J/ApJS/272/19 Variable sources from HST in the JWST NEP TDF (O'Brien+, 2024)
TREASUREHUNT: transients and variability discovered with HST in the JWST North
Ecliptic Pole Time-Domain Field.
O'Brien R., Jansen R.A., Grogin N.A., Cohen S.H., Smith B.M., Silver R.M.,
Maksym W.P.I., Windhorst R.A., Carleton T., Koekemoer A.M., Hathi N.P.,
Willmer C.N.A., Frye B.L., Alpaslan M., Ashby M.L.N., Ashcraft T.A.,
Bonoli S., Brisken W., Cappelluti N., Civano F., Conselice C.J.,
Dhillon V.S., Driver S.P., Duncan K.J., Dupke R., Elvis M., Fazio G.G.,
Finkelstein S.L., Gim H.B., Griffiths A., Hammel H.B., Hyun M., Im M.,
Jones V.R., Kim D., Ladjelate B., Larson R.L., Malhotra S., Marshall M.A.,
Milam S.N., Pierel J.D.R., Rhoads J.E., Rodney S.A., Rottgering H.J.A.,
Rutkowski M.J., Ryan R.E.J., Ward M.J., White C.W., van Weeren R.J.,
Zhao X., Summers J., D'Silva J.C.J., Ortiz R.I., Robotham A.S.G., Coe D.,
Nonino M., Pirzkal N., Yan H., Acharya T.
<Astrophys. J. Suppl. Ser., 272, 19 (2024)>
=2024ApJS..272...19O 2024ApJS..272...19O
ADC_Keywords: Active gal. nuclei; Transient; Supernovae; Photometry, HST;
Optical
Keywords: Time domain astronomy ; Transient sources ; Supernovae ;
AGN host galaxies ; HST photometry
Abstract:
The James Webb Space Telescope (JWST) North Ecliptic Pole (NEP)
Time-domain Field (TDF) is a >14' diameter field optimized for
multiwavelength time-domain science with JWST. It has been observed
across the electromagnetic spectrum both from the ground and from
space, including with the Hubble Space Telescope (HST). As part of HST
observations over three cycles (the "TREASUREHUNT" program), deep
images were obtained with the Wide Field Camera on the Advanced Camera
for Surveys in F435W and F606W that cover almost the entire JWST NEP
TDF. Many of the individual pointings of these programs partially
overlap, allowing an initial assessment of the potential of this field
for time-domain science with HST and JWST. The cumulative area of
overlapping pointings is ∼88arcmin2, with time intervals between
individual epochs that range between 1 day and 4+ yr. To a depth of
mAB∼29.5mag (F606W), we present the discovery of 12 transients and
190 variable candidates. For the variable candidates, we demonstrate
that Gaussian statistics are applicable and estimate that ∼80 are
false positives. The majority of the transients will be supernovae,
although at least two are likely quasars. Most variable candidates are
active galactic nuclei (AGNs), where we find 0.42% of the general z≲6
field galaxy population to vary at the ∼3σ level. Based on a 5yr
time frame, this translates into a random supernova areal density of
up to ∼0.07 transients arcmin-2 (∼245deg-2) per epoch and a
variable AGN areal density of ∼1.25 variables arcmin-2 (∼4500deg-2)
to these depths.
Description:
Observations from HST GO 15278 (PI: R. Jansen) were taken between
2017-Oct-01 and 2019-Feb-09, and those from GO 16252+16793
(TREASUREHUNT; PIs: R. Jansen and N. Grogin) were taken between
2020-Sep-25 and 2022-Oct-31.
The former program targeted the central (r≲5') portion of the JWST
North Ecliptic Pole (NEP) Time-domain Field (TDF), and the latter
targeted an outer annulus to r∼7.8'. Together, these programs provide
near-contiguous coverage with the Wide Field Camera 3 (WFC3/UVIS) in
the F275W filter (λc∼0.272um) and with the Advanced Camera
for Surveys (ACS/WFC) in the F435W and F606W filters
(λc∼0.433 and ∼0.592um), with a total area of ∼194arcmin2
(ACS/WFC). The full HST coverage of the JWST NEP TDF is shown in
Figure 1. See Section 2.1.
The JWST NEP TDF is a >14'-diameter field centered on
RAJ2000=17:22:47.896,DEJ2000=+65:49:21.54
JWST/NIRCam observations within the JWST NEP TDF were obtained between
2022-Aug-25 and 2023-May-30 as part of JWST GTO 2738 (PIs:
R. Windhorst and H. Hammel) in seven broadband filters (F090W through
F444W) and one medium-band filter (F410M) as part of the PEARLS
program (Windhorst+ 2023AJ....165...13W 2023AJ....165...13W). See Section 2.2 and Figure 1.
In this work, we provide the first time-domain study of the JWST NEP
TDF at visible wavelengths, presenting 12 transients (SN candidates;
see Table 2) and 190 unique galaxies exhibiting variability (where
∼80 are expected to be false positives) identified using TREASUREHUNT
data. See Section 4.
The JWST NEP TDF has also been observed extensively in X-rays with
NuSTAR, XMM-Newton, and Chandra. NuSTAR has monitored the field since
Cycle 5 (PID 5192, 6218, 8180, and 9267; PI: F. Civano). For this work
we use the Cycle 5+6 data and catalog published in
Zhao+ (2021, J/MNRAS/508/5176 and 2024, J/ApJ/965/188).
The 21 NuSTAR observations took place over 28 months (between
2019 September and 2022 January), while the three XMM-Newton
observations (part of the NuSTAR Cycle 6 program) were taken over
15 months (between 2020 October and 2022 January). We also use the
first 1.3Ms of Chandra observations of the JWST NEP TDF (PID 19900666,
20900658, 21900294, and 22900038; PI: W.P. Maksym) spanning Cycles 19-23.
Chandra observed the field 46 times between 2018 April 12 and
2022 September 25 (a span of 4.6yr), with exposures ranging from 9 to
59.9ks. See Section 2.3.
MMT/Binospec observations of the JWST NEP TDF in 2019 September (PI:
C. Willmer) yield spectra spanning ∼3900-9240Å with a resolution of
∼4.9Å (FWHM) at 6500Å. See Section 2.4.
All magnitudes are in AB units.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 85 12 Transients identified in HST TREASUREHUNT
observations of the James Webb Space Telescope
(JWST) North Ecliptic Pole (NEP)
Time-domain Field (TDF); see Section 4.1
table5.dat 118 190 Variable sources identified in HST TREASUREHUNT
observations of the JWST NEP TDF; see Section 4.2
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
J/MNRAS/268/305 : Variability of optically selected quasars (Hook+ 1994)
J/A+A/321/123 : Optical variability of QSOs (Cristiani+ 1997)
J/AJ/120/2747 : HDF-South WFPC2 observations (Casertano+, 2000)
J/AJ/125/1107 : Ultra-deep near-IR observation in HDF-S (Labbe+, 2003)
J/MNRAS/375/989 : Quasar variability (Wold+, 2007)
J/A+A/497/81 : Variability-selected AGN in CDFS (Boutsia+, 2009)
J/ApJ/723/737 : Variability selected AGNs in GOODS (Villforth+, 2010)
J/ApJ/731/97 : Variable AGNs in GOODS fields (Sarajedini+, 2011)
J/ApJ/735/86 : NEWFIRM MBS: photometric catalogs (Whitaker+, 2011)
J/AJ/148/13 : Redshifts of 65 CANDELS supernovae (Rodney+, 2014)
J/A+A/584/A62 : SUDARE VST-OmegaCAM search SN rates (Cappellaro+, 2015)
J/MNRAS/487/4285 : Variable AGN candidates catalog (Pouliasis+, 2019)
J/ApJ/888/36 : SDSS/FIRST dwarf gal. with VLA HR obs. (Reines+, 2020)
J/ApJ/897/41 : Lyman Cont. in 111 GOODS and ERS galaxies (Smith+, 2020)
J/other/Sci/373.789 : optical variability of AGNs (Burke+, 2021)
J/MNRAS/508/5176 : NuSTAR Extragalactic Surveys, NEP Field (Zhao+, 2021)
J/ApJ/965/188 : JWST NEP TDF NuSTAR and XMM-Newton survey (Zhao+, 2024)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- ID Transient identifier (T1 to T12)
5- 14 F10.6 deg RAdeg [260.47/261] Right Ascension (J2000) (1)
16- 24 F9.6 deg DEdeg [65.7/66] Declination (J2000) (1)
26- 31 A6 --- V1 Root name of the visit where the transient is
present (Visit 1)
33- 38 A6 --- V2 Root name of the visit where the transient is
absent (Visit 2)
40- 47 F8.3 yr t1 [2017.9/2022.9] Date of Visit 1 observation
in decimal years
49- 56 F8.3 yr t2 [2017.7/2022.6] Date of Visit 2 observation
in decimal years
58- 63 F6.3 yr Delt [-4/1.2] Time interval between Visits 1 and 2
65- 69 F5.2 mag F435Wmag [24.44/27.75]? HST ACS/WFC F435W AB
magnitude (2)
71- 74 F4.2 mag e_F435Wmag [0.08/1.7]? Uncertainty on F435Wmag
76- 80 F5.2 mag F606Wmag [24.8/27.6] HST ACS/WFC F606W AB magnitude (2)
82- 85 F4.2 mag e_F606Wmag [0.05/0.7] Uncertainty on F606Wmag
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Note (1): The celestial coordinates (identified by eye) of the transient.
Note (2): The measured F435W and F606W magnitudes of the transient
(mAB at t1 relative to t2, measured within a circular aperture
centered on the transient with a radius of 8 pixels).
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- ID Variable source identifier (V001 to V190)
6- 10 I5 --- CatID [48/49278] Internal SourceExtractor catalog
identifier
12- 22 F11.7 deg RAdeg [260.4/261] Right Ascension (J2000) (1)
24- 33 F10.7 deg DEdeg [65.7/66] Declination (J2000) (1)
35- 40 A6 --- V1 Root name of the overlapping visit 1 variable
was detected
42- 47 A6 --- V2 Root name of the overlapping visit 2 variable
was detected
49- 56 F8.3 yr t1 [2017.7/2022.9] Fractional year of first
visit; UT
58- 65 F8.3 yr t2 [2017.9/2022.9] Fractional year of second
visit; UT
67- 72 F6.3 yr Delt [-3.9/4.2] Time interval between visits 1 and
2
74- 78 F5.2 mag F435Wmag [19.18/30] Brightest HST ACS/WFC F435W band
apparent AB magnitude in two visits (1)
80- 83 F4.2 mag e_F435Wmag [0.01/0.9] Uncertainty in F435Wmag
85- 89 F5.2 mag DelF435W [-1.8/1.4] Change in F435W band magnitudes
between two visits (1)
91- 95 F5.2 --- sigF435W [0.01/14] Significance of F435W band
variability in units of σΔm (2)
97- 101 F5.2 mag F606Wmag [19.46/29.4] Brightest HST ACS/WFC F606W band
apparent AB magnitude in two visits (1)
103- 106 F4.2 mag e_F606Wmag [0.01/0.4] Uncertainty in F606Wmag
108- 112 F5.2 mag DelF606W [-2.1/1.42] Change in F606W band magnitudes
between two visits (1)
114- 118 F5.2 --- sigF606W [0.2/14.8] Significance of F606W band
variability in units of σΔm (2)
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Note (1): Corresponding to the 0.24 arcsec aperture.
Note (2): We emphasize that we cannot claim any individual variable candidate
varying at <5σΔm significance to be a genuine variable.
See Section 4.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 13-Aug-2024