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Determining Black Hole Masses in Distant Quasars

Determining Black Hole Masses in Distant Quasars

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Determining Black Hole Masses in Distant Quasars

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  1. Determining Black Hole Masses in Distant Quasars Marianne Vestergaard Dark Cosmology Centre, Copenhagen Collaborators: M. Bentz, S. Collin, K. Denney, X. Fan, C. Grier, L. Jiang, T. Kawaguchi, B. Kelly, P.S. Osmer, B.M. Peterson, G. Richards, C.T. Tremonti First Galaxies, Quasars, and GRBs, June 8 2010

  2. Possible Virial Estimators MBH = v2 RBLR/G In units of the Schwarzschild radius RS = 2GM/c2 = 3 × 1013M8 cm. Note: the reverberation technique is independent of angular resolution

  3. R Virialized BLR  Filled circles: 1989 data from IUE and ground-based telescopes.  Open circles: 1993 data from HST and IUE. • Dotted line corresponds to virial relationship with M = 6 × 107 M. Highest ionization lines have smallest lags and largest Doppler widths. V R (M/V2) Peterson and Wandel 1999

  4. Radius – Luminosity Relation Variability Studies:RBLR=cτ, vBLR (Kaspi et al. 2005; Bentz et al. 2006, 2009) (Kaspi ea 2007) L(1350Å) [erg s-1] 1039 1047 RBLR  Lλ(nuclear)0.50 (Data from Bentz et al., 2006) CIV Hβ

  5. Virial Mass Estimates: MBH = v2 RBLR/G Variability Studies:RBLR=cτ, vBLR (Kaspi et al. 2005; Bentz et al. 2006, 2009) For individual spectra: MBH= k(line)FWHM2 Lβ;   0.5 Lines: Hβ, MgII 2800, CIV 1549 RBLR  Lλ(nuclear)0.50 (see e.g. MV 2002, McLure & Jarvis 2002, MV & Peterson 2006; MV & Osmer 2009)

  6. Scaling Relationships: (calibrated to 2004 Reverberation MBH) Hβ: MgII: CIV: 1σ absolute uncertainty: factor ~3.5 – 4 Virial Mass Estimates:MBH=f v2 RBLR/G    (Vestergaard 2002; Vestergaard & Peterson 2006) (MgII : MV & Osmer 2009; cf. McLure & Jarvis 2002)

  7. Word of Caution • Comparing masses from different lines? Use equations on the same mass scale • Have multiple lines? • Use equations on the same mass scale. • Use all applicable emission lines. • Formula simple but method non-trivial! : care is crucial

  8. Radius – Luminosity Relation Using the highest quality data only! Scatter: 0.11dex The limitation is thus the profile width! RBLR  Lλ(nuclear)0.50 (Peterson 2010)

  9. No Broad Emission Line is Perfect! • H and MgII FWHM are not always the same – contrary to common claims SDSS DR3

  10. No Broad Emission Line is Perfect! • H and MgII FWHM are not always the same – contrary to common claims • MgII is strongly contaminated by strong, broad features of FeII, complicating its measurement Half the MgII line flux is submerged in FeII emission (Vestergaard & Wilkes 2001)

  11. No Broad Emission Line is Perfect! • H and MgII FWHM are not always the same – contrary to common claims • MgII is strongly contaminated by strong, broad features of FeII, complicating its measurement • MgII and CIV FWHM often deviate • - but cause is unclear: MgII is likely also problematic due to systematic narrowing with z • Note: CIV is prone tostrong broadabsorption! • Better understanding of profile differences needed • Investigations of systematic biases needed to improve and enhance black hole mass estimates (Study under way) More accurate MBH values crucial for cosmological studies!

  12. S/N Matters: Hβ & MgII 2008 FWHM difference: MgII - Hβ • Denney et al 2009: In lower S/N data FWHM is: • underestimated in direct measurements: -0.1 dex shift, distr. broader • overestimated in fits to profile: +0.1 dex shift, distribution broadens

  13. S/N Matters: MgII & CIV FWHM difference: MgII - CIV • Denney et al 2009: In lower S/N data FWHM is: • underestimated in direct measurements: -0.1 dex shift, distr. broader • overestimated in fits to profile: +0.1 dex shift, distribution broadens

  14. Are Quasar CIV Profiles Problematic? ~15% (EW) (FWHM) (Richards et al. 2002)

  15. Improving the Scaling Relationships • What causes spread around the M-σ relationship?? • Inclination? • - BLR kinematics is likely planar(Wills & Browne 1986, Vestergaard et al. 2000) • Accretion rate? • (Collin +. 2006; Shen + 2007) • Radiation Pressure? • (Marconi + 2008)

  16. Masses of Distant Quasars z~6 • Ceilings at MBH≈1010 M LBOL< 1048 ergs/s • MBH ≈ 109 M - even beyond space density drop at z ≈ 3 CIV MgII Kurk et al. 2007; Jiang et al. 2007, 2010 Hβ SDSS DR3: ~41,000 QSOs (MV et al. in prep) (DR3 Qcat: Schneider et al. 2005)

  17. Mass Functions of Active Supermassive Black Holes • BQS: 10 700 sq. deg; B16.16mag • LBQS: 454 sq. deg; 16.0BJ18.85mag • SDSS: 182 sq. deg; i* 20mag • DR3: 1622 sq. deg.; i* >15, 19.1, 20.2 Factor ~ 17 (H0=70 km/s/Mpc; ΩΛ = 0.7) (Vestergaard & Osmer 2009)

  18. LBQS MF(z|M) Evidence of ‘downsizing’ (MV & Osmer 2009)

  19. Summary • At present MBH can be estimated to within a factor of a few: M  FWHM2 L0.5 • R-L relation scatter is low for best data: Profile width is the limitation • Line profile depends on multiple factors – under investigation • Important points: • No emission line is perfect • Profile issues: not a show stopper • S/N ratio of data matters for mass accuracy! • Quasar Mass Functions: • Not simple scalings of Luminosity Function • We see downsizing from redshifts of 3

  20. Luminosity Functions of Active Supermassive Black Holes DR3: 1622 sq. deg.; i* >15, 19.1, 20.2 (Richards et al. 2006)

  21. Mass Functions of Active Supermassive Black Holes DR3: 1622 sq. deg.; i* >15, 19.1, 20.2  = 3.3 (MV et al. 2008)

  22. Summary • At present MBH can be estimated to within a factor of a few: M  FWHM2 L0.5 • R-L relation scatter is low for best data: Profile width is the limitation • Line profile depends on multiple factors – under investigation • Important points: • No emission line is perfect • Profile issues: not a show stopper • S/N ratio of data matters for mass accuracy! • Quasar Mass Functions: • Not simple scalings of Luminosity Function • We see downsizing from redshifts of 3

  23. Extra Slides

  24. (Dietrich et al 2002) Virial Relationships • All 4 testable AGNs comply: • NGC 7469: 1.2 107M • NGC 3783: 3.0 107M • NGC 5548: 6.7 107M • 3C 390.3: 2.9 108M • R-L relation extends to high-z and high luminosity quasars: • spectra similar(Dietrich ea 2002) • luminosities are not extreme Emission lines: SiIV1400, CIV1549, HeII1640, CIII]1909, H4861, HeII4686 (Peterson & Wandel 1999, 2000; Onken & Peterson 2002)

  25. Radius – Luminosity Relation Luminosities are not extreme R – L defined for 1041 –1046 erg/s Optical(Bentz et al. 2009) 1040 – 1047 erg/sUV (Peterson + 2005; Kaspi + 2007) (Kaspi ea 2007) L(1350Å) [erg s-1] 1039 1047 (Data from Bentz et al., 2006) CIV Hβ

  26. Luminosities of Distant Quasars • Ceilings at LBOL< 1048 ergs/s • LBOL  4.5 · L(1350Å)  10 · L(5100Å) • Maximum LBOL value does not extend much beyond R-L relation: 47dex & 47.65 dex CIV MgII Hβ SDSS DR3: ~41,000 QSOs (Vestergaard et al. in prep) (DR3 Qcat: Schneider et al. 2005)

  27. S/N Matters: Mass Estimates Ratio: MgII / Hβ Ratio: MgII / CIV Note: here MgII and CIV are not on entirely same mass scale!

  28. Improve Mass Estimates • Reduce scatterfurther • Can we account for radiation pressure on broad line gas? (eg Marconi et al. 2008) 0.4 dex 0.2 dex (Data from Vestergaard & Peterson 2006, Marconi et al. 2008)

  29. Reverberation Mapping Masses

  30. Virial Mass Estimates MBH = f v2 RBLR/G Reverberation Mapping: • RBLR= c τ • vBLR Line width in variable spectrum t +   t 24

  31. Reverberation Mapping Hβ [OIII] H Hδ H NGC 5548, the most closely monitored active galaxy (Peterson et al. 1999) 25

  32. Reverberation Mapping Results Continuum Light Curves galaxy 13 years of data Emission line NGC 5548, the most closely monitored active galaxy (Peterson et al. 2002) 23

  33. Velocity Dispersion of the Broad Line Region and the Virial Mass MBH = f v2 RBLR/G • Velocity dispersion is measured from the line in the rms spectrum. • The rms spectrum isolates the variable part of the lines. • Constant components (like narrow lines) vanish in rms spectrum f depends on structure and geometry of broad line region f1 for v = FWHM (based on Korista et al. 1995)

  34. Are black hole masses overestimated, eg by factor of 10?

  35. To first order quasar spectra look similar at all redshifts (Dietrich et al 2002)

  36. rL1/2 Radius – Luminosity Relations To first order, AGN spectra look the same • Same ionization parameter • Same density [Kaspi et al (2000) data]

  37. Radius-UV Luminosity Relationship for High-z Quasars M = VFWHM2 RBLR/G ↑ ↑ ↓ 0.1109 M 4500km/s 33 lt-days Ф RBLR-2 L <L> ≈ 1047 ergs/s LogФ  Log n(H)  (Korista et al. 1997)

  38. Radius-UV Luminosity Relationship for High-z Quasars M = VFWHM2 RBLR/G Ф RBLR-2 (Dietrich et al. 2002)