2018/04/26 by Francesco Gabriele Saturni, F. G. Saturni, M. Bischetti +10
Chemistry · Mathematics · Physics and Astronomy · #Absorption (acoustics) #Absorption spectroscopy #Analytical Chemistry (journal) #Astronomy #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Astrophysics #Chemistry #Doubly ionized oxygen #Emission spectrum #Galaxies: Formation, Evolution, Phenomena #Galaxy #Ionization #Line (geometry) #Mathematics #Optics #Physics #Quasar #Spectral line #Spectroscopy #astro-ph.CO #astro-ph.GA
paper · pdf · doi:10.1051/0004-6361/201832794
published as A&A 617, A118 (2018) · 10 pages, 4 figures, 4 tables, accepted for publication in A&A
arxiv created 2018/04/26 · openalex publication_date 2018/05/24 · arxiv updated 2018/09/26 · openalex created_date 2022/08/03 · openalex updated_date 2026/08/04
We present the analysis of the restframe optical-to-UV spectrum of APM 08279+5255, a well-known lensed broad absorption line (BAL) quasar at z = 3.911. The spectroscopic data were taken with the optical DOLoRes and near-IR NICS instruments at TNG, and include the previously unexplored range between C III ] λ 1910 and [O III ] λλ 4959,5007. We have investigated the possible presence of multiple BALs by computing “balnicity” and absorption indexes (i.e., BI, BI 0 , and AI) for the transitions Si IV λ 1400, C IV λ 1549, Al III λ 1860, and Mg II λ 2800. No clear evidence for the presence of absorption features is found in addition to the already known, prominent BAL associated to C IV , which supports a high-ionization BAL classification for APM 08279+5255. We also studied the properties of the [O III ], H β , and Mg II emission lines. We find that [O III ] is intrinsically weak ( F [OIII] ∕ F H β ≲ 0.04), as it is typically found in luminous quasars with a strongly blueshifted C IV emission line (~2500 km s −1 for APM 08279+5255). We computed the single-epoch black hole mass based on Mg II and H β broad emission lines, finding M BH = (2 ÷ 3) × 10 10 μ −1 M ⊙ , with the magnification factor μ that can vary between 4 and 100 according to CO and restframe UV-to-mid-IR imaging respectively. Using a Mg II equivalent width (EW)-to-Eddington ratio relation, the EW MgII ~ 27 Å measured for APM 08279+5255 translates into an Eddington ratio of ~0.4, which is more consistent with μ = 4. This magnification factor also provides a value of M BH that is consistent with recent reverberation-mapping measurements derived from C IV and Si IV .