J/ApJ/916/47 GECKO follow-up obs. of 3 binary BH GW events (Kim+, 2021)
GECKO optical follow-up observation of three binary black hole merger events:
GW190408_181802, GW190412, and GW190503_185404.
Kim J., Im M., Paek G.S.H., Lee C.-U., Kim S.-L., Chang S.-W., Choi C.,
Hwang S., Kang W., Kim S., Kim T., Lee H.M., Lim Gu, Seo J., Sung H.-I.
<Astrophys. J., 916, 47 (2021)>
=2021ApJ...916...47K 2021ApJ...916...47K
ADC_Keywords: Gravitational wave; Black holes; Photometry; Optical
Keywords: Gravitational wave astronomy ; Black holes ;
Gravitational wave sources ; Gravitational waves ;
Optical identification ; Compact binary stars ;
High energy astrophysics ; Stellar mass black holes ; Novae ;
Time domain astronomy ; Time series analysis ; Compact objects
Abstract:
We present optical follow-up observation results of three binary black
hole merger (BBH) events, GW190408_181802, GW190412, and
GW190503_185404, which were detected by the Advanced LIGO and Virgo
gravitational wave (GW) detectors. Electromagnetic (EM) counterparts
are generally not expected for BBH merger events. However, some
theoretical models suggest that EM counterparts of BBH can possibly
arise in special environments, prompting motivation to search for EM
counterparts for such events. We observed high-credibility regions of
the sky for the three BBH merger events with telescopes of the
Gravitational-wave EM Counterpart Korean Observatory (GECKO),
including the KMTNet. Our observation started as soon as 100 minutes
after the GW event alerts and covered 29-63deg2 for each event with
a depth of ∼22.5mag in the R band within hours of observation. No
plausible EM counterparts were found for these events, but based on
there being no detection of the GW190503_185404 event, for which we
covered the 69% credibility region, we place the BBH merger EM
counterpart signal to be Mg>-18.0 AB mag within about one day of
the GW event. The comparison of our detection limits with light curves
of several kilonova models suggests that a kilonova event could have
been identified within hours of the GW alert with GECKO observations
if the compact merger happened at <400Mpc and the localization
accuracy was on the order of 50deg2. Our result shows great promise
for the GECKO facilities to find EM counterparts within a few hours
from GW detection in future GW observation runs.
Description:
For the follow-up observation of the gravitational wave (GW) events,
we mainly used the KMTNet which is a network of three identical 1.6m
telescopes with a wide field of view (∼4deg2) located at the Cerro
Tololo Inter-American Observatory (CTIO), the South African
Astronomical Observatory (SAAO), and the Siding Spring Observatory (SSO).
Additionally, we used four telescopes of the Intensive Monitoring
Survey of Nearby Galaxies (IMSNG; Im+ 2019JKAS...52...11I 2019JKAS...52...11I) to observe
the Northern Hemisphere. The wide-field IFU telescope (WIT), a
wide-field (∼5.5deg2) imager with a 0.25m telescope equipped with
multiple medium-band and broadband filters at the McDonald Observatory
(McD) performed tiling observation to cover the wide GW localization
area, but to a rather shallow depth (∼19.0mag in the V band at
5σ depth with a 7.5 minute exposure). The other three are 1.0m
telescopes at the Deokheung Optical Astronomy Observatory (DOAO), the
Mt. Lemmon Optical Astronomy Observatory (LOAO), and the Seoul
National University Astronomical Observatory (SAO).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 70 3 Target gravitational wave (GW) events
table2.dat 69 145 Tiling observation of the three GW events
table3.dat 77 211 Galaxy observation of GW190412
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See also:
II/357 : The Dark Energy Survey (DES): Data Release 1 (Abbott+, 2018)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
VII/281 : GLADE v2.3 catalog (Dalya+, 2018)
J/ApJ/766/109 : Color/age/metallicity gradients of E galaxies (Kim+, 2013)
J/ApJ/848/L16 : Counterpart of GW170817. I. DECam obs. (Soares-Santos+, 2017)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Event Target GW event ID
10- 12 A3 --- Type Source type ("BBH"=binary black hole)
14- 32 A19 "datime" Date Event time (UT)
34- 36 I3 deg2 Area90 [156/448] Initial 90% area
38- 41 I4 Mpc Dist [412/1473] Initial distance
43- 45 I3 Mpc e_Dist [105/358] Dist uncertainty
47- 49 I3 deg2 AreaGWTC [21/140] GWTC-2 90% area
51- 54 I4 Mpc DistGWTC [740/1580] GWTC-2 distance
56- 58 I3 Mpc e_DistGWTC [170/660] Lower uncertainty on DistGWTC
60- 62 I3 Mpc E_DistGWTC [140/710] Upper uncertainty on DistGWTC
64 A1 --- l_FAR Upper limit flag on FAR
65- 70 E6.2 yr-1 FAR [7.9e-5] False alarm rate taken from the
result of PyCBC BBH pipeline in the
GWTC-2 catalog (Abbott+ 2021PhRvX..11b1053A 2021PhRvX..11b1053A)
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Event Gravitational wave event identifier
10- 15 A6 --- Tel Telescope identifier (1)
17- 20 I4 yr Obs.Y [2019] Year of the observation start time
22- 23 I2 "month" Obs.M [4/5] Month of the observation start time
25- 26 I2 d Obs.D Day of the observation start time
28- 29 I2 h Obs.h Hour of the observation start time
31- 32 I2 min Obs.m Minute of the observation start time
34- 35 I2 s Obs.s Second of the observation start time
37- 41 F5.2 h Time [1.6/89.2] Time since GW alert
43- 44 I2 h RAh [4/22] Hour of Right Ascension (J2000) (2)
46- 47 I2 min RAm Minute of Right Ascension (J2000) (2)
49- 52 F4.1 s RAs Second of Right Ascension (J2000) (2)
54 A1 --- DE- [±] Sign of the Declination (J2000) (2)
55- 56 I2 deg DEd [0/55] Degree of Declination (J2000) (2)
58- 59 I2 arcmin DEm Arcminute of Declination (J2000) (2)
61- 62 I2 arcsec DEs Arcsecond of Declination (J2000) (2)
64 A1 --- Band Filter used (B, V or R)
66- 69 F4.1 mag Depth [17/23.3] Image depth in 5-sigma; AB
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Note (1): Telescope as follows:
KMTNet = Network of three identical 1.6m telescopes located at the Cerro
Tololo Inter-American Observatory in Chile, the South African
Astronomical Observatory, and the Siding Spring Observatory in
Australia (117 occurrences)
WIT = The wide-field IFU telescope at the McDonald Observatory
(28 occurrences)
Note (2): Central coordinate of the field.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- Tel Telescope identifier (1)
6- 9 I4 yr Obs.Y [2019] Year of the observation start time
11- 12 I2 "month" Obs.M [4] Month of the observation start time
14- 15 I2 d Obs.D Day of the observation start time
17- 18 I2 h Obs.h Hour of the observation start time
20- 21 I2 min Obs.m Minute of the observation start time
23- 24 I2 s Obs.s Second of the observation start time
26- 49 A24 --- Name Target identifier (2)
51- 52 I2 h RAh [12/15] Hour of Right Ascension (J2000) (2)
54- 55 I2 min RAm Minute of Right Ascension (J2000) (2)
57- 60 F4.1 s RAs Second of Right Ascension (J2000) (2)
62 A1 --- DE- [±] Sign of the Declination (J2000) (2)
63- 64 I2 deg DEd [0/36] Degree of Declination (J2000) (2)
66- 67 I2 arcmin DEm Arcminute of Declination (J2000) (2)
69- 70 I2 arcsec DEs Arcsecond of Declination (J2000) (2)
72 A1 --- Band Filter used (B, V, R or I)
74- 77 F4.1 mag Depth [15.7/21.4] Image depth in 5-sigma; AB
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Note (1): Telescope as follows:
SAO = 1m telescope at the Seoul National University Astronomical Observatory
(120 occurrences)
DOAO = 1m telescope at the Deokheung Optical Astronomy Observatory
(89 occurrences)
LOAO = 1m telescope at the Mt. Lemmon Optical Astronomy Observatory
(2 occurrences)
Note (2): From the GLADE catalog (Dalya+ 2018, VII/281).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 22-Dec-2022