J/ApJ/954/33 Swift/UVOT and ground-based telescope LCs of Mrk 335 (Lewin+, 2023)
X-ray/UVOIR frequency-resolved time lag analysis of Mrk 335 reveals accretion
disk reprocessing.
Lewin C., Kara E., Cackett E.M., Wilkins D., Panagiotou C., Garcia J.A.,
Gelbord J.
<Astrophys. J., 954, 33 (2023)>
=2023ApJ...954...33L 2023ApJ...954...33L
ADC_Keywords: Active gal. nuclei; Photometry, ugriz; Photometry, ultraviolet
Keywords: Active galactic nuclei ; Supermassive black holes ;
Reverberation mapping ; Seyfert galaxies ; Accretion ;
Gaussian Processes regression
Abstract:
UV and optical continuum reverberation mapping is a powerful tool for
probing the accretion disk and inner broad-line region. However,
recent reverberation mapping campaigns in the X-ray, UV, and optical
have found lags consistently longer than those expected from the
standard disk reprocessing picture. The largest discrepancy to date
was recently reported in Mrk 335, where UV/optical lags are up to
12 times longer than expected. Here, we perform a frequency-resolved
time lag analysis of Mrk 335, using Gaussian processes to account for
irregular sampling. For the first time, we compare the Fourier
frequency-resolved lags directly to those computed using the popular
interpolated cross-correlation function method applied to both the
original and detrended light curves. We show that the anticipated disk
reverberation lags are recovered by the Fourier lags when zeroing in
on the short-timescale variability. This suggests that a separate
variability component is present on long timescales. If this separate
component is modeled as reverberation from another region beyond the
accretion disk, we constrain a size scale of roughly 15 lt-days from
the central black hole. This is consistent with the size of the broad-
line region inferred from Hβ reverberation lags. We also find
tentative evidence for a soft X-ray lag, which we propose may be due
to light travel time delays between the hard X-ray corona and distant
photoionized gas that dominates the soft X-ray spectrum below 2 keV.
Description:
Kara+ (2023, J/ApJ/947/62) presented the first results on a
high-cadence (roughly three visits per day) 100 day X-ray, UV, and
optical reverberation mapping campaign of Mrk 335, which began on
2019-Oct-14. Our analysis focuses on the data collected by Swift (XRT,
UVOT) and ground-based telescopes in the 94 day time window
(MJD2450000=8770-8864) where the data are simultaneous between
observatories.
The ground-based observations were carried out by the following
observatories/telescopes: Las Cumbres Observatory 1m network,
Liverpool Telescope 2m, San Pedro Martir Observatory 1.5m, Wise
Observatory 18 inch, and the Zowada Observatory 20 inch. Using the
Sloan Digital Sky Survey (SDSS) g'r'i'z' and Pan-STARRS zs
filters, with the measurements in both the SDSS and Pan-STARRS
z-labeled filters combined. We henceforth refer to the filters as the
griz bands. Like Kara+ (2023), we use the Swift UBV bands instead of
the ground-based data collected in the SDSS u' (poor signal-to-noise)
and Johnson BV bands (poor time sampling versus Swift).
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
00 06 19.53 +20 12 10.6 Mrk 335 = LEDA 473
----------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
uvot.dat 173 1448 Mrk 335 Swift UVOT light curve data
(Data behind Figure 1)
griz.dat 32 1102 Mrk 335 ground-based (griz) light curve data
(Data behind Figure 1)
--------------------------------------------------------------------------------
See also:
B/swift : Swift Master Catalog (HEASARC, 2004-)
VI/139 : Herschel Observation Log (Herschel Science Centre, 2013)
I/356 : Gaia DR3 Part 2. Extra-galactic (Gaia Collaboration, 2022)
I/358 : Gaia DR3 Part 4. Variability (Gaia Collaboration, 2022)
J/A+A/389/845 : Spectra of blue compact galaxies (Kong+, 2002)
J/A+A/418/465 : Mid-infrared and hard X-ray emission in AGN (Lutz+, 2004)
J/ApJ/618/L83 : Narrow iron Kα lines in AGN (Zhou+, 2005)
J/ApJ/622/129 : Lag-luminosity relationship in AGN (Sergeev+, 2005)
J/ApJ/658/815 : Radio loudness of active galactic nuclei (Sikora+, 2007)
J/ApJ/679/194 : Low-z intergalactic medium. III. (Danforth+, 2008)
J/ApJ/702/767 : CIV and FeKα Baldwin effects in AGNs (Wu+, 2009)
J/ApJ/702/1472 : Column densities for HI, AlIII, SiIV, CIV, OVI (Savage+, 2009)
J/ApJ/705/14 : Seyfert galaxies in the mid-IR (Deo+, 2009)
J/ApJ/713/L11 : X-ray properties of Seyfert 1 galaxies (Zhou+, 2010)
J/ApJ/739/57 : Ultra hard X-ray AGNs in the Swift/BAT survey (Koss+, 2011)
J/ApJ/753/104 : AGN identifications from AKARI and Swift (Matsuta+, 2012)
J/ApJ/753/L2 : Reverberation mapping of AGNs (Assef+, 2012)
J/ApJ/755/60 : Reverberation mapping for 5 Seyfert 1 galaxies (Grier+, 2012)
J/ApJ/759/112 : The UV low-redshift intergalactic medium (Tilton+, 2012)
J/ApJ/782/45 : SEAMBHs. I. Mrk 142, Mrk 335, and IRAS F12397+3333 (Du+, 2014)
J/ApJ/788/159 : 17 Seyfert 1 galaxies light curves (Koshida+, 2014)
J/ApJ/793/108 : SEAMBHs. II. Continuum and Hbeta LCs (Wang+, 2014)
J/ApJ/794/75 : HST-COS UV spectra observations of AGNs (Stevans+, 2014)
J/ApJ/806/22 : SEAMBHs IV. Hβ time lags (Du+, 2015)
J/MNRAS/448/1541 : Spectral parameters for Mrk 335 and Ark 564 (Sarma+, 2015)
J/ApJS/216/17 : AKARI 2.5-5um spectra of nearby Type-1 AGNs (Kim+, 2015)
J/A+A/588/A70 : Hard X-ray view of the soft excess in AGN (Boissay+, 2016)
J/ApJS/230/6 : HST -COS & -STIS absorption-line sp. II. (Keeney+, 2017)
J/MNRAS/466/3309 : X-ray flux variability of AGN (Rani+, 2017)
J/MNRAS/467/540 : BASS. IV. NIR lines & correl. with X-ray (Lamperti+, 2017)
J/ApJ/871/35 : HST/COS spectra of QSOs with SiIV data (Zheng+, 2019)
J/ApJ/886/42 : Reverberation mapping & opt. spectra data of AGNs (Du+, 2019)
J/ApJS/253/20 : SEAMBHs XII. Reberberation mapping for 15 PG QSOs (Hu+, 2021)
J/A+A/645/A18 : SVOM-ECLAIRs known X-ray sources catalogue (Dagoneau+, 2021)
J/other/Sci/373.789 : optical variability of AGNs (Burke+, 2021)
J/ApJ/941/46 : X-ray to FIR observations for an AGN sample (Spinoglio+, 2022)
J/ApJ/947/62 : griz light curves of Mrk 335 (Kara+, 2023)
J/ApJS/269/15 : Survey of bare z<0.2 AGNs. I. X-ray soft excess (Nandi+, 2023)
J/A+A/691/A203 : Multiwavelength properties of unobscured AGN (Gupta+, 2024)
J/A+A/691/A15 : High-redshift quasars spectra (Deconto-Machado+, 2024)
J/A+A/698/A105 : AGN optical ASAS-SN and TESS light curves (Yuk+, 2025)
Byte-by-byte Description of file: uvot.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 F18.12 d MJD [58770.1/58869.32] MJD time stamp at the
mid-point of the UVOT exposure
(JD-2400000.5)
20- 40 E21.6 d e_MJD [0.0001/0.005] A symmetric "error" bar for
the MJD values (1)
42- 59 F18.12 d HJD [58770.6/58869.81] Mid-point of UVOT
exposure translated to HJD; HJD-2400000
61- 70 A10 "Y/M/D" Obs.Date Calendar date derived from MJD value
72- 79 A8 "h:m:s" Obs.Time Time (UTC) based upon MJD value
81- 90 F10.6 s ExpTime [26.7/800] Integrated time of the exposure
(2)
92- 95 A4 --- Filt Swift UVOT Filter
97- 107 I11 --- ObsID Swift observation ID (3)
109 I1 --- Ext [1/2] Number of the image extension in the
Swift sky data file (4)
111- 124 E14.6 cW/m2/nm Flux [4.8e-15/2.2e-14] UVOT flux in
erg/cm2/s/Å, measured in a 5 arcsec
radius aperture
126- 139 E14.6 cW/m2/nm e_Flux [9.3e-17/6.6e-16] 1-sigma flux measurement
uncertainty
141- 145 A5 --- LowMask Flag, LowMasksmScaleSensflag (5)
147- 151 A5 --- MidMask Flag, MidMasksmScaleSensflag (5)
153- 157 A5 --- HighMask Flag, HighMasksmScaleSensflag (5)
159- 162 A4 --- IBRM [true] Flag, true if an observation was
made during the IBRM campaign
(always "true")
164- 173 F10.8 --- Fluxcorr [0.97/1.22] Flag,
FluxcorrFactorsmScaleSens_provisional (6)
--------------------------------------------------------------------------------
Note (1): A symmetric "error" bar for the MJD values, equal to half
of the exposure duration (i.e., MJD±e_MJD gives the start
and end times of the exposure).
Note (2): Integrated time of the exposure (seconds). This is
slightly smaller than 2*e_MJD due to deadtime and possibly
other corrections.
Note (3): Swift observation ID. Applies to one or more pointings,
generally on the same day.
Note (4): The number of the image extension in the Swift sky data
file. If more than one exposure was made in the same filter as
part of a single ObsID, each will be in a separate file extension.
Note (5): Flags to indicate data points that would be screened out
when the small scale sensitivity masks are applied. To apply the
Low, Mid, or High masks, eliminate data for which the
corresponding flag is set to "true".
Note (6): A simple multiplicative factor to correct the measured
fluxes for the impact of local variations in the detector
sensitivity.
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Byte-by-byte Description of file: griz.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- Filt [griz] Filter
3- 10 F8.3 d HJD [8700.9/8886.2] Heliocentric Julian Date;
HJD-2450000
12- 16 F5.3 10-17W/m2/nm Flux [3.2/7.7] Observed Flux in units of
10-15erg/cm2/s/Å
18- 22 F5.3 10-17W/m2/nm e_Flux [0.003/0.2] Flux Uncertainty
24- 32 A9 --- Tel Telescope Used (1)
--------------------------------------------------------------------------------
Note (1): Telescopes as follows:
LCO-### = Las Cumbres Observatory 1m network + Sinistro;
Liverpool = Liverpool Telescope 2m + IO:O (126 occurrences)
RATIR = San Pedro Martir Observatory 1.5m + RATIR (97 occurrences)
WISE = Wise Observatory 18-inch + QSI683 (174 occurrences)
Zowada = Zowada Observatory 20-inch (401 occurrences)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 04-Nov-2025