J/MNRAS/435/1300 Intranight optical variability of AGN (Goyal+, 2013)
Improved characterization of intranight optical variability of prominent
AGN classes.
Goyal A., Gopal-Krishna, Wiita P.J., Stalin C.S., Sagar R.
<Mon. Not. R. Astron. Soc., 435, 1300-1312 (2013)>
=2013MNRAS.435.1300G 2013MNRAS.435.1300G
ADC_Keywords: Active gal. nuclei ; Photometry
Keywords: methods: data analysis - methods: statistical -
techniques: photometric - galaxies: active
Abstract:
The incidence of intranight optical variability (INOV) is known to
differ significantly among different classes of powerful active
galactic nuclei (AGN). A number of statistical methods have been
employed in the literature for testing the presence of INOV in the
light curves, sometimes leading to discordant results. In this paper,
we compare the INOV characteristics of six prominent classes of AGN,
as evaluated using three commonly used statistical tests, namely the
χ2-test, the modified C-test and the F-test, which has
recently begun to gain popularity. The AGN classes considered are:
radio-quiet quasars, radio-intermediate quasars, lobe-dominated
quasars, low optical polarization core-dominated quasars, high optical
polarization core-dominated quasars and TeV blazars. Our analysis is
based on a large body of AGN monitoring data, involving 262 sessions
of intranight monitoring of a total 77 AGN, using 1-2m class optical
telescopes located in India. In order to compare the usefulness of the
statistical tests, we have also subjected them to a 'sanity check' by
comparing the number of false positives yielded by each test with the
corresponding statistical prediction. The present analysis is intended
to serve as a benchmark for future INOV studies of AGN of different
classes.
Description:
Our sample of TeV blazars consists of two sets. Set 1 is derived from
the list of TeV-detected extragalactic AGNs, published by Weekes
(2008, AIP Conf. Ser. Vol. 1085, p. 3, table 2 of his paper).
Our set 2 of TeV blazars was derived from table 1 of Abdo et al.
(2010ApJ...715..429A 2010ApJ...715..429A, Cat. J/ApJ/715/429), consisting of 709
TeV-detected AGNs, which is based on 11 months of monitoring with
Fermi LAT.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
sources.dat 124 78 List of studied sources
table1.dat 168 262 Summary of the IntraNight Optical Variability (INOV)
observations and the derived variability status for
the target AGN and the corresponding 'steady'
star-star differential light curves (DLCs)
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See also:
J/ApJ/723/737 : Catalog of variability selected AGNs in GOODS (Villforth+ 201)
J/ApJ/641/78 : CIV variability in 105 SDSS quasars (Wilhite+, 2006)
J/A+A/473/105 : Lockman Hole AGN variability with XMM (Mateos+, 2007)
J/A+A/487/475 : X-ray variability of AGNs in Lockman Hole (Papadakis+, 2008)
J/A+A/488/73 : Variability-selected AGN in Chandra DFS (Trevese+, 2008)
J/A+A/497/81 : Variability-selected AGN in CDFS (Boutsia+, 2009)
J/A+A/536/A84 : X-ray variability of AGN (Vagnetti+, 2011)
J/AJ/142/108 : Radio variability of compact, flat-spectrum AGNs (Koay+, 2011)
J/ApJ/731/97 : Variable AGNs in GOODS fields (Sarajedini+, 2011)
J/ApJ/748/124 : AGN X-ray variability in the 4Ms catalog (Young+, 2012)
J/A+A/555/A2 : J-band variability of AGN (Nesci+, 2013)
J/A+A/560/A104 : UV variability of quasars (Meusinger+, 2013)
J/A+A/563/A57 : Long-term variability of AGN at hard X-rays (Soldi+, 2014)
Byte-by-byte Description of file: sources.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Source name (JHHMM+DDMM)
13- 14 I2 h RAh Simbad right ascension (J2000)
16- 17 I2 min RAm Simbad right ascension (J2000)
19- 23 F5.2 s RAs ? Simbad right ascension (J2000)
25 A1 --- DE- Simbad declination sign (J2000)
26- 27 I2 deg DEd Simbad declination (J2000)
29- 30 I2 arcmin DEm Simbad declination (J2000)
32- 36 F5.2 arcsec DEs ? Simbad declination (J2000)
37- 62 A26 --- SName Simbad name
64-124 A61 --- Com Comments for Simbad identification (from CDS)
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Type Type of source (1)
8- 17 A10 --- Name Source name (JHHMM+DDMM)
18 A1 --- n_Name [d] d: blazar detected at TeV energies
20- 29 A10 "date" ObsDate Date of observation
31- 33 A3 --- Tel Telescope used (2)
35 A1 --- Filt [R] Filter used
37- 40 F4.2 h Dur [1.6/9.2] Duration of monitoring
42- 44 I3 --- Np [9/123] Number of data points in the DLC
46- 48 F3.1 % rms [0.1/3.1] rms of the steadiest star-star DLC
50- 54 F5.2 % psi [0/26] INOV amplitude (ψ)
56- 60 F5.2 mag Dmt-s1 Mean magnitude difference of t-s1 DLC (3)
62- 66 F5.2 mag Dmt-s2 Mean magnitude difference of t-s2 DLC (3)
68- 72 F5.2 mag Dms1-s2 Mean magnitude difference of s1-s2 DLC (3)
74- 81 F8.3 --- X2t-s1 χ2-value obtained for t-s1 DLC (3)
83- 84 A2 --- SXt-s1 chi2t-s1 variability status of the DLC (4)
86- 93 F8.3 --- X2t-s2 χ2-value obtained for t-s2 DLC (3)
95- 96 A2 --- SXt-s2 chi2t-s1 variability status of the DLC (4)
98-105 F8.3 --- X2s1-s2 χ2-value obtained for s1-s2 DLC (3)
107-108 A2 --- SXs1-s2 chi2s1-s2 variability status of the DLC (4)
110-115 F6.2 --- Ft-s1 F-value obtained for the t-s1 DLC (3)
117-118 A2 --- SFt-s1 Ft-s1 variability status of the DLC (4)
120-126 F7.3 --- Ft-s2 F-value obtained for the t-s2 DLC (3)
128-129 A2 --- SFt-s2 Ft-s2 variability status of the DLC (4)
131-136 F6.3 --- Fs1-s2 F-value obtained for the s1-s2 DLC (3)
138-139 A2 --- SFs1-s2 Fs1-s2 variability status of the DLC (4)
141-145 F5.2 --- Ct-s1 Modified C-value obtained for t-s1 DLC (3)
147-148 A2 --- SCt-s1 Ct-s1 variability status of the DLC (4)
150-155 F6.3 --- Ct-s2 Modified C-value obtained for t-s2 DLC (3)
157-158 A2 --- SCt-s2 Ct-s2 variability status of the DLC (4)
160-163 F4.2 --- Cs1-s2 Modified C-value obtained for s1-s2 DLC (3)
165-166 A2 --- SCs1-s2 Cs1-s2 variability status of the DLC (4)
168 A1 --- Ref [a-j] Reference for the INOV data (5)
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Note (1): Types as follows:
RQQ = Radio-quiet quasars (22 sources; 68 DLCs)
RIQ = Radio intermediate quasars (10sources; 31 DLCs)
LDQ = Lobe-dominated quasars (9 sources; 25 DLCs)
LPCDQ = Low optical polarization core-dominated quasars (12 sources; 43 DLCs)
HPCDQ = High optical polarization core-dominated quasars (11 sources; 31 DLCs)
TeV-BL = TeV detected BL Lac objects BLs) (13 sources; 54 DLCs)
Note (2): Telescopes as follows:
ST = Sampurnanand Telescope (ARIES)
HCT = Himalayan Chandra Telescope (IIA)
IGO = IUCAA Girawali Observatory
VBT = Vainu Bappu Telescope (IIA)
GSO = Gurushikhar telescope (PRL)
Note (3): t for target stars, s1 for first and s2 for second comparison star.
The statistical tests are χ2 (Sec.4.1), F-test for the ratio of
variances (Sec.4.2) and and C-test for the ratio of observed to expected
dispersions (Sec.4.3).
Note (4): Status code as follows:
V = Variable
N = Non-variable
PV = Probable Variable
Note (5): References for the INOV data as follows:
a = Stalin et al. (2005MNRAS.356..607S 2005MNRAS.356..607S)
b = Goyal et al. (2007BASI...35..141G 2007BASI...35..141G)
c = Stalin et al. (2004MNRAS.350..175S 2004MNRAS.350..175S)
d = Goyal et al. (2010MNRAS.401.2622G 2010MNRAS.401.2622G)
e = Sagar et al. (2004MNRAS.348..176S 2004MNRAS.348..176S)
f = Goyal et al. (2012A&A...544A..37G 2012A&A...544A..37G)
g = Gopal-Krishna et al. (2011MNRAS.416..101G 2011MNRAS.416..101G)
h = AGs unpublished data
i = Stalin et al. (2004JApA...25....1S 2004JApA...25....1S)
j = Goyal et al. (2009MNRAS.399.1622G 2009MNRAS.399.1622G)
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 25-Sep-2014