAM is a future satellite mission which will lead the time-domain astronomy and the multi-messenger astronomy through observations of high-energy transient phenomena. A mission concept of HiZ-GUNDAM was approved by ISAS/JAXA, and it is one of the future satellite candidates of JAXA’s competitive medium-class mission. We are in pre-phase A (before pre-project) and elaborating the mission concept, mission/system requirements for the launch in the late 2020s. The main themes of HiZ-GUNDAM mission are (1) exploration of the early universe with high-redshift gamma-ray bursts, and (2) contribution to the multi-messenger astronomy.

HiZ-GUNDAM has two kinds of mission payload, i.e. the wide field X-ray monitors and the near infrared telescope. The wide field X-ray monitors consist of Lobster Eye optics array and pnCCD focal imaging sensor, and monitor 0.5 steradian field of view in 0.5 – 4 keV energy range. An expected detection sensitivity of HiZ-GUNDAM in 0.5 – 4 keV is ~10^-10 erg/cm²/s for X-ray transient with 100 second time duration which is roughly equivalent to GRB with 10⁵² erg at the redshift of 7 < z < 12. The sensitivity will be improved by one or two orders of magnitude than the conventional wide field monitor. Once HiZ-GUNDAM finds X-ray transient, the spacecraft automatically changes its pointing direction toward it, and start a follow-up observation with the near infrared telescope. The near infrared telescope has an aperture size 30 cm in diameter, and simultaneously observes four wavelength bands between 0.5 – 2.5 micron with expected sensitivity of 20-21 mag(AB). We select the high-redshift GRB candidate and the kilonova candidate with photometric data.

A down-selection judging session will be held in February and March in 2023. In this presentation, we introduce the current mission overview of HiZ-GUNDAM as well as the status progress.