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The build-up of SMBHs in z<1 red galaxies

The build-up of SMBHs in z<1 red galaxies. Kate Brand, STScI “Galaxy and BH evolution: Towards a unified view” Tucson, 29 th Sept 2007

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The build-up of SMBHs in z<1 red galaxies

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  1. The build-up of SMBHs in z<1 red galaxies Kate Brand, STScI “Galaxy and BH evolution: Towards a unified view” Tucson, 29th Sept 2007 Collaborators: Michael Brown, Richard Cool, Vandana Desai, Arjun Dey, Buell Jannuzi, Emeric Le Floc’h, John Moustakas, Tom Soifer & the Xbootes, IRAC and AGES teams.

  2. Questions • How did the mass of SMBHs grow? • Have SMBHs accreted a significant fraction of their mass between z=1 and the present? • How is this related to the build-up of the red sequence? • What is connection between SMBH growth and massive galaxy evolution? Kate Brand - 29th Nov 2007

  3. Outline • A sample of red galaxies from the NDWFS Bootes field • X-ray & 24m stacking • Optical line diagnostics • Infrared color-color diagram • The build up of SMBHs between z=1 and z=0 Kate Brand - 29th Nov 2007

  4. The NDWFS Bootes field 9 deg2 Bw, R, I, K ~ 27.1, 26.1, 25.4, 19.0 mag (Vega). PIs: A. Dey & B. Jannuzi Kate Brand - 29th Nov 2007

  5. Multi-wavelength observations in the Bootes field VLA P-band 90 cm 7 sq.deg. 100mJy 100% complete; van Breugel, PI VLA L-band 21 cm 1 sq.deg. 15mJy 100% complete; Higdon, PI VLA (FIRST) 21 cm 9 sq.deg. 1mJy 100% complete; public Westerbork 21 cm 7 sq.deg. 8mJy 100% complete; Rottgering, PI Spitzer/MIPS 24,70,160um 9 sq.deg. 3.0, 30, 100 mJy 100% complete; Jan 2004 GTO Spitzer/IRAC 3.6 - 8um 9 sq.deg. 6.4, 8.8, 51, 50mJy 100% complete; Eisenhardt et al. Spitzer/IRAC 3.6,4.5,5.8,8um 9 sq.deg. 3.2, 4.4, 25, 25mJy Stern et al. large GO5 Spitzer program NOAO/FLAMEX J, Ks 4.7 sq.deg. 19.3 mag 100% complete; Elston et al. (2005) NOAO K, Ks 9 sq.deg. 18.6 mag 100% complete NOAO J, H 9 sq.deg. 21 mag 40% complete NOAO BW, R, I 9 sq.deg. 25.5-26.6 mag 100% complete NOAO U 9 sq.deg. 25 AB mag 100% complete GALEX FUV, NUV 1 sq.deg. 26 AB mag 100% complete, GTO GALEX FUV, NUV 9 sq.deg. 25 AB mag in progress, GTO HST I, H sparse 26, 23 mag in progress Chandra 0.5-7 keV 9 sq.deg. 4e-15 erg/s/cm2 100% complete NOAO/Keck spectroscopy sparse 24 mag in progress (500 so far) MMT/Hectospec spectra 9 sq.deg. R~20.5 mag completed (~25,000 redshifts) Spitzer/IRS spectroscopy sparse in progress Kate Brand - 29th Nov 2007

  6. The red galaxy sample • Reliable photometric redshifts for entire NDWFS catalog from ANNZ calibrated using ~20,000 galaxies from AGES (Brown et al. 2005). • U-V vs. Mv color selection  ~26,000 red galaxies Kate Brand - 29th Nov 2007

  7. 0.2 < z < 0.4 0.4 < z < 0.6 0.6 < z < 0.8 0.8 < z < 1.0 Nuclear accretion in “red and dead” galaxies at z<1 • Used Chandra XBootes survey to stack up the X-ray images to obtain a mean X-ray luminosity. • 5-ks on a single object -> for 1000 galaxies, a 5-Ms observation on the mean object. Brand et al. (2005) Brand et al. in prep. ~3200 ~6400 ~7900 ~8900 Kate Brand - 29th Nov 2007

  8. Contribution of LMXBs and HMXBs • HMXBs: • Short lifetime  Lx SFR • (Grimm et al.2003) • - Population Synthesis fits to optical photometry  SFR •  Expected Lx X-ray Luminosity SFR • LMXBs: • long lifetime  Lx  stellar mass • (Kimm et al.2004) • - Population Synthesis fits to optical photometry  abs K-mag •  Expected Lx X-ray Luminosity Lk Kate Brand - 29th Nov 2007

  9. Basic X-ray stacking results for red galaxies • <Lx> ~ 1041-1042 ergs s-1 is 5-10x too high to be due to stellar sources. The X-ray emission is dominated by accretion onto a SMBH • <Lx> is ~10-100x fainter than typical Seyferts The accretion rate is very low and/or radiatively inefficient • The X-ray spectrum is hard and can be explained by: • Absorbed =1.7 power-law with NH = 1 - 5 x 1022 cm-2 (increasing with z) • Unabsorbed =0.7 power-law (e.g. ADAF) The AGN must be obscured or radiatively inefficient Brand et al. in prep. Kate Brand - 29th Nov 2007

  10. The mean X-ray luminosity increases with redshift Absorbed Total Hard Lx Soft Stellar Unabsorbed Total Log (1+z) Hard Lx (1+z) 6.6 ± 0.9 Soft Stellar Brand et al. in prep. Kate Brand - 29th Nov 2007

  11. The mean X-ray luminosity is higher for more massive galaxies Stellar Mass (x1E10 M0) Stellar Mass (x1E10 M0) Kate Brand - 29th Nov 2007

  12. 24m stacking of red galaxies 0.2 < z < 0.4 0.4 < z < 0.6 • ~700/18000 (4%) of red galaxies have f24>0.3 mJy (<f24> = 0.5 mJy) • 22/49 (45%) of X-ray detected sources have f24>0.3mJy. • Mean 24m flux is far larger than expected by mass loss from evolved stars (cf. Rodighiero et al. 2007, Davoodi et al. 2006). 0.6 < z < 0.8 0.8 < z < 1.0 Kate Brand - 29th Nov 2007

  13. The mean infrared luminosity increases with redshift LIR (1+z) 6.8 ± 1.0 LIR (1+z) 8.6 ± 1.3 Kate Brand - 29th Nov 2007

  14. The mean infrared luminosity is a less strong function of mass Same plots for X-ray luminosity Kate Brand - 29th Nov 2007

  15. Optical line diagnostics Yan et al. 2006 Kate Brand - 29th Nov 2007 Optical spectra from the AGN and Galaxy Evolution Survey (AGES; Kochanek et al. in prep)

  16. IRAC color-color diagram Red galaxies with 24m emission have redder [5.8]-[8.0] colors than the general red galaxy population  PAH emission  a tracer of star formation. Kate Brand - 29th Nov 2007

  17. How important is the z<1 low accretion phase in the build-up of SMBHs? . . •  M = Lbol/c2 • M =1.76 10-5 M/yr (0.1/) (Lx/1041) x CB • = radiative efficiency of accretion energy CB=bolometric correction MEDD = 2.2 (MBH/108) M/yr Eddington ratio = M / MEDD . . . Kate Brand - 29th Nov 2007

  18. How important is the z<1 low accretion phase in the build-up of SMBHs? Integrating accretion rate from z=1 to present ( = 0.1)  increase in BH mass ~ 5107 M MBH ~ 0.002 Mbulge  <MBH> ~ 1 x 108M at z~1  SMBH mass could have increased by ~50% since z=1 in this low accretion-level regime ~ half of this build-up due to ~1% of population (bursty activity) complications: - Contribution from star-formation? - Non-static population (red sequence doubling between z=1 and the present) - Sensitivity to spectral shape (absorption correction) - Bolometric luminosity correction - if use ~20, half the inferred growth - Accretion efficiency ( if  = 0.001 (ADAF) increase in BH mass ~ 5109 Mif no outflows) Kate Brand - 29th Nov 2007

  19. Summary • We have analyzed the X-ray, optical, and infrared light emitted from ~20,000 red galaxies in the NDWFS Bootes field. • An X-ray stacking analysis shows that the X-ray emission is dominated by AGN activity - low level “radio mode” accretion rates? • The nuclear accretion rate increases significantly with redshift and is larger for more massive red galaxies. • Infrared stacking shows more infrared emission than expected for “red and dead” galaxies. The mean infrared luminosity increases with redshift but relation with mass is less strong. • Although X-ray emission is likely to be dominated by AGN activity, infrared light may be more dominated by star formation activity, and optical emission may be a mixture of the two. • The X-ray analysis shows that the average SMBH mass could have increased by ~50% between z=1 and the present. Kate Brand - 29th Nov 2007

  20. The End Kate Brand - 29th Nov 2007

  21. The evolving Luminosity function of red galaxies Luminosity Function Luminosity density of all red galaxies - ~ 50% increase in luminosity density between z=0 and z=1 - Total stellar mass has ~ doubled since z=1 Only >4 L* red galaxies - 80% of the stellar mass in massive galaxies was already in place at z=0.9. Brown et al. 2006 Kate Brand - 29th Nov 2007

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