Black holes and revelations: unseen companions in stellar binaries

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• Kareem El-Badry, Assistant Professor of Astronomy at the California Institute of Technology
• Thursday 12 March 2026, 16:00-17:00
• Hoyle Lecture Theatre, IoA (tea at 3:30 pm).

If you have a question about this talk, please contact Ruby Ng.

The Milky Way contains of order 100 million stellar-mass black holes. Yet, fewer than 100 black hole candidates are known in the Milky Way, and only about 25 are dynamically confirmed. Our view of the black hole population has been shaped almost entirely by observations of X-ray binaries and gravitational wave sources, both of which represent rare outcomes of binary evolution. I will discuss recent efforts to uncover the much larger population of Galactic black holes in non-interacting binaries, focusing particularly on astrometry from the Gaia mission. Compared to previous surveys, Gaia is revealing post-interaction binaries in wider orbits, whose properties are difficult to explain with standard binary evolution models. I will discuss how the Gaia catalogs can be leveraged for statistical inference, despite their complex selection function, and how they can discriminate between competing formation models.

This talk is part of the The Eddington Lectures series.

This talk is included in these lists:

• Cambridge Astronomy Talks
• Combined External Astrophysics Talks DAMTP
• Cosmology lists
• Cosmology, Astrophysics and General Relativity
• Hoyle Lecture Theatre, IoA (tea at 3:30 pm)
• Institute of Astronomy Colloquia
• Institute of Astronomy Talk Lists
• Kavli Institute for Cosmology Talk Lists
• Priscilla
• The Eddington Lectures

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