Metallicity Evolution of Active Galactic Nuclei Tohru Nagao (National Astronomical Observatory of Japan) Roberto Maiolino (INAF — Roma) Alessandro Marconi (INAF — Arcetri)

Galaxies or AGNs ?? Why Metallicity? by focusing on … ~ heavy elements  SNe of massive stars, mass-loss from less-massive stars ~ “imprint” of past star-formation history in each (host) galaxy ~ metallicity evolution  star-formation / metal-production history of the universe ~ investigating metallicity as a function of the age of the universe (= redshift) by focusing on … Galaxies or AGNs ?? ◎ high number density × low × rest-optical important lines ◎ rest-UV × 0<z<3 (or less) target redshift ◎ 0<z<6 (or more) × faint intrinsic luminosity ◎ bright

Composites at 2.0 < z < 2.5 Study on BLR metallicity example: Composites at 2.0 < z < 2.5 -24.5>MB>-25.5 (643 QSOs) -25.5>MB>-26.5 (1497 QSOs) -26.5>MB>-27.5 (917 QSOs) -27.5>MB>-28.5 (105 QSOs) -28.5>MB>-29.5 (5 QSOs) TN, AM, RM (2006a) Rest Wavelength (A) Study on BLR metallicity SDSS-DR2 5344 spectra of quasars @ 2.0<z<4.5 making Composite Spectra for each (z, LAGN) bins  very high S/N spectra

Dependences of emission-line flux ratios on (z, L) Redshift absolute B mag TN, AM, RM (2006a)

ZBLR / Zsun ZBLR / Zsun Dependences of BLR metallicity on (z, L) BLR metallicity is strongly correlated with AGN luminosity, but… NO redshift evolution up to z=4.5 !! ZBLR / Zsun TN, AM, RM (2006a)

NVl1240 / HeIIl1640 NVl1240 / CIVl1549 Study on NLR metallicity DeBreuck et al. (2000) 2 < z < 5 Narrow-Line Radio Galaxies BLR model NLR model NV emission from NLR is generally VERY weak Only upper limits on F(NV) have been obtained for most of radio galaxies… Metallicity diagnostics without NV emission should be applied !!

NLR metallicity diagnostic TN, RM, AM (2006b) 49 radio galaxies at 1.2 < z < 3.8 correlation: consistent to model how depends on z and LAGN ?? CLOUDY calculations one-zone, dust-free clouds CIV/HeII : sensitive to ZNLR CIII]/CIV : correction for U

Dependences of NLR metallicity on (z, L) TN, RM, AM (2006b) Not only BLR, the NLR metallicity also depends on LAGN but does not show any redshift evolution at 1.2<z<3.8

galaxies AGNs Why no metallicity evolution? z=0 Metallicity z=2 Galaxy Mass z=0 z=2 Erb et al. (2006) redshift evolution galaxies AGNs NV/HeII NV/CIV absolute B mag TN, AM, RM (2006a) INCONSISTENT !? a possible interpretation: SDSS QSOs are too bright  host galaxies are too massive  Z evolution has been completed Metallicity studies on high-z low-luminous AGNs are crucially important !!

Summary BLR metallicity Composite spectra of 5344 SDSS quasars Correlations with LAGN: non-correlations with z NV/CIV, NV/HeII, (SiIV+OIV])/CIV, AlIII/CIV, etc. LAGN-ZBLR relation does not show z-evolution up to z = 4.5 NLR metallicity Compiled data of 49 narrow-line radio galaxies at 1.2 < z < 3.8 Correlations with LAGN: non-correlations with z new metal diagnostic CIV/HeII with U-corrector CIII]/CIV LAGN-ZNLR relation does not show z-evolution up to z = 3.8 Possible interpretation Main star-formation activities in host galaxies of bright AGNs might be already completed even at z ~ 4  studies on lower-LAGN / higher-z AGNs are important

Appendix

Photoionization Model Calculations