Taiwan’s Possible Interests in SKA Hiroyuki Hirashita (ASIAA, Taiwan) and members of the SKA discussion group at ASIAA Outline 1. Physical State of the ISM in DLAs 2. Topics of interest in ASIAA 3. Summary 1. Physical State of the ISM in DLAs Hirashita et al. (2003) Damped Lyman α clouds (DLAs): NH > 2×1020 cm–2 background quasar DLAs are viable targets for 21 cm absorption studies. Merit of 21 cm ⇒ Spin temperature, Velocity dispersion ガスの物理状態の重要性: H2の分布 Hirashita et al. (2003) 平衡となるH2量 (1) ダスト上での形成率 (2) UVによる破壊率 (1) = (2) 50 pc log (molecular fraction) with i21 = 0.1, D = 0.1Dsun H2は非常に非一様に分布し、小さな領域に局在する観測シミュレーション数値計算された銀河上で任意に視線を選び「観測」 Hirashita & Ferrara (2005) log (molecular fraction) 正の相関  log (D/Dsun) ‒1.5 でmolecular fraction急増(←self-shielding)  molecular fractionの分散大 log (dust-to-gas ratio) ×: Ledoux et al. (2003) ◆: our simulation DLAに対する21 cm線観測の現状 Srianand et al. (2012) • detection rate: 1/10 • upper limits of τ(21 cm) with N(H I) from Lyα Consistent with the small covering fraction of cold gas see also Curran et al. (2010) Kanekar et al. (2009): anticorrelation between metallicity and Ts 現状に比べて最低でも1桁高いS/Nが必要角分解能、広い視野は不要 10倍の集光力 2. Topics of Interest in ASIAA HI Emission: Intensity Mapping at z=0.8 Cross-correlating GBT HI & DEEP2 optical galaxies at z ~ 0.7-1.1 Chang, Pen, Bandura, Peterson, in Nature 2010 Measure HI & DEEP2 optical cross-correlation on 9 Mpc (spatial) x 2 Mpc (redshift) comoving scales HI brightness temperature on these scales at z=0.8: T = 157 ± 42 μK ΩHI r b = (5.5 ± 1.5) x 10-4 Highest-redshift detection of HI in emission at 4-sigma statistical significance. Radio Continuum as a SF Indicator Hirashita (2012) Condon (1992) (M82) Radio dust synchrotron free-free Synchrotron from Supernova Remnants nearby dwarf → Related to star formation activity galaxies (BCDs) With SKA, we can extend the sample to high-z metal-poor (primeval) galaxies. AGN Feedback in Cooling Core Cluster M. Nakamura Magnetically dominated model (Li+ 06’; Nakamura+ 06’, 07’, 08’) Hydro model w/ γ=5/3 Hydro model w/ γ=4/3 Wise+ (2007), ApJ Diehl+ (2008), ApJ - Exploring fossil radio bubbles (X-ray cavities) at low freq. ‣ SKA will give further constraints on models ‣ Do AGN inflations carry magnetic energy over ICM scales? Imaging Re-collimation Process of the M87 jet Asada & Nakamura (2012) collimation Dynamic Range of current our EVN image is ~ 2500 ‣ SKA will improve it > 1,000,000 - Is the M87 jet over-collimated ? expansion 3. Summary (1) Small science group in ASIAA. ⇒ Collaboration is necessary. (2) Possible science collaborations a. H I & CO emission/absorption at high z b. Galaxy evolution in the radio c. AGN and magnetism (3) Requirements: a. Microjansky sensitivities b. A wide coverage of wavelength