Status of Korean Participation in the SKA Project Minho Choi (KASI) SKA Japan Workshop NAOJ, Mitaka

Status of Radio Telescopes in Korea TRAO 14 m telescope at Daejeon (KASI) –3 mm multibeam receiver array in operation SRAO 6 m telescope at Seoul (SNU) –1 mm and 3 mm receivers in operation Korean VLBI Network (KASI) –3-element VLBI with 21 m antennas and km baselines –Antenna and correlator construction completed –Receivers under construction –Single-dish mode observations at 22/44 GHz bands in operation –KVN-VERA VLBI test observation at 22/43 GHz in operation –Regular VLBI observations from 2012 expected

Status of KVN 22 and 43 GHz receivers –Installed in 2009 –Single-dish observations under way –Fringes acquired –22/43 GHz simultaneous phase referencing test under way 86 and 129 GHz receivers –to be completed by 2011 East Asian VLBI Network –Joint operation with VERA tested –Image sensitivity test

Korea-Japan Joint VLBI Correlator 16 stations –8 Mark5B –4 VERA2000+DMS-24 –4 K5 16 RVDBs –(raw VLBI data buffer) Data Archive –100 TB VSOP-2 correlator EA VLBI Network Correlation Center to be constructed in a few years (at KASI HQ in Daejeon)

Korean Astronomy Community and SKA KASI –KASI joined the Giant Magellan Telescope Project. KASI staffs are getting more familiar with large-scale international collaboration projects. –KASI Radio Division will perform a feasibility study for a post-KVN project, and SKA is one of the major possibilities. Korean Government –Policymakers recognized the need to participate in large-scale international projects. –SKA listed in the National Roadmap for Large-scale Research Facilities of National Research Facilities & Equipment Center (coordinating agency in the government).

SKA-related Activities SKA (SSEC/SPDO) participation –Participated as an observer in SSEC4 (2010 March). –KASI formally joined SSEC as a member, as of 2010 September. PrepSKA participation (KASI) –EU-FP7 collaboration program funded by NRF of Korea (M. Choi et al.) –PrepSKA WP2 –Software correlator development (J. Kim) RadioNet participation (KASI) –EU-FP7 collaboration program funded by NRF of Korea (B. Sohn et al.) –JRA Uniboard development SKA-related science –ASKAP Polarization Sky Survey of the Universe's Magnetism (D. Ryu, T. Akahori) –Other activities and individual efforts

Software Correlator for SKA 1 Mid (Dishes) We designed a software correlator for SKA 1 Mid (dishes). Specifications assumed (Memo 125) –250 15m antennas –4GHz bandwidth –4 bits sampling Technologies used –100 Gigabit Ethernet –many-core processing units (CPUs/GPUs) –high-performance interconnect (infiniband) Milestones –Design of a software correlator for the SKA 1 sparse aperture array –Do benchmark tests of FX correlation using currently available high-performance many-core clusters. –Write a SKA memo on software correlators for the SKA 1. –Look at technology options of a software correlator for the SKA 2 sparse aperture array. (Jongsoo Kim)

CPUs+(GPUs) Infiniband Or Other options 100 Gb/s Ethernet Software Correlator for SKA 1 1x4x2x4GHz =32Gb/s 1 pols, 4bit sampling, Nyquist, BW 500 nodes >8 TFLOPS CPUs+(GPUs) 1x4x2x4GHz =32Gb/s 250 dishes CPUs+(GPUs) >4 PFLOPS

RadioNet Participation UniBoard –FPGA based multipurpose rich board, 40 Gbps I/O –Prototype production in 2010 December (ASTRON) –Prototype tests at KVN –Applications for KVN KVN wideband data formatter (one board for 4 freq. bands) eVLBI correlator study –Mass production in 2012 ~1000 uniboards (Bong Won Sohn)

Faraday Rotation Measure (RM) due to the Intergalactic Magnetic Field (IGMF) Takuya Akahori and Dongsu Ryu Chungnam National University Oct 13, 2010 Main References Ryu D., Kang H., Cho J., Das S. (2008), Science, 320, 909 Cho J., Ryu D. (2009), ApJ, 705, L90 Akahori T., Ryu D. (2010), ApJ, 723, 476 Akahori T., Ryu D., in preparation Abstract The origin and nature of the IGMF still remains largely unknown. Measuring RM is one of promising methods to explore the IGMF. We are theoretically investigating RM through filaments using a model of the IGMF based on the turbulence dynamo. Our results could be tested with the Square Kilometer Array (SKA).

Modeling for the IGMF Simulation of cosmological structure formation + theoretically-motivated turbulence dynamo model time [t eddy ] Energy density WHIM ICM Ryu+ (08) μG |B| 10μG 100 h -1 Mpc Ryu+ (08) Cho & Ryu (09) turbulence dynamo model 1. vorticity energy ε w 2. regard ε w as ε turb 3. ε B /ε turb =f(t/t eddy ) 4. B=(8πε B ) 1/2 Estimation of the rms value of RM for filaments (Left) the growth curves of magnetic and kinetic energy densities (right) 3D map of IGMF

RM in a local universe Inducement of RM is a random walk process Rms value of RM through filaments is ~1.4 rad m -2 (Left) RM map for the present-day (z=0) local (depth=100Mpc/h) universe (right) examples of radial profiles Akahori, Ryu (2010)

RM integrated up to z=5 Rms of RM through filaments is ~several rad m -2 Power spectrum peaks at ~0.2 degrees scale 1.4º 0.14º ~0.2º z<0.05 z<0.3 z<5 TM7 (left) The rms value of RM as a function of redshift. In runs except ALL, the ICM are excluded with different ways. (right) Power spectrum of RM through filaments. Akahori, Ryu in prep.

SKA-Korea Workshop 2010 August at KASI About 60 participants Scientific interests in the Korean astronomy community –Large-scale structure of magnetic fields –Galaxy clusters –Dark matter –Epoch of reionization Everyone agreed that SKA is a good opportunity for both scientists and engineers.

Summary Current status and activities –KASI is participating in SSEC/SPDO as a member. –Participating in EU-FP programs (PrepSKA, RadioNet) –Participating in engineering developments Software correlator UniBoard –Scientific activities Large-scale magnetic fields (ASKAP POSSUM) Simulations of EoR and more… Future prospects –SKA-Korea Workshop confirmed that there are good motivations in the community. –SKA listed in the National Roadmap –SKA Science/Engineering Working Groups are being organized and will push for further involvements in the SKA project. –Korean astronomers hope to make significant contributions to the SKA project.