SDSS J1058+5443: A Blue Quasar without Optical/NUV Broad Emission Lines

Abstract

In this paper, the blue quasar SDSS J105816.19+544310.2 (=SDSS J1058+5443) at redshift 0.479 has been reported as the best true type 2 quasar candidate with the disappearance of central broad-line regions. There are no definite conclusions on the very existence of true type 2 active galactic nuclei (AGN), mainly due to detected optical broad emission lines in high-quality spectra of some previously classified true type 2 AGN candidates. Here, unlike previously reported true type 2 AGN candidates among narrow emission-line galaxies with weak AGN activities but strong stellar lights, the definitely blue quasar SDSS J1058+5443 can be well confirmed as a true type 2 quasar due to apparent quasar-shape blue continuum emissions but an apparent loss of both the optical broad Balmer emission lines and the near-UV (NUV) broad Mg ii emission line. Based on different model functions and the F-test statistical technique, after considering blueshifted optical and UV Fe ii emissions, there are no apparent broad optical Balmer emission lines and/or broad NUV Mg ii lines, and the confidence level is smaller than 1σ in support of broad optical and NUV emission lines. Moreover, assuming the virialization assumption to broad-line emission clouds, the reconstructed broad emission lines strongly indicate that the probable intrinsic broad emission lines, if they exist, cannot be hidden or overwhelmed in the noise of the Sloan Digital Sky Survey spectrum of SDSS J1058+5443. Therefore, SDSS J1058+5443 is so far the best and most robust true type 2 quasar candidate, leading to the clear conclusion of the very existence of true type 2 AGN.

A candidate of binary black hole system in AGN with broad Balmer emission lines having quite different line widths

“…Therefore, there are quite different line widths of broad H and broad H . Moreover, considering the quite different values of 2 / through applications of different model functions, the additional broad Gaussian component can be well confirmed and preferred with confidence level well higher than 5 through applications of F-test statistical technique as what we have recently done in Zhang (2022d). In other words, the quite different line widths of broad Balmer lines can be confirmed with confidence level higher than 5 in SDSS J1257+2023.…”

On Strong Correlation between Shifted Velocity and Line Width of Broad Blueshifted [O iii] Components in Quasars

“…Motivated by our previous measurements of opening angle of central dust tours in a Type-1.9 AGN with double-peaked broad H𝛼 in Zhang (2022c), on studying properties of Type-1.9 AGN is one of our ongoing projects. Among our sample of Type-1.9 AGN, SDSS J1619 is selected as the subject of this Letter, due to its apparent blue-shifted broad components in both Balmer emission lines and forbidden [O iii] lines.…”

Unobscured Central Broad-line Regions in Type-1.9 AGN SDSS J1241+2602

“…After subtractions of the host galaxy contributions and the AGN continuum emissions, emission lines in the line spectrum can be measured, similarly to what we have previously done in Zhang (2021bZhang ( , 2021cZhang ( , 2022aZhang ( , 2022bZhang ( , 2022c. For the emission lines within the rest wavelength range from 4750 Å to 5100 Å, there is one Gaussian function applied to describe narrow Hβ and four Gaussian functions applied to describe the [O III] λλ4959, 5007 doublet (two for the core components and two for the blueshifted wings).…”