Oral Presentation

Exploring the Accretion Flows of M87 and 3C 84 with the Faraday Rotation Measure Observations

Author(s): Yaping Li (Xiamen University), Feng Yuan (SHAO), Fu-Guo Xie (SHAO)

Presenter: Yaping Li (Xiamen University)

Low-luminosity active galactic nuclei (LLAGNs) are generally believed to be powered by an inner advection-dominated accretion flow (ADAF), an outer truncated standard thin disk, and a jet (namely accretion−jet model). However, the model degeneracy is a conspicuous problem. With resort to the Faraday rotation measure (RM) observations, we can further test and constrain the accretion−jet model. In this work, we calculate the RM based on the accretion−jet model of M87 and 3C 84, for which the RM in the submillimeter (sub-mm) band have been recently detected. With the upper limit of the RM for M87, the ADAF origin of its X-ray emission can be ruled out, which agrees well with the theoretical predication of Yuan & Cui 2005. By adopting a jet origin for the X-ray emission, our accretion−jet model can be reconciled with the RM upper limit. We further suggest that the sub-mm emission likely originate from the inner region of the accretion flow based on the broad-band spectra modeling and RM observations, although the possibility of the jet origin cannot be ruled out from the RM measurement alone. We further discuss the constraints on the accretion flow dynamics and geometry set by the RM observations if a robust detection of the RM in the sub-mm band is detected in the future. For 3C 84, we find that the sub-mm emission is dominated by the jet component, while the Faraday screen is attributed to the outer region of the ADAFs. This scenario is in well agreement with the spectral, temporal and polarization observations for 3C 84. We can further constrain the viewing angle of the jet to be 42◦ ≤ θ ≤ 57◦.