Black Hole Masses from Reverberation Mapping

1. Black Hole Masses fromReverberation Mapping Bradley M. Peterson The Ohio State University • Collaborators:M. Bentz, S. Collin, K. Dasyra, K. Denney, • L. Ferrarese, K. Horne, S. Kaspi, T. Kawaguchi, C. Kuehn, • D. Maoz, K. Metzroth, T. Minezaki, H. Netzer, C.A. Onken, • R.W. Pogge, S.G. Sergeev, L. Tacconi, M. Vestergaard, • A. Wandel, Y. Yoshii

2. Key Points • The line-width measure used for reverberation-based masses should be the line dispersion line rather than FWHM. • New observations are leading to improved results, better identification of systematics.

3. Reverberation Mapping Results • Reverberation lags have been measured for 36 AGNs, mostly for one or more Balmer lines, but in some cases for multiple lines. • AGNs with lags for multiple lines show that highest ionization emission lines respond most rapidly  ionization stratification.

4.  H Other Lines Evidence for a Virialized BLR • Gravity is important • Broad-lines show virial relationship between size of line-emitting region and line width, r 2 • Yields measurement of black-hole mass M = f (ccent 2 /G) based on Peterson & Wandel (1999)

5. Ferrarese slope Tremaine slope Calibration of the Reverberation Mass Scale M = f (ccent 2 /G) • Determine scale factor f that matches AGNs to the quiescent-galaxy MBH-*. relationship • Current best estimate: f = 5.5 ± 1.8 • Scaling factor is empirically determined • This removes bias from the ensemble • Equal numbers of masses are overestimated and underestimated based on Onken et al. (2004)

6. Physical Interpretation of f • The Onken value is an average over the projection factors. • Example: thin ring Aside: since unification requires 0  i  imax, simple disks without a polar component are formally ruled out.

7. FWHM: Trivial to measure Less sensitive to blending and extended wings Line dispersion line: Well defined Less sensitive to narrow-line components More accurate for low-contrast lines 2.45 2.35 3.46 2.83 Characterizing Line Widths Some trivial profiles:

8. NLS1 + I Zw 1-type NGC 5548 H • Reverberation-mapped AGNs show broad range of FWHM/line. • Mass calibration is sensitive to which line-width measure is used! • Even worse, there is a bias with respect to AGN type (as reflected in the profiles) Extreme examples

10. NGC3227 NGC 3516 NGC 4051

11. I Zw 1 type NLS1

12. I Zw 1 type NLS1 NGC 5548

13. Subset of the above for which host-galaxy luminosity can be removed accurately.

14. Pop 2 Collin et al. Pop 1 Pop B Pop A similar to Sulentic et al. Mean spectra RMS spectra From Collin et al. (2006)

15. f = 5.7  1.5 f = 5.4  2.7 f = 6.2  3.5 f = 4.7  1.1 Mean spectra Pop 2 line-based calibration RMS spectra Collin et al. Pop 1 Pop B Pop A similar to Sulentic et al. From Collin et al. (2006)

16. f = 0.9  0.3 f = 2.2  1.2 f = 2.5  1.5 f = 0.8  0.2 Mean spectra Pop 2 FWHM-based RMS spectra Collin et al. Pop 1 Pop B Pop A similar to Sulentic et al. From Collin et al. (2006)

17. Line Width Measures • Conclusion: line is probably a less biased indicator of the mass than FWHM. • Use of FWHM will lead us to underestimate the masses of NLS1s, I Zw 1-type objects, and narrower-line objects in general. • Can be corrected for empirically, however (seeCollin, Kawaguchi, Peterson, & Vestergaard 2006).

18. HST ACS images are used to decompose light into nuclear and starlight components. Effect is to flatten radius-luminosity relationship. Starlight components are stronger than previously supposed. Bentz et al. (2006)

19. Other New Developments • New reverberation program on bright well-known Seyfert galaxies • Improve time sampling interval over original programs by as much as an order of magnitude in some cases. • Ultimate goal: a velocity-delay map for at least one line in one AGN. • Secondary goal: improve black hole mass measurements. Denney et al., in preparation Bentz et al., in preparation

20. C IV (upper limit) Other UV lines New H result NGC 4151 • Reanalyzed two UV monitoring data sets from IUE archive. • UV and optical give consistent mass, 5  107M Metzroth, Onken, & Peterson (2006) Bentz et al., in preparation

21. Mrev NGC 4151 • Moreover, the reverberation-based mass is consistent with the (highly uncertain) stellar dynamical mass based on long-slit spectra of the Ca II triplet. Onken, Valluri, et al., in preparation

22. The AGN MBH– * Relationship AGNs: Ca II triplet AGNs: CO bandhead (Dasyra & Tacconi) Quiescent: (Tremaine et al. 2002)

23. Onken calibration 

24. Could Inclination Play a Role? • Assume line width V  (a2 + sin2i )1/2 Vkep • Then f  M / VP  1 / (a2 + sin2i )1/2 • M / VP cannot be used to deduce inclination for individual sources because NGC 5548 shows that VP values can span a factor ~3. Collin et al. (2006)

25. Could Inclination Play a Role? • However, we can compare the OBSERVED cumulative distribution of M / VP with that predicted by this simple model for various values of a. • Reasonable agreement with simple model if only Population 1/A is used. • Implication is that at least some AGNs have narrow lines because of low inclination. Collin et al. (2006)

26. Summary • As the database on reverberation mapped AGNs improves, identification of systematic biases becomes easier. • Evidence that inclination plays a role. • Reverberation-masses are less biased with respect to profile by using line as the line-width measure. • FWHM / lineis sensitive to Eddington rate and inclination.

27. What Do Line Widths Say About Masses?

28. Brad’s gripe du jour: • For fixed Eddington rate, more massive sources have larger line widths: • NLS1 criterion of FWHM < 2000 km s-1 omits higher-luminosity objects from class (“I Zw 1–type” objects, including, for example, 3C 273)