With contributions from Shea Brown & Damon Farnsworth, UMN PUSHING into the WHIM Lawrence Rudnick, Univ. Minnesota, EVLA Wkshp 2008 With contributions from Shea Brown & Damon Farnsworth, UMN and R. F. Cardoso, U WI Work supported by NSF grant AST 0607674 at UMN

Local pressure radio surface brightness Mass distribution of shock heated gas (z=0) Kang, Ryu, Cen, Song 2005 ApJ 620, 21

LSS Shocks Synchrotron Chris Pfrommer, various Conference proceedings

2 Mpc

Finding diffuse - confusion

Finding diffuse - filtering

Finding diffuse - subtraction Abell 1367

~ EVLA D config convolved to 8’ (2 Mpc)

Diffuse POLARIZATION as WHIM probe RICH X-ray cluster POOR, non-X-ray cluster

Finding diffuse polarization – undersampled reconstruction

Missing large scale

Polarized emission Large AND small scale

Faraday clouds at high latitude? ► (<P>800) new diffuse source candidate. Symbols: clusters of galaxies Gal et al. 2003 (AJ 125, 1064). ► Stokes Q image WSRT @ 350 MHz (see text to right), with (<P>800) contours overlayed. Green: ~0 rad/m2 Yellow: ~ 13 rad/ m2

EVLA & Polarization EVLA

Depolarization Intrinsic disorder (no l dependence) within beam (plane of sky) along line of sight Faraday rotation ( l2 dependence) Within beam Along line of sight in source Across bandwidth

Faraday rotation within beam CGPS Figure 1.21: An image at   21 cm of effects of the diffuse Faraday Screen in the Milky Way. This image from the Canadian Galactic Plane Survey shows the spatial variations in polarisation posiion angle imposed by changes in the structure of the Galactic magnetic field and diffuse electrons distribution on scales of 10's of pc. The SKA allow this technique to be used on other galaxies to investigate the structure and generation mechanisms of galactic magnetic fields. www.ras.ucalgary.ca/SKA/science/node11.html 5” 1.5” Laing et al. 2008   Volume 391, Issue 2, Pages 521-549 Structures of the magnetoionic media around the Fanaroff–Riley Class I radio galaxies 3C 31 and Hydra A R. A. Laing 1★ , A. H. Bridle 2 , P. Parma 3 and M. Murgia 3,4

Internal (line of sight) depolarization 6cm 21cm Anderson, Keohane, Rudnick 1995

Rotation across band λ1 λ2 λ0 P = Q + iU λ1 λ2 λ0

RM synthesis A&A 441, 1217-1228 (2005) DOI: 10.1051/0004-6361:20052990 Faraday rotation measure synthesis      M. A. Brentjens - A. G. de Bruyn

RM movie of 3C33/Abell 150 field available at http://www.astro.umn.edu/~larry/RESEARCH/a150rm.mpg

1000

The EVLA niche – mixed thermal/relativistic

PUSHING into the WHIM