English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We analyzed the thermodynamics of hypothetical exoplanets at very lowKeplerian circular orbits in close vicinity of rapidly spinning supermassiveblack holes. Such black hole exoplanets are heated by strongly blueshifted andfocused flux of the incoming cosmic microwave background (CMB) and cooled bythe cold part of the local sky containing the black hole shadow. This givesrise to a temperature difference, which can drive processes far fromthermodynamic equilibrium in a hypothetical life form inhabiting black holeexoplanets, similar to the case of a planet heated by the radiation of theparent star and cooled by the night sky. We found that for a narrow range ofradii of very low Keplerian circular orbits and for very high spin of asupermassive black hole, the temperature regime of the black hole exoplanetscorresponds to the habitable zone around standard stars. The thermodynamics ofblack hole exoplanets therefore, in principle, does not exclude the existenceof life based on known biology. The peak of the multiblackbody spectral profileof the CMB heating the exoplanet is located in the ultraviolet band, but asignificant fraction of the flux comes also in the visible and infrared bands.The minimum mass of a black hole ensuring the resistance to tidal disruption ofan Earth-like exoplanet orbiting in the habitable zone is estimated to $1.63\cdot 10^8 \, m_{\odot}$.

Habitable zones around almost extremely spinning black holes (black sun revisited)