Determination of the mass of black holes in active galaxies

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Determination of the mass of Determination of the mass of black holes in active galaxiesblack holes in active galaxies

O. MarcoO. Marco

ESOESO

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MMBHBH vsvs host galaxy 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 pcBulge potential scale ~103 pc

radio-quiet QSO

radio-loud QSO

Seyfert 1

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Direct measurement of MDirect measurement of MBHBH

• A direct method: gas kinematics around A direct method: gas kinematics around the central BHthe central BH

• Near IR: use of emission lines, Near IR: use of emission lines, HH22 2.12µm & Br 2.12µm & Br2.17µm 2.17µm

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First try: “seeing limited” spectroscopyFirst try: “seeing limited” spectroscopy

• Nearby object: NGC1068, D=~14 MpcNearby object: NGC1068, D=~14 Mpc• 1” = 70 pc1” = 70 pc

• spectral resolution corresponding to 35 km sspectral resolution corresponding to 35 km s-1-1

• Seeing resolution~0.4” in K band (2.2 µm)Seeing resolution~0.4” in K band (2.2 µm)

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Alloin D., et al., A&A, 369L33

Galliano E., et al., A&A, 393, 43

velocity difference of 140 km s-1 MBH ~ 108 M

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Need for Adaptive OpticsNeed for Adaptive Optics(high angular resolution)(high angular resolution)

• For remote objects, all would happen For remote objects, all would happen within seeing task: the “sphere of within seeing task: the “sphere of influence” of massive BH is <1” even for influence” of massive BH is <1” even for the closest galaxiesthe closest galaxies

• Use of HUse of H22 2.12 µm emission, CO 2.3 µm 2.12 µm emission, CO 2.3 µm absorption, [Fe II] 1.64 µm emissionabsorption, [Fe II] 1.64 µm emission

• Need a very large telescope, D≥8mNeed a very large telescope, D≥8m

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Centaurus ACentaurus A• Very close AGN: D~3.5 MpcVery close AGN: D~3.5 Mpc• 1” = 17 pc1” = 17 pc• The closest massive elliptical galaxyThe closest massive elliptical galaxy• Using [Fe II] emission linesUsing [Fe II] emission lines

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Häring N., et al., astro-ph 0507094MBH=8.6 107 M

[Fe II]

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Adaptive Optics Adaptive Optics vsvs normal observations normal observations

no-AO

AO