Kavli Affiliate: Khee-Gan Lee
| Summary:
We report the discovery of four narrow-line type-1 quasars (NLQ1s) from the Subaru ‘Onohi’ula Prime Focus Spectrograph Subaru Strategic Program (PFS-SSP). To extend a comprehensive understanding of this population to the distant universe, we searched for broad-line AGNs (quasars) whose rest-UV spectral shapes resemble those of local NLS1 galaxies, utilizing the Ly$α$ line profile. We identified four NLQ1s, including one candidate, at $z=2.54$ — $6.06$. The obtained spectra show a prominent Ly$α$ emission line with a very low continuum level. The measured full width at half maximum (FWHM) of Ly$α$ ranges from $1410 mathrmkm,s^-1$ to $1510 mathrmkm,s^-1$ with a mean of $sim 1430 ,mathrmkm,s^-1$. Although we used only line width information for the NLQ1 selection, the resulting equivalent widths (EW) of Ly$α$ are higher (the mean $sim 190$,Å in the rest frame) than the typical values of quasars. Two quasars have exceptionally large Ly$α$ luminosity, accounting for $sim 3$ — $4$% of the bolometric luminosity. We measured black hole masses and Eddington ratios for three objects whose C,textsciv line is available. The resulting black hole masses are $sim 10^6.9$ — $10^7.7, M_odot$ with high Eddington ratios ($> 0.1$), consistent with those of NLS1 galaxies reported in the low-$z$ universe. N,textscv and C,textsciv broad absorption lines are detected in one object. This quasar can be classified as a mini-BAL quasar, which further supports the idea that this NLQ1 is indeed a luminous version of an NLS1 galaxy.
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