EUSO-SPB2 sensitivity to macroscopic dark matter

TL;DR

This work investigates the detectability of macroscopic dark matter (macros) via fluorescence produced as they pass through the atmosphere. It models energy deposition with $dE/dx = - \sigma \rho_{atm} v^2$, compute UV photon yield with emission fraction $\eta$, and derives luminosity $L = \eta \rho_{atm} \sigma v^3$ and cooling time $t_{cool} = \sigma v^2 /(4 \pi \alpha c_p T_N)$ that govern the observable plasma. Using the local DM flux $F_m = (\rho_{DM}/M) v$ and EUSO-SPB2's exposure, the authors obtain a visibility threshold $\sigma \approx 5\times 10^{-7}$ cm$^2$ and a 90% CL flux limit $F_m < 8.8\times 10^{-19}$ cm$^{-2}$ s$^{-1}$ sr$^{-1}$ for $M \approx 3$ g, corresponding to sensitivity to $M \lesssim 3$ g and $\rho_m \lesssim 10^{-5} \rho_s$. The study shows EUSO-SPB2 can provide competitive, complementary constraints on macro DM and emphasizes adapting trigger timing (e.g., $t_{cool} \ll \tau_{bin}$) for slower macros.

Abstract

Macroscopic dark matter (or macro) provides a broad class of alternative candidates to particle dark matter. These candidates would transfer energy primarily through elastic scattering, and this linear energy deposition would produce observable signals if a macro were to traverse the atmosphere. We study the fluorescence emission produced by a macro passing through the atmosphere. We estimate the sensitivity of EUSO-SPB2 to constrain the two-dimensional parameter space ($σ$ vs. $M$), where $M$ is the macro mass and $σ$ its cross sectional area.

Figures (3)

• Figure 1: EUSO-SPB2 design with two telescopes: a fluorescence telescope and a Cherenkov telescope. The fluorescence telescope can observe at nadir, while the Cherenkov telescope is aimed at the limb of the Earth.
• Figure 2: Light pollution heat map of the world.
• Figure 3: The cooling time as a function of the macro's cross-sectional area for a Maxwellian distribution of velocity. nameref-fig:3 fith LAB: fig:3