Microlensing Signatures of Dyson Sphere-like Structures around Primordial Black Holes as Technosignatures of Extraterrestrial Advanced Civilizations

TL;DR

This work expands microlensing searches to include technosignatures from Dyson-sphere–like swarms around primordial black holes, proposing a probabilistic, stochastic framework that accounts for time-dependent transmission and infrared reradiation. By analyzing standard lensing theory alongside a swarm-augmented anomaly model, it identifies observable signatures such as partial optical suppression, chromatic deviations, and IR excess, and provides estimates of optical depths and event rates under plausible fiducial parameters. The results highlight complementary observational pathways—time-domain microlensing surveys and infrared observations (e.g., JWST, Roman, Rubin)—for probing advanced civilizations. If realized, this approach would open a novel intersection of SETI, PBH microlensing, and megastructure phenomenology, guiding future Bayesian inference, high-cadence monitoring, and ML-enabled detection strategies.

Abstract

We investigate the microlensing detectability of extraterrestrial technosignatures originating from Dyson sphere \textendash like structures, such as Dyson Swarms surrounding primordial black holes (PBHs). These hypothetical swarms consist of stochastically varying, partially opaque structures that could modulate standard microlensing light curves through time-dependent transmission effects. We introduce a probabilistic framework that includes a stochastic transmission model governed by variable optical depth and random gap distributions. We perform a parameter scan and generate heatmaps of the optical transit duration. We study the infrared excess radiation and peak emission wavelength as complementary observational signatures. Additionally, we define and analyze the effective optical depth and the anomalous microlensing event rate for these stochastic structures. Our findings provide a new avenue for searching for extraterrestrial advanced civilizations by extending microlensing studies to include artificial, dynamic modulation signatures.

Figures (7)

• Figure 1: Microlensing light-curve of a solar mass PBH with Dyson sphere– like structure (swarm) is plotted versus time in days. The temperature and radius of this structure are assigned to be $T_{\rm{DS}}=300~ \rm{K}$ and $R_{\rm{DS}}= 2.68~ {\rm{au}}$. We assume an optical depth of $\tau_{\rm{Dyson}}=0.2$ with $10$ flickers.
• Figure 2: Microlensing light-curve of a solar mass PBH with Dyson sphere– like structure (swarm) is plotted versus time in days. The temperature and radius of this structure are assigned to be $T_{\rm{DS}}=300~ \rm{K}$ and $R_{\rm{DS}}= 2.68~ {\rm{au}}$. We assume an optical depth of $\tau_{\rm{Dyson}}=0.5$ with $50$ flickers.
• Figure 3: Microlensing light-curve of a solar mass PBH with Dyson sphere– like structure (swarm) is plotted versus time in days. The temperature and radius of this structure are assigned to be $T_{\rm{DS}}=150~ \rm{K}$ and $R_{\rm{DS}}= 10.73~ {\rm{au}}$. We assume an optical depth of $\tau_{\rm{Dyson}}=0.5$ with $50$ flickers.
• Figure 4: Microlensing light-curve of a solar mass PBH with Dyson sphere– like structure (swarm) is plotted versus time in days. The temperature and radius of this structure are assigned to be $T_{\rm{DS}}=900~\rm{K}$ and $R_{\rm{DS}}= 0.30~ {\rm{au}}$. We assume an optical depth of $\tau_{\rm{Dyson}}=0.5$ with $50$ flickers.
• Figure 5: The heatmap of optical transit duration of Dyson sphere– like structure in days plotted versus the mass range of PBH in scale of $0.1-100 ~M_{\odot}$ and Dyson swarm temperature with Eddington ratio $\eta=10^{-4}$, efficiency $\epsilon=0.2$ and transverse velocity of $v_{\rm{T}}=200 ~\rm{km/s}$.