J/A+A/698/A105 AGN optical ASAS-SN and TESS light curves (Yuk+, 2025)
High frequency breaks in the optical active galactic nuclei power spectral
density.
Yuk H., Dai X.
<Astron. Astrophys. 698, A105 (2025)>
=2025A&A...698A.105Y 2025A&A...698A.105Y (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Photometry ; Optical
Keywords: galaxies: active
Abstract:
Variability is a ubiquitous feature of active galactic nuclei (AGNs),
and the characterisation of the variability is crucial to constrain
its physical mechanism and proper applications in AGN studies. The
advent of all-sky and high-cadence optical surveys allows more
accurate measurements of AGNs variability down to short timescales and
direct comparisons with X-ray variability from the same sample of
sources.
We aim to analyse the optical power spectral density (PSDs) of AGNs
with measured X-ray PSDs.
We use light curves from the All-Sky Automated Survey for SuperNovae
(ASAS-SN) and the Transiting Exoplanet Survey Satellite (TESS) and use
the Lomb-Scargle periodogram to obtain PSDs. The joint optical PSD is
measured over up to six orders of magnitude in frequency space from
timescales of minutes to a decade. We fit either a damped random walk
(DRW) or a broken power law (BPL) model to constrain the PSD model and
break frequency.
We find a set of break frequencies (<10-2day-1) from DRW and BPL
fits that generally confirm previously reported correlations between
break frequencies and the black hole mass. In addition, we find a
second set of break frequencies at higher frequencies
(>10-2day-1). We observe a potential weak correlation between the
high-frequency breaks with the X-ray break frequencies and black hole
mass. We further explore the dependence of the correlations on other
AGN parameters, finding that adding either X-ray, optical, or
bolometric luminosity as the third correlation parameter can
substantially improve the correlation significances. The newly
identified high-frequency optical breaks can constrain different
aspects of the physics of AGNs.
Description:
We present the reduced ASAS-SN and TESS light curves of the AGNs used
for the PSD analysis in this study.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
sources.dat 42 22 List of studied AGNs
tablea1.dat 45 20408 ASAS-SN light curves
tablea2.dat 45 147738 TESS light curves
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See also:
II/366 : ASAS-SN catalog of variable stars (Jayasinghe+, 2018-2020)
IV/39 : TESS Input Catalog version 8.2 (TIC v8.2) (Paegert+, 2021)
Byte-by-byte Description of file: sources.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Name of the galaxy
16- 17 I2 h RAh Simbad right ascension (J2000)
19- 20 I2 min RAm Simbad right ascension (J2000)
22- 26 F5.2 s RAs Simbad right ascension (J2000)
28 A1 --- DE- Simbad declination sign (J2000)
29- 30 I2 deg DEd Simbad declination (J2000)
32- 33 I2 arcmin DEm Simbad declination (J2000)
35- 38 F4.1 arcsec DEs Simbad declination (J2000)
40 A1 --- LCasas [*] Light curve data from ASAS-SN in tablea2.dat
42 A1 --- LCtess [*] Light curve data from TESS in tablea2.dat
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Name of the galaxy
14 A1 --- Filter [Vg] Filter (V or g)
16- 28 F13.5 d HJD Heliocentric Julian date of observation
30- 37 F8.5 mJy Flux Flux in filter
39- 45 F7.5 mJy e_Flux Flux in filter error
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Name of the galaxy
14- 15 I2 --- Sector TESS observing sector
17- 27 F11.6 d JD TESS observation Julian date (JD-2457000)
29- 37 F9.5 mJy Flux Flux
39- 45 F7.5 mJy e_Flux Flux error
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Acknowledgements:
Heechan Yuk, hyuk(at)ou.edu
(End) Heechan Yuk [Univ. of Oklahoma], Patricia Vannier [CDS] 04-Apr-2025