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COSMIC DOWNSIZING and AGN METALLICITY at HIGH REDSHIFT Roberto Maiolino INAF - Oss. Arcetri & Oss. Roma Tohru Nagao INAF - Oss. Arcetri & NAOJ Alessandro Marconi INAF - Oss. Arcetri Mass-Metallicity relation in galaxies at z=0 Tremonti et al. 2004 Chemical version of the cosmic downsizing (anti-hierarchical growth) Evolution of the Mass-Metallicity relation: massive galaxies chemically evolve rapidly at high-z QSOs QSOs 12 11 z=0 1 10 3 5 9 lg M* = 8 (Kobulnicky et al. 2003, Shapley et al. 2005, Savaglio et al. 2005, Maiolino et al. 2006) The metallicity of the Broad Line Region at 2<z<4.5 ~ 5000 QSO optical spectra (UV-rest) from SDSS DR2 Sample large enough to disentagle the dependence on redshift and on luminosity 22 high quality composite spectra in bins of redshift and luminosity Lya NV SiII OI+SiII CIV SiIV OIV] NIV] CII HeII OIII] AlII SiIII] AlIII CIII] “1600A bump” NIV+AlII+NIII+Fe fit residuals Nagao, Marconi & Maiolino 2006 Photoionization models: Accurate fluxes for 15 emission lines - Cloudy - Integration over different distributions (in r and n) of gas clouds - Spanning various gas metallicities (abundances prop. to solar, except for N) matching flux ratios (+ constraints from EW) “best” metallicity for each [z,L] bin Hagai (!) Nagao et al. 2006 Metallicity of the BLR at 2<z<4.5 Average trends - Significant dependence on Luminosity Consequence of the mass-metallicity relation Z M* MBH LQSO ...but also dependence on accretion rate (Shemmer et al. 2004) - No evolution with redshift No metallicity evolution even in the most distant QSOs at 4.5<z<6.4 (close to re-ionization) From near-IR spectra (=UV rest-frame) of 20 QSO J1148+52 z=6.4 QSOs probe the most extreme cases of anti-hierarchical growth: their host galaxies are fully evolved, from the chemicalpoint of view, already at very high redshift QSOs QSOs 12 11 z=0 1 10 3 5 9 lg M* = 8 Selection effects associated with QSO-galaxy coevolution Passive evolution + Unobscured QSO Star formation + Obscured AGN wind Large number of emission lines: possible to contrain abundances patterns Best matches with abundances at/after the wind Pipino & Matteucci 2004 Granato et al. 2004 QSOs best fit The Broad Lines sample only a tiny, nuclear region ... not representative of the host galaxy? Use Narrow Lines in obscured AGNs NLR evolution at 1.2<z<3.8 - 51 optical spectra (UV-rest) of high redshift narrow line radio galaxies (HzRG) - 10 optical spectra (UV-rest) of high redshfit X-ray selected QSO2 in the Chandra Deep Field South CIV/HeII vs. CIII]/CIV diagram: - sensitive to metallicity - removes degeneracy from U - possible to control effects of shocks and dust Nagao, Maiolino & Marconi 2006 NLR evolution at 1.2<z<3.8 CIV / HeII No evolution with redshift among HzRG at 1.2<z<3.8 3 1 (local) 0.5 Dependence on Luminosity CIV / HeII 3 1 (local) 0.5 0.3 CIII] / CIV 1 At z>4 little information on NLR metallicity ...but information on gas in host galaxy for some QSOs J1148+52 z=6.4 same [CII]/CO as loc. ULIRGs same [CII]/FIR as loc. ULIRGs strong enrichment of carbon in the host already at z=6.4 CONCLUSIONS Luminosity-Metallicity relation: consequence of Mass-Metallicity relation BLR in galaxies & NLR No metallicity evolution with redshift: QSO are extreme cases of the cosmic downsizing (in its chemical version) Abundance patterns matching expectations of AGN-galaxy joint evolutionary models