J/ApJ/705/14 Seyfert galaxies in the mid-IR (Deo+, 2009)
The mid-infrared continua of Seyfert galaxies.
Deo R.P., Richards G.T., Crenshaw D.M., Kraemer S.B.
<Astrophys. J., 705, 14-31 (2009)>
=2009ApJ...705...14D 2009ApJ...705...14D
ADC_Keywords: Active gal. nuclei ; Galaxies, Seyfert ; Spectra, infrared
Keywords: galaxies: active - galaxies: nuclei - galaxies: Seyfert -
infrared: galaxies
Abstract:
An analysis of archival mid-infrared (mid-IR) spectra of Seyfert
galaxies from the Spitzer Space Telescope observations is presented.
We characterize the nature of the mid-IR active nuclear continuum by
subtracting a template starburst spectrum from the Seyfert spectra.
The long wavelength part of the spectrum contains a strong
contribution from the starburst-heated cool dust; this is used to
effectively separate starburst-dominated Seyferts from those dominated
by the active nuclear continuum. Within the latter category, the
strength of the active nuclear continuum drops rapidly beyond ∼20um.
On average, type 2 Seyferts have weaker short-wavelength active
nuclear continua as compared to type 1 Seyferts. Type 2 Seyferts can
be divided into two types, those with strong polycyclic aromatic
hydrocarbon (PAH) bands and those without.
Description:
We primarily use archival Spitzer InfraRed Spectrograph spectra
extracted from programs 3069 (PI: J. Gallimore, mapping-mode spectra),
3374 (PI: S. Kraemer, staring mode spectra) and Weedman et al.
(2005ApJ...633..706W 2005ApJ...633..706W; Mrk 3, low-resolution staring mode spectrum).
Deo et al. (2007ApJ...671..124D 2007ApJ...671..124D) presented single slit extractions of
spectra from above-mentioned programs for about half of the current
sample.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 94 109 Observation summary, redshifts, optical Seyfert
types, and extraction apertures
table2.dat 117 108 Continuum flux densities and apparent optical
depth at 9.7um
table3.dat 61 93 Starburst-to-AGN flux density ratios
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See also:
VII/248 : Quasars and Active Galactic Nuclei (12th Ed.) (Veron+ 2006)
VII/173 : Catalogue of Seyfert Galaxies (Lipovetsky+, 1988)
J/A+A/473/369 : VISIR/VLT mid-infrared imaging of Seyfert nuclei (Haas+,
2007)
J/A+A/418/465 : Mid-infrared and hard X-ray emission in AGN (Lutz+, 2004)
J/ApJS/125/349 : Morphology of 12micron Seyfert Galaxies (Hunt+, 1999)
J/other/PBeiO/18.7 : Far infrared Seyfert galaxies (Liu 1991)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- Name Galaxy name
21- 28 F8.6 --- z NED redshift
30- 33 A4 --- SyT Seyfert type (1)
35- 38 F4.2 --- b/a Axial ratio (2)
40- 47 I8 --- AOR Spitzer archive AOR number
49 A1 --- Obs [SM] Observing mode for Spitzer/IRS spectrum:
(S=staring or M=mapping)
51- 60 F10.6 deg RAdeg ? Extraction rectangle for mapping mode:
right ascension in decimal degrees (J2000) (3)
62- 71 F10.6 deg DEdeg ? Extraction rectangle for mapping mode:
declination in decimal degrees (J2000) (3)
73- 78 F6.3 arcsec Ap1 ? First extraction aperture
79 A1 --- --- [x]
80- 85 F6.3 arcsec Ap2 ? Second extraction aperture
87- 94 F8.2 pc/arcsec scale Radial extent of the extraction aperture for
the galaxy
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Note (1): Seyfert type from Veron-Cetty & Veron (2006, Cat. VII/248; superseded
by Cat. VII/258) as follows:
S1 = Seyfert 1 optical spectrum;
S1h = broad polarized Balmer lines detected;
S1i = broad Paschen lines observed in the infrared;
S1n = narrow-line Seyfert 1;
S1.0, S1.2, S1.5, S1.8, and S1.9 = intermediate Seyfert galaxies (Note: In
this paper, we consider S1.0-1.5 to be broadly Seyfert 1s in all
analysis.);
S2 = Seyfert 2 spectrum;
S3 = LINER;
S3b = LINER with broad Balmer lines;
S3h = LINER with broad polarized Balmer lines detected;
H2 = nuclear HII region
Note (2): Axial ratio, minor-to-major axis ratio of host galaxy obtained from
NED, for host galaxies where b/a was not available we assumed it to be 1.
Note (3): Extraction rectangle for mapping-mode spectra: R.A. and Decl. of
center-point.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- Name Galaxy name
21- 28 E8.3 Jy 5.5um ? Spitzer/IRS 5.5um continuum flux density
30- 37 E8.3 Jy 10um ? Spitzer/IRS 10um continuum flux density
39- 46 E8.3 Jy 14.7um ? Spitzer/IRS 14.7um continuum flux density
48- 55 E8.3 Jy 20um ? Spitzer/IRS 20um continuum flux density
57- 64 E8.3 Jy 30um ? Spitzer/IRS 30um continuum flux density
66- 72 F7.4 --- tau ? Observed optical depth (apparent) at 9.7um
74- 81 E8.3 Jy e_5.5um ? 1σ error in 5.5um
83- 90 E8.3 Jy e_10um ? 1σ error in 10um
92- 99 E8.3 Jy e_14.7um ? 1σ error in 14.7um
101-108 E8.3 Jy e_20um ? 1σ error in 20um
110-117 E8.3 Jy e_30um ? 1σ error in 30um
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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- 19 A19 --- Name Galaxy name
21- 26 F6.4 --- R5.5 ? Starbust-to-AGN flux density ratio at 5.5um (1)
28- 34 F7.4 --- R10 ? Starbust-to-AGN flux density ratio at 10um (1)
36- 44 F9.4 --- R14.7 ? Starbust-to-AGN flux density ratio at 14.7um (1)
46- 53 F8.4 --- R20 ? Starbust-to-AGN flux density ratio at 20um (1)
55- 61 F7.4 --- R30 ? Starbust-to-AGN flux density ratio at 30um (1)
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Note (1): A missing ratio implies either the spectrum was incomplete at
that wavelength or the AGN contribution was negative after starburst
subtraction. A very large ratio indicates very weak AGN contribution,
these typically occur at or beyond 14.7um in a few galaxies. See
Figure 10 for a visual representation of these ratios, and Table 1 for
aperture size in parsecs. Even in nearby AGN, Spitzer spectra sample
regions of size ∼1kpc. See Section 5 for discussion of the starburst
subtraction process and results.
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 28-Nov-2011