SeminarUpcomingCosmology

Does the quasar dipole break LambdaCDM?

Tuesday, September 22, 2026
11:00 America/Toronto
Arefe Abghari

University of British Columbia

Check the official event for registration, eligibility and attendance details.

Hosted by Perimeter Institute for Theoretical Physics90 minutes

Abstract

The Cosmological Principle assumes large-scale homogeneity and isotropy, implying that the cosmic-microwave-background dipole is caused by our motion and that the number-density dipole of distant quasars should agree with it. Recent analyses have reported a larger quasar dipole. This seminar examines selection and estimation systematics and shows how higher multipoles in the quasar density map, plausibly introduced by survey and selection effects, can account for the difference. The result motivates more careful control of systematics before drawing conclusions about the Cosmological Principle or the standard cosmological model.

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