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Observing the Feedback Process?

Observing the Feedback Process?. Peter Capak (SSC-Caltech) Nick Scoville (Caltech) Mara Salvato (MPIA- Garching) Dan Masters (UC Riverside) Tommy Wiklind (ESO-ALMA) Bahram Mobasher (UC Riverside). Questions. What are the parameters affecting the feedback process?

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Observing the Feedback Process?

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  1. Observing the Feedback Process? Peter Capak (SSC-Caltech) Nick Scoville (Caltech) Mara Salvato (MPIA- Garching) Dan Masters (UC Riverside) Tommy Wiklind (ESO-ALMA) Bahram Mobasher (UC Riverside)

  2. Questions What are the parameters affecting the feedback process? What are the relative contributions of starburst and AGN to the feedback process? What is the observational evidence for the starburst-AGN connection/co-evolution?

  3. AIM Find galaxies while undergoing the feedback process- by star formation or AGN This needs selection of evolved galaxies with high stellar mass at relatively high redshifts, hosting AGN Select bright enough galaxies to allow follow-up spectroscopy

  4. Use near– and mid–IR to select high redshift and evolved galaxies? The Balmer break is a prominent feature for stellar populations age t > 100 Myrs z = 7 no extinction t = 50 Myr t = 100 Myr t = 300 Myr t = 500 Myr t = 600 Myr t = 800 Myr

  5. Source Selection Construct a Spitzer/IRAC 4.5 micron selected sample, using COSMOS data This corresponds to a “mass-selected” sample at z~2-5 Select galaxies with zphot > 4 from this sample Select objects with bright IRAC ch1 and ch2 fluxes (high mass & evolved systems) Objects with marginal or no detection at optical bands

  6. z = 5 • z = 8 • z = 5 • z = 8 • z = 2 • z = 4 • z = 5 • z = 8 • z = 5 • z = 8 • z = 2 • z = 4 Model tracks from BC03 Post-starburst galaxies (age 0.2–1.0 Gyr) Elliptical (age > 3 Gyr) Dusty starburst galaxies K-selected sample from GOODS-S HST/ACS (BViz); VLT/ISAAC (JHKs); SST/IRAC (3.6, 4.5, 5.8, 8mm) 5754 sources 155 / 85 selected; 14/12 z > 5 (total 17) ~82% complete at KAB = 23.5

  7. Stellar Population Models • Population synthesis models (Bruzual & Charlot 2003): • Redshift range z = 0.2 - 8.6 • Age range = 5 Myr - 2.4 Gyr • Calzetti attenuation law EB-V = 0.0 - 1.0 • IGM absorption • Metallicities Z = 0.2, 0.4 1.0, 2.5 Zo • Salpeter IMF: 0.1 – 100 Mo • Star formation history: exponentially declining SFR t = 0 - 1.0 Gyr

  8. Fit to the Stellar Component Redshift 4.37 EB-V = 0.20 Age (Gyr) = 1.4 SF time-scale (Gyr) =0.6 Log(M*) = 11.10 Msun Corrected for dust Not corrected for dust

  9. Observations at longer Wavelengths The source is detected at 24 micron At 4.5-24 microns the SED has a power-law shape. the galaxy is not detected at mm wavelengths with IRAM; at sub-mm (1.2 mm) with MAMBO; at radio continuum (1.4 GHz) and X-ray. The absence of sub-mm and mm flux implies there is little or no cold dust => no on-going star formation activity

  10. Pure AGN SEDs AGN + dust (NGC6240) QSO (type 2) Stellar Component

  11. Pure Starburst SEDs Pure starburst SEDs: Arp220 M82 The template SEDs contain significant extinction

  12. Obscured AGN+Starburst SED Mkr231 SED: Stellar+ AGN-heated dust with an intense starburst at the center. Large Infrared luminosity Stellar Component

  13. Higher Redshift Counterparts

  14. JD2 (J-dropout) in HUDF (Mobasher et al. 2005) z = 6.5 no current star formation age ~ 0.65 – 1.0 Gyr EB-V = 0.0 M* = 5 1011 Mo Z ~ 0.2 – 1.0 Zo

  15. z = 4.9 EB-V = 0.150 age = 1.0 Gyr t = 0.3 Gyr M* = 2 1011 Mo z = 5.6 EB-V = 0.025 age = 0.8 Gyr t = 0.2 Gyr M* = 1 1011 Mo

  16. zspec = 5.554 Vanzella et al. 2006

  17. Stellar mass density from Yan et al. 2006 The stellar mass density derived from M*~1011 Mo at z~5.4 and z~4.5 appear consistent with the observed decrease with redshift (Yan et al. 2006)

  18. Conclusions The discovered galaxy appears to be a lower redshift counterpart of the more distant (old and evolved) systems It has gone through intense star formation activity (77 Msun/year) Given that there is an AGN at the core of the galaxy, the SF is not the only process responsible for removal of gas Number density of these galaxies strongly constrains the CDM models for formation of galaxies

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