Research

My research focuses on disentangling the complexities of Active Galactic Nuclei (AGN) using optical spectroscopy. I mainly use spectra from the Six-degree Field Galaxy Survey (6dFGS: 2001-2009), along with modern spectra from ANU 2.3m Wide Field Spectrograph (WiFeS) to compare changes in the Hβ/[OIII] line ratios on a 15-20 year timescale.

Understanding AGN Sub-Types

My Ph.D. project aims on unraveling the physical distinctions among AGN sub-types and examining their correlations with the orientation of the AGN and host galaxy, the accretion rate of the AGN, and the dust obscuration of the host galaxy. Specifically, my work entails a comprehensive exploration of variations in the Hβ and [OIII] emission line ratios over two epochs. By analysing these ratios, I aim to infer the transient properties of AGN.

Changing Look AGN

The [OIII] emission line is a tracer of the host galaxy star formation along with AGN narrow-line emission. This is not expected to change in short timescales. In contrast, the broad Hβ emission line is a tracer of the accretion rate of the AGN and is expected to vary in short timescales. Therefore, the ratio of the Hβ to [OIII] emission lines is expected to vary on short timescales. However, certain AGN exhibit extreme fluctuations, including the abrupt appearance or disappearance of the broad component of the Hβ emission line within just a few months. Such phenomena are classified as Changing Look AGN (CLAGN). For my Honours Thesis, I focused on the identification of CLAGN through the analysis of light curves.