Quality-Selected Lensing Analysis of Galaxy Clusters in Subaru Telescope Fields
Michney, Ryan J (creator)
Dell'Antonio, Ian (Director)
Dell'Antonio, Ian (Reader)
Gaitskell, Richard (Reader)
Tucker, Gregory (Reader)
Brown University. Physics (sponsor)
In recent years, weak gravitational lensing has become an indispensable method for understanding the concentration of matter on the largest scales. Galaxy clusters, the largest virialized structures in the universe, provide a crucial environment in which to examine cosmological evolution. Because most matter is non-luminous, weak lensing provides an opportunity for direct measurement of large scale mass clustering, independent of considerations involving cluster dynamics.
This study takes advantage of the large amount of deep and high quality optical imaging freely available from the Subaru Telescope data archive to perform a semi-blind cluster search across an extraordinarily large field of view, 10.34 deg2 of the sky, at high source density (utilizing 1.27 × 106 galaxies). Our precise 2D mass reconstruction, spanning five low-extinction Milky Way windows, detects 90 unique cluster candidates above S/N≥3. Of these, 67 possess S/N≥4, and 18 possess S/N≥5. From the fields analyzed, 43 independently confirm prior detections, 6 of these match (but with offsets in the location of the cluster barycenter), and the remaining 47 represent potential new cluster discoveries.
Previous cluster candidates in these regions were uncovered through non-WL techniques, therefore, our analysis represents a significant contrast against other wide-field cluster search methods, and is one of the largest lensing surveys completed to date.
Convergence reconstructions also detect SZ & X-ray cluster candidate PLCKG100.2-30.4 in multiple independent waveband data, but fails to measure the more observationally difficult PLCKG18.7+23.6. We estimate the mass of the former, as well as that of clusters Abell 383, Abell 1672, and RXCJ1651.1+0459.
The scale of this project necessitated the invention of numerous automated data reduction algorithms and a comprehensive pipeline optimizing the shape information and object detections of deep-field galaxies in available imaging. Most notably, a novel flux-independent identification system for stars was created in order to find ideal stellar objects necessary for accurate PSF circularization. Our techniques allow us to stack and circularize Subaru images to better than <0.5% mean ellipticity without introducing spurious effects.