Determination of the mass of black holes in active galaxies

1. Determination of the mass of black holes in active galaxies O. Marco ESO Albert Einstein Century International Conference

2. MBHvs host galaxy • Active Galactic Nuclei (AGN) are powered by accretion of matter onto massive black holes (BH) • A significant fraction of luminous galaxies must host black holes, relics of past activity • BH mass seems proportional to both the mass/luminosity of the host spheroid and its velocity dispersion * • BH scale ~10-5 pc Bulge potential scale ~103 pc radio-loud QSO radio-quiet QSO Seyfert 1 Albert Einstein Century International Conference

3. Direct measurement of MBH • A direct method: gas kinematics around the central BH • Near IR: use of emission lines, H2 2.12µm & Br 2.17µm Albert Einstein Century International Conference

4. First try: “seeing limited” spectroscopy • Nearby object: NGC1068, D=~14 Mpc • 1” = 70 pc • spectral resolution corresponding to 35 km s-1 • Seeing resolution~0.4” in K band (2.2 µm) Albert Einstein Century International Conference

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6. velocity difference of 140 km s-1 MBH ~ 108 M Alloin D., et al., A&A, 369L33 Galliano E., et al., A&A, 393, 43 Albert Einstein Century International Conference

7. Need for Adaptive Optics(high angular resolution) • For remote objects, all would happen within seeing task: the “sphere of influence” of massive BH is <1” even for the closest galaxies • Use of H2 2.12 µm emission, CO 2.3 µm absorption, [Fe II] 1.64 µm emission • Need a very large telescope, D≥8m Albert Einstein Century International Conference

8. Centaurus A • Very close AGN: D~3.5 Mpc • 1” = 17 pc • The closest massive elliptical galaxy • Using [Fe II] emission lines Albert Einstein Century International Conference

9. [Fe II] Häring N., et al., astro-ph 0507094 MBH=8.6 107 M Albert Einstein Century International Conference

10. Adaptive Optics vs normal observations  no-AO  AO Albert Einstein Century International Conference