J/ApJ/890/131 Follow-up of candidate counterparts of S190814bv (Andreoni+, 2020)
GROWTH on S190814bv: deep synoptic limits on the optical/near-infrared
counterpart to a neutron star-black hole merger.
Andreoni I., Goldstein D.A., Kasliwal M.M., Nugent P.E., Zhou R.,
Newman J.A., Bulla M., Foucart F., Hotokezaka K., Nakar E., Nissanke S.,
Raaijmakers G., Bloom J.S., De K., Jencson J.E., Ward C., Ahumada T.,
Anand S., Buckley D.A.H., Caballero-Garcia M.D., Castro-Tirado A.J.,
Copperwheat C.M., Coughlin M.W., Cenko S.B., Gromadzki M., Hu Y.,
Karambelkar V.R., Perley D.A., Sharma Y., Valeev A.F., Cook D.O.,
Fremling U.C., Kumar H., Taggart K., Bagdasaryan A., Cooke J.,
Dahiwale A., Dhawan S., Dobie D., Gatkine P., Golkhou V.Z., Goobar A.,
Chaves A.G., Hankins M., Kaplan D.L., Kong A.K.H., Kool E.C., Mohite S.,
Sollerman J., Tzanidakis A., Webb S., Zhang K.
<Astrophys. J., 890, 131 (2020)>
=2020ApJ...890..131A 2020ApJ...890..131A
ADC_Keywords: Supernovae; Photometry, ugriz; Redshifts; Spectroscopy;
Gravitational wave
Keywords: Neutron stars ; Binary stars ; Gravitational wave sources ;
Gravitational waves ; Transient sources ; Black hole physics ;
Observational astronomy
Abstract:
On 2019 August 14, the Advanced LIGO and Virgo interferometers
detected the high-significance gravitational wave (GW) signal
S190814bv. The GW data indicated that the event resulted from a
neutron star-black hole (NSBH) merger, or potentially a low-mass
binary BH merger. Due to the low false-alarm rate and the precise
localization (23deg2 at 90%), S190814bv presented the community with
the best opportunity yet to directly observe an optical/near-infrared
counterpart to an NSBH merger. To search for potential counterparts,
the GROWTH Collaboration performed real-time image subtraction on six
nights of public Dark Energy Camera images acquired in the 3 weeks
following the merger, covering >98% of the localization probability.
Using a worldwide network of follow-up facilities, we systematically
undertook spectroscopy and imaging of optical counterpart candidates.
Combining these data with a photometric redshift catalog, we ruled out
each candidate as the counterpart to S190814bv and placed deep,
uniform limits on the optical emission associated with S190814bv. For
the nearest consistent GW distance, radiative transfer simulations of
NSBH mergers constrain the ejecta mass of S190814bv to be
Mej<0.04M☉ at polar viewing angles, or Mej<0.03M☉ if
the opacity is κ<2cm2g-1. Assuming a tidal deformability for
the NS at the high end of the range compatible with GW170817 results,
our limits would constrain the BH spin component aligned with the
orbital momentum to be χ<0.7 for mass ratios Q<6, with weaker
constraints for more compact NSs.
Description:
S190814bv was considered a suitable candidate for the Dark Energy
Camera (DECam) follow-up under the NOAO program ID 2019B-0372
(PI Soares-Santos), which conducts observations of binary BH mergers.
The first exposure was taken roughly 7hr after the merger at UTC 2019
August 15 06:32:43. Data were acquired on six distinct Chilean
calendar nights (2019 August 14, 2019 August 15, 2019 August 16,
2019 August 17, 2019 August 20, and 2019 August 30), lasting from
1.5 to 4.5hr each night. Figure 1 shows the locations of the DECam
exposures. See Section 3.
The photometric evolution of the most promising counterpart candidates
was monitored using the optical imaging component of the
Infrared-Optical suite of instruments (IO:O) on the 2m Liverpool
Telescope (LT) at Observatorio del Roque de los Muchachos.
Optical photometric follow-up data were also acquired using the Las
Cumbres Observatory (LCO) telescope network under proposal ID
2019B-0244 (PI Coughlin).
At infrared wavelengths we obtained photometry using the Wide-field
Infrared Camera (WIRC) on the Palomar 200-inch Hale telescope (P200).
See Section 4.3.
The spectroscopic results presented in this paper include data
obtained using the Near Infrared Echellete Spectrometer (NIRES) and
the Low Resolution Imaging Spectrometer (LRIS) at the W. M. Keck
Observatory.
We observed three potential candidates with the 10.4m Gran Telescopio
de Canarias (GTC; PI A. Castro-Tirado), located at the observatory of
Roque de los Muchachos in La Palma (Canary Islands, Spain), equipped
with the Optical System for Imaging and low-intermediate-Resolution
Integrated Spectroscopy (OSIRIS).
Spectroscopy of one candidate of interest was also obtained with the
10m Southern African Large Telescope (SALT) equipped with the Robert
Stobie Spectrograph (RSS).
See Section 4.3.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 167 9 *Subset of candidates discovered or independently
detected by the DECam-GROWTH team during the
follow-up of S190814bv that were spectroscopically
classified
table3.dat 77 13 *Additional candidates discovered during the
follow-up of S190814bv, whose host galaxy redshift
is compatible with the LIGO/Virgo distance (2σ)
fig3.dat 72 50 Photometry of DECam candidates with LCO, LT/IO:O,
and P200/WIRC
fig3b.dat 41 481 DECam photometry of candidates
refs.dat 47 39 References
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Note on table2.dat: None of them is a viable optical counterpart to S190814bv.
The reported candidates passed the selection criteria described in
Section 4.2. Specifically, they lie within the 95% probability region
of the LALInference skymap and are within 20" from galaxies whose
redshifts (2σ uncertainty) are compatible with the LIGO/Virgo
distance (2σ). All the transients reported in this table were
detected using the image-subtraction pipeline described in Section 4.
Note on table3.dat: All candidates are ruled out based on their photometric
evolution being slower than 0.1mag/day.
--------------------------------------------------------------------------------
See also:
VII/250 : The 2dF Galaxy Redshift Survey (2dFGRS) (2dFGRS Team, 1998-2003)
VII/281 : GLADE v2.3 catalog (Dalya+, 2018)
J/AJ/108/2128 : RC3 corrections and additions (Corwin+ 1994)
J/A+A/562/A73 : ZJ VISTA photometry in NGC253 stellar halo (Greggio+, 2014)
J/A+A/593/A68 : PTF12os & iPTF13bvn spectra and light curves (Fremling+, 2016)
J/A+A/625/A152 : Light-curve models of black hole (Barbieri+, 2019)
J/ApJ/884/L55 : Opt. follow-up of gal. within S190814bv region (Gomez+, 2019)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- ID Internal identifier
15- 17 A3 --- f_ID [adp, ] Flag(s) on ID (1)
19- 27 A9 --- Name IAU identifier
29- 37 F9.6 deg RAdeg [10.83/23.56] Right ascension (J2000)
39- 48 F10.6 deg DEdeg [-32.71/-22.96] Declination (J2000)
50- 53 F4.1 arcsec Offset [1/11.6]? Offset from host galaxy
55- 60 F6.4 --- zspec [0.05/0.22]? Spectroscopic redshift
62- 66 F5.3 --- e_zspec [0.001/0.013]? zspec uncertainty
68- 73 A6 --- Class Classification
75-167 A93 --- Ref References (see refs.dat file)
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Note (1): Flag as follows:
a = We note that DG19sbzkc was observed with <10 visits and was added to
this table for completeness.
p = Photometric evolution available in fig3.dat; flag added by CDS
d = DECam photometry available in fig3b.dat; flag added by CDS
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- ID Internal identifier
11 A1 --- f_ID [a] Flag on ID (1)
13- 21 A9 --- Name IAU name
23- 31 F9.6 deg RAdeg [11.73/15.03] Right ascension (J2000)
33- 42 F10.6 deg DEdeg [-27.61/-22.39] Declination (J2000)
44- 48 F5.2 arcsec Offset [0.08/19.5] Offset
50- 54 F5.3 --- zphot [0.05/0.3] Photometric redshift
56- 59 F4.2 --- e_zphot [0.01/0.13] zphot uncertainty
61- 65 F5.2 mag i-z [-0.23/0.43]? Average i-band minus z-band
magnitudes
67- 71 F5.2 mag/d dimag/dt [-0.09/0.03]? i-band magnitude rate
73- 77 F5.2 mag/d dzmag/dt [-0.09/0.09]? z-band magnitude rate
--------------------------------------------------------------------------------
Note (1): Flag as follows:
a = DG19hcsgc, with Pan-STARRS1 pre-discovery on 2019 August 09.
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Byte-by-byte Description of file: fig3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- ID Internal identifier
15- 23 A9 --- Name IAU identifier
25- 34 F10.4 d MJD [58713.46/58722.75] Modified Julian Date
36- 44 A9 --- Tel Telescope identifier
46- 47 A2 --- Filt Filter used (g,r,i,z or J,Ks)
49- 53 F5.2 mag mag [21.11/23.93]? Apparent magnitude in Filt
55- 58 F4.2 mag e_mag [0.07/0.9]? Uncertainty in mag (1)
59 A1 --- f_mag [*] Flag on mag (2)
61- 65 F5.2 mag Limit [20.3/23]? Magnitude limit
67- 72 F6.2 mag Mag [-18.42/-13.85]? Absolute magnitude in Filt
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Note (1): The LCO and LT photometry upper limits are quoted to 3σ.
P200/WIRC photometry was obtained without image subtraction, thus
the measurements are affected by host contaminations.
Note (2):
* = Photometry obtained without image subtraction.
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Byte-by-byte Description of file: fig3b.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- ID Internal identifier
12- 22 F11.5 d MJD [58710.27/58726.3] Modified Julian Date
24 A1 --- Filt Filter used (i or z)
26- 30 F5.2 mag mag [18.58/23.7]? Apparent magnitude in Filt
32- 35 F4.2 mag e_mag [0.02/0.3]? The 5σ uncertainty in mag
37- 41 F5.2 mag Limit [12.2/24.3] Magnitude limit
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Byte-by-byte Description of file: refs.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- Ref Reference code
7- 25 A19 --- BibCode Bibcode of the reference
28- 47 A20 --- Auth First author's name(s)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 03-Aug-2021