The extreme super-eddington NLS1 RX J0134.2-4258-II. A weak-line Seyfert linking to the weak-line quasar

RX J0134.2-4258 is one of the most super-Eddington narrow-line Seyfert 1 (NLS1) galaxies, on which we conducted a monitoring campaign from radio to X-rays. In this paper, we present a detailed analysis of its optical/UV spectra and broad-band spectral energy distribution. Our study shows that the preferred black hole mass of RX J0134.2-4258 is M-BH similar to 2 x 10(7) M-?, giving a mass accretion rate through the outer disc of (m) over dot(out) similar to 20 (assuming zero spin), compared to the observed luminosity ratio L-bol/L-Edd similar to 6. This reduction in radiative efficiency is expected for super-Eddington flows, as power can be lost via advection and/or disc winds. We find that the optical/UV lines of RX J0134.2-4258 resemble those from weak-like quasars (WLQs), as it has notably weak C IV and N V emission lines. It also has drastic X-ray variability, again similar to that recently observed in some other WLQs. Ho we ver, WLQs have systematically higher masses (>= 10(8 )M(?)), and lower Eddington ratios ((m) over dot(out)similar to 1) than RX J0134.2-4258. We compare instead to the most extreme NLS1s, with similarly large (m) over dot(out) but smaller masses. These show similarly large reductions in radiative efficiency but their UV lines are not similarly wind dominated. We suggest a new category of weak-line Seyfert galaxies to describe sources like RX J0134.2-4258, and interpret its (so far unique) properties in a model, where the lower disc temperature in the higher mass black holes leads to the UV-line-driving mechanism, which enhances the super-Eddington radiation-pressure-driven wind.