SDSS J1042-0018 a broad line AGN but mis-classified as a HII galaxy in the BPT diagram by flux ratios of narrow emission lines

Abstract In the manuscript, we discuss properties of SDSS J1042-0018 which is a broad line AGN but mis-classified as HII galaxy in BPT diagram (SDSS called AGN). The emission lines around H$\alpha$ and H$\beta$ are well described by different model functions, considering Balmer to be Gaussian or Lorentz functions. Different functions lead determined narrow fluxes, flux ratios diagram. order explain unique J1042-0018, two methods proposed, starforming contributions compressed NLRs with high electron densities near critical forbidden lines. Fortunately, strong can preferred J1042-0018. explained contributions, could provide further clues on applications diagrams normal AGN.