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COSMOS 24 / 100 / 160 μ m

z~2 star formation as seen by Herschel-PACS Dieter Lutz MPE Ringberg, June 20, 2011. COSMOS 24 / 100 / 160 μ m. PACS Evolutionary Probe (PEP) special thanks for today’s talk: Benjamin Magnelli, Raanan Nordon, Stijn Wuyts, Giulia Rodighiero. Jose Acosta Bruno Altieri Paola Andreani

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COSMOS 24 / 100 / 160 μ m

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  1. z~2 star formation as seen by Herschel-PACS Dieter Lutz MPE Ringberg, June 20, 2011 COSMOS 24/100/160μm

  2. PACS Evolutionary Probe (PEP)special thanks for today’s talk: Benjamin Magnelli, Raanan Nordon, Stijn Wuyts, Giulia Rodighiero Jose Acosta Bruno Altieri Paola Andreani Herve Aussel Stefano Berta Angel Bongiovanni Damien Le Borgne Drew Brisbin Marcella Brusa Hector Castaneda Antonio Cava Jordi Cepa Andrea Cimatti Emanuele Daddi Helmut Dannerbauer Helena Dominguez-Sanchez David Elbaz Emeric Le Floc’h Natascha Förster Schreiber Reinhard Genzel Ignacio Gonzalez Gianluigi Granato Andrea Grazian Carlotta Gruppioni Martin Harwit Ho-Seong Hwang Georgios Magdis Manuela Magliocchetti Benjamin Magnelli Roberto Maiolino Leo Metcalfe Marco Mignoli Hagai Netzer Raanan Nordon Koryo Okumura Ana Perez Ismael Perez Fournon Albrecht Poglitsch Paola Popesso Lucia Pozzetti Francesca Pozzi Laurie Riguccini Giulia Rodighiero Jose Miguel Rodriguez David Rosario Amelie Saintonge Fadia Salmi Mara Salvato Miguel Sanchez Paola Santini Joana Santos Li Shao Eckhard Sturm Linda Tacconi Margherita Talia Silvia Tomassin Ivan Valtchanov Michael Wetzstein Eckhard Wieprecht Stijn Wuyts

  3. Conventional (local) wisdom on infrared galaxies and star formation Normal galaxy LIRG ULIRG 2 MSun/yr Star formation rate 200 MSun/yr disk Morphology major merger low AGN importance high several kpc Extent of star formation few 100pc on Position wrt `main sequence’ above cool Dust temperature from FIR warm high Ratio PAH/FIR low … CO conversion factor FIR line deficits …

  4. The IR ‘excess’ – overpredicted SFR from 24μm at z~2 Spitzer indications for SFR overestimate using 24μm and local SED template families : Papovich+ 07, Daddi+ 07 Change of SEDs’ PAH/IR at given L, or mid-IR contribution by (obscured) AGN? Strongly seen in Herschel Science Demonstration Data: Nordon+ 10, Elbaz+10 … and again in the deepest current Herschel data (Elbaz+11, Nordon+11)

  5. Local galaxies The role of the main sequence Elbaz+11 1105.2537 (GOODS-Herschel KP)

  6. Average SEDs for high-z galaxies on and above MS On MS Above MS High PAH/FIR, cold FIR Low PAH/FIR, warm FIR Elbaz+11 1105.2537 (GOODS-Herschel KP)

  7. Reconstructing average mid-to FIR SEDs of z~1-2 FIR detected galaxies SEDs and L(8)/IR from combination of Herschel/PEP with deep Spitzer MIPS/IRS peakup imaging Nordon+ 1106.1186

  8. But what is the physical quantity best correlating with L(8)/IR?

  9. ~0.75 dex ‘Traditional’ view SED as F(LIR) Consistent relation between L(8)/IR and offset from main sequence Nordon+11 1106.1186

  10. IRS spectra: influence of AGN is minor Using IRS spectra from Fadda+10 Nordon+11 1106.1186

  11. … even most AGN hosts follow these scalings Nordon+11 1106.1186

  12. Local KS on cloud scale: Changing mode, cloud conditions, merger Main sequence galaxy with distributed such ~identical clouds: SSFR Gas fraction Local conditions Rising gas fraction, filling factor, SSFR, MS with redshift A toy view

  13. Combining UV SED – mid-IR – far-IR star formation indicators SED fitting misses SFR for highly dusty and star forming systems • Continuous and consistent hierarchy of SF indicators • PACS+UV • 24μm+UV • SED fitting • (avoiding age underestimates) Biases in 24μm based SFRs taken out Wuyts+ 11 arXiv

  14. Morphologies on and off the main sequence z=0 N~640000 z=1 N~97000 z=2 N~24500 Wuyts+ in prep.

  15. ‘Mode’ Gas content Sizes and star formation densities

  16. What is the importance of off-MS star formation? Rodighiero+ in prep PACS-shallow PACS-deep BzK

  17. What is the importance of above-MS star formation?

  18. Objects >4x above main sequence ~10% of SF density ~2% of number density On average, each galaxy ~20Myr in this phase - short wrt period of elevated SFR in major mergers Not all galaxies going through major merger in 1.5<z<2.5

  19. Properties of the most luminous objects: The case of SMGs LIR > 6 1012 LIR < 6 1012 ~20% of sample Magnelli et al. in prep.

  20. The most luminous star forming galaxies OFRGs Star formation rates ~1000MSun/yr .. Note selection effects SMGs Magnelli et al. 2010 and in prep., see also Chapman et al. 2010

  21. 24μm and radio-based star formation rates vs. Herschel 24μm Radio Magnelli et al. 2010 and in prep., Ivison et al. 2010

  22. Summary • Herschel is correcting previous mid-IR based star formation rate estimates • Infrared SED properties are more naturally explained in relation to the redshift-dependent main sequence than in the traditional way as a function of IR luminosity • Out to z~2, relations between morphology and position on/above main sequence are in place • At z~2, galaxies above main sequence contribute ~10% in SFRD and ~2% in number • Herschel characterizes submm galaxies and substantiates huge SFRs, consistent with major mergers Related Posters: Berta et al. Magnelli et al. Nordon et al. Popesso et al. Wuyts et al. (x2)

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