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The Population and Luminosity Function of AGNs from SDSS

Carnegie Symposium (I) 2002. The Population and Luminosity Function of AGNs from SDSS. Lei Hao Collaborators : Michael Strauss SDSS collaboration Princeton University. Data Sample. 114,772 galaxy spectra (mostly r<17.7) in 1151 sq degrees

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The Population and Luminosity Function of AGNs from SDSS

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  1. Carnegie Symposium (I) 2002 The Population and Luminosity Function of AGNs from SDSS Lei Hao Collaborators: Michael Strauss SDSS collaboration Princeton University

  2. Data Sample • 114,772 galaxy spectra (mostly r<17.7) in 1151 sq degrees • 58,038 low redshift (z<0.33) emission line galaxies. • AGNs are identified by their emission line characteristics.

  3. 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.

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

  5. AGN selections • Broad Line AGNs – FWHM(Hα)>1,200 km/s – 3069 are identified • Narrow Line AGNs – 3456 are identified

  6. The Redshift and Magnitude Distribution • AGN sample • r-band Petrosian <17.7 • 1281 broad line AGNs • 2696 narrow line AGNs

  7. The Luminosity Function (LF) of AGNs • 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 probability function for each AGN. Nuclei Spectrum Host galaxy Weakened nuclei Noise New Spectrum AGN?

  8. Luminosity Function Result

  9. 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.

  10. 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.

  11. Conclusion • From SDSS, we compiled an AGN catalog including over 3000 broad-line AGNs and over 3000 narrow-line AGNs • The LF of the AGNs are calculated and checked. • Future work • AGN LF evolution • The connection btw. AGNs and host galaxies • The accretion rate of AGNs • Radio and X-ray properties • ……

  12. Assumption Evaluation • Galaxy Magnitude vs. Hα Luminosity 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

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