A Dyson Sphere Around A Black Hole

Possible wavelengths for a hot Dyson Sphere to be detected in different black hole mass. The purple, blue, green, orange, and red regions indicate X-ray(0.01 − 10 nm), UV(10 − 400 nm), optical(400 − 760 nm), NIR(760 nm − 5 𝜇m), and MIR(5 − 40 𝜇m) wavelength, respectively. The shaded region is the peak wavelength from black body radiation of the waste heat, covering a wide range of parameters of a Dyson Sphere. The region enclosed by blue, magenta, and black lines indicate stellar-mass, intermediate mass and SMBH. Three arrows show how the peak wavelengths change with increasing parameters. The arrow lengths are arbitrary.

The search for extraterrestrial intelligence (SETI) has been conducted for nearly 60 years.

A Dyson Sphere, a spherical structure that surrounds a star and transports its radiative energy outward as an energy source for an advanced civilisation, is one of the main targets of SETI.

In this study, we discuss whether building a Dyson Sphere around a black hole is effective. We consider six energy sources: (i) the cosmic microwave background, (ii) the Hawking radiation, (iii) an accretion disk, (iv) Bondi accretion, (v) a corona, and (vi) relativistic jets. To develop future civilisations (for example, a Type II civilisation), 4×1026W(1L⊙) is expected to be needed. Among (iii) to (vi), the largest luminosity can be collected from an accretion disk, reaching 105L⊙, enough to maintain a Type II civilisation.

Moreover, if a Dyson Sphere collects not only the electromagnetic radiation but also other types of energy (e.g., kinetic energy) from the jets, the total collected energy would be approximately 5 times larger. Considering the emission from a Dyson Sphere, our results show that the Dyson Sphere around a stellar-mass black hole in the Milky Way (10kpc away from us) is detectable in the ultraviolet(10−400nm), optical(400−760nm), near-infrared(760nm−5μm), and mid-infrared(5−40μm) wavelengths via the waste heat radiation using current telescopes such as Galaxy Evolution Explorer Ultraviolet Sky Surveys. Performing model fitting to observed spectral energy distributions and measuring the variability of radial velocity may help us to identify these possible artificial structures.

Tiger Yu-Yang Hsiao, Tomotsugu Goto, Tetsuya Hashimoto, Daryl Joe D. Santos, Alvina Y. L. On, Ece Kilerci-Eser, Yi Hang Valerie Wong, Seong Jin Kim, Cossas K.-W. Wu, Simon C.-C. Ho, Ting-Yi Lu
Comments: This paper have accepted for publication in MNRAS
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA); Popular Physics (physics.pop-ph)
DOI: 10.1093/mnras/stab1832
Cite as: arXiv:2106.15181 [astro-ph.HE] (or arXiv:2106.15181v1 [astro-ph.HE] for this version)
Submission history
From: Tiger Hsiao
[v1] Tue, 29 Jun 2021 08:57:58 UTC (843 KB)
Astrobiology, SETI,

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