J/A+A/578/A74 Nuclear obscuration in LINERs (Gonzalez-Martin+, 2015)
Nuclear obscuration in LINERs. Clues from Spitzer/IRS spectra on the Compton
thickness and the existence of the dusty torus.
Gonzalez-Martin O., Masegosa J., Marquez I., Rodriguez-Espinosa J.M.,
Acosta-Pulido J.A., Ramos Almeida C., Dultzin D., Hernandez-Garcia L.,
Ruschel-Dutra D., Alonso-Herrero A.
<Astron. Astrophys., 578, A74-74 (2015)>
=2015A&A...578A..74G 2015A&A...578A..74G (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Galaxies, IR
Keywords: galaxies: active - galaxies: nuclei - infrared: galaxies
Abstract:
Most of the optically classified low-ionisation, narrow emission-line
regions (LINERs) nuclei host an active galactic nucleus (AGN).
However, how they fit into the unified model (UM) of AGN is still an
open question.
The aims of this work are to study at mid-infrared (mid-IR) (1) the
Compton-thick nature of LINERs (i.e. hydrogen column densities of
NH>1.5x1024cm-2) and (2) the disappearance of the dusty torus in
LINERs predicted from theoretical arguments.
We have compiled all the available low spectral-resolution, mid-IR
spectra of LINERs from the InfraRed Spectrograph (IRS) onboard
Spitzer. The sample contains 40 LINERs. We have complemented the LINER
sample with Spitzer/IRS spectra of PGQSOs, Type-1 Seyferts (S1s),
Type-2 Seyferts (S2s), and StarBurst (SB) nuclei. We studied the AGN
compared to the starburst content in our sample using different
indicators: the equivalent width of the polycyclic aromatic
hydrocarbon at 6.2µm, the strength of the silicate feature at
9.7µm, and the steepness of the mid-IR spectra. We classified the
spectra as SB-dominated and AGN-dominated, according to these
diagnostics and compared the average mid-IR spectra of the various
classes. Moreover, we studied the correlation between the 12µm
luminosity, νLν(12µm), and the 2-10keV energy band X-ray
luminosity, LX(2-10keV).
Description:
Our initial sample of LINERs comes from the catalog of LINERs observed
at X-rays published by Gonzalez-Martin et al. (2009A&A...506.1107G 2009A&A...506.1107G).
For each object we have measured the 12um and 30um luminosities
using the Spitzer/IRS spectra.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 107 127 Sample and results
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See also:
J/ApJ/648/111 : Chandra sources near AGNs (Levenson+, 2006)
J/MNRAS/443/1999 : X-ray spectral analysis of AGNs (Brightman+, 2014)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Name Target name
16- 21 A6 --- Type Object type
23- 25 A3 --- Thick Thickness (1)
27 A1 --- l_logLX Limit flag on logLX
28- 32 F5.1 [10-7W] logLX Logarithm of the intrinsic X-ray luminosity
in the 2-10keV band
34- 37 F4.1 [10-7W] logL12um Logarithm of the mid-IR luminosity
obtained with Spitzer at 12um
39 A1 --- l_logLMIR Limit flag on logLMIR
40- 43 F4.1 [10-7W] logLMIR ? Mid-IR luminosity obtained with
ground-based observations
44 A1 --- n_logLMIR [*] * when presented here for the first
time, using proprietary CanariCam/GTC
observations
47- 52 F6.3 [-] log(L20/L30) Mid-IR steepness expressed as the ratio
between the mid-IR luminosity at
20 and 30um
54- 61 F8.3 --- tau9.7 Silicate attenuation strength at 9.7um
63- 67 F5.3 --- e_tau9.7 rms uncertainty on tau9.7
69- 74 F6.3 0.1nm EW(PAH6.2) Equivalent width of the PAH features
at 6.2um
76- 80 F5.3 0.1nm e_EW(PAH6.2) rms uncertainty on EW(PAH6.2um)
82- 87 F6.3 0.1nm EW(PAH11.3) Equivalent width of the PAH features
at 11.3um
89- 93 F5.3 0.1nm e_EW(PAH11.3) rms uncertainty on EW(PAH11.3um)
95-100 A6 --- Class Classification according to the EW(PAH 6.2)
and the tau9.7 (PAH-vs-tau9.7) (2)
103-107 A5 --- Steep Classification according to the steepness
of mid-IR spectrum (i.e. log(L20/L30)) (2)
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Note (1): Compton-thickness code as follows;
CT = Compton-thick
NCT = No Compton-thick (i.e. Compton-thin)
CTc = Compton-thick candidate using indirect arguments (see text);
Note (2): Classification as follows:
Weak = EW(PAH6.2)<0.233um
Strong = EW(PAH6.2)>0.233um
Deep = tau9.7>1.25
Steep = log(L20/L30)>-0.24
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 24-Sep-2015