The MegaMapper: A Stage-5 Spectroscopic Instrument Concept for the Study of Inflation and Dark Energy

TL;DR

The MegaMapper is a proposed ground-based spectroscopic instrument designed to measure inflation and dark energy parameters by observing galaxy redshifts between redshifts 2 and 5, combining existing and innovative technologies for high multiplexing.

Contribution

It introduces a novel design for a 6.5-meter telescope with advanced multiplexing capabilities to significantly improve redshift measurements for cosmological studies.

Findings

Achieves at least 26,000 target density in redshift range

Provides 10x capability over current state-of-the-art instruments

Proposes a cost-effective design with existing technologies

Abstract

In this white paper, we present the MegaMapper concept. The MegaMapper is a proposed ground-based experiment to measure Inflation parameters and Dark Energy from galaxy redshifts at $2<z<5$. In order to achieve path-breaking results with a mid-scale investment, the MegaMapper combines existing technologies for critical path elements and pushes innovative development in other design areas. To this aim, we envision a 6.5-m Magellan-like telescope, with a newly designed wide field, coupled with DESI spectrographs, and small-pitch robots to achieve multiplexing of at least 26,000. This will match the expected achievable target density in the redshift range of interest and provide a 10x capability over the existing state-of the art, without a 10x increase in project budget.