Descope of the ALIA mission

TL;DR

This study explores alternative space-based gravitational wave missions to eLISA/LISA, focusing on feasible designs that can detect early Universe black hole mergers with moderate technological advancements.

Contribution

It proposes specific mission configurations that are technologically feasible and capable of probing light seed black holes at high redshift, expanding gravitational wave detection options.

Findings

Mission options with 3 million km armlength can detect high-redshift black hole mergers.

Sensitivity shifted to around 0.01 Hz enhances detection of light seed black holes.

Technological requirements are within reach for China in the next few decades.

Abstract

The present work reports on a feasibility study commissioned by the Chinese Academy of Sciences of China to explore various possible mission options to detect gravitational waves in space alternative to that of the eLISA/LISA mission concept. Based on the relative merits assigned to science and technological viability, a few representative mission options descoped from the ALIA mission are considered. A semi-analytic Monte Carlo simulation is carried out to understand the cosmic black hole merger histories starting from intermediate mass black holes at high redshift as well as the possible scientific merits of the mission options considered in probing the light seed black holes and their coevolution with galaxies in early Universe. The study indicates that, by choosing the armlength of the interferometer to be three million kilometers and shifting the sensitivity floor to around one-hundredth Hz, together with a very moderate improvement on the position noise budget, there are certain mission options capable of exploring light seed, intermediate mass black hole binaries at high redshift that are not readily accessible to eLISA/LISA, and yet the technological requirements seem to within reach in the next few decades for China.