J/A+A/664/A46 Narrow Fe Ka emission within bright AGN (Andonie+, 2022)
Localizing narrow Fe Ka emission within bright AGN.
Andonie C., Bauer F.E., Carraro R., Arevalo P., Alexander D.M., Brandt W.N.,
Buchner J., He A., Koss M.J., Ricci C., Salinas V., Solimano M., Tortosa A.,
Treister E.
<Astron. Astrophys. 664, A46 (2022)>
=2022A&A...664A..46A 2022A&A...664A..46A
ADC_Keywords: Active gal. nuclei ; X-ray sources
Keywords: galaxies: active - X-rays: galaxies - methods: data analysis
Abstract:
The 6.4keV Fe Kα emission line is a ubiquitous feature in X-ray
spectra of active galactic nuclei (AGN), and its properties track the
interaction between the variable primary X-ray continuum and the
surrounding structure from which it arises.
We clarify the nature and origin of the narrow Fe Kα emission
using X-ray spectral, timing, and imaging constraints, plus possible
correlations to AGN and host galaxy properties, for 38 bright nearby
AGN (z<0.5) from the Burst Alert Telescope AGN Spectroscopic Survey.
Modeling Chandra and XMM-Newton spectra, we computed line full-width
half-maxima (FWHMs) and constructed Fe Kα line and 2-10keV
continuum light curves. The FWHM provides one estimate of the Fe
Kα emitting region size, RFeKα, assuming virial motion. A
second estimate comes from comparing the degree of correlation between
the variability of the continuum and line-only light curves, compared
to simulated light curves. Finally, we extracted Chandra radial
profiles to place upper limits on RFeKα.
For 90% (21/24) of AGN with FWHM measurements, RFeKα is smaller
than the fiducial dust sublimation radius, Rsub. From timing analysis,
37 and 18 AGN show significant continuum and Fe Kα variability,
respectively. Despite a wide range of variability properties, the
constraints on the Fe Kα photon reprocessor size independently
confirm that RFeKα is smaller than Rsub in 83% of AGN. Finally,
the imaging analysis yields loose upper limits for all but two
sources; notably, the Circinus Galaxy and NGC 1068 show significant
but subdominant extended Fe Kα emission out to ∼100 and ∼800pc,
respectively.
Based on independent constraints, we conclude that the majority of the
narrow Fe Kα emission in typical AGN predominantly arises from
regions smaller than and presumably inside Rsub, and thus it is
associated either with the outer broad line region or outer accretion
disk. However, the large diversity of continuum and narrow Fe Kα
variability properties are not easily accommodated by a universal
scenario.
Description:
Summary of each observation used in this paper, along with the
best-fitting parameters, including the photon index, column density,
and intrinsic 2-10keV and Fe Kα line fluxes.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
sources.dat 65 38 List of observed sources
tablea1.dat 199 653 Summary of each observation used in this paper
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See also:
J/ApJ/850/74 : Swift/BAT AGN Spectroscopic Survey. I. (Koss+, 2017)
Byte-by-byte Description of file: sources.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Source Source name
16- 17 I2 h RAh Simbad right ascension (J2000)
19- 20 I2 min RAm Simbad right ascension (J2000)
22- 26 F5.2 s RAs Simbad right ascension (J2000)
28 A1 --- DE- Simbad declination sign (J2000)
29- 30 I2 deg DEd Simbad declination (J2000)
32- 33 I2 arcmin DEm Simbad declination (J2000)
35- 38 F4.1 arcsec DEs Simbad declination (J2000)
40- 41 I2 --- N Number of observations in bfparams.dat file
43- 65 A23 --- SName Simbad name
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Source Source name
16- 25 A10 --- Obs Observatory name
27- 37 A11 --- Inst Instrument
39- 47 I9 --- ObsID Observation ID
49- 58 A10 "date" ObsDate Start Observation date (YYYY-MM-DD)
60- 65 F6.2 ks ExpTime [2.0/184.6] Exposure time (ks)
67- 74 A8 --- Spectrum Shape of the extracted spectrum (1)
76- 80 F5.3 --- z Redshift (2)
82- 87 F6.2 --- Gamma ?=-99 Photon index
89- 94 F6.2 --- bGamma ?=-99 Lower bound (90%) of the
Photon index (3)
96-101 F6.2 --- BGamma ?=-99 Upper bound (90%) of the
Photon index (3)
103-108 F6.2 [cm-2] logNH Line of sight column density in
logarithmic scale
110-115 F6.2 [cm-2] blogNH ?=-99 Lower bound (90%) NH in
logarithmic scale (3)
117-122 F6.2 [cm-2] BlogNH ?=-99 Upper bound (90%) NH in
logarithmic scale
124-129 F6.2 eV Sigma ?=-99 Fe Ka line width
131-136 F6.2 eV bSigma ?=-99 Lower bound (90%) Fe Ka line width (3)
138-143 F6.2 eV BSigma ?=-99 Upper bound (90%) Fe Ka line width (3)
145-150 F6.2 mW/m2 F210keV Intrinsic 2-10 keV continuum flux
152-157 F6.2 mW/m2 b_F210keV ?=-99 Lower bound (90%) 2-10 keV
continuum flux (3)
159-164 F6.2 mW/m2 B_F210keV Upper bound (90%) 2-10 keV continuum flux
166-171 F6.2 mW/m2 FFeKa Intrinsic Fe Ka line flux
173-178 F6.2 mW/m2 b_FFeKa ?=-99 Lower bound (90%) Fe Ka line flux (3)
180-185 F6.2 mW/m2 B_FFeKa Upper bound (90%) Fe Ka line flux
187-194 F8.2 --- Stat Value of the statistic
196-199 I4 --- DOF Number of degrees of freedom
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Note (1): Shape/type extracted spectrum: circular, ann35 (3-5" annuli), grating
Note (2): From Koss et al. (2017ApJ...850...74K 2017ApJ...850...74K, Cat. J/ApJ/850/74)
Note (3): -99 when the value is unconstrained.
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Acknowledgements:
Carolina Andonie, carolina.p.andonie(at)durham.ac.uk
(End) Patricia Vannier [CDS] 14-Apr-2022