Status of Korean Participationin the SKA Project

Minho Choi (KASI)

SKA Japan Workshop

2010. 11. 4. 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 310-480 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 SKA1 Mid (Dishes)

• We designed a software correlator for SKA1 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 SKA1 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 SKA1.

– Look at technology options of a software correlator for the SKA2 sparse aperture array.

(Jongsoo Kim)

CPUs+(GPUs)

CPUs+(GPUs)

CPUs+(GPUs)

CPUs+(GPUs)

CPUs+(GPUs)

CPUs+(GPUs)

InfinibandOr

Other options

100 Gb/s Ethernet

Software Correlator for SKA1

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 ReferencesRyu D., Kang H., Cho J., Das S. (2008), Science, 320, 909Cho J., Ryu D. (2009), ApJ, 705, L90Akahori T., Ryu D. (2010), ApJ, 723, 476Akahori T., Ryu D., in preparation

AbstractThe 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 [teddy]

Ene

rgy

dens

ity

WHIM

ICM

Ryu+ (08) 10-4μG |B| 10μG

100 h-1 Mpc

Ryu+ (08)

Cho & Ryu (09)

turbulence dynamo model 1. vorticity energy εw

2. regard εw as εturb

3. εB/εturb=f(t/teddy) 4. B=(8πεB)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.