Speaker
Description
Galaxy cluster abundance measurements serve as a powerful probe for constraining cosmological parameters such as the matter density ($\Omega_m$) and the amplitude of density fluctuations ($\sigma_8$). Wide-area surveys detect clusters using observables like the thermal Sunyaev-Zeldovich (SZ) effect, a spectral distortion in the Cosmic Microwave Background (CMB). Accurate cosmological constraints require precise characterization of the survey selection function, which, in SZ surveys, is typically defined by the probability of detecting a cluster based on its total SZ signal and angular scale.
In this talk, we investigate the impact of triaxiality and orientation on the selection function of the Planck SZ survey. Employing a Monte-Carlo method, we inject triaxial cluster profiles at random positions within the Planck all-sky maps and subsequently detect them using the Multi-Matched Filtering Planck algorithm (MMF3). Our analysis reveals that cluster orientation significantly affects detection probability: for a given total SZ signal and angular size, clusters elongated along the line of sight are more likely to be detected. This results in a systematic upward bias in the derived Weak Lensing (WL) mass estimates of SZ selected clusters relative to cluster samples with random orientations, with bias values as high as 5% for clusters near the low-mass limit of the survey. Given the percent-level mass calibration requirements of upcoming cluster surveys, quantifying such biases is critical for precision cosmology.
| Would you be interested in presenting a poster if the conference is oversubcribed? | Yes |
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