EolisaSpaceEngine v7.0.0: A Dual-Source Test of the Kerr Hypothesis
- Aug 30
- 2 min read
Constraining exotic compact object alternatives to the black hole using the Event Horizon Telescope's 2017 observations of Sagittarius A and M87*.*
For decades, general relativity has predicted a single, precise geometry for the boundary of a black hole. The Event Horizon Telescope's 2017 observations of Sagittarius A*, the supermassive black hole at the center of our galaxy, and of M87*, gave us the first direct measurements of that geometry. The question the Eolisa Space Research Team set out to answer is simple to state and difficult to answer honestly: how much room do those measurements actually leave for something other than a Kerr black hole?
EolisaSpaceEngine v7.0.0 is our answer. It is a fully reproducible Bayesian framework that fits a joint model interferometric visibility amplitudes, closure phases built directly from the released EHT data, and GRAVITY infrared astrometry to both sources simultaneously, tests the Kerr prediction against five competing exotic compact object models, and reports a single, model-agnostic number: the fractional shadow-size deviation the data will permit, once every known systematic uncertainty is properly included.
That last clause is the discipline we hold ourselves to. Many shadow-size claims in the literature quote a deviation without folding in the uncertainty on the source's own mass and distance an omission that, for Sagittarius A*, understates the true error by an order of magnitude. v7 marginalises that uncertainty inside the likelihood by default, propagates the documented coefficient uncertainty of every exotic model rather than treating it as a footnote, and separates closure-phase triangles by frequency band so no measurement is ever built by mixing incompatible data. None of this sits behind an optional flag it is the default behavior of the pipeline, and every posterior, figure, and report in this release is generated by the shipped code itself, from a fixed random seed, with nothing transcribed by hand.
We are equally direct about what this framework does not do. It does not claim to have detected a deviation from Kerr it reports where the data are consistent with Kerr, and how tightly. It does not map a measured deviation to a specific alternative metric; that step requires full ray-tracing through curved spacetime, and we say so plainly rather than implying otherwise. Rigor, to us, includes stating the boundary of a result as clearly as the result itself.
This release includes the complete analysis pipeline, two methodology papers Paper I on the framework, Paper II on validation and the real-data constraints full documentation, and a public, citable archive on Zenodo. It is released under the MIT License.
Onur H. Evgin President of Eolisa Space
Eolisa Space Research Team
10.5281/zenodo.22181788
