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Spectral Line Survey with SKA

Spectral Line Survey with SKA. Satoshi Yamamoto and Nami Sakai Department of Physics, The Univ. of Tokyo Tomoya Hirota National Astronomical Observatory of Japan. Interstellar Chemistry. Various new research fields in chemistry. A useful tool to study star formation processes. .

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Spectral Line Survey with SKA

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  1. Spectral Line Surveywith SKA Satoshi Yamamoto and Nami Sakai Department of Physics, The Univ. of Tokyo TomoyaHirota National Astronomical Observatory of Japan

  2. Interstellar Chemistry Various new research fields in chemistry A useful tool to study star formation processes.

  3. Interstellar Molecules • H2 • CO • HCN, HNC, H2CO, NH3, CS, SiO, CN, SO, SO2 • H3+, HCO+, HN2+, HCS+, C6H- • HC3N, HC5N, HC7N, HC9N, HC11N • C2H, C3H, C4H, C5H, C6H, C8H, CCS, C3S • CH3OH, HCOOCH3, (CH3)2O, C2H5CN, CH3CHO, HCOOH, C2H5OH, ～140 Species

  4. Line Survey of TMC-1 with NRO 45 m Kaifu et al. (2004) HC3N CCS, CCCS, c-C3H, CCO, CCCO, C4H2, etc HC5N HC7N

  5. Suzuki et al. 1984 Laboratory Spectrum Saito et al. 1987 Discovery of CCS as a Carrier of U45379

  6. CCS NH3 CCS NH3 Chemical Evolution of Dense Cores

  7. ＋ Caselli et al. 2002 Ohashi et al. 1999

  8. Carbon Chains HN2+, NH3 Deuterated Species DCO+, H2D+ Complex Organic Molecules Chemical Evolution of Molecular Clouds C → CO Conversion CO Depletion Mantle Evaporation

  9. Molecular Line Observations • ALMA • Higher frequency: mainly >85 GHz • Basic, simple light molecules • Higher temperature regions (GMCs, HCs, YSOs, UCHIIs) • SKA • Lower frequency: < 20 GHz • Complex, large and heavy molecules • Lower temperature region (dark clouds, prestellarcores, YSOs)

  10. Target Molecules with SKA Large molecules in cold clouds Carbon-chains & their isomers / PAHs ? High or mid band is necessary. Low line density per frequency/ less confusion OH, CH, (HI) Transition from atomic clouds to molecular clouds Recombination Lines H, He, C, S Depletion Prebiotic molecules Advantage over ALMA? Maybe yes. But high band is essential.

  11. Carbon-chain Molecules • Largest species HC11N and next candidates HC13N • Rich in cold dark cloud cores • SKA Mid/High-band is better than ALMA band-1 Red: HC11NGreen: HC13N

  12. Organic Molecules • Glycine • From cold to hot cores, comets, planets • From SKA High-band to ALMA

  13. Carbon-Chain Growth in Cold Starless Cores Longer Chains, PAHs, Small Grains? TMC-1 (Taurus Molecular Cloud-1) 13

  14. 14

  15. Here ! Lupus 1 Molecular Cloud D ～ 140 pc 15

  16. Long Carbon Chains in Lupus-1A Sakai et al. ApJ, 718, L49 (2010)

  17. Negative Ions in Lupus-1A First detection of C4H- in starless cores

  18. Second TMC-1 !!

  19. Efficient Production of Various Carbon-Chain Molecules around the Protostar Triggered by Evaporation of Methane from Grain Mantles Discovery of Warm Carbon-Chain Chemistry (WCCC) Sakai et al. (2008) Existence of Various Carbon Chains N=9-8, F2 Eu = 21 K C4H e.g.) CH4 + C+ C2H3+ + H C2H3+ + e C2H+ H + H  - - - - C6H－ L1527 C5H, C6H, C4H2, HC5N, HC7N, HC9N, C4H- etc. 60” (Tobin et al. 2008)

  20. CH Observations TMC-1 TMC-1 Narrow and Broad Components 20

  21. Taurus Molecular Cloud color：CI contours：C18O Formation Site of Molecular Cloud Maezawa et al. 1999, Astrophys. J. 524, L129.

  22. Summary • SKA should be optimized for nonthermal emission and strong thermal emission including HI and OH. ( Thermal emission: I = 2kν2T/c2) • DI, CH, H2CO, CH3OH(maser) are good targets. • Nevertheless, observations of molecules are still interesting, because of its high sensitivity.

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