Probing Multi‐Wavelength Spectral Energy Distribution of <scp>NGC</scp> 315

ABSTRACT The majority of nearby low‐luminosity active galactic nuclei (LLAGNs), are widely found in compact radio cores and/or weak jets. The central of galaxy is believed to be powered by hot accretion flow and jet. Besides the famous LLAGN sources M87 and Sgr A*, NGC 315 is also a well‐known supermassive black hole (SMBH), which can be used to explore accretion and jet physics. The aim of this work is to model the multi‐wavelength spectral energy distribution (SED) of the NGC 315, and all the data we used here in the literature correspond to the core emission. Similarly to M87 and Sgr A*, we find that the SED is hard to fit with a pure jet model or pure advection‐dominated accretion flow (ADAF). And with a coupled ADAF‐jet model, we find that the low‐frequency radio emission is better fitted by the synchrotron radiation of nonthermal electrons in the jet, and high‐frequency radio emission is mainly consistent with the inverse Compton radiation from electrons in ADAF. Furthermore, the high‐energy X‐ray emission can also be simultaneously explained by ADAF. From the SED fitting, we obtain important parameters of the central engine, we find that the SMBH in NGC 315 should be fast rotating with a dimensionless spin parameter , and only a small fraction of the material captured at the outer radius reaches the SMBH. These results will help us better understand the accretion and jet physics. And future further simultaneous multi‐wavelength observations will help us to better understand these questions.