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
Jan 04, 2016
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