J/A+A/664/A117 677 AGN of VST-COSMOS (De Cicco+, 2022)
A structure function analysis of VST-COSMOS AGN.
De Cicco D., Bauer F.E., Paolillo M., Sanchez-Saez P., Brandt W.N.,
Vagnetti F., Pignata G., Radovich M., Vaccari M.
<Astron. Astrophys. 664, A117 (2022)>
=2022A&A...664A.117D 2022A&A...664A.117D (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Photometry ; Optical ; Redshifts
Keywords: galaxies: active - X-rays: galaxies - infrared: galaxies - surveys -
methods: statistical
Abstract:
We present our sixth work in a series dedicated to variability studies
of active galactic nuclei (AGN), based on the survey of the COSMOS
field by the VLT Survey Telescope (VST). Its 54 r-band visits over
3.3yr and single-visit depth of 24.6 r-band mag make this dataset a
valuable scaled-down version that can help forecast the performance of
the Rubin Observatory Legacy Survey of Space and Time (LSST).
This work is centered on the analysis of the structure function (SF)
of VST-COSMOS AGN, investigating possible differences in its shape and
slope related to how the AGN were selected, and explores possible
connections between the AGN ensemble variability and the black-hole
mass, accretion rate, bolometric luminosity, redshift, and obscuration
of the source. Given its features, our dataset opens up the
exploration of samples ∼2mag fainter than most literature to date.
We identified several samples of AGN - 677 in total - obtained through
a variety of selection techniques partly overlapping. Our analysis
compares the results for the various samples. We split each sample in
two based on the median of the physical property of interest, and
analyzed the differences in the SF shape and slope, and their possible
causes.
While the SF shape does not change with depth, it is highly affected
by the type of AGN (unobscured or obscured) included in the sample.
Where a linear region can be identified, we find that the variability
amplitude is anticorrelated to the accretion rate and bolometric
luminosity, consistent with previous literature on the topic, while no
dependence on black-hole mass emerges from this study. With its longer
baseline and denser and more regular sampling, the LSST will allow for
an improved characterization of the SF and its dependencies on the
mentioned physical properties over much larger AGN samples.
Description:
In this work we presented an analysis of the SF of 677 AGN in the
VST-COSMOS area, defining a sample of AGN as a result of different
diagnostics based on: spectroscopy, X-ray properties, MIR properties,
and selection via optical variability.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table6.dat 59 677 *List of the 677 AGN constituting the main sample
--------------------------------------------------------------------------------
Note on table6.dat: Information about the other physical properties analyzed in
this work is partly non public, hence we do not include it here.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- ID Identification number
5- 13 F9.5 deg RAdeg Right ascension (J2000) (1)
15- 23 F9.7 deg DEdeg Declination (J2000) (1)
25- 29 F5.2 mag rmag Average VST r(AB) magnitude, obtained from all
the visits where the source is detected
31- 34 F4.2 --- rms r.m.s. of the light curve
36- 37 I2 --- N number of visits where the source is detected
39- 42 I4 --- Length observed length of the light curve
44- 49 F6.4 --- z Redshift (see Sect. 2.1 of De Cicco et al.,
2021A&A...645A.103D 2021A&A...645A.103D)
51 I1 --- XAGN [0/1] X-ray confirmed AGN (2)
53 I1 --- MIRAGN [0/1] MIR-confirmed AGN (2)
55 I1 --- OptAGN [0/1] optical variability-confirmed AGN (2)
57 I1 --- AGNI [0/1] spectroscopically confirmed Type I AGN (2)
59 I1 --- AGNII [0/1] spectroscopically confirmed Type II AGN (2)
--------------------------------------------------------------------------------
Note (1): right ascension and declination obtained as an average from all the
visits where the source is detected.
Note (2): see Sect. 2 of the paper.
--------------------------------------------------------------------------------
Acknowledgements:
Demetra De Cicco, demetradecicco(at)gmail.com
References:
De Cicco et al., 2021A&A...645A.103D 2021A&A...645A.103D, A random forest-based selection of
optically variable AGN in the VST-COSMOS field.
(End) Patricia Vannier [CDS] 24-May-2022