A Radio Study Of Nearby Low-Luminosity Active Galactic Nuclei With Interferometric Observations

Supermassive Black Holes (SMBH), as the central engine of Active Galactic Nu-clei (AGNs), play an important role in galaxy evolution. This accretion powered system influences ambient medium by radiation and mechanical energy output carried by jets, outflows, and/or winds. As shown by multi-wavelength surveys of the local universe, the formation and evolution of host galaxies are related to the growth/activity of the central SMBH. However, as one of the keystones of modern astrophysics, the accre-tion and feedback processes are still unclear. Surveys of nearby galaxies reveal that low-luminosity AGNs (LLAGNs) are found in a large fraction of galactic nuclei, and a radio core is pervasive in those LLAGNs. Those surveys also reveal flux variations in the LLAGNs, and provide observational support for the SMBH accretion model. How-ever, there are still lots of key questions to be answered:do the jets dominate the radio emission from SMBHs? Are there any changes in the direction of the jets that will evolve in the evolution? What is the origin of the flares close to the central SMBH?In this thesis, I will try to answer some of these questions by analyzing the high-resolution radio interferometric observations toward three special low-luminosity AGNs: M31, M32, and M104, and emphasize:1. the physical properties of the radio emission from low-luminosity AGNs; 2. The energy feedback of the jet in edge-on galaxies. We studied the properties of the radio emission from low-activity SMBHs, aiming to constrain the low-activity SMBH model and understand corresponding accretion and feedback processes.In Chapter 2, the " Andromeda"galaxy (M31) hosts one of the nearest low-luminosity active galactic nuclei (LLAGNs). We investigated its radio properties using deep, parsec-scale, quasi-simultaneous, multi-frequency (6,8.5,10,15 and 20 GHz) Karl G. Jansky Very Large Array (JVLA) continuums observations and archival data from the historical Very Large Array. We firstly detected a radio compact core at 10,15 and 20 GHz, and the presence of the extended structure emanating from the core at 6 GHz. We also reported its flux has a milder fluctuate at 6 GHz, and the variability interval appears random from day to month. Based on the multi-frequency observations, we built the spectral energy distribution (SED) from 6 to 20 GHz to obtain a spectral index ??0.45 (Sv ??) and discussed whether the radio emission is dominated by the part of the jet further away from the SMBH.In Chapter 3, the Local Group compact elliptical galaxy M32 hosts one of the near-est candidate super-massive black holes (SMBHs), which has a previously suggested X-ray counter- part. Based on sensitive observations taken with the Karl G. Jansky Very Large Array (VLA), we detect for the first time a compact radio source coincident with the nucleus of M32, which exhibits an integrated flux density of?47.3 ± 6.1?Jy at 6.6 GHz. We discuss several possibilities for the nature of this source, favoring an origin of the long-sought radio emission from the central SMBH, for which we also revisit the X-ray properties based on recently acquired Chandra and XMM-Newton data. Our VLA observations also discover radio emission from three previously known optical planetary nebulae in the inner region of M32.In Chapter 4, M104 (NGC 4594) is a massive early-type spiral galaxies, also known as Sombrero galaxies, there is a SMBH. We used JVLA to observe the con-tinuous of M104 at different resolutions in multi-band. It was shown that the kpc-scale extended structure in M104 is likely to come from the pc-scale jet. We found that the direction of the kpc-scale radio structure is significantly different from that of the pc-scale jet, It suggests that the jet is deflected during the evolution process or that the jet of different scales arise from different active periods of the center black hole. The mag-netic pressure of the kpc-scale jet was found to be comparable to that of the interstellar hot gas, implying that the mechanical work of the jet transport a considerable amount of energy into the gas.In Chapter 5,1 provide a summary and discuss directions for future work.