The Future of Direct Supermassive Black Hole Mass

Measurements

Dan Batcheldor

Rochester Institute of Technology

- The Role of SMBHs measurements.- Current Status of SMBH masses.- Mass estimate techniques.- Observational requirements.- Current and future abilities.

Dan Batcheldor, RIT, Astro2020 2

The Role of SMBHs

• Energy output, variability and longevity of AGN require accretion onto a SMBH.

• QSO number density higher in the past, expect to find relic SMBHs in local quiescent galaxies.

• Observed correlations between SMBH and host bulge properties.

• Correlations used to calibrate secondary techniques for higher redshift SMBH mass estimates.

• See review by Ferrarese & Ford (2005).

Dan Batcheldor, RIT, Astro2020 3

Current Status

• Only 3 cases that require a SMBH: NGC 4258, Circinus, Milky Way = 3.7(0.2) x 106 M

• ~ 30 direct mass estimates (106 M - 3.6 x 109 M)

• 25 with resolved spheres of influence up to 240 Mpc• Mostly early type hosts, mostly observed with HST.

• Modes: ~ 108 M, ~ 20 Mpc.

• Estimates from different methods may not be consistent.

Dan Batcheldor, RIT, Astro2020 4

Mass Measurement Techniques

• Resolved Proper Motions – Milky Way only

• 22 GHz water masers (NGC 4258)– Alignment issues– AGN required

• Asymmetric Fe K emission line (NGC 3516)– AGN required– Rev map, but crossing times < integration times

• Nucleated disk gas dynamics• Stellar dynamics

Dan Batcheldor, RIT, Astro2020 5

Mass Measurement Techniques

Gas Dynamics• Assumes rotating nuclear gas/dust disk. tot= stars + bh

• Relies on bright emission lines.• Keplerian rotation relatively easy to model and

positive signature of SMBH.• Arguments over non-gravitational forces.• Nuclear disks not present in all galaxies.• Inclination unconstrained in many cases.

Dan Batcheldor, RIT, Astro2020 6

Mass Measurement Techniques

Stellar Dynamics• 2 - integral models (Jeans equations).• 3 - integral models (orbital super-positioning).• Observed kinematics are purely gravitational.• Applicable to all galaxies.• Requires the use of faint stellar absorption lines at

low surface brightness. • Effected by extinction.• Systematic uncertainties.

Dan Batcheldor, RIT, Astro2020 7

Observational requirements

• Gas and stellar dynamics complementary. • 2D kinematics essential in both cases.• High sensitivity (STIS needs 100 orbits for

S/N 50 in M87 continuum).

• High resolution. Sphere of influence of 108 M

at 10 Mpc ( = 200 km s-1) is ~ 0.2 arcsec.

Dan Batcheldor, RIT, Astro2020 8

• Equate diffraction limit to sphere of influence.

• Evaluate for = 5200, 6563 & 8500Å.

• Assume modal distance values from current SMBH mass estimates.

• Consider sensitivities…

Current abilities

Dan Batcheldor, RIT, Astro2020 9

Future abilities

• JWST + NIRSpec.– At 9500Å R = 35, at 1.9m R = 2200 (135 km s-1) + IFU– At 8500Å R = 39, at 2.3m R = 2500 (120 km s-1) + IFU

• JWST + MIRI. – At 7.6m R = 3000 + IFU

• 16 m + ??

• TMT + ??

Dan Batcheldor, RIT, Astro2020 10

Summary

• Galaxy and SMBH formation and evolution intimately linked.

• 30 mass estimates over limited ranges.• Gas and stellar dynamics are complimentary

methods.• HST is exhausted, JWST limited abilities• To fully explore the M- plane

– 30+ m diffraction limited facility

– High spectral resolution in optical and near-mid IR

Dan Batcheldor, RIT, Astro2020 11