Possible evidence for the disk origin for the powering of jets in Sgr A*   and nearby elliptical galaxies
  The predicted radio flux for nearby ellipticals by the canonical ADAF(advection-dominated accretion flow) model is well above the observations. If the mass accretion rate favored by the numerical simulation were adopted, the ADAF model would also significantly overpredict the radio flux of Sgr A*. On the observational side, strong evidence for the existence of jets in Sgr A$^*$ and these ellipticals has been obtained. Based on these facts, we propose a truncated ADAF model for these sources. We assume that the accretion disk is truncated at a certain radius within which a jet forms by extracting the energy of the disk therefore the radio flux is greatly suppressed due to the radiative truncation of the disk and the fits to the observational data are excellent. For example, for Sgr A*, the model fits the spectrum very well from radio including the ``excess'' below the break frequency to hard X-ray under a high accretion rate near the simulation value; for M87, the predicted upper limit of the jet location is 24 $R_g$, in excellent agreement with the observational result of < 30 $R_g$. The success of the model supplies a possible piece of evidence for the disk rather than the hole origin for the powering of jets. 
Feng Yuan (Nanjing University)