Early Polarization Science with ASKAP – Galactic Pole

1. Early Polarization Science with ASKAP – Galactic Pole Takuya Akahori Sydney Institute for Astronomy (SIfA), The University of Sydney, Australia JSPS Postdoctoral Fellow for Research Abroad, Japan with B. M. Gaensler, and the POSSUM Collaboration 2013/8/5 @ ATNF, Australia ASKAP Early Science Workshop

2. Continuum Polarization Observation Cosmic Magnetism Impossible to know our universe without knowing Cosmic Magnetism ISM, SNR IGM • SFR, IMF • Turbulence • Cosmology • UHECRs Milky Way AGN • Spiral/Halo • Instabilities • Environment • Feedback Galaxies • Population • Morphology Key Sciences in Modern Cosmology CMB Polarization Inflation theory QUIET, PolarBeaR, LiteBIRD Epock of Reionization Dark age / First stars MWA, LOFAR, SKA ・・・ “Foreground”

3. Observation toward Galactic Pole Best to study the IGMF • Galactic RM depends on b, and is smallest toward the poles Galactic latitude RM NVSS-RM (Schnitzeler 10) Galactic Halo IGMF Parker Loop +0.0±0.5 rad/m2 ~0.00±0.02 µG • +6.3±0.5 rad/m2 • ~0.31±0.02 µG MRI Mao+ (10) Stil+ (11) TA+ (13) TA, Ryu (10;11)

4. The IGMF in the Cosmic Web Big Mystery and New Frontier • What is the origin and nature of the IGMF? • Practically, radio polarimetry is a uniqueprobe • RM~1-10 rad/m2through filaments? (TA, Ryu 10;11) AMR-MHD initial uniform B~10 pG (Dubois & Tessier 08) SPH-MHD magnet-gas injection (Donnert+ 09; Stasyszyn+ 10) (M)HD Biermann battery & turbulence dynamo (Ryu+ 98; Ryu+ 08) Coma cluster (Kim+ 89) log B(µG) -0 -2 -4 log B(µG) -1 -2 -3 -4 log B(µG) -0 -1 -2 -3 -4 log ρ/ρ0 0 1 2 3 4 log ρ/ρ0 0 2 4 6 log ρ/ρ0 0 1 2 3 4

5. Progress of Extragalactic RM Studies Intrinsic, Intervening, and the IGMF 5 Bernet+ (12) Hammond+ (12) • Multiple RMs along LoSs • Which RM component contributes to the observed RM? • And how? Solid: RM 6cm Dashed: RM 21cm Radio Galaxies Quasars “risk hedge” Bryan Gaensler’sTalk Thermal emvironment of active galaxies. Galaxy evolution over cosmic time. Turbulence properties and covering fraction of absorbers <~50%? [1,2] This talk Challenge to discover RM of the IGMF (1-10 rad/m2) σINT~5-12 rad/m2? [2] [1] Zhu, M’erard13, [2] TA, Gaensler, Ryu in prep.

6. Is the IGMF good for Early Science? Yes. Statistics of RM Mock Obs. Map • RM of the IGMF could be extracted(D>10) FoV = 900 deg2 toward the South GP ー Model IGMーMock Obs.ーResidual RM ASKAP-12, 6 hours Previous Observation • Galaxy filter • High-z filter • High-pass filter Extracted Map TA, Ryu 10;11; TA et al. 13; TA, Gaensler, Ryu, in prep.

7. Is the IGMF good for Early Science? Yes. Synthesis of RM Model • Null IGMF could be excluded at 2-3σ signif. (700-1800 MHz) ASKAP-12, 1 hour, 1 mJy source, RMIGMF=10 rad/m2 ー1150-1450 MHzー700-1000 MHz ー(700-1000+1150-1450) MHzー700-1800 MHz 1σ • RM Synthesis 1σ 1σ 1σ 1σ • QU-fitting Mock Obs. Spectrum TA+ submitted; Ideguchi, TA+, submitted

8. Is the IGMF good for FullScience?Of course, Yes! • Statistics of RM  Structure Function • Synthesis of RM  RM~a few rad/m2 ーASKAP-12 ーASKAP-18 ーASKAP-36 ーASKAP-36 1σ 1σ 1σ FoV = 900 deg2 toward the South GP ー Model IGMーMock Obs.ーResidual RM ASKAP-12, 6 hours ASKAP-36, 15 hours 3σ 3σ TA, Gaensler, Ryu, in prep.; TA+ submitted; Ideguchi, TA+, submitted

9. Summary: Continuum Polarization Observation toward Galactic Pole