SPINS OF SUPERMASSIVE BLACK HOLES IN M87. II. FULLY GENERAL RELATIVISTIC CALCULATIONS
- Key Laboratory for Particle Astrophysics, Institute of High Energy Physics, CAS, 19B Yuquan Road, Beijing 100049 (China)
- Key Laboratory for Research in Galaxies and Cosmology, University of Sciences and Technology of China, CAS, Hefei, Anhui 230026 (China)
- Yunnan Observatory, CAS, Kunming 650011 (China)
The fast variability of energetic TeV photons from the center of M87 has been detected, offering a new clue to estimate spins of supermassive black holes (SMBHs). We extend the study of Wang et al. by including all of the general relativistic effects. We numerically solve the full set of relativistic hydrodynamical equations of the radiatively inefficient accretion flows (RIAFs) and then obtain the radiation fields around the black hole. The optical depth of the radiation fields to TeV photons due to pair productions is calculated in the Kerr metric. We find that the optical depth strongly depends on (1) accretion rates as {tau}{sub TeV}{proportional_to}M-dot{sup 2.2-5.0}, (2) black hole spins, and (3) location of the TeV source. Jointly considering the optical depth and the spectral energy distribution radiated from the RIAFs, the strong degeneration of the spin with the other free parameters in the RIAF model can be largely relaxed. We apply the present model to M87, wherein the RIAFs are expected to be at work, and find that the minimum specific angular momentum of the hole is a {approx} 0.8. The present methodology is applicable to M87-like sources with future detection of TeV emissions to constrain the spins of SMBHs.
- OSTI ID:
- 21307639
- Journal Information:
- Astrophysical Journal, Vol. 699, Issue 1; Other Information: DOI: 10.1088/0004-637X/699/1/513; Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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