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Gas in local galaxies and beyond with ALMA

Gas in local galaxies and beyond with ALMA. Alberto D. Bolatto University of Maryland. How are galaxies put together?. red sequence. green valley. Salim et al. (2007), Kauffmann et al. (2003). NUV- r (SSFR). blue sequence. M r (stellar mass).

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Gas in local galaxies and beyond with ALMA

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  1. Gas in local galaxies and beyond with ALMA Alberto D. Bolatto University of Maryland

  2. How are galaxies put together? red sequence green valley Salim et al. (2007), Kauffmann et al. (2003) NUV-r (SSFR) blue sequence Mr (stellar mass) • Two groups: red and dead, and blue and star-forming • Star formation activity is related to the presence (or absence) of gas • What are the relevant physical processes?

  3. The importance of ALMA: star formation on galaxy scales diffuse phase dense phase ALMA molecular gas HI H2 SFR accretion cooling transitions ALMA UV, X-rays, cosmic rays thermodynamics, chemistry ALMA metals, H, dust gas temperature turbulence many molecules ALMA ALMA ALMA mechanical feedback instabilities n high resolution velocity field dust continuum magnetic field ALMA gravity ALMA polarization ALMA high resolution velocity field, shock tracers ALMA rotation, velocity dispersion multiline excitation

  4. The importance of ALMA: star formation on galaxy scales diffuse phase dense phase ALMA molecular gas HI H2 SFR accretion cooling transitions ALMA UV, X-rays, cosmic rays thermodynamics, chemistry ALMA metals, H, dust gas temperature turbulence many molecules ALMA ALMA ALMA mechanical feedback instabilities n high resolution velocity field dust continuum magnetic field ALMA gravity ALMA polarization ALMA high resolution velocity field, shock tracers ALMA rotation, velocity dispersion multiline excitation

  5. The Star Formation Law ΣSFRαΣ(HI+2H2)1.4 Genzel et al. (2010) Kennicutt (1998) Global correlation • Relation between gas (volume) density and star formation activity (Schmidt 1959)

  6. Recent Star Formation Composite of FUV (GALEX),mid-IR (SINGS/LVL),and Hα (SINGS/LVL) Molecular Gas Peak CO intensity From HERACLES Kinematics Here from HI line Also from CO Atomic Gas VLA 21cm data THINGS + new & archival Old Stars Near infrared intensity From SINGS and LVL NGC 4579 NGC 3184 NGC 4254 AHERACLES (A. Leroy)

  7. CARMA STING (Survey Towards IR-bright Nearby Galaxies) • BIMA SONG (Helfer, Wong, et al.) • OVRO MAIN (Baker, Jogee, et al.) • PdBI NUGA (Garcia-Burillos et al.) • CARMA-Nobeyama (Koda et al. ) • Sample sizes of 10-40, with substantial overlap

  8. Molecular gas to star formation Rahman et al. (in prep.) ALMA will allow us to substantially improve sample sizes, reduce biases in galaxy types, and explore the low surface brightness regime Bigiel et al. (2011)

  9. Molecular gas or dense gas? • We know that star formation is, globally, better correlated with dense gas tracers in ULIRGs(Gao & Solomon 2004) • In MW GMCs, star formation happens in dense cores • Observations in nearby galaxies suggest the SFR-CO (3-2) is tighter than with CO (1-0) • Density or temperature effect? • Can we measure actual gas densities? Wilson et al. (2009)

  10. Why does molecular gas produce stars with constant efficiency? Milky Way Solomon+ 87 Local Group Spirals M31 & M33 Dwarfs outside the Local Group NGC 1569, 2976, 3077, 4214, 4449, 4605 Local Group dwarfs IC 10, LMC, NGC 185, NGC 205 SMC N83, LIRS36, LIRS49 Line Width [km s-1] Radius [parsecs] OUTER DISK OF M33 Bolatto et al. (2008) Bigielet al. (2011)

  11. Resolving GMCs in ULIRGs? • Using atmospheric phase correction CARMA can reach 0.15” resolution at 1.3 mm (2km baselines) • That is 70 pc at 100 Mpc!!! • GMCs are 20-50 pc in size for the MW. We are not that far from resolving them. • ALMA will be able to pin down GMC properties across a range of galaxy types Arp 193: CO 2-1 at 0.15” (Zauderer et al., in prep.)

  12. Imaging feedback CO 1-0 wind in Mrk 231 (Feruglio et al. 2010) M82 wind (Veilleux et al. 2005) Walter et al. (2002); high-v CO • Pollution of the ISM, galaxy mass function fall-off at large masses, solution to overcooling problem • There is molecular gas entrained in Galactic outflows, maybe enough to shut down SF • Low SB material. If it is optically thin, it will be brighter in the higher J transitions • AGN feeding: NUGA results

  13. Panchromatic studies • Access to the full rotational ladder with good calibration and spatial resolution • Density, temperature, and column density • Access to some “optically thin” transition is key • Energy sources in the molecular ISM (dynamical heating, cosmic rays, e.g. Bradford et al. 2003) • Allows us to bypassXco? • Needs to be spatially resolved Carilli et al. (2010) SPIRE FTS spectrum of IC342

  14. Chemistry: another handle on the conditions Meier et al. (2008) Meier et al. (2005) • The distribution of chemical species produced under different conditions (PDRs, shocks, X-ray) illuminates the local conditions of the gas • Example: bar-driven shocks in IC 342 IC342

  15. C+ the cosmic candle • Detectable from ULIRGs to z~8 or more • Here, sensitivity in 4 hours to e.g. [CII], [OI] & [NII] is shown • Milky Way type galaxy detectable to z>3 in 24 hrs.

  16. ALMA represents a new era in galaxy studies • Go beyond the “butterfly collecting” stage for nearby and high-z systems • Access to new windows with unprecedented sensitivity • For the first time we will be able to do astrophysics on representative samples

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