J/ApJ/841/37 Tori in AGNs through Spitzer/IRS spectra (Gonzalez-Martin+, 2017)
Hints on the gradual resizing of the torus in AGNs through decomposition of
Spitzer/IRS spectra.
Gonzalez-Martin O., Masegosa J., Hernan-Caballero A., Marquez I.,
Almeida C.R., Alonso-Herrero A., Aretxaga I., Rodriguez-Espinosa J.M.,
Acosta-Pulido J.A., Hernandez-Garcia L., Esparza-Arredondo D.,
Martinez-Paredes M., Bonfini P., Pasetto A., Dultzin D.
<Astrophys. J., 841, 37 (2017)>
=2017ApJ...841...37G 2017ApJ...841...37G
ADC_Keywords: Active gal. nuclei ; Spectra, infrared
Keywords: galaxies: active ; galaxies: nuclei ; infrared: galaxies
Abstract:
Several authors have claimed that less luminous active galactic nuclei
(AGNs) are not capable of sustaining a dusty torus structure. Thus, a
gradual resizing of the torus is expected when the AGN luminosity
decreases. Our aim is to examine mid-infrared observations of local
AGNs of different luminosities for the gradual resizing and
disappearance of the torus. We applied the decomposition method
described by Hernan-Caballero+ (2015, J/ApJ/803/109) to a sample of
∼100 Spitzer/IRS spectra of low-luminosity AGNs and powerful Seyferts
in order to decontaminate the torus component from other contributors.
We have also included Starburst objects to ensure secure decomposition
of the Spitzer/IRS spectra. We have used the affinity propagation (AP)
method to cluster the data into five groups within the sample
according to torus contribution to the 5-15µm range (Ctorus) and
bolometric luminosity (Lbol).
Description:
The sample was originally presented by Gonzalez-Martin+ (2015,
J/A+A/578/A74). The LINER sample is selected as those objects with
reported X-ray luminosities from Gonzalez-Martin+
(2009A&A...506.1107G 2009A&A...506.1107G) with full coverage of the 5-30um range with the
InfraRed Spectrograph (Spitzer/IRS) spectra. This guarantees that all
of the LINERs have LX(2-10keV) measurements. Among the 48 LINERs with
Spitzer/IRS spectra, 40 mid-infrared spectra were taken from the
CASSIS atlas (Lebouteiller+ 2011ApJS..196....8L 2011ApJS..196....8L) and 8 from the SINGS
database (Kennicutt+ 2003PASP..115..928K 2003PASP..115..928K).
We have included in our analysis mid-infrared spatially resolved
images taken with CanariCam/GTC using the filter "Si6" centered at
11.5um. These observations are part of proprietary data of a sample of
faint and Compton-thick LINERs observed with CanariCam/GTC (proposal
ID GTC10-14A, P.I. Gonzalez-Martin). The summary of the observations
used in this paper is reported in Table 4. See section 3.2 for further
explanations.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 92 48 Details of the LINER sample and results of
IRS/Spitzer decomposition
table2.dat 92 42 Details of the Seyfert samples and results of
IRS/Spitzer decomposition
table3.dat 92 19 Details of the Starburst samples and results of
IRS/Spitzer decomposition
table4.dat 101 20 CanariCam Observations
table5.dat 42 286 Archival high resolution mid-IR imaging results
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See also:
VII/258 : Quasars and Active Galactic Nuclei (13th Ed.) (Veron+ 2010)
J/other/RMxAA/35.187 : Multifrequency catalog of LINERs (Carrillo+, 1999)
J/A+A/418/465 : MIR and hard X-ray emission in AGN (Lutz+, 2004)
J/ApJ/653/127 : 9.7um silicate features in AGNs (Shi+, 2006)
J/ApJ/669/959 : Warm molecular hydrogen in SINGS sample (Roussel+, 2007)
J/ApJ/704/1570 : LINERs within the AGN family (Gonzalez-Martin+, 2009)
J/MNRAS/407/2399 : AGN activity and black hole mass (McKernan+, 2010)
J/AJ/144/11 : IR imaging, nuclear SEDs & IR sp. of AGNs (Mason+, 2012)
J/A+A/558/A149 : VLTI/MIDI AGN Large Program obs. (Burtscher+, 2013)
J/MNRAS/439/1648 : Subarcsecond MIR atlas of local AGN (Asmus+, 2014)
J/A+A/578/A74 : Nuclear obscuration in LINERs (Gonzalez-Martin+, 2015)
J/ApJ/803/109 : IRS spectral decompositon of AGN (Hernan-Caballero+, 2015)
J/A+A/587/A1 : 11.5um image of NGC 835 (Gonzalez-Martin+, 2016)
Byte-by-byte Description of file: table[123].dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Name AGN name
16 A1 --- f_Name [c] Flag on Name (1)
18- 23 A6 --- Type Source type ("SB" = starburst)
25- 29 F5.1 Mpc Dist [3/356] Distance
31- 34 F4.1 [10-7W] logLX [36/45] Log X-ray luminosity; erg/s
36- 39 I4 pc Width [69/7354] Slit width (2)
41- 44 F4.1 % Ctorus [0/89] Torus contribution percentage (3)
46- 49 F4.1 % e_Ctorus Lower uncertainty in Ctorus
51- 54 F4.1 % E_Ctorus Upper uncertainty in C*
56- 59 F4.1 % C* [0/98] Stellar contribution percentage (3)
61- 64 F4.1 % e_C* Lower uncertainty in C*
66- 69 F4.1 % E_C* Upper uncertainty in C*
71- 74 F4.1 % CISM [1/99] ISM contribution percentage (3)
76- 79 F4.1 % e_CISM Lower uncertainty in CISM
81- 84 F4.1 % E_CISM Upper uncertainty in CISM
86- 90 F5.3 --- RMSE [0.02/1.1] Root-mean-square error of final fit
92 I1 --- AP [1/5] Affinity Propagation group (4)
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Note (1):
c = candidate that lacks a torus because it belongs to Group 1 with
CISM<50% (see text).
Note (2): Portion of galaxy extending out from the nucleus.
Note (3): Contributing to the 5-15 micron wavelength range.
Note (4): We have used the affinity propagation (AP) method to cluster the data
into five groups within the sample according to torus contribution to
the 5-15um range (Ctorus) and bolometric luminosity (Lbol).
The AP groups show a progressively higher torus contribution and an
increase of the bolometric luminosity from Group 1 (Ctorus∼1% and
log(Lbol)∼41) up to Group 5 (Ctorus∼80% and log(Lbol)∼44).
See section 5.1.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Name AGN name
16 A1 --- f_Name [*] NGC 2685 not detected with CanariCam
18- 28 A11 "Y/M/D" Date UT date of the observation
30- 33 I4 --- ObsID [1048/7644] Observation ID for the target
observation
35- 37 I3 s Exp [308/993] Exposure time for the target
observation
39- 51 A13 --- Config Nod throw, chop throw, instrument PA and
chop PA (1)
53- 58 I6 --- HD [4502/153210] HD number of the associated
standard star
60- 63 I4 --- ObsStd [1045/7640] Observation ID for the standard
star observation
65- 66 I2 s ExpStd [66/83] Integrating time for the standard
star observation
68- 76 A9 arcsec FWHMPSF FWHMPSF range for the standard star
associated with the target (2)
78- 86 A9 arcsec FWHMN FWHMN result (2)
88- 89 I2 mJy FluxT [14/96]? Nuclear flux (FluxT)
91- 92 I2 mJy e_FluxT [2/15]? FluxT uncertainty
94- 97 F4.1 mJy FluxN [3/27]? FluxN value
99-101 F3.1 mJy e_FluxN [0.6/4]? FluxN uncertainty
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Note (1): "Config." corresponds to the nod throw (keyword NODTHROW, in units of
arcseconds), chop throw (keyword CHPTHROW, in units of arcseconds),
instrument position angle (keyword INSTRPA, in degrees), and chop
position angle (keyword CHPPA, in degrees; written as
NODTHROW/CHPTHROW/INSTRPA/CHPPA).
Note (2): We followed several steps until the results converge to the final
solution.
(1) We fit the image using a single 2D Gaussian. At this stage, the width of
the Gaussian is fixed to the width of the standard star associated with
the target for CanariCam data (FWHM reported in "FWHMPSF") or with the
major axis of the FWHM of the Gaussian fit reported
by Asmus+ (2014, J/MNRAS/439/1648). This is considered as an initial
guess for the nuclear component.
(2) The fitted Gaussian is subtracted from the original images, producing a
first guess of the extended structure. This extended structure is fitted
with another Gaussian, which is centered at the position of the first
Gaussian but now allowing the widths of the Gaussian to vary.
(3) This Gaussian fit to the extended emission is now subtracted from the
original image, producing a new guess for the nuclear component. At this
stage, the process starts over in (1), using this new guess for the
nuclear component as the input image. This process continues until the
residuals are within three standard deviations over the background of
the image.
The resulting minor and major axes of the FWHM are recorded in "FWHMN"
See section 4.1.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Name AGN name
16- 19 F4.1 um lambda [7.8/19.5] Wavelength
21- 23 F3.1 arcsec FWHM1 [0.2/1.5] Full-Width at Half-Maximum lower range
24 A1 --- --- [-]
25- 27 F3.1 arcsec FWHM2 [0.2/2] Full-Width at Half-Maximum upper range
29- 35 F7.1 mJy Flux [0.4/24100] Flux density
37- 42 F6.1 mJy e_Flux [0.1/3900] Uncertainty in Flux
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 15-Jan-2018