Constraining Spins of SMBHs from TeV Variability Yan-Rong Li (IHEP) Ye-Fei Yuan (USTC), Jian-Min Wang (IHEP) Jian-Cheng Wang (YNAO), Shu Zhang (IHEP) Refs: Wang, J. -M., Li, Y. -R. et al. 2008, ApJ, 676, L109 Li, Y.-R. et al. 2009, ApJ in press

Outline I.Introduction: TeV variability in M87 II.Constraints of Pair Production III.ADAFs/RIAFs in M87 IV.Optical Depth to ~TeV photons V.Summary

I. Introduction A radio galaxy at 16Mpc with M bh =3.0×10 9 M ⊙ (Macchetto et al 1996, Harms et al. 1994) Inclination of jet: 30 ° (Bicknell et al. 1996) Variability time scale: Aharonian et al 2006, Science HESS M87

I. Introduction The characteristic size, Size: 20R g The possible source of the TeV-rays is the nucleus of M87 itself (Aharonian et al. 2006). emission mechanism: Levinson 2000, Neronov & Aharonian 2007, Rieger & Aharonian 2008 Question: how do TeV photons escape?

II Constraints of Pair Production Pair production processes

II. Constraints of Pair Production TeV photons are used as a tracer to probe the radiation fields around BHs

II. Constraints of Pair Production Radiation field: accretion rate and spin orientation: 30° BH mass: M bh =3.0×10 9 M ⊙ accretion rate? spin? Only fitting SED is not enough! Supplementing TeV constraints relax the degeneration of the spin and the accretion rate.

III. ADAFs/RIAFs in M87 SED shows: ADAFs/RIAFs is working due to the absence of Big Blue Bump Radio: VLBI (0.1″), IR: Gemini (460″), Optical: HST (22″), X-ray: Chandra (500″) (see Di Matteo et al. 2003, Wang et al. 2008)

III. ADAFs/RIAFs in M87 Fully GR ADAFs/RIAFs model (Manmoto 2000) Radiation Processes Synchrotron Inverse Compton Scattering Bremsstrahlung

III. ADAFs/RIAFs in M87 Free Parameters : spin : accretion rate : viscoisty : magnetic : viscous dissipation that heats electrons : the observation angle. have typical value from physical model. Spectral fit To reduce the freedom, fix, adjust.

III. ADAFs/RIAFs in M87 (data see Di Matteo et al. 2003, Wang et al. 2008)

III. ADAFs/RIAFs in M87 (data see Di Matteo et al. 2003, Wang et al add HST observation from Sparks et al. 1996, Maoz et al )

IV. Optical Depth to TeV Photons Ray tracing

IV. Optical Depth to TeV Photons

To avoid being optically thick to 10TeV photons, the spin of SMBH in M87 should be a>0.8

V. Summary We use fully GR solutions of ADAFs/RIAFs. We use the GR time-space to calculate the optical depth. The SMBH in M87 is spinning fast.

V. Summary The TeV variability can be used to probe the innermost regions around the central black hole and allows us to disentangle the spin from other parameters in modeling the continuum spectrum. Future H.E.S.S. (phase II) observations may reveal the TeV variability of M87-like sources.