Deep redshift survey of galaxies suggests million‐${\mathrm{Mpc}}^3$ void

Surveying the redshifts of bright galaxies out to 800 megaparsecs, a group of astronomers has found preliminary evidence for the existence of a gigantic void—a million‐cubic‐megaparsec volume devoid of bright galaxies—in the northern sky. In a recent Astrophysical Journal Letter, Robert Kirshner (University of Michigan), Augustus Oemler (Yale), Paul Schechter (Harvard–Smithsonian and Kitt Peak) and Stephen Shectman (Mount Wilson and Las Campanas Observatories) report that their deep redshift surveys of three small angular regions in the constellation Boötes show identical 6000‐km/second gaps in the velocity distribution of galaxies down to 16th magnitude. The three sampled regions, each 1.4° square, form a roughly equilateral triangle on the celestial sphere, about 35° on a side. Assuming that the entire triangular region will ultimately prove to be “empty” in this same 6000‐km/second velocity interval, centered at 15 000 km/second, one would deduce the existence of a void more than 100 megaparsecs across, about 300 Mpc (${10}^9$ light years) distant from us.

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