The Subaru HSC weak lensing mass-observable scaling relations of spectroscopic galaxy groups from the GAMA survey

Abstract

We utilize the galaxy shape catalogue from the first year data release of the Subaru Hyper Suprime-cam Survey (HSC) to study the dark matter content of galaxy groups in the Universe using weak gravitational lensing. As our lens sample, we use galaxy groups that have been spectroscopically selected from the Galaxy Mass and Assembly (GAMA) galaxy survey in approximately 100 sq. degrees of the sky that overlap with the HSC survey. We restrict our analysis to the 1587 groups with at least five group members. We divide these galaxy groups into six bins each of galaxy group luminosity and group member velocity dispersion and measure the coherent tangential ellipticity pattern on background HSC galaxies imprinted by weak gravitational lensing. We measure the weak lensing signal with a total signal-to-noise ratio of 55 and 51 for these two different selections, respectively. We use a Bayesian halo model framework to infer the halo mass distribution of our galaxy groups binned in the two different observable properties and obtain constraints on the power law scaling relation between mean halo masses and the two group observable properties. We obtain a 5 percent constraint on the amplitude of the scaling relation between halo mass and group luminosity with 𝑀 = (0.81 ± 0.04) × 10 14 ℎ −1 𝑀 for 𝐿 grp = 10 11.5 ℎ −2 𝐿 , and a power law index of 𝛼 = 1.01 ± 0.07. We also obtain a 5 percent constraint on the amplitude of the scaling relation between halo mass and velocity dispersion with 𝑀 = (0.93 ± 0.05) × 10 14 ℎ −1 𝑀 for 𝜎 = 500km s −1 and a power law index 𝛼 = 1.52 ± 0.10, although these scaling relations are sensitive to the exact cuts applied to the number of group members. Comparisons with similar scaling relations from the literature indicate that our results are consistent, but have significantly reduced errors.

An empirical measurement of the Halo Mass Function from the combination of GAMA DR4, SDSS DR12, and REFLEX II data

“…A more statistical approach to probing the HMF comes from weak lensing studies (see e.g. Viola et al 2015;Dong et al 2019;Rana et al 2021), in which an adopted HMF combined with assumptions of the DM profiles, can be used to predict the lensing signature and compared to that measured. This method too has issues, mainly the need for a calibration, or adoption, of a specific HMF form and a universal DM profile shape that is poorly constrained especially at intermediate halo masses.…”