J/ApJS/241/33 Long-term variability in the radio-quiet AGN Ark120 (Li+, 2019)
A possible ∼20yr periodicity in long-term optical photometric and spectral
variations of the nearby radio-quiet active galactic nucleus Ark 120.
Li Y.-R., Wang J.-M., Zhang Z.-X., Wang K., Huang Y.-K., Lu K.-X., Hu C.,
Du P., Bon E., Ho L.C., Bai J.-M., Bian W.-H., Yuan Y.-F., Winkler H.,
Denissyuk E.K., Valiullin R.R., Bon N., Popovic L.C.
<Astrophys. J. Suppl. Ser., 241, 33 (2019)>
=2019ApJS..241...33L 2019ApJS..241...33L
ADC_Keywords: Active gal. nuclei; Spectra, optical
Keywords: galaxies: active; galaxies: individual (Ark 120);
methods: data analysis; methods: statistical; quasars: general
Abstract:
We study the long-term variability in the optical monitoring database
of Ark 120, a nearby radio-quiet active galactic nucleus (AGN) at a
distance of 143Mpc (z=0.03271). We compiled the historical archival
photometric and spectroscopic data since 1974 and conducted a new
two-year monitoring campaign in 2015-2017, resulting in a total
temporal baseline over four decades. The long-term variations in the
optical continuum exhibit a wave-like pattern and the Hβ
integrated flux series varies with a similar behavior. The broad
Hβ profiles have asymmetric double peaks, which change strongly
with time and tend to merge into a single peak during some epochs. The
period in the optical continuum determined from various period-search
methods is about 20yr, and the estimated false alarm probability with
null hypothesis simulations is about 1x10-3. The overall variations
of the broad Hβ profiles also follow the same period. However,
the present database only covers two cycles of the suggested period,
which strongly encourages continued monitoring to track more cycles
and confirm the periodicity. Nevertheless, in light of the possible
periodicity and the complicated Hβ profile, Ark 120 is one
candidate of the nearest radio-quiet AGNs with possible periodic
variability, and it is thereby a potential candidate host for a
sub-parsec supermassive black hole binary.
Description:
We carried out a two-year observation campaign between 2015 and 2017
using the Lijiang 2.4m telescope, located in Yunnan Province, China,
operated by the Yunnan Observatories. We used the Yunnan Faint Object
Spectrograph and Camera with Grism 14, which covers a wavelength range
of 3800-7200Å and provides a resolution of 1.8Å/pixel.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
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05 16 11.41 -00 08 59.2 Ark 120 = Mrk 1095
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 78 17 Data sets for the light curves of Ark 120
table3.dat 28 1492 Compiled optical light curve of Ark 120
table4.dat 24 76 The centroid wavelength and dispersion data of
the broad Hβ line
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See also:
III/218 : ELODIE archive (Prugniel+, 2001)
VII/259 : 6dF galaxy survey final redshift release (Jones+, 2009)
J/PASP/111/438 : Updated Zwicky catalog (UZC) (Falco+, 1999)
J/ApJ/622/129 : Lag-luminosity relationship in AGN (Sergeev+, 2005)
J/ApJ/696/870 : Catalina Real-time Transient Survey (CRTS) (Drake+, 2009)
J/ApJ/698/895 : Variations in QSOs optical flux (Kelly+, 2009)
J/ApJS/189/15 : FeII emission in a sample of AGN spectra (Kovacevic+, 2010)
J/ApJ/730/19 : IR spectra & SEDs for starbursts and AGNs (Sargsyan+, 2011)
J/ApJ/753/L2 : Reverberation mapping of AGNs (Assef+, 2012)
J/ApJ/779/109 : Long-term monitoring of NGC 5548 (Peterson+, 2013)
J/ApJ/782/45 : SEAMBHs. I. Mrk 142, Mrk 335 & IRAS F12397+3333 (Du+, 2014)
J/ApJ/788/159 : 17 Seyfert 1 galaxies light curves (Koshida+, 2014)
J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)
J/MNRAS/453/1562 : CRTS close supermassive black hole binaries (Graham+, 2015)
J/ApJS/225/29 : NGC 5548 43 year-long monitoring in Hβ (Bon+, 2016)
J/ApJ/818/L14 : RM AGNs accretion rates and BH masses (Du+, 2016)
J/ApJ/825/126 : SEAMBHs. V. The third year (Du+, 2016)
J/ApJ/869/142 : Monitoring AGNs with Hβ Asymmetry (MAHA). (Du+, 2018)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- n_Set p: photometric data at the V-band, except
for M79 at M-band; or s: spectroscopy
3- 8 A6 --- Set Dataset ID
10 A1 --- f_Set Flag on Set (1)
12- 13 I2 --- Ref [1/15] Reference (2)
15- 19 I5 d JDl Julian Date of observation, start
20 A1 --- --- [-]
21- 25 I5 d JDu Julian Date of observation, end
27- 30 I4 yr Datel Year of observation, start
31 A1 --- --- [-]
32- 35 I4 yr Dateu Year of observation, end
37- 39 I3 --- Nobs [20/476] Number of observations
41- 49 A9 arcsec Ap Aperture
51- 55 F5.3 10-16W/m2 FOIII [0.7/1.4]? Flux of [OIII]λ5007
used for absolute calibration of spectra
in the data set; in 10-13erg/s/cm2
57- 61 F5.3 --- phi [0.3/1.2]? Scale factor φ (3)
63- 67 F5.3 --- e_phi [0.003/0.3]? φ uncertainty
69- 73 F5.2 10-17W/m2/nm G [-8.1/6.6]? Flux adjustment (G);
in 10-15erg/s/cm^2/Å units (3)
75- 78 F4.2 10-17W/m2/nm e_G [0.03/1.1]? G uncertainty
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Note (1): Flag as follows:
c = This data set has no temporal overlap with the other data sets so it is
impossible to do intercalibration. We simply adjust the fluxes to make
the mean and standard deviation to be at the same scales as those of
the other data sets. We do not use this data set for a periodicity
analysis.
d = This data set includes 15 additional observations (50863-52282) that
have not been made public.
e = There is a large flux difference with respect to the other data sets.
We offset the fluxes by -20x10-15erg/s/cm2/Å before performing
intercalibration.
f = This data set has a poor temporal overlap with the other data sets,
and we simply fix φ=1.
Note (2): Reference as follows:
1 = Doroshenko et al. (1999AstL...25..569D 1999AstL...25..569D )
2 = Peterson et al. (1989AJ.....98..500P 1989AJ.....98..500P)
3 = Peterson et al. (1998ApJ...501...82P 1998ApJ...501...82P)
4 = Winge et al. (1996ApJ...469..648W 1996ApJ...469..648W)
5 = Doroshenko et al. (2008ARep...52..442D 2008ARep...52..442D)
6 = this work
7 = Miller (1979A&AS...35..387M 1979A&AS...35..387M)
8 = Peterson et al. (1983AJ.....88..926P 1983AJ.....88..926P)
9 = Doroshenko & Lyuty (1999AstL...25..771D 1999AstL...25..771D)
10 = Winkler et al. (1992MNRAS.257..659W 1992MNRAS.257..659W) and Winkler (1997MNRAS.292..273W 1997MNRAS.292..273W)
11 = Roberts & Rumstay (2012JSARA...6...47R 2012JSARA...6...47R)
12 = Koshida et al. (2014ApJ...788..159K 2014ApJ...788..159K)
13 = the Catalina Real-Time Survey database (Drake+ 2009, J/ApJ/696/870)
14 = Haas et al. (2011A&A...535A..73H 2011A&A...535A..73H)
15 = the All-Sky Automated Survey for Supernovae database
(Shappee+ 2014, J/ApJ/788/48 and Kochanek+ 2017PASP..129j4502K 2017PASP..129j4502K).
Note (3): To account for the different aperture sizes, we apply a scale factor
φ and a flux modulation G to the 5100Å flux densities and Hβ
fluxes of each data set with respect to the reference using
Equation (1): F(5100Å)=φF(5100Å)obs+G and
Equation (2): F(Hβ)=φF(Hβ)obs
See section 2.2.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 F10.4 d JD [42392/58451.1] Julian Date;
JD-2400000
12- 16 F5.2 10-17W/m2/nm F5100 [3.9/19.8] Flux density at 5100Å;
in 10-15erg/s/cm^2/Å units
18- 21 F4.2 10-17W/m2/nm e_F5100 [0.07/3.1] Uncertainty in F5100
23- 28 A6 --- Set Dataset (as in Table 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- 10 F10.4 d JD [43104.5/57748.3] Julian Date; JD-2400000
12- 18 F7.2 0.1nm lamHb [4860.17/4881.89] Centroid wavelength,
broad Hβ line; in Angstrom units
20- 24 F5.2 0.1nm sigHb [24.97/46.95] Dispersion, broad Hβ line;
in Angstrom units
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 25-Nov-2019