Optical and Near-Infrared Follow-up
Observations for Gravitational Wave
Sources and Neutrinos

Tomoki Morokuma(Institute of Astronomy@Mitaka, University of Tokyo)
tmorokuma@ioa.s.u-tokyo.ac.jp

Contents
optical/NIR transient surveys (in general)
optical/NIR follow-up observations
for GW sources
optical/NIR follow-up observations
for neutrino sources (IceCube)
optical/NIR follow-up observations
for CTA sources
Summary

optical/NIR for GW/Neutrino

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optical/NIR telescopes

E-ELTaperture [m]
3x30m telescopes in 2020s?
~10x 8-10m telescopes

30TMT
GMT

Keck
10P200SubaruCFHT

PS1

3Hooker

P48

1
1900

1950

optical/NIR for GW/Neutrino

LSST

HST
1990year
2000

2010

2020

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optical/NIR transient/variable objects
triggere d byvariable staro ptical/NIR obser va[high proper motion star]t io nssupernova (SN)
active galactic nuclei (AGN)
gamma-ray burst (GRB)
X/gamma-ray transient: Fermi, Swift, MAXI, …
fast radio burst (FRB): Parkes, …
Gravitational Wave: LIGO, Virgo, KAGRA
neutrino: IceCube, KamiokandesnoitavresboRIN/lacit
pononybderegg
tr i

optical/NIR for GW/Neutrino

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optical/NIR transient/variable objects
triggere d byvariable staro ptical/NIR obser va[high proper motion star]t io nssupernova (SN)
active galactic nuclei (AGN)
gamma-ray burst (GRB)
X/gamma-ray transient: Fermi, Swift, MAXI, …
fast radio burst (FRB): Parkes, …
Gravitational Wave: LIGO, Virgo, KAGRAsnneutrino: IceCube, Kamiokandeoitavresbo
RIN/lacit
pononybderegg
tr i
beforeafter
after
beforeNugent+2011, SN 2011fe@M101
optical/NIR for GW/Neutrino

SN 1987A@LMC

The extreme Universe viewed in very-high-energy gamma-rays 2017, 2017/12/18-19

7No. 1, 2008

How to find supernovae effectively
Most of optical/NIR sources are quiescent.
<==> high energy sources
image subtraction: an effective way tosearch for transient/variable sources in
optical/NIR
different PSFs
different depths
rare phenomena~1 supernova / galaxy / 100 yrs# density of galaxies~103 deg-2 (R<20, 1m-class)~105 deg-2 (R<25, 8m-class)# density of variable sources~1 deg-2 (R<20, 1m-class)~102 deg-2 (R<25, 8m-class)wide-field survey
optical/NIR for GW/Neutrino

TM+2008

before

The extreme Universe viewed in very-high-energy gamma-rays 2017, 2017/12/18-19

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!!! Let’s find a new supernova !!!
beforeafter

beforeoptical/NIR for GW/Neutrino

The extreme Universe viewed in very-high-energy gamma-rays 2017, 2017/12/18-19

9!!! Let’s find a new supernova !!!
beforeafter

beforeoptical/NIR for GW/Neutrino

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10

Example: image subtraction

beforeoptical/NIR for GW/Neutrino

The extreme Universe viewed in very-high-energy gamma-rays 2017, 2017/12/18-19

11differencenewdifference

0.2deg

new>

|ref.

0.2deg==refAre(all(of(these(points(really(the(transient(objects(?
subtracted image

real vs bogus~ 1 : 1000All(of(these(detected(points(are(bogus
not the(real(transient(objects.((Image subtraction
is not perfect.
optical/NIR for GW/Neutrino

realbefore
12©Takahiro Kato, Masaomi Tanaka

The extreme Universe viewed in very-high-energy gamma-rays 2017, 2017/12/18-19

Fig. 3. Distribution of magnitude of bogus objects and artificial “real” objects

Machine Learning for Transient Detection

1.0

true positive rate(fraction to detect real as real)

Mikio Morii, JST/CREST collaboration, et al. 2016, PASJ
(Kavli IPMU, Institute for Statistical Mathematics, NTT Communication
Science, and Tsukuba Univ.)
bogu
miss 10% of real

0.0

better0.0

false positive rate
(fractionto judgebogusas real)Fig. 4. ROC curve for auc
Boostingfor every
magnitude
slice.
optical/NIR for GW/Neutrino

1.0

before13©Masaomi Tanaka

The extreme Universe viewed in very-high-energy gamma-rays 2017, 2017/12/18-19

©Masaomi Tanaka

beforeoptical/NIR for GW/Neutrino

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July 2014 (reference)

Tominaga+2015,
ATel, 7565
optical/NIR for GW/Neutrino The extreme Universe viewed in very-high-energy gamma-rays 2017, 2017/12/18-19

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May 2015 (search)

Tominaga+2015,
ATel, 7565
optical/NIR for GW/Neutrino The extreme Universe viewed in very-high-energy gamma-rays 2017, 2017/12/18-19

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[May 2015] - [July 2014] (subtraction)

Tominaga+2015,
ATel, 7565
optical/NIR for GW/Neutrino The extreme Universe viewed in very-high-energy gamma-rays 2017, 2017/12/18-19

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optical/NIR
transient/variableobjects
IceCube
LIGO
triggere d byvariable staro ptical/NIR obser va[high proper motion star]t io nssupernova (SN)
active galactic nuclei (AGN)
gamma-ray burst (GRB)
X/gamma-ray transient: Fermi, Swift, MAXI, …
fast radio burst (FRB): Parkes, …
Gravitational Wave: LIGO, Virgo, KAGRA
neutrino: IceCube, Kamiokande
snoitavresboRIN/laParkescit
pononybdereggtr iFermi
optical/NIR for GW/Neutrino

The extreme Universe viewed in very-high-energy gamma-rays 2017, 2017/12/18-1918

TYPICAL optical/NIR telescopes/instruments~10 arcmin

Hubble Space Telescope

CTA
optical/NIR for GW/Neutrino

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WIDE-FIELD optical/NIR telescopes/instruments>1 degCTIODECam(4)

Kiso Schmidt
Tomo-e Gozen(1.05)

PalomarZwicky Transient Facility (ZTF)
(1.2)

CTA
SubaruHSC(8.2)

optical/NIR for GW/Neutrino

ASAS-SN(0.14)
x ~10

The extreme Universe viewed in very-high-energy gamma-rays 2017, 2017/12/18-19

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field-of-view [deg2]

survey power = mirror area x field-of-view (optical NIR)
ASAS-SN
100

1010.1

0.01

Palomar/ZTF

Kiso/Tomo-e[LSST]
PS1
PTF
DECam
Kiso/KWFC
Subaru/HSC
MOAII
VISTA

[WFIRST]

Subaru/SCamFRONTIER

HST/ACS
0.125 0.25 0.5

12

4

81632

telescope aperture [m][]: future
projects
optical/NIR for GW/Neutrino The extreme Universe viewed in very-high-energy gamma-rays 2017, 2017/12/18-19

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Subaru Telescope (8.2m)

http://subarutelescope.org

Large Synoptic Survey Telescope (LSST; 8.4m), 2022-https://www.lsst.org
optical/NIR for GW/Neutrino

The extreme Universe viewed in very-high-energy gamma-rays 2017, 2017/12/18-1922

how to identify optical/NIR counterparts
blind surveys w/ wide-field telescopes
targeted observations w/ “normal” telescopes
GW: if the source is close to us ==> nearby galaxies
IceCube: if the source is a specific type (e.g., blazar)

optical/NIR for GW/Neutrino

The extreme Universe viewed in very-high-energy gamma-rays 2017, 2017/12/18-1923

LIGO x 2 (Hanford, Livingston)
https://www.ligo.caltech.edu/page/ligo-detectors

VirgoKAGRA

http://public.virgo-gw.eu/index.php?gmedia=5vp4v&t=g

optical/NIR for GW/Neutrino

https://www.nao.ac.jp/contents/news/topics/2015/20151116-kagra-fig3-origin.jpg

The extreme Universe viewed in very-high-energy gamma-rays 2017, 2017/12/18-1924

GW Localization

LIGOx2: O(100) deg2
LIGOx2 + Virgo: O(10) deg2

http:/optical/NIR/ligo.org/detections/GW170817.php
for GW/Neutrino The extreme Universe viewed in very-high-energy gamma-rays 2017, 2017/12/18-1925

Galaxy List for the Advanced Detector Era (GLADE)
assembled for GW EM counterpart search
LIGO sensitivity (NS-NS mergers): ~80 Mpc@O2 ==> ~200 Mpc
2MASSXSCand+ 2comparison
MPZ + HyperLEDA
Summarywith other catalogs
aquarius.elte.hu/glade
B mag + redshift + IR magnitudes
No. of galaxies
Completeness % at 60 Mpc
Completeness% ofat galaxies
120 Mpc
DensityCompleteness % at 180 Mpc

GWGC [1]

CLU [2]53,25560?
1008040

GLADE
2,068,841 ~50 galaxies / deg2
104 ± 771 ± 565 ± 590350

Other advantages:70300

Declination [deg]50! Value-addedwith B mag and z data
30! We are working on associating stellar masses to each galaxy

250

10! We have a working pipeline to associate any other parameters200
relevant−10for the Collaboration
150−30[1] White, D. J., Daw, E. J. & Dhillon, V. S., 2011, Class. Quantum Grav., 28 085016

100−50 J. K., Kanner, J. et al., 2015, submitted to ApJ[2] Gehrels, N., Cannizzo,
http://arxiv.org/abs/1508.03608
Gergely Dálya −70(ELTE)

dalyag@caesar.elte.hu

50

optical/NIR for GW/Neutrino

100150200

September 01, 2015

250300350

10 / 115002

ρ [1/deg
The extreme Universe
viewed [deg]in very-high-energy gamma-rays
2017,] 2017/12/18-19
Right ascention

26

Japanese collaboration for Gravitational wave
J-GEM =
ElectroMagnetic follow-up
4 deg2==> 20 deg2

1.8 deg2

2 deg2

optical/NIR for GW/Neutrino

radio wide-field

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Abbott et al. 2016, ApJL, 826, L13

EM observations (GW150914 = 1st GW, BH-BH)
The Astrophysical Journal Letters, 826:L13 (8pp), 2016 July 20

Abbott et al.

opticalNIR
100Figure 1. Timeline of observations of GW150914, separated by band and relative to the time of the GW trigger. The top row shows GW information releases. The[days]
bottom four rows show high-energy, optical, near-infrared, and radio observations, respectively. Optical spectroscopy and narrow-ﬁeld radio observations
are2

The Astrophysical Journal Letters, 826:L13 (8pp), 2016 July 201Abbott et al.

10~900 deg>~50%ofinitialskymap
LIGO and Virgo detectors and several EM astronomy facilities
Multi-Band Template Analysis (MBTA; Adams et al. 2015)
in 2009 and 2010 (Abadie et al. 2012a, 2012b; Evans et al.
searchspeciﬁcally for NS binary
mergers using matched~60
extragalactictransients
2012; Aasi et al. 2014). In preparing for Advanced detector
ﬁltering. Because CBC waveforms can be precisely computedoperations, the LIGO and Virgo collaborations worked with thefrom general relativity, GSTLAL and MBTA are more(Kasliwal+2016,Smartt+2016)broader astronomy community to set up an evolved and greatly
sensitive to CBC signals thanthe burst search pipelines are.
indicated with darker tick marks and boldface text. Table 1 reports more detailed information on the times of observations made with each instrument.

expanded EM follow-up program.381 Seventy-four groups withAll four detection pipelines report candidates within a few
access to ground- and space-based facilities joined, of which 63
minutes of data acquisition.
were operational during Advanced LIGOʼs ﬁrst observing run
LIGO conducted a series of engineering runs throughout(O1). Details of the 2009 to 2010 EM follow campaign andAdvanced LIGOʼs construction and commissioning to preparechanges for O1 are given in Section 1 of the Supplement
to collect and analyze data in a stable conﬁguration. The eighth(Abbott et al. 2016b).
engineering run (ER8) began on 2015 August 17 at 15:00 and
After years of construction and commissioning, the Advanced
critical software was frozen by August 30.383 The rest of ER8
LIGO detectors at Livingston, Louisiana, and Hanford,
was to be used to calibrate the detectors, to carry out diagnostic
Washington, began observing in 2015 September with about
studies, to practice maintaining a high coincident duty cycle,
3.5 times the distance reach (<40 times the sensitive volume) ofand to train and tune the data analysis pipelines. Calibration
the earlier detectors. A strong GW event was identiﬁed shortly
was complete by September 12 and O1 was scheduled to begin28
Figure 3. Footprints of observations in comparison with the 50% and 90% credible levels of the initially distributed GW localization maps. Radio ﬁelds are shaded inTheextreme
Universeviewedinvery-high-energy
gamma-rays
2017, 2017/12/18-19
red, optical/infraredoptical/NIR
ﬁelds are in green, andthe XRT
ﬁelds areindicated by the bluecircles. The all-sky Fermi
GBM, LAT, was
INTEGRALcompleted.
SPI-ACS, and MAXI Deep
after
thepre-run
calibration
processfor
GW/Neutrino
on September 18.
On 2015 September
14, cWB reported aGW170817: 1st NS-NS merger

http://ligo.org/detections/GW170817.php
week ending
VIEW
LETTERS
Abbott+2017
20 OCTOBER 2017

LIGO+Virgo~30 deg2

LIGO
forrepresentations
GW/Neutrino
FIG. 1.optical/NIR
Time-frequency[65] ofThedataextremecontainingUniverse viewed in very-high-energy gamma-rays 2017, 2017/12/18-1929

EM observations(GW170817)
Abbott et al. 2017, ApJL, 848, L12Coulter+2017, GCN, 21529
discovery w/ 1m Swope telescopetargeted galaxy survey
11 hours after GW detection
host galaxy: NGC 4993@~40 Mpc
GW: dL=40+8-14 Mpc
LIGO sensitivity: ~80 Mpc

1EM counterpart:TheSSS17a
extreme Universe viewed in very-high-energy gamma-rays 2017, 2017/12/18-19

optical/NIR for GW/Neutrino1030

Wide-Field Surveys for GW170817

2Publications of the Astronomical Society of Japanno good candidates except for SSS17a
02 rebotcO 7102 ,)pp7( 61L:848 ,sretteL lanruoJ lacisyhportsA ehTsiD .1.2
a demrofrep eWdnﬁ ot segami maCEDosirapmoc ni seixalag
te srebmahC( segamis wen a fo yrevocsidyxalag ehT .)1 erugiF
mk 07 fo 0H fo eulaveht yb detroper cpM
ta detacol si tneisnart
4m90h31( 594183.32ni sruotnoc %09 dna.)2 erugiF
t nehw emit eht tAsnart lacitpo eht )regrem
10.0 34.71 = z dna
CED htiw trapretnuoca( elbatcetednu emaceb
col ecruos eht dna dnabo egami peed tsal ruO
sehT .regrem-tsop syad
tiawhtrepwoC ni liatedgami lla ssecorp eW.la te rengaW-acilrD(refer dna ,noitaraperp
K( senilepip )gmﬁfid(s gnirapmoc yb skrowatbo )setalpmet( segami
lp gnigami nwo ruo esu
hcrA ecneicS OAON
fo serusopxe gniriuqer
nitsixe-erp ,trapretnuoc
w segami Y , z , i , u roF
tsuguA 7102 :u( dedaf
ser cirtemotohp ehT
fid ehT .1 elbaT dna
eludom noitarbilac
1 elbaT ni detneserp.%2⪅ fo yrtemotohp
noitcartbus dna tﬁ
tfos gnittﬁ tnenopmoc
noitcnuf daerps-tniop
od ot noitarbilac 1SP
a seitniatrecnu nihtiw
txen eht ni desu yrtem
gnisu derusaem ,)7102
talpmet 1SP SRRATS

300o

30o

ytilibaborp eht no 718071WG fo trapretnuoc lacitpo eht fo noitacoL .2 erugiF
dna renni ;desiver :dehsad nayc ;laitini :dilos etihw( CVL eht yb dedivorp spamruo ot evitaler dna )ylevitcepser ,ytilibaborp %09 dna %05 wohs sruotnoc retuo.)tnirptoof yks maCED :der( aera hcraes

300o

30o

CTIO (4m) / DECami-band (0.8 um) & z-band (0.9 um).3cﬁitneicS OGIL( MBG-imreF yb detceted syar-ammag fo tsrub
ruoF .)d7102 ,b7102 noitaroballoC ogriV & noitaroballoC-eerht eht morf deniatbo pam noitazilacol yks a retal sruoh
cﬁitneicS OGIL( dedivorp saw krowten VLA rotceted.)c7102 noitaroballoC ogriV & noitaroballoCeht ta elihC morf elbisiv saw noiger noitazilacol WG eritne ehTruO .rh 5.1∼ tsrﬁ eht nihtiw gnittes ,thgin eht fo gninnigeb-tsop rh 35.01( TU 31:32 ta decnemmoc snoitavresbo maCED
s5 gnitluser ehT .sdnab z dna i eht ni serusopxe s 03 htiw )regrem.secruos tniop rof 3.12 » z dna 0.22 » i era sedutingam gnitimil
81 fo detsisnoc snoitavresbo fo ecneuqes denimretederp ehT
dnoces a htiw ,egarevoc 2ged 3 a htiw hcae ,)sexeh( sgnitniop
neewteb spag ot eud ,.g.e( aera fo ssol etagitim ot ecneuqes tesffo
4.07 saw egarevoc laera gnitluser ehT .)enalp lacof eht ni srotceted
eht fo %4.39 fo ytilibaborp detargetni na ot gnidnopserroc ,2ged
dna gnitniop eht fo sliated lanoitiddA .pamyks WG laitini.la te renreH ni elbaliava era mhtirogla noitanimreted gnicneuqes
wen a ,gniogno saw snoitavresbo fo ecneuqes ruo elihW .)7102(cﬁitneicS OGIL( TU 45:32 ta desaeler saw pam noitazilacolllarevo eht elihW .)e7102 noitaroballoC ogriV & noitaroballoC
detfihs saw kaep ytilibaborp eht ,ralimis era spam owt eht fo epahs
ruo fo ytilibaborp detargetni eht ,pam desiver eht nI .yltnacﬁingis.%7.08 si snoitavresbo

Soares-Santos+2017

Subaru (8.2m) / Hyper Suprime-Camg. 1. Pointing map for GW170817 overlaid on the probability map(LALInferencev2.fits.gz; Abbott et al. 2017c).
z-band(~0.9 um)
argorp yramirp ruO
aes ot pam ytilibaborp
deniatbo dah ew tneve
libaborp OGIL desiver
ynam woh enimreted

ED eht yolpme eW
Tominaga,
Tanaka,edible
region. Circles represent the field-of-view of HSC,
changing theirface color TM+2017
with an order of observation. O
a ecudorp ot senilepip.3

sopxe 27 era segami
owt ot gnidnopserroc(eht fo tsom esuaceB

optical/NIR for GW/Neutrino

The extreme Universe viewed in very-high-energy gamma-rays 2017, 2017/12/18-1931Search for optical/NIR IceCube counterparts
blind surveys w/ wide-field telescopes
targeted observations w/ “normal” telescopes
IceCuube-170922A
Subaru/HSC
IceCubeKanata/HONIR
optical/NIR for GW/Neutrino

Kiso/KWFC

The extreme Universe viewed in very-high-energy gamma-rays 2017, 2017/12/18-19

32

possible counterpart: TXS 0506+056
NIR variability detected w/ Kanata/HONIR
discovery of recent gamma-ray flare (Fermi; Tanaka+2017)
other observations
spectroscopy for redshift determination
imaging w/ Subaru/HSC, Kanata, Kiso, etc.

be-170922A 増光天体探索②
いた。

2MASSカタログ[Sep. 23] image

かなた
9/23ーかなた
9/24
差分FermiKanata/HONIR©Mori
subtraction: [Sep. 23] - [Sep. 24]

beが稼働して以来、初めてpossiblesource（の候補）を発見！！
Universe viewed in very-high-energy gamma-rays 2017, 2017/12/18-19
optical/NIR for GW/Neutrino The extreme

33

Prospects for optical/NIR follow-up for CTA sources
optical/NIR identification
all-sky imaging map available
r<22 (northern 3pi w/ PS1, available)r<26 (southern 3pi w/ LSST, 2022-)
1/3 of Fermi sources: unidentified in other wavelengths
also not easy for CTA sources?
follow-up flaring CTA sources~1 arcmin uncertainty: good for optical/NIR follow-up# of optical/NIR objects
O(1) for 1m-class telescopes (R<20)
O(100) for 8m-class telescopes (R<25)“monitoring” all ~1000 CTA sources
all-sky monitoring surveys (w/o extra efforts)
1m wide-field telescopes (ZTF, Kiso/Tomo-e Gozen)
Pan-STARRS1 (1.8m), LSST (8.4m)
optical/NIR for GW/Neutrino

The extreme Universe viewed in very-high-energy gamma-rays 2017, 2017/12/18-19

35all-sky monitoring surveys
Tomo-e Gozen
1.05m, <18
Kisonorthern 3pi
2018-oi, M.a,c, Kobayashi, N.a, Aoki,, Kawakita, H.i, Kokubo, M.a,T.a, Mori, K.a, Mori, Y.d, Morii,Okumura, S.l, Onozato, H.g,M.e, Taniguchi, Y.a, Tanikawa,S.l, Usui, F.p, Watanabe, J.e,ZTF
1.2m, <20
Palomarnorthern 3pi
2018-

de‐field Movie camera

Gozen

Kiso 105‐cm wide‐field Schmidt

20 deg2 in φ9 deg

Pan-STARRS1
84 chips of high‐sensitive CMOS sensors

84 chips of CMOS

2 fps (max)

1.8m, r<22
Jan. 2019
10Hawaii
years
northern 3pi
2010-

30 TB/night (max)

8.4m, r<26
Chilesouthern 3pi
2022-

front‐side CMOSw micro‐lenses

Large Synoptic Survey Telescope
optical/NIR for GW/Neutrino

The extreme Universe viewed in very-high-energy gamma-rays 2017, 2017/12/18-19

36

Summary
Many optical/NIR transient surveys have been done forthese 20 years.
Telescopes/Instruments w/ deep wide-field imaging
capability are available.
Small (~1m) telescopes are also powerful in terms ofwider field-of-view
flexibility (telescope time)
We are conducting follow-up observations for GW/
IceCube/MAXI sources w/ Subaru, Kanata, Kiso etc.
CTA positional accuracy is good for optical/NIR followup observations
to identify the counterpart for flaring CTA sources
all-sky surveyors available (from 1m to 8m)
Kiso/Tomo-e Gozen, ZTF, Pan-STARRS, LSST
optical/NIR for GW/Neutrino

The extreme Universe viewed in very-high-energy gamma-rays 2017, 2017/12/18-1937