J/MNRAS/483/2362 WISE view of narrow-line Seyfert 1 galaxies (Rakshit+, 2019)
WISE view of narrow-line Seyfert 1 galaxies: mid-infrared colour and variability
Rakshit S., Johnson A., Stalin C.S., Gandhi P., Hoenig S.
<Mon. Not. R. Astron. Soc., 483, 2362-2370 (2019)>
=2019MNRAS.483.2362R 2019MNRAS.483.2362R (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, photometry ; Galaxies, Seyfert ; Photometry, infrared ;
Galaxies, IR
Keywords: techniques: photometric - galaxies: active - galaxies: Seyfert
Abstract:
We present the colour and flux variability analysis at 3.4µm (W1
band) and 4.6µm (W2 band) of 492 narrow-line Seyfert 1 (NLSy1)
galaxies using archival data from the Wide-field Infrared Survey
Explorer (WISE). In the WISE colour-colour, (W1-W2) versus (W2-W3)
diagram, ∼58 per cent of the NLSy1 galaxies of our sample lie in the
region occupied by the blazar category of active galactic nuclei
(AGNs). The mean W1-W2 colour of candidate variable NLSy1 galaxies is
0.99±0.18mag. The average amplitude of variability is 0.11±0.07mag
in long term (multiyear) with no difference in variability between W1
and W2 bands. The W1-W2 colour of NLSy1 galaxies is anticorrelated
with the relative strength of [OIII] to Hβ, strongly correlated
with continuum luminosity, black hole mass, and Eddington ratio. The
long-term amplitude of variability shows weak anticorrelation with the
FeII strength, continuum luminosity and Eddington ratio. A positive
correlation between colour as well as the amplitude of variability
with the radio power at 1.4GHz was found for the radio-detected NLSy1
galaxies. This suggests non-thermal synchrotron contribution to the
mid-infrared colour and flux variability in radio-detected NLSy1
galaxies.
Description:
For this work, we have taken all NLSy1 galaxies from the catalogue of
Rakshit et al. (2017ApJS..229...39R 2017ApJS..229...39R, Cat. J/ApJS/229/39), the
selection of which was based on the spectroscopic database of the
Sloan Digital Sky Survey Data Release 12 (SDSS DR12; Alam et al.
2015ApJS..219...12A 2015ApJS..219...12A, Cat. V/147). The catalogue consists of a total of
11 101 NLSy1 galaxies. Since the main motivation of this work is to
characterize the IR variability properties of the population of NLSy1
galaxies, we looked for the IR counterparts to these sources in the
Wide-field Infrared Survey Explorer (WISE; Wright et al.
2010AJ....140.1868W 2010AJ....140.1868W) database. WISE has mapped the entire sky in four
different IR bands centred at 3.4µm (W1 band), 4.6µm (W2 band),
12µm (W3 band), and 22µm (W4 band) with angular resolution of
6.1, 6.4, 6.5, and 12arcsec, respectively. It has much higher
sensitivity than any previous all sky surveys in IR. WISE has a field
of view of 47arcminx47arcmin and scans the entire sky once in every
six months. The observations were performed (i) under WISE full
cryogenic and NEOWISE Post-Cryo mission in three windows in 2010-2011
in W1, W2, W3, and W4 bands. All photometric magnitudes from this
mission are included in the 'AllWISE MultiEpoch Photometry (MEP)
Database' and (ii) under the near-Earth objects WISE (NEOWISE)
Reactivation mission (Mainzer et al. 2014ApJ...792...30M 2014ApJ...792...30M, Cat.
J/ApJ/792/30) in eight windows in 2014-2017 in W1 and W2 bands.
Variability information of all the 492 candidate variables are
provided in Table 1.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 85 492 Variability information
--------------------------------------------------------------------------------
See also:
II/328 : AllWISE Data Release (Cutri+ 2013)
J/ApJ/792/30 : NEOWISE magnitudes for near-Earth objects (Mainzer+, 2014)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- ID SDSS ID (plate-mjd-fiber)
17- 24 F8.4 deg RAdeg Right ascension (J2000)
26- 33 F8.4 deg DEdeg Declination (J2000)
35- 40 F6.4 --- z Redshift
42- 46 F5.2 [10-7W] logL5100 Log of continuum luminosity at
λ=5100Å multiplied by λ
48- 50 I3 --- NpW1 Number of points in W1 band light curve
52- 54 I3 --- NpW2 Number of points in W2 band light curve
56- 57 I2 --- Nlc Number of short-term light curves with
minimum 5 points in both W1 and W2 bands
59- 63 F5.2 mag W1mag Average W1-band magnitude
65- 69 F5.2 mag W2mag Average W2-band magnitude
71- 74 F4.2 mag VarW1 Variability amplitude in W1-band
76- 79 F4.2 mag VarW2 Variability amplitude in W2-band
81- 85 F5.2 [10-7W] P1.4GHz ? Radio power at 1.4GHz
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 21-Jul-2022