M87* - the supermassive black hole in Messier 87

Assembled from 17 blocks · 3 evidence · 15 related

1. Story
2. The first black hole to be imaged, at the centre of the giant elliptical galaxy Messier 87 in the Virgo Cluster. The Event Horizon Telescope reported a mass of about six and a half billion solar masses and a distance of roughly 16.8 megaparsecs - some 55 million light-years - from an emission ring 42 microarcseconds across measured in April 2017 data. Two things make it the right first target despite its distance: its enormous mass gives it the largest angular shadow of any known black hole apart from Sagittarius A*, and its accretion flow changes on timescales of days rather than minutes, so a week of observation can be averaged into a single image without smearing. The measurement also settled a standing disagreement: stellar-dynamical modelling had given a mass near six and a half billion solar masses while gas-dynamical modelling had given roughly half that, and the shadow diameter agreed with the higher value. The ring is brighter on one side, which is read as relativistic beaming of material moving toward the observer. Not a place on Earth.
3. Knowledge
4. M87* - the supermassive black hole in Messier 87
5. Connections
6. Relativistic jet
7. Sagittarius A* - the black hole at the centre of the Milky Way
8. Heber Curtis records a curious straight ray in Messier 87
9. A mechanism for extracting energy from a spinning black hole
10. The Event Horizon Telescope observes M87* and Sagittarius A*
11. The first image of a black hole shadow is published
12. The M87* ring is imaged in polarised light
13. A second epoch shows the ring persists and the bright spot moves
14. Evidence
15. Reports the first image of a black hole shadow, an asymmetric ring about 42 microarcseconds across, together with the array, observing campaign and imaging methodology. V55 VERIFICATION BASIS: not consulted in session; WebFetch to iopscience.iop.org and eventhorizontelescope.org was refused by the egress proxy and no search could be issued. Volume and article number are from recall of a canonical citation.
16. Relates the measured ring diameter to the mass of M87*, giving approximately six and a half billion solar masses and testing the shadow prediction of general relativity. V55 VERIFICATION BASIS: not consulted in session; no research tool was available. Volume and article number are from recall; the quoted mass uncertainty is not reproduced in this pack.
17. Maps the magnetic field structure in the emitting plasma around M87*, favouring a magnetically arrested accretion state of the kind jet-launching models require. V55 VERIFICATION BASIS: not consulted in session; no research tool was available. Volume and article number are from recall and must be checked; a companion paper on the magnetic field is deliberately not cited separately.