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The spectra energy distribution and nuclear properties of Seyfert galaxies

The spectra energy distribution and nuclear properties of Seyfert galaxies. Reporter: Ran Wang Supervisor: Xue-Bing Wu Department of Astronomy Peking University. Introduction - Two populations of Seyfert 2s. Observation

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The spectra energy distribution and nuclear properties of Seyfert galaxies

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  1. The spectra energy distribution and nuclear properties of Seyfert galaxies Reporter: Ran Wang Supervisor: Xue-Bing Wu Department of Astronomy Peking University

  2. Introduction- Two populations of Seyfert 2s • Observation • Polarized observations for large Seyfert 2 samples show that only about half of the sources have polarized broad lines. • Young et al. 1996; Moran et al. 2000; Tran 2001 • Researches and physical explanations • Different properties were seen between Seyfert 2s with polarized broad line regions (HBLRs) and without polarized broad line regions (Non-HBLRs) in IRAS color f25/f60, hard X-ray luminosity, O[III]5007 luminosity, and so on

  3. Introduction • A true type Seyfert 2 was predicted from observation and theoretic explanation was discussed • we present a further study by comparing the spectral energy distributions (SEDs) among different kinds of Seyfert galaxies, especially HBLRs and Non-HBLRs and investigate the nuclear activities to see if they are reflected in the SEDs.

  4. Result – average SEDs • Different properties are seen in the SEDs • S1s: the UV/optical and infrared emissions are comparable • HBLRs: the infrared emission is relatively stronger than the UV/optical band • Non-HBLRs: a steeper increasing towards the FIR band and the emission from FIR band seems to dominate the bolometric luminosity

  5. Result – nuclear properties • Compton thin HBLRs seem to follow S1s' relation. • The Non-HBLRs have the smallest X-ray luminosities and seem to have no agreement between X-ray and total luminosities

  6. Result – nuclear properties • the bolometric luminosities of Non-HBLRs are obviously much lager than the total nuclear emission predicted by their 2-10keV luminosities. • From the Non-HBLR’s SED, the bolometric luminosities are dominated by the FIR emission • From the comparison with X-ray luminosities, the bolometric luminosities are no longer sensitive to the nuclear power for Non-HBLRs

  7. Discussion – starburst activities andeddington ratios • A comparison between Seyfers and Starburst galaxies • Similar slope is found between Non-HBLRs and SBs • We calculated the nuclear energy emission for Non-HBLRs and compared the eddington ratio • Consistant with Nicastro et al. (2003) lower eddington ratio was found in Non-HBLRs

  8. summary • Compared with S1s and HBLRs, the mean SED of Non-HBLRs show a different feature, which indicate the differences in the central AGN properties. • The mean SED of Non-HBLRs shows an extremely • brighter feature towards the far infrared band, which was believed to be contributed mostly by the circumnuclear starbursts. The power in this band seems to dominate their bolometric luminosities • A weaker hard X-ray emission was also found in Non-HBLRs, which is believed to be the indicator of a weaker nuclear power • The inclination dependent unification model may not work • Better model including accretion and evolution are needed • Still ask for larger samples

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