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Metallicity Evolution of Active Galactic Nuclei

Metallicity Evolution of Active Galactic Nuclei. Tohru Nagao (National Astronomical Observatory of Japan) Roberto Maiolino (INAF — Roma) Alessandro Marconi (INAF — Arcetri). by focusing on …. Galaxies or AGNs ?? ◎ high number density × low

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Metallicity Evolution of Active Galactic Nuclei

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

  2. by focusing on… Galaxies orAGNs?? ◎ highnumber density × low × rest-opticalimportant lines ◎ rest-UV × 0<z<3 (or less)target redshift ◎ 0<z<6 (or more) × faint intrinsic luminosity◎ bright Why Metallicity? ~ heavy elements  SNe of massive stars, mass-loss from less-massive stars ~ “imprint” of past star-formation historyin 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)

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

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

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

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

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

  8. 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

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

  10. 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

  11. Appendix

  12. Photoionization Model Calculations

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