Environments of dwarf galaxies with optical AGN characteristics
  This study aims to explore the relation between dwarf galaxies ($M_* \leq
5\times10^9 M_\odot$) with AGNs and their environment by comparing
neighbourhood parameters of AGN and non-AGN samples. Using the NASA-Sloan
Atlas, both the local environment and the immediate environment of dwarf
galaxies with $z \leq 0.055$ are analysed. Of the 145,155 galaxies in the
catalogue, 62,258 of them are classified as dwarf galaxies, and by employing
two AGN selection methods based on emission line fluxes (BPT and WHAN), 4,476
are found to have AGN characteristics in their optical spectra. Regardless of
selection method, this study finds no discernible differences in environment
between AGN and non-AGN host dwarf galaxies and these results indicate that
environment is not an important factor in triggering AGN activity in dwarf
galaxies. This is in line with existing literature on environments of regular
galaxies with AGNs and suggests universality in terms of reaction to
environment across the mass regime. The biases of AGN selection in low-mass
galaxies, and the biases of different measures of environment are also
considered. It is found that there are several mass-trends in emission line
ratios and that the SDSS fiber covers galaxies non-uniformly with redshift.
These biases should be accounted for in future work by possibly including other
wavelength regimes or mass-weighting of emission line ratios. Lastly, a
discussion of the environment estimation methods is included since they may not
gauge the desired properties due to factors such as time delay or using loosely
constrained proxy parameters.
