Abstract
Identifying galaxy clusters through overdensities of galaxies in
photometric surveys is the oldest1,2 and arguably the most
economical and mass-sensitive detection method3,4, compared
with X-ray5-7 and Sunyaev-Zel'dovich effect8
surveys that detect the hot intracluster medium. However, a perennial
problem has been the mapping of optical `richness' measurements onto
total cluster mass3,9-12. Emitted at a conformal distance of
14 gigaparsecs, the cosmic microwave background acts as a backlight to
all intervening mass in the Universe, and therefore has been
gravitationally lensed13-15. Experiments such as the Atacama
Cosmology Telescope16, South Pole Telescope17-19
and the Planck20 satellite have now detected gravitational
lensing of the cosmic microwave background and produced large-area maps
of the foreground deflecting structures. Here we present a calibration
of cluster optical richness at the 10% level by measuring the average
cosmic microwave background lensing measured by Planck towards the
positions of large numbers of optically selected clusters, detecting the
deflection of photons by structures of total mass of order
1014 M⊙. Although mainly aimed at the study of
larger-scale structures, the Planck estimate of the cosmic microwave
background lensing field can be used to recover a nearly unbiased
lensing signal for stacked clusters on arcminute scales15,21.
This approach offers a clean measure of total cluster masses over most
of cosmic history, largely independent of baryon physics.
Original language | English |
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Pages (from-to) | 795-799 |
Journal | Nature Astronomy |
Volume | 1 |
Early online date | 9 Oct 2017 |
DOIs | |
Publication status | E-pub ahead of print - 9 Oct 2017 |