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Line vs Continuum Correlations

Line vs Continuum Correlations. Joe Shields Ohio University. Baldwin (1977). The “ Baldwin Effect ” - Carswell & Smith (1979) Negative correlation between luminosity and line equivalent width. QSO spectra as function of luminosity (Dietrich et al. 2002). Baldwin Effect.

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Line vs Continuum Correlations

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  1. Line vs Continuum Correlations Joe Shields Ohio University

  2. Baldwin (1977) • The “Baldwin Effect” - Carswell & Smith (1979) • Negative correlation between luminosity and line equivalent width

  3. QSO spectra as function of luminosity (Dietrich et al. 2002)

  4. Baldwin Effect Log L(line)  Log EW  Log L(continuum)  Log L(continuum) 

  5. Baldwin Effect - Why Do We Care? • Originally cosmology • Early pattern emerging out of chaos of phenomenology • Indicator of broad-line region/accretion physics 30 years later: • Still interesting for BLR physics (see Baldwin 1999 for cosmology) • Much better data • Context has grown (PCA, EV1, black hole masses, L/Ledd, etc.) • EWs easy to measure 5

  6. Multiple Baldwin Effects ? • Ensemble (“global”): single-epoch observations of multiple QSOs • Intrinsic: multi-epoch observations of a single, variable AGN • Broad lines • Narrow lines • X-ray (Fe K) • WR stars?? • Novae??

  7. Ensemble Baldwin Effect: what do we know? UV/optical Broad Lines: • It exists • Formerly controversial • Lots of scatter common • Need sufficient range of L Kinney et al. 1990

  8. Ensemble Baldwin Effect: what do we know? 2) Different slope for different lines • Steeper slope for higher ionization lines Dietrich et al. 2002 NV 1240 is an exception

  9. Ensemble Baldwin Effect: lines of special interest • NV 1240 : • Most studies show no BE • Probable explanation: metallicity effect N/H  Z2, higher Z goes with higher L (Hamann et al.) • Different behavior for NIII] 1750, NIV] 1486 (but weak lines) • H 4861 : • Recent studies show weak, inverse trend (negative BE) • Important for use of Balmer lines as tracer of luminosity (e.g., Greene & Ho 2005, X.B. Wu talk)

  10. EW  L0.2 EW  L0.1 (2dF, Croom et al. 2002) (SDSS, Greene & Ho 2005)

  11. Ensemble Baldwin Effect: explanations • Luminosity-dependent covering factor/ionization parameter (e.g. Mushotzky & Ferland 1984) • Luminosity-dependent continuum shape (e.g. Netzer et al. 1992, Korista et al. 1998) Another fundamental parameter correlated with luminosity? E.g. • redshift • L/Ledd • MBH 11

  12. Ensemble Baldwin Effect: L vs. z Observational Problem: L strongly correlated with z in most samples (LBQS, Green et al. 2001) Log (z) Solution: fill in L-z plane (Dietrich et al. 2002)

  13. Ensemble Baldwin Effect: L vs. z Bottom line: z dependence weak compared to L (Dietrich et al. 2002)

  14. Ensemble Baldwin Effect: L vs. L/LEdd LEdd: derive from MBH based on linewidth, L BQS: Baskin & Laor 2004  Tighter correlation with L/LEdd (also Bachev et al. 2004)

  15. Ensemble Baldwin Effect: L vs. L/LEdd Results for H: Netzer et al. 2004 Baldwin Effect in H ?? 15

  16. Ensemble Baldwin Effect: L vs. L/LEdd Log EW Further correlations with L/LEdd Warner et al. 2004

  17. Ensemble Baldwin Effect: a function of L or … Caution: L, L/Ledd, MBH often highly correlated Log L/LEdd Log L Warner et al. 2004

  18. Ensemble Baldwin Effect: L/LEdd vs MBH  Stronger correlation with MBH Warner et al., submitted

  19. Ensemble Baldwin Effect: L vs MBH Warner et al., submitted  Stronger correlation with MBH

  20. Ensemble Baldwin Effect and PCA Results • Shang et al. (2003): • SPC1 mostly responsible for BE, • linked to L SPC3 linked to Boroson & Green EV1  L/LEdd or MBH Shang et al. 2003

  21. Narrow-Line Seyfert 1s and the Baldwin Effect • Believed to be extreme EV1 or L/LEdd objects Osmer, Porter, & Green (1994) Constantin & Shields (2003) 21

  22. Baldwin Effect in NLS1s UV Baldwin Effect • seen in NLS1s • Offset to smaller EWs Points: NLS1 sample Lines: Dietrich QSOs (Leighly & Moore 2004) (H shows negative trend also in NLS1s: Zhou et al. 2006) Is BE more uniform in L/LEdd ?

  23. Ensemble Baldwin Effect: L vs. L/LEdd Triangles: NLS1 average Log EW Warner et al. 2004  Additional parameter involved

  24. Intrinsic Baldwin Effect Example: NGC 4151 (Kong et al. 2006)

  25. Intrinsic vs Ensemble Baldwin Effect Kinney et al. (1990) 25

  26. Intrinsic Baldwin Effect: what do we know? • Steeper than ensemble BE • Causes may be quite different • Curvature seen • Tighter relation seen if lag removed (e.g., Pogge & Peterson 1992) (Lag is itself a function of L) • Consistent with photoionization theory (Korista, Goad, Cackett, Horne, Knigge, …) • Luminosity-dependent response a diagnostic tool for BLR

  27. Intrinsic Baldwin Effect: what do we know? 4) Some evidence of ionization-dependent slope • e.g. CIV steeper than Ly • FeII: • Mixed results for slope (optical), e.g. NGC 5548 (Vestergaard & Peterson 2005), NGC 4051 (= NLS1; Wang et al. 2005) • FeII does respond to continuum photon excitation • Measuring FeII is hard! Wang et al. 2005

  28. The Baldwin Effect in Narrow Lines • Detection claimed in several studies, esp. [O III] 5007 Log EW [NeV] [NeIII] [OII] MB (Also IR: Keremedjev & Hao) [OIII] 2dF: Croom et al. 2002

  29. The Baldwin Effect in Narrow Lines Popular explanation: high L NLR reaches limiting size = galaxy size Implications for detection of Type II QSOs (e.g. Netzer et al. 2006) • Weak lines  harder to find Implications for star formation and detection via nebular lines? (cf. Ho 2005: weak [OII]) • Star formation suppressed? Or confined to dense regions with low filling factor? Netzer et al. 2004

  30. X-Ray Baldwin Effect: Fe K(Iwasawa & Taniguchi 1993) • Broad Fe K (Nandra 1997) • Probable origin: “reflection” from accretion disk • Models: luminosity-dependent ionization of disk (Nandra, Nayakshin), and gravitational light-bending (Miniutti & Fabian 2004) • Questions regarding broad component measurements • Narrow Fe K(e.g. Page et al. 2004) • Probable origin: reflection from outer disk or torus • Model: luminosity dependent covering factor (receding torus) • Due primarily to radio-loud sources with extra continuum component? (Jiang et al. 2006)

  31. Summary • Baldwin Effect still significant for understanding AGN structure, physics • Seen in broad and narrow lines • BE calibration useful when shifting between measures of luminosity • Correlation with L may trace fundamental correlation(s) with MBH, L/Ledd, … no consensus yet? • Some disagreement regarding PCA connection • NLS1s outliers • Existence of X-ray Baldwin Effect uncertain • Sample details still very important Lots of progress, still work to do!

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