Issue |
A&A
Volume 617, September 2018
|
|
---|---|---|
Article Number | A118 | |
Number of page(s) | 10 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361/201832794 | |
Published online | 26 September 2018 |
Restframe UV-to-optical spectroscopy of APM 08279+5255
BAL classification and black hole mass estimates★
1
INAF – Osservatorio Astronomico di Roma,
Via Frascati 33,
00040
Monte Porzio Catone (RM),
Italy
e-mail: francescogabriele.saturni@oa-roma.inaf.it
2
Space Science Data Center, Agenzia Spaziale Italiana,
Via del Politecnico snc,
00133
Roma,
Italy
3
Dip. di Fisica, Università degli Studi di Roma “Tor Vergata”,
Via della Ricerca Scientifica 1,
00133
Roma,
Italy
4
INAF – Osservatorio Astronomico di Brera,
Via Brera 28,
20121
Milano,
Italy
5
INAF – Osservatorio Astronomico di Trieste,
Via G. B. Tiepolo 11,
34143
Trieste,
Italy
6
Scuola Normale Superiore,
P.zza dei Cavalieri 7,
56126
Pisa,
Italy
7
SRON – Netherlands Institute for Space Research,
Sorbonnelaan 2,
3584
CA Utrecht,
The Netherlands
8
Excellence Cluster Universe, Technische Universität München,
Boltzmannstr. 2,
85748
Garching b. München,
Germany
9
European Southern Observatory,
Karl-Schwarzschild-Str. 2,
85748
Garching b. München,
Germany
10
Dip. di Fisica e Astronomia, Alma Mater Studiorum, Università degli Studi di Bologna,
Via P. Gobetti 93/2,
40129
Bologna,
Italy
11
INAF – Osservatorio di Astrofisica e Scienza dello Spazio di Bologna,
Via P. Gobetti 93/3.
40129
Bologna,
Italy
Received:
8
February
2018
Accepted:
24
April
2018
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] λ1910 and [O III] λλ4959,5007. We have investigated the possible presence of multiple BALs by computing “balnicity” and absorption indexes (i.e., BI, BI0, and AI) for the transitions Si IV λ1400, C IV λ1549, Al III λ1860, and Mg II λ2800. 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], Hβ, and Mg II emission lines. We find that [O III] is intrinsically weak (F[OIII]∕FHβ ≲ 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 Hβ broad emission lines, finding MBH = (2 ÷ 3) × 1010μ−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 EWMgII ~ 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 MBH that is consistent with recent reverberation-mapping measurements derived from C IV and Si IV.
Key words: galaxies: active / quasars: general / quasars: absorption lines / quasars: emission lines / quasars: supermassive black holes / quasars: individual: APM 08279+5255
The reduced spectrum is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/617/A118
© ESO 2018
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