J/ApJ/958/195 AGN STORM 2. IV. Swift XRT and UVOT monitoring (Cackett+, 2023)
AGN STORM 2.
IV. Swift X-ray and ultraviolet/optical monitoring of Mrk 817.
Cackett E.M., Gelbord J., Barth A.J., De Rosa G., Edelson R., Goad M.R.,
Homayouni Y., Horne K., Kara E.A., Kriss G.A., Korista K.T., Landt H.,
Plesha R., Arav N., Bentz M.C., Boizelle B.D., Dalla Bonta E.,
Dehghanian M., Donnan F., Du Pu, Ferland G.J., Fian C., Filippenko A.V.,
Gonzalez Buitrago D.H., Grier C.J., Hall P.B., Hu C., Ilic D., Kaastra J.,
Kaspi S., Kochanek C.S., Kovacevic A.B., Kynoch D., Li Y.-R., McLane J.N.,
Mehdipour M., Miller J.A., Montano J., Netzer H., Panagiotou C.,
Partington E., Popovic L. C, Proga D., Rogantini D., Sanmartim D.,
Siebert M.R., Storchi-Bergmann T., Vestergaard M., Wang J.-M., Waters T.,
Zaidouni F.
<Astrophys. J., 958, 195 (2023)>
=2023ApJ...958..195C 2023ApJ...958..195C
ADC_Keywords: Active gal. nuclei; Photometry, UBV; Ultraviolet; X-ray sources
Keywords: Active galactic nuclei ; Supermassive black holes ;
Reverberation mapping ; Seyfert galaxies ; Accretion
Abstract:
The AGN STORM 2 campaign is a large, multiwavelength reverberation
mapping project designed to trace out the structure of Mrk 817 from
the inner accretion disk to the broad emission line region and out to
the dusty torus. As part of this campaign, Swift performed daily
monitoring of Mrk 817 for approximately 15 months, obtaining
observations in X-rays and six UV/optical filters. The X-ray
monitoring shows that Mrk 817 was in a significantly fainter state
than in previous observations, with only a brief flare where it
reached prior flux levels. The X-ray spectrum is heavily obscured. The
UV/optical light curves show significant variability throughout the
campaign and are well correlated with one another, but uncorrelated
with the X-rays. Combining the Swift UV/optical light curves with
Hubble Space Telescope UV continuum light curves, we measure interband
continuum lags, τ(λ), that increase with increasing
wavelength roughly following τ(λ)∝λ4/3, the
dependence expected for a geometrically thin, optically thick,
centrally illuminated disk. Modeling of the light curves reveals a
period at the beginning of the campaign where the response of the
continuum is suppressed compared to later in the light curve-the light
curves are not simple shifted and scaled versions of each other. The
interval of suppressed response corresponds to a period of high UV
line and X-ray absorption, and reduced emission line variability
amplitudes. We suggest that this indicates a significant contribution
to the continuum from the broad-line region gas that sees an absorbed
ionizing continuum.
Description:
The Neil Gehrels Swift Observatory monitored Mrk 817 daily,
concurrently with HST, with 1ks observations for ∼15 months from
2020-Nov-22 to 2022-Feb-24. Data were obtained both through a target
of opportunity request and a Swift Key Project (proposal number
1720084, PI: Cackett). Swift monitoring is continuing as part of an
extended campaign (proposal number 1821087, PI: Gelbord), but we limit
this analysis to those data that overlap with the HST project.
The X-ray light curves are produced using the Swift/XRT data products
generator (http://www.swift.ac.uk/user_objects/), with
background-subtracted count rates obtained in the 0.3-1.5keV (soft, S)
and 1.5-10keV (hard, H) bands per snapshot (spacecraft orbit).
See Section 2 for further explanations.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
14 36 22.08 +58 47 39.3 Mrk 817 = Z 296-15
----------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 38 2745 Swift photometry of Mrk 817
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See also:
J/ApJ/613/682 : AGN masses and broad-line region sizes (Peterson+, 2004)
J/MNRAS/397/1177 : Swift-XRT observations of GRBs (Evans+, 2009)
J/ApJ/806/128 : Space telescope RM project. I. NGC5548 (De Rosa+, 2015)
J/ApJ/806/129 : Space telescope RM project. II. Swift data (Edelson+, 2015)
J/ApJ/821/56 : Space telescope RM project. III. LCs (Fausnaugh+, 2016)
J/ApJ/840/41 : X-ray/UV Swift monitoring of NGC 4151 (Edelson+, 2017)
J/ApJ/836/186 : Continuum-band lags in SDSS QSOs from PS1 (Jiang+, 2017)
J/ApJ/837/131 : Space telescope RM project. V. NGC5548 sp. (Pei+, 2017)
J/ApJ/854/107 : Light curves of 2 Seyfert 1 galaxies (Fausnaugh+, 2018)
J/ApJ/862/123 : griz light curves of 15 DES quasars (Mudd+, 2018)
J/ApJ/870/123 : Swift optical & UV flux of four AGNs (Edelson+, 2019)
J/ApJ/896/1 : SEAMBHs. XI. Mrk 142 X-ray to optical LCs (Cackett+, 2020)
J/A+A/659/A13 : PG 2130+099 narrowband light curves (Fian+, 2022)
J/ApJ/948/85 : AGN STORM 2. II. HST/COS obs. of Mrk817 (Homayouni+, 2023)
J/ApJ/947/2 : AGN STORM 2. III. NICER obs. of Mrk 817 (Partington+, 2023)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 F8.3 d HJD [9176.5/9692.2] Heliocentric Julian Date;
HJD-2450000
10- 13 A4 --- Filt Filter/Band (1)
15- 20 F6.3 10-15cW/m2/nm Flux [6.8/53.5]? Swift/UVOT Flux in Filt
in 10-15erg/cm2/s/Å
22- 26 F5.3 10-15cW/m2/nm e_Flux [0.1/1.7]? Uncertainty in Flux
28- 32 F5.3 ct/s CRate [0.007/0.6]? X-ray rate in band
34- 38 F5.3 ct/s e_CRate [0.003/0.06]? Uncertainty in CRate
--------------------------------------------------------------------------------
Note (1): Filter/Band as follows:
H = Swift/XRT 1.5-10keV X-ray band (414 occurrences)
S = Swift/XRT 0.3-1.5keV X-ray band (414 occurrences)
UVW2 = Swift/UVOT UVW2-band; λobs=1928Å (314 occurrences)
UVM2 = Swift/UVOT UVM2-band; λobs=2246Å (292 occurrences)
UVW1 = Swift/UVOT UVW1-band; λobs=2600Å (302 occurrences)
U = Swift/UVOT U-band; λobs=3465Å (324 occurrences)
B = Swift/UVOT B-band; λobs=4392Å (339 occurrences)
V = Swift/UVOT V-band; λobs=5468Å (346 occurrences)
--------------------------------------------------------------------------------
History:
From electronic version of the journal
References:
Kara et al. Paper I. 2021ApJ...922..151K 2021ApJ...922..151K
Homayouni et al. Paper II. 2023ApJ...948...85H 2023ApJ...948...85H Cat. J/ApJ/948/85
Partington et al. Paper III. 2023ApJ...947....2P 2023ApJ...947....2P Cat. J/ApJ/947/2
Cackett et al. Paper IV. 2023ApJ...958..195C 2023ApJ...958..195C This catalog
Homayouni et al. Paper V. 2024ApJ...963..123H 2024ApJ...963..123H
Neustadt et al. Paper VI. 2024ApJ...961..219N 2024ApJ...961..219N
Lewin et al. Paper VII. 2024ApJ...974..271L 2024ApJ...974..271L
DEHGHANIAN et al. Paper VIII. 2024ApJ...972..141D 2024ApJ...972..141D
ZAIDOUNI et al. Paper IX. 2024ApJ...974...91Z 2024ApJ...974...91Z
Netzer et al. Paper X. 2024ApJ...976...59N 2024ApJ...976...59N
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 27-Jan-2026