Simulating the Cluster Weak Lensing Signal

Joe HollowedPhysics 526 Final PresentationUniversity of MichiganDecember 10 2019

PHY526 12/10/2019

Cosmology from galaxy cluster masses

2

Observable mass proxies:➔ X-ray temperature➔ Optical richness➔ Thermal CMB distortion

(SZ)➔ Distortion of background

sources (gravitational lensing)

High mass end of the halo population is sensitive probe of cosmology:

Cosmological Parameters from Observations of Galaxy Clusters, Allen, Evrard & Mantz, Annual Rev. of A&A, 2011

PHY526 12/10/2019

Weak Gravitational Lensing and the Halo Profile

3Image: ESA

Strongly lensed arc

Weakly lensed

Abell S1063

PHY526 12/10/2019 4

Shear magnitude is easily described under spherical symmetry of the lens:

Weak Gravitational Lensing and the Halo Profile

Projected potential, surface density, and deflection field:

Convergence Shear

PHY526 12/10/2019 5

Pipeline

Generate a particle-sampled NFW

halo realization

Obtain continuous expression of the density

field

Compute lensing quantities, esp. shear

field

Fit shear profile to NFW form to recover input

parameters

PHY526 12/10/2019 6

Random realizations of NFW halos

PHY526 12/10/2019 7

Projected density estimation via Delaunay triangulation

PHY526 12/10/2019

Ray-tracing through the integrated density field

Ray-tracing equation:

PHY526 12/10/2019 9

Ray-tracing through the integrated density field

Deflection components: Interpolated shear field:

PHY526 12/10/2019 10

Recovering the input NFW form

PHY526 12/10/2019 11

Recovering the input NFW form

PHY526 12/10/2019 12

Recovering the input NFW form