1. 1 The Population and Luminosity Function of AGNs from SDSS Lei Hao Collaborators: Michael Strauss SDSS collaboration Princeton University CFA Lunch Talk: November, 14, 2002

2. 2 Introduction: AGN emission lines Broad-line AGNs Star-forming galaxies Narrow-line AGNs Veilleux & Osterbrock (1987)

3. 3 Introduction:Sloan Digital Sky Survey AGNs are interesting but rare SDSS is very promising in having a large AGN sample: –one-quarter of the sky –collect spectra of ~ 10 6 galaxies, 10 5 quasars, … Galaxies: r<17.77 Quasars: i<19.0; color selection Spectra resolution: ~ 2000 Over 400,000 spectra have been taken.

4. 4 Data Sample 114,772 galaxy and quasar spectra in 1151 sq degrees 58,038 low redshift (z<0.33) emission line galaxies. AGNs are identified by their emission line characteristics.

5. 5 Stellar Subtraction Emission lines are very easy to be contaminated by the underlying absorption lines. Apply Principle Component Analysis (PCA) to pure absorption line galaxies. Use Eigenspectra as stellar templates. Plus an A star spectrum; Power-law continuum

6. 6 Stellar Subtraction The emission lines of AGN are often contaminated by the host galaxy absorption lines. To correct the contamination,the underlying stellar absorption spectrum is removed from the original spectrum.

7. 7 AGN Selections – FWHM(Hα)>1,200 km/s – 3069 are identified Broad Line AGNs Narrow Line AGNs Distinguishing AGNs from star-forming galaxies Theoretical separation lines predicted by Kewley et.al 2001

8. 8 AGN Selections – FWHM(Hα)>1,200 km/s – 3069 are identified Broad Line AGNs – 3456 are identified Narrow Line AGNs Seyferts: Galaxy targeted for spectra in SDSS Quasars: Quasar targeted for spectra in SDSS

9. 9 The Redshift and Magnitude Distribution Seyfert sample –r-band Petrosian <17.77 –1281 broad line AGNs –2696 narrow line AGNs

10. 10 The Luminosity Function (LF) of Seyferts We measure the luminosity function as a function of Hα luminosity. Assumption –The luminosity of the nuclei is independent of the luminosity of its host galaxy. We measure the detection probability function for each AGN. Nucleus Spectrum Host galaxy Weakened nucleus Noise New Spectrum AGN?

11. 11 Luminosity Function: Seyfert 2s

12. 12 Luminosity Function: Seyfert 2s vs. Seyfert 1s

13. 13 Luminosity Function Result and Check Divide the AGN sample into subgroups by their redshifts. For each group, evaluate the expected AGN luminosity distribution using the LF calculated. If LF is correct, the expected distribution should match the observed distribution.

14. 14 Luminosity Function Result and Check Divide the AGN sample into subgroups by their host galaxy magnitudes. No systematic discrepancy  the nuclei luminosity is not strongly correlated with its host galaxy luminosity.

15. 15 Host galaxy luminosity vs. Nuclear luminosity Galaxy Magnitude vs. Hα Luminosity plot 0.01<z<0.03 0.03<z<0.06 0.06<z<0.09 0.09<z<0.12 0.12<z<0.14 0.14<z<0.2 0.12<z<0.14

16. 16 Host galaxy luminosity vs. Nuclear luminosity Correlation test (Kendall’s  -statistic) study to check the independency. L(host) ~ L(nuclei)  The principal quantity that determines the AGN luminosity is the Eddington ratio, not the black hole mass. Galaxy Magnitude vs. Hα Luminosity plot L(host) ~ L(nuclei) (0.0062±0.0005)

17. 17 Summary and Future Work From SDSS, we compiled an AGN sample including over 3000 broad-line AGNs and over 3000 narrow-line AGNs The LF of the AGNs are calculated and carefully checked. Nuclear luminosity is independent to the host galaxy luminosity. Future work: –Seyfert LF normalization and low redshift quasar LF –AGN LF evolution –The connection btw. AGNs and host galaxies –The accretion rate of AGNs

18. 18 Galaxies in Diagnostic Diagram

19. 19 Sersic Index Animation