ECO-spotting: Looking for extremely compact objects with bosonic fields

Vitor Cardoso, Caio F.B. Macedo*, Kei Ichi Maeda, Hirotada Okawa

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


Black holes are thought to describe the geometry of massive, dark compact objects in the Universe. To further support and quantify this long-held belief requires knowledge of possible, if exotic alternatives. Here, we wish to understand how compact can self-gravitating solutions be. We discuss theories with a well-posed initial value problem, consisting in either a single self-interacting scalar, vector or both. We focus on spherically symmetric solutions, investigating the influence of self-interacting potentials into the compactness of the solutions, in particular those that allow for flat-spacetime solutions. We are able to connect such stars to hairy black hole solutions, which emerge as a zero-mass black hole. We show that such stars can have light rings, but their compactness is never parametrically close to that of black holes. The challenge of finding black hole mimickers to investigate full numerical-relativity binary setups remains open.

Original languageEnglish
Article number034001
JournalClassical and Quantum Gravity
Issue number3
Publication statusPublished - 2022 Feb 3


  • boson stars
  • compact objects
  • exotic compact objects

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)


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