Distinguishing the nature of dark matter by mapping cosmic filaments from Lyman-alpha emission

TL;DR

This paper explores how Lyman-alpha emission can be used to distinguish between cold and warm dark matter by analyzing the structure and brightness of cosmic filaments at high redshifts, with future telescopes playing a key role.

Contribution

It demonstrates that Lyman-alpha emission can serve as an observational tool to differentiate dark matter models based on filament smoothness and brightness at high redshifts.

Findings

Lyα filaments can distinguish dark matter types at z=4.

Differences in filament smoothness are detectable with upcoming telescopes.

Surface brightness variations serve as signatures for dark matter nature.

Abstract

The standard $\Lambda$CDM cosmological model predicts that cosmic filaments are highly clumpy, whereas warm dark matter -- invoked to address small-scale challenges in $\Lambda$CDM -- produces filaments that are noticeably smoother and less structured. In this work, we investigate the potential of Lyman $\alpha$ (Ly$\alpha$) emission to trace cosmic filaments at redshifts $z=2.5$ and $z=4$, and assess their potential for constraining the nature of dark matter. Our analysis shows that Ly$\alpha$ filaments provide a promising observational probe of dark matter: at $z=4$, differences in filament smoothness and surface brightness serve as distinctive signatures between models. Looking ahead, the upcoming generation of 30-meter class telescopes will be critical for enabling these measurements, offering a compelling opportunity to distinguish the nature of dark matter by mapping the structure of cosmic filaments.