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Theoretical Strategy for High-Redshift Galaxy Survey

Theoretical Strategy for High-Redshift Galaxy Survey. Hiroyuki Hirashita (ASIAA, Taiwan). Topics. First Metal and Dust Production Theoretical Framework and Perspectives for ALMA Nearby “Laboratories” of Primeval Galaxies Summary of Strategy. Metal Production History. C, N, O, …, Fe.

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Theoretical Strategy for High-Redshift Galaxy Survey

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  1. Theoretical StrategyforHigh-RedshiftGalaxySurvey Hiroyuki Hirashita (ASIAA, Taiwan)

  2. Topics • First Metal and Dust Production • Theoretical Framework and Perspectives for ALMA • Nearby “Laboratories” of Primeval Galaxies • Summary of Strategy

  3. Metal Production History C, N, O, …, Fe H, He, Li Big Bang ビッグバン Dust already existed at z ~ 6 (Mambo-2: Bertoldi et al. 2003). Beginning of Metal (dust) Production Grasp of “primeval galaxies” in the Universe ＝ Understanding of the initial metal enrichment Subaru 1. First Metal and Dust Production FIRST Project Homepage at Univ. of Tsukuba 13.7 Gyr 1 Gyr 0.1 Gyr Dark Age 0.4 Myr CMB First Objects in the Universe Cosmic Reionization Galaxy Evolution Black Holes Stars Planets

  4. Radiative Processes Dust grains emit far-infrared (FIR) light. UV, optical, NIR absorption of stellar light reemission FIR M33: Hinz et al. (2004) dust grains a < 1 mm considered to be composed by silicate, graphite, etc.

  5. Important to trace FIR emission in understanding the cosmic star formation history. Luminous FIR Emission Active “starbursts” tend to have dominated FIR emission. optical FIR Sanders & Mirabel (1996)

  6. Long wavelengths (~ 220 GHz band) are suitable for very high-z. (The field-of-view is also large.) Arp 220 at Various Redshifts SED model by Totani & Takeuchi (2002) Tdust = 42 K LIR = 1.4×1012 L Detection limits: 100 arcmin2 survey with 500 h (Tamura). Galaxies with 1011 L can be detected (redshift-independent).

  7. Fundamental Problems I • Understand the first (primeval) stage of galaxy evolution: • A frontier of galactic astronomy • First dust (and metal) production (→ origin of the present metal-rich universe) • Quantify the hidden star formation: • Importance of FIR seems to be enhanced up to z ~ 1 (Takeuchi et al. 2005). • Statistical studies up to z ~ 3 have been made possible by SCUBA (e.g., Chapman et al. 2005), ASTE (Tamura et al. 2008), etc. • ⇒ Important to trace the cosmic star formation history.

  8. UV heating Theoretical Importance of Dust in Star Formation Scenario Scenario of Star Formation on Galaxy Scale Dust supply Interstellar Gas Molecular Clouds Stars Gravitational Contraction Cooling by molecules and dust Gas pressure (∝ Temperature) should be kept low. Dust blocks UV radiation. Dust (surface) also helps the molecular cloud formation. ⇒ Dust helps heating and cooling of the interstellar gas.

  9. Primeval ISM molecular clouds Evolved ISM Transition Dust supply Fundamental Problems II • Investigate the role of dust in star formation • Absorption of UV and emission in FIR ⇒ UV heating is suppressed. ⇒ favorable for star formation • Promotion of molecule formation ⇒ favorable for star formation Hirashita & Ferrara (2002); Hirashita & Hunt (2004)

  10. An aim of ALMA: Detection of the first dust enrichment in the Universe Aim of this Talk • Provide a basic simple theoretical tool to construct a strategy for ALMA high-z survey. ⇒ N-body + Dust enrichment. • Indicate an example what to do until ALMA starts. ⇒ Analysis and interpretation of AKARI and Spitzer data of nearby template of primeval galaxies (blue compact dwarf galaxies).

  11. 0,3 Gyr 0.6 Gyr 0.9 Gyr 1.2 Gyr 1.5 Gyr 2.2 Gyr 2. Theoretical Strategy and Perspectives for ALMA • N-body Simulation (Suwa et al. 2006) • LCDM model Cosmological Simulation • Box Size: (150Mpc/h)3 ⇔ 104 arcmin2 Distribution of dark halos in the Universe. FIRST (Univ. Tsukuba)

  12. Model of Dust Enrichment to be applied to individual halos Hirashita & Ferrara (2002); Hirashita & Hunt (2004) We concentrate on young (t < 1 Gyr) galaxies. • SFR(t) = t/Mgas exp(–t /) • t: Star formation timescale (= R/vcir) •  ~0.3 (t < t)  ~ 0.1 (t > t) • Dust is supplied by Type II SNe (m* > 8 Msun). • Dust per SN = 0.4Msun (Todini & Ferrara 2001; Nozawa et al. 2003): initial Mdust = 0 • Galaxies are treated as one zone. SFR (t) ⇒ SN II rate (t) ⇒ Mdust (t): t: Age of the dark halo (Salpeter IMF)

  13. UV radiation IR radiation Dust grains (~0.1mm) Absorb UV Radiate IR Observer Massive stars 3～100MO LUV and LIR Estimation • LUV= [1-exp(-dust)]/dustLUV* (LUV* ∝ SFR) • LIR= (1-[1-exp(-dust)]/dust) LUV* dust: Optical depth of dust, ∝ Mdust/R2

  14. Comparison at z ~ 3 The highest-z statistical sub-mm sample Our prediction at z ~ 3 z ~ 2.5 z ~ 1 Chapman et al. (2005)

  15. Further Test (Ongoing) Tamura et al. (2008) Cross correlation between sub-mm (ASTE) galaxies and Ly emitters. If young halos are selected as Ly emitters, we can reproduce the correlation also theoretically. Comparison with known optical/UV sample may be useful to test our model.

  16. Prediction for ALMA Galaxies (LIR>1011LO) at z = 6 497 galaxies (LIR>1011LO) are found in (150Mpc/h)3. Detectable with ALMA. Correlation with clustering of optical sources is good.

  17. Results (LIR>1011LO) at z = 10 30 galaxies (LIR>1011LO) are found in (50Mpc/h)3 ~1000arcmin2

  18. Vanzi et al. (2000) SBS 0335–052 (Z/41) is genuinely young(< 5 Myr). 300 pc D = 53 Mpc 3. Nearby “Laboratories” of Primeval Galaxies • BCD = Blue Compact Dwarfs • Star formation (blue) • Small (compact) • Low metallicity⇒ early stage of evolution BCDs are nearby “laboratories” of high-z primeval galaxies.

  19. Dust is concentrated ⇒large t Vanzi et al. (2000) Vanzi et al. (2000) Observational Constraints from SBS 0335–052 Evolution of dust mass Evolution of FIR lum.

  20. l = 90 mm l = 90 mm 3 kpc 3 kpc Mrk 71 II Zw 40 AKARI Observations of BCDs Hirashita, Kaneda, & Onaka (2008) 9 BCDs at  = 65, 90, 140 m. This kind of observations are important before ALMA!!

  21. Ichikawa & Hirashita (2008) Dust Temperature sub main Milky Way BCDs are on the same sequence as the MW and the MCs toward the high T extension (30 - 40 K ~ high-z LBGs). （Hibi et al. 2007） FIR Color-Color Diagram

  22. 4. Summary of Strategy • Dust optical depth at z ~ 6 is lower but we can detect a few tens of galaxies with 100 arcmin2 (Tamura et al.) survey. ←We should observe a known clustered region if we want a statistical sample of galaxies. • We could also detect a few z ~ 10 galaxies. (We should construct a deep (as deep as possible) 220 GHz sample. + A MIR pre-survey may be useful to select extremely high-z galaxies efficiently. Where???) • Nearby BCDs can be used as a scale-down version of high-z star formation. (intense radiation field in low metallicity environment)

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