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Star formation at high redshift (2 < z < 7)

Star formation at high redshift (2 < z < 7). Methods for deriving star formation rates UV continuum = ionizing photons (dust obscuration?) Ly a = ionizing photons (dust obscuration?) Far IR = bolometric (covering factor?) Radio continuum (synchrotron) = empirical (radio – FIR correlation?)

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Star formation at high redshift (2 < z < 7)

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  1. Star formation at high redshift (2 < z < 7) • Methods for deriving star formation rates • UV continuum = ionizing photons (dust obscuration?) • Ly a = ionizing photons (dust obscuration?) • Far IR = bolometric (covering factor?) • Radio continuum (synchrotron) = empirical (radio – FIR correlation?) • Radio free-free/RRLs = ionizing photons (sensitivity, spectral confusion?) • All relate mostly to massive stars (> 5 M_sun) => total SFR depends on extrapolation of IMF, and temporal behavior

  2. Cosmic (proper) time

  3. Radio-FIR correlation: tightest correlation in extragalactic astronomy Separating FF – Synch is difficult Thermal dust M82 Synch. Free-free

  4. SKA in context EVLA z=8

  5. Cosmic ‘background’: ½ starlight reprocessed by dust

  6. Madau-Lilly plot: evolution of cosmic star formation rate density Evolution of space density of luminous QSOs (Fan et al. 2003)

  7. Galaxy populations at high redshift (2 < z < 7) • Radio galaxies: only z > 0.5 galaxies before 90’s • UV dropouts/Ly-break: broadband colors • Ly a: narrow band imaging • Submm: (sub)mm bolometer camera imaging • QSO Hosts: HST, (sub)mm • QSO absorption lines: metalicity evolution, parent galaxies • z=0.3 to 2: EROs, faint blue, Butcher-Oemler, mJy radio sources, ISO • GRB hosts • Pop III stars: early reionization by 100 M_sun stars in minihalos at z = 20?

  8. High z radio galaxies (L_1.4 > 1e28 W/Hz) z=0.057 1954 z=3.8 1990 10kpc 10kpc z=0.49 1980 z = 5.2 2000

  9. K-z relation: HzRGs = Giant Ellipticals z>8 radio galaxies?

  10. Alignment effect: Jet-induced star formation? Clumpy morphologies => forming ellipticals? 1138-262 z=2.2

  11. Alignement effect: Radio-Xray 18kpc Radio-Lya halo

  12. Clustering on Mpc scales around HzRGs (1138-262 z=2.2) => protoclusters?

  13. Dusty radio galaxies at high z? Overdensity of submm galaxies?

  14. UV dropouts/Ly break (Ly a)

  15. Star formation rates in Ly break galaxies Extinction uncorrected corrected

  16. Correlation between extinction and SFR => L_UV is independent of SFR

  17. Ly break galaxies = highly biased (ie. clustered) galaxy formation

  18. Ly break galaxies with Ly a halos

  19. SUBMM galaxies: dust obscured galaxy formation HDF – 850 mm HDF - optical

  20. Dust obscured star formation dominates at z>2? Submm galaxies: L_FIR = 1e12 to 1e13 L_sun => SFR = 100 to 1000 M_sun /yr M_dust = 1e8-9 M_sun

  21. Magic of submm 350 GHz 250 GHz

  22. Brightest mm source in HDF: K = 23.5

  23. Radio photometric redshifts: two colors, or ‘drop-outs’

  24. Redshift distribution

  25. Next step: photometric redshifts

  26. CO emission => M(H_2) = 1e10-11 M_sun

  27. Submm galaxies

  28. QSO host galaxies • Most low z spheroidal galaxies have SMBH • M_BH = 0.002 M_bulge • => ‘Causal connection between SMBH and spheroidal galaxy formationn’ (Gebhardt et al. 2002)?

  29. z=6.4 S_250=5.5mJy 2322+1944 • 30% of luminous QSOs have S_250 > 2 mJy • L_FIR > 7e12 M_sun Dust heating: starburst or AGN?

  30. Radio-to-IR SED = M82

  31. CO(1-0) w. VLA: L_FIR = 3e13 L_sun M(H_2) = 1e11 M_sun

  32. A Molecular Einstein Ring: VLA 45 GHz observations of CO2-1 emission from the gravitationally lensed QSO 2322+1944 at z=4.12 (Carilli et al. 2003) Keck Rband VLA CO2-1 2”

  33. Using the gravitational lens to probe sub-kpc scales in 2322+1944: A starburst disk surrounding a SMBH => coeval SMBH – galaxy formation? Optical QSO Starburst disk: molecular gas, dust, radio continuum

  34. Starbursts in QSO host galaxies? • 30% of luminous QSOs (M_B < -27) have L_FIR = 1e13 L_sun (independent of redshift) • Z= 2 sample: All L_FIR luminous QSOs detected at 1.4 GHz, and in all cases ‘q’ consistent with star forming galaxy (2.3 +/- 0.3)

  35. Questions • Relationships between different high z galaxy types? • Halos masses and end-products (spirals, ellipticals)? • Is > 1000 M_sun/yr possible, sustainable (Heckman limit)? • IMF: top heavy? Star formation in extreme environments (P=100xISM)? Timescales? • Dust formation at z>6: >1e8 M_sun in < 0.7 Gyr? • What fraction of high z galaxy formation is dust-obscured? • Submm galaxies – redshift distribution? • radio – FIR correlation: mechanism? vs. redshift? • M-s relation – coeval SMBH and galaxy formation? • QSO dust heating: star formation or AGN? • L_FIR from S_250? • X = gas mass to CO luminosity conversion? L_FIR to dust mass conversion? • Pop III stars, minihalos, and first luminous objects: role of radio astronomy?

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