J/ApJS/267/19 SDSS DR17 type 1 AGNs with broad line em. regions (Ilic+, 2023)
Fantastic fits with FANTASY of active galactic nuclei spectra: exploring the
FeII emission near the Hα line.
Ilic D., Rakic N., Popovic L.C.
<Astrophys. J. Suppl. Ser., 267, 19 (2023)>
=2023ApJS..267...19I 2023ApJS..267...19I
ADC_Keywords: Active gal. nuclei; Spectra, optical; Redshifts; Surveys
Keywords: Active galactic nuclei ; Quasars ; Atomic data ; Spectral line lists
Abstract:
In this study, a refined approach for multicomponent fitting of active
galactic nuclei (AGNs) spectra is presented utilizing the newly
developed Python code Fully Automated pythoN Tool for AGN Spectra
analYsis (fantasy). AGN spectra are modeled by simultaneously
considering the underlying broken power-law continuum, predefined
emission line lists, and an FeII model, which is here extended to
cover the wavelength range 3700-11000Å. The FeII model, founded
solely on atomic data, effectively describes the extensive emission of
the complex iron ion in the vicinity of the Hγ and Hβ
lines, as well as near the Hα line, which was previously rarely
studied. The proposed spectral fitting approach is tested on a sample
of high-quality AGN spectra from the Sloan Digital Sky Survey DR17.
The results indicate that when FeII emission is present near Hβ,
it is also detected redward from Hα, potentially contaminating
the broad Hα line wings and thus affecting the measurements of
its flux and width. The production of FeII emission is found to be
strongly correlated with Eddington luminosity and appears to be
controlled by a similar mechanism as the hydrogen Balmer lines. The
study highlights the benefits of fitting type 1 AGN spectra with the
fantasy code, pointing that it may be used as a robust tool for
analyzing a large number of AGN spectra in the coming spectral
surveys.
Description:
We select a sample of type 1 AGNs from SDSS DR17
(Abdurro'uf+ 2022ApJS..259...35A 2022ApJS..259...35A), where we specify as selection
criteria the high signal-to-noise ratio (S/N) of the optical spectra
(S/N>35) and the redshift (z<0.4).
DR17 is the fourth data release from the fourth phase of the survey
(SDSS-IV), which contains the complete data set of optical
single-fiber spectroscopy of the SDSS through 2021 January.
The query yielded 676 objects, of which 21 were discarded either
because Hα emission was absent or distorted, or objects were
misclassified as type 1 AGNs while they are rather type 2 as no broad
component is seen. The remaining 655 SDSS AGN type 1 objects were
further investigated (referred to as the SDSS sample).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 62 283 FeII transitions used in the model
table2.dat 178 622 Measured spectral quantities for the total
SDSS sample
table3.dat 50 219 *Predefined lists of emission lines used in FANTASY
code (see Appendix)
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Note on table3.dat: Here we use the recently developed Python code Fully
Automated pythoN Tool for AGN Spectra analYsis (fantasy;
Ilic+ 2020, J/A+A/638/A13 ; Rakic 2022MNRAS.516.1624R 2022MNRAS.516.1624R), which is an
updated approach to multicomponent fitting of AGN spectra.
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See also:
V/154 : Sloan Digital Sky Surveys (SDSS), Release 16 (DR16) (Ahumada+, 2020)
J/A+A/417/515 : I Zw 1 unusual emission line spectrum (Veron-Cetty+, 2004)
J/ApJS/166/470 : SDSS-Spitzer type I QSOs IR photometry (Richards+, 2006)
J/AJ/131/84 : AGNs and host galaxies information (Vanden Berk+, 2006)
J/MNRAS/383/581 : Broad-line Balmer decrements in blue AGN (Dong+, 2008)
J/ApJS/189/15 : FeII emission in a sample of AGN spectra (Kovacevic+, 2010)
J/ApJ/736/86 : FeII emission in SDSS type 1 AGNs (Dong+, 2011)
J/ApJS/194/45 : QSO properties from SDSS-DR7 (Shen+, 2011)
J/A+A/579/A40 : PESSTO catalog (Smartt+, 2015)
J/ApJ/818/L14 : RM AGNs accretion rates and BH masses (Du+, 2016)
J/ApJS/229/39 : Narrow line Seyfert 1 gal. from SDSS-DR12 (Rakshit+, 2017)
J/ApJS/243/21 : Broad-line AGN from SDSS-DR7 (Liu+, 2019)
J/ApJS/241/34 : SDSS Reverberation Mapping (SDSS-RM) project (Shen+, 2019)
J/ApJ/903/112 : SDSS Hb & CIV reverberation mapped AGNs (Dalla Bonta+, 2020)
J/A+A/638/A13 : NGC 3516 optical flare (Ilic+, 2020)
J/ApJS/249/17 : SDSS QSO DR14 spectral properties (Rakshit+, 2020)
J/ApJS/258/38 : Iron template sp. from Mrk493 HST/STIS obs. (Park+, 2022)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 F8.2 0.1nm lambda [3720/10872] Line transition wavelength, air,
in Angstroms
10- 15 F6.3 [-] loggf [-4.991/0.527] log of statistical weight*oscillator
strength
17- 39 A23 --- TR lower-upper level transition
42- 46 F5.3 eV Elo [2.54/9.97] Energy of lower state
48- 53 F6.3 eV Eup [4.79/11.52] Energy of upper state
55- 59 F5.3 --- I [0/1.35] Relative intensity (1)
61- 62 I2 --- Ref [1/3] References (2)
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Note (1): Relative intensity with respect to the reference line,
where intensity is set to 1.000
Note (2): Reference as follows:
1 = Fuhr+ (1981JPCRD..10..305F 1981JPCRD..10..305F);
2 = Kovacevic+ (2010, J/ApJS/189/15);
3 = Atomic database,
http://lweb.cfa.harvard.edu/amp/ampdata/kurucz23/sekur.html
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- --- [SDSS]
6- 24 A19 --- SDSS SDSS DR17 name (JHHMMSS.ss+DDMMSS.s)
26 A1 --- Avg A=Averaged measurements of all values
28- 32 F5.3 --- zspec [0.013/0.4]? Spectroscopic redshift; null
for average row
34- 38 F5.2 --- alpha1 [-3.7/1] Broken power-law index,
α1 (1)
40- 44 F5.2 --- alpha2 [-4.7/2.8] Broken power-law index,
α2 (1)
46- 51 F6.3 [10-7W] logL5100 [40.9/45.6] Log of 5100Å continuum
luminosity, λ*Lλ, in erg/s
53- 57 F5.3 [10-7W] e_logL5100 [0.001/0.008] Uncertainty in logL5100
59- 64 F6.3 [10-7W] logL6200 [41/45.6] Log of 6200Å continuum
luminosity, λ*Lλ, in erg/s
66- 70 F5.3 [10-7W] e_logL6200 [0.001/0.005] Uncertainty in logL6200
72- 77 F6.3 [10-7W] logLHb [3.1/43.9] Log of Hβ broad line
luminosity, in erg/s
79- 83 F5.3 [10-7W] e_logLHb [0.001/0.05] Uncertainty in logLHb
85- 90 F6.3 [10-7W] logLHa [39.9/44.2] Log of Hβ broad line
luminosity, in erg/s
92- 96 F5.3 [10-7W] e_logLHa [0.001/0.3] Uncertainty in logLHa
98-103 F6.3 [10-7W] logLFeIIb [36/43.7] Log of FeII blue band
luminosity, in erg/s
105-109 F5.3 [10-7W] e_logLFeIIb [0/2.1] Uncertainty in logLFeIIb
111-116 F6.3 [10-7W] logLFeIIg [38.4/43.6] Log of FeII green band
luminosity, in erg/s
118-122 F5.3 [10-7W] e_logLFeIIg [0/1.5] Uncertainty in logLFeIIg
124-129 F6.3 [10-7W] logLFeIIr [36.8/43.2] Log of FeII red band
luminosity, in erg/s
131-136 F6.3 [10-7W] e_logLFeIIr [0/29] Uncertainty in logLFeIIr
138-142 I5 km/s FWHMHb [1449/10881] Full width half maximum,
broad Hβ
144-146 I3 km/s e_FWHMHb [0/552] Uncertainty in FWHMHb
148-151 I4 km/s FWHMHa [1105/9553] Full width half maximum, broad
Hα
153-156 I4 km/s e_FWHMHa [0/1380] Uncertainty in FWHMHa
158-161 I4 km/s FWHMFeII [1225/6000] Full width half maximum, FeII
163-166 I4 km/s e_FWHMFeII [0/1820] Uncertainty in FWHMFeII
168-172 F5.3 --- L/LEdd [0.002/1.5] Eddington ratio
174-178 F5.3 --- e_L/LEdd [0/0.3] Uncertainty in L/LEdd
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Note (1): Indices α1, α2 of the broken power-law fitting
the underlying AGN continuum, where α1 describes the part
of spectra with wavelengths larger than the break wavelength and
α1+α2 the lower ones.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Line Line name
13- 21 F9.3 0.1nm lambda [1640.4/10938.1] Line wavelength in air,
in Angstroms
23- 35 A13 --- Type Type based on line width expected in AGN spectra
37- 50 A14 --- Group FANTASY code group name (1)
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Note (1): Group as follows:
hydrogen = hydrogen lines (Balmer and Paschen series) (14 occurrences)
helium = helium lines (both HeI and HeII) (17 occurrences)
narrow plus = strongest narrow emission lines ([OIII] and [NII])
(47 occurrences)
narrow basic = other AGN narrow lines (e.g., [SII] and [OI])
(13 occurrences)
broad = other AGN broad lines (CaI and OI) (15 occurrences)
coronal = coronal lines (e.g., [FeX] and [ArV]) (44 occurrences)
FeII forbidden = forbidden FeII lines (69 occurrences)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 23-Aug-2023