PUSHING into the WHIM

Lawrence Rudnick, Univ. Minnesota, EVLA Wkshp 2008With 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, variousConference proceedings

2 Mpc

Finding diffuse - confusion

Finding diffuse - filtering

Finding diffuse - subtraction

Abell 1367Abell 1367

~ EVLA D configconvolved to 8’ (2 Mpc)

Diffuse POLARIZATIONas 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 dependence)– within beam (plane of sky)– along line of sight

• Faraday rotation ( dependence)– Within beam– Along line of sight in source– Across bandwidth

Faraday rotation within beam

www.ras.ucalgary.ca/SKA/science/node11.html

CG

PS

5” 1.5”Laing et al. 2008

Internal (line of sight) depolarization

6cm 21cm

Anderson, Keohane, Rudnick 1995

Rotation across band

λ1 λ2λ0

λ1 λ2λ0

P = Q + iU

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 fieldavailable at http://www.astro.umn.edu/~larry/RESEARCH/a150rm.mpg

1000

The EVLA niche – mixed thermal/relativistic

EVLA

PUSHING into the WHIM