The outer stellar mass of massive galaxies: a simple tracer of halo mass with scatter comparable to richness and reduced projection effects

Song Huang, Alexie Leauthaud, Christopher Bradshaw, Andrew Hearin, Peter Behroozi, Johannes Lange, Jenny Greene, Joseph DeRose, Joshua S. Speagle, Enia Xhakaj

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Using the weak gravitational lensing data from the Hyper Suprime-Cam Subaru Strategic Program (HSC survey), we study the potential of different stellar mass estimates in tracing halo mass. We consider galaxies with log10(M∗/M⊙) > 11.5 at 0.2 < z < 0.5 with carefully measured light profiles, and clusters from the redMaPPer and CAMIRA richness-based algorithms. We devise a method (the 'Top-N test') to evaluate the scatter in the halo mass-observable relation for different tracers, and to inter-compare halo mass proxies in four number density bins using stacked galaxy-galaxy lensing profiles. This test reveals three key findings. Stellar masses based on CModel photometry and aperture luminosity within R <30 kpc are poor proxies of halo mass. In contrast, the stellar mass of the outer envelope is an excellent halo mass proxy. The stellar mass within R = [50, 100] kpc, M∗, [50, 100], has performance comparable to the state-of-the-art richness-based cluster finders at log10Mvir ⪎ 14.0 and could be a better halo mass tracer at lower halo masses. Finally, using N-body simulations, we find that the lensing profiles of massive haloes selected by M∗, [50, 100] are consistent with the expectation for a sample without projection or mis-centring effects. Richness-selected clusters, on the other hand, display an excess at R ∼1 Mpc in their lensing profiles, which may suggest a more significant impact from selection biases. These results suggest that M∗-based tracers have distinct advantages in identifying massive haloes, which could open up new avenues for cluster cosmology.

Original languageEnglish (US)
Pages (from-to)4722-4752
Number of pages31
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
StatePublished - Oct 1 2022


  • cosmology: observations
  • galaxies: clusters: general
  • galaxies: haloes
  • galaxies: structure
  • gravitational lensing: weak

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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