重力波・ニュートリノ放射天体に対する
可視光・赤外線観測
光赤外

諸隈 智貴 / Tomoki Morokuma (tmorokuma@perc.it-chiba.ac.jp)(千葉工業大学 / Chiba Institute of Technology)
J-GEM Collaboration, IceCubeニュートリノ光赤外追観測グループ

ASJ 2023B Meeting (Z1 Session)

Nagoya University

2023/09/21

1

Contents
光赤外観測から見たMMA
光赤外観測の役割・特長
過去の成功例 + 今後の展望
重力波: GW170817
IceCube高エネルギーニュートリノ:
170922A/TXS 0506+056 (blazar), 潮汐破壊現象
まとめ

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光赤外観測から見たMMA
重力波
位置決定
精度

高エネルギーニュートリノ (track)~> 1,000 deg2 w/ 2 detectors~0.5 deg sigma (singlet) [2]
Prospects
for Observing
with sigma
aLIGO, AdV
and KAGRA[2]~< 100 deg2 w/ 3/4
detectors[1] and Localizing GW Transients~0.3 deg(multiplet)

天体種族

BNS, NS-BH, BBH
supernova

blazar, TDE, supernova, GRB(type-2 AGN, Galactic Plane)

距離~< 160-190 Mpc (LIGO) [3]O(kpc) (Galactic)z ~ 0.5-1 (singlet)z < 0.15 (multiplet) [4]

見かけの~17 mag (GW170817/AT2017gfo)@ 40 Mpc [5]~14-15 mag (IC170922A/TXS 0506+056)@ z=0.34 [6,7]明るさ

光赤外 kilonova: theoretically predicted, (partly)
性質 confirmed for GW170817/AT2017gfo

19

wide variety「パイオニア・スピリット」 [8][1] Nissanke, S., et al. 2013, ApJ, 767, 124[2] 清水さん講演 (Z103a)[3] https://observing.docs.ligo.org/plan/[4] Yoshida, S., et al. 2022, ApJ, 937, 108[5] Utsumi, Y., et al. 2017, PASJ, 69, 101[6] Morokuma, T., et al. 2021, PASJ, 73, 25[7] Paiano, S., et al. 2018, ApJL, 854, L32[8] 吉田さん講演 (Z101r)
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光赤外観測の役割・特長
Pros
多種多様な放射天体候補を観測可能 (あらゆる天体現象が可視・赤外放射を伴う)
起源天体の熱放射や噴出物の情報から爆発エネルギー・ 元素合成等の情報を抽出可能
天体までの赤方偏移 (距離) の精度良い決定が可能
母銀河も同時に観測可能
広視野・深撮像観測 (confusionなし) を同時に実現可能
大型望遠鏡を含め世界に多くの望遠鏡が存在

1,824 supernova candidates over ~7 deg2
Subaru (8.2m) + Hyper Suprime-Cam
74-4

Publications of the Astronomical Society ofCons
重力波・ニュートリノ放射天体と無関係な天体の大量混入不可避
起源天体の同定 + 他にいないことの証明
天体面密度
定常天体: O(105-6) deg-2 (Furusawa+2008)
突発天体: O(102) deg-2 (TM+2008, Yoshida+2018)==> 機械学習を利用した効率的かつ正確な天体選出手法の開発
地上からは夜間のみ(1/3日程度)観測可能==> 複数の異なる経度にまたがる望遠鏡ネットワークの構築

Yasuda+2019

Fig. 2. Pointing layout on the sky (ultra-deep: blue (solid), deep: blue (dashed), original COSMOS (Scoville et al. 2007)
overlaid on an SFD (Schlegel et al. 1998) reddening map. Positions of detected supernova (SN) candidates are indicat
were dithering around fiducial pointings, the actual coverage is wider than that indicated by the dashed blue line. So
in those area. (Color online)

ASJ 2023B Meeting (Z1 Session)table 1. Each image was taken with five-point dithering, as
described in Aihara et al. (2018a), to fill the gaps between
the HSC CCDs. There are overlaps between ultra-deep anddeep pointings, as mentioned earlier; additionally, the expo-

Nagoya University

into a predefined sky grid, which
image. Data were processed on a
For the image subtraction,
method of Alard & Lupton (Ala2023/09/21

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光赤外観測網@MMA@日本

広視野サーベイ観測

w/ 広視野望遠鏡・装置 (O(100-1) deg2 FoV)J-GEM講演: 笹田さん (Z126a)

追観測 + 近傍銀河サーベイ観測
w/ 普通視野望遠鏡・装置 (O(10-2) deg2 FoV)

突発天体(候補天体)検出
ASJ 2023B Meeting (Z1 Session)

他波長等での候補天体発見

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2023/09/21

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光赤外観測網@MMA@日本

OISTER講演: 村田さん (Z119b)

重力波: J-GEM = Japanese collaboration for Gravitational wave ElectroMagnetic
follow-up (PI: 吉田 道利さん@NAOJ; 笹田さん講演 Z126a; TM+2016; Sasada+2021)
IceCube高エネルギーニュートリノ: J-GEM/OISTER有志 + ニュートリノ/CR理論の方々

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重力波源に対する光赤外観測

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EM observations(GW170817)
EM counterpart: SSS17a/AT2017gfo
report: Coulter+2017, GCN, 21529
Discovery w/ 1m Swope@Chile
galaxy-targeted survey~11 hours after GW detection
host galaxy: NGC 4993@~40 Mpc
GW: dL=40+8-14 Mpc

1m-class

Abbott+2017
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EM observations(GW170817, J-GEM)
optical+NIR photometry (Utsumi+2017)
IRSF/SIRIUS@South Africa
Subaru/MOIRCS@Hawaii
MOA-II/MOA-cam3@New Zealand
B&C/Tripol5@New Zealand
optical wide-field “survey” (Tominaga+2018)
Subaru/HSC@Hawaii

Publications of the Astronomical Society of Japan (2017), Vol. 00, No. 0

557% (Subaru/HSC@Hawaii) Tominaga+2018
c.g. 81% (CTIO/DECam@Chile) Soares-Santos+2017

19

Type Ia SN
20 Fig. 1. PointingNS-NS(100Mpc)
map
for GW170817 overlaid on the proba
BH-NS (200Mpc)
1dayRed
in optical(Abbottetal.
2017d).
The white
contour
represents the 921

i magnitude (AB)z=0.1

red i-zofcolor
region. Circles represent the field-of-view
HSC; their colo
22
AT2017gfo was blue
with anorder
z=0.2
6days of observation. Observations have been carri
HSC 50sec
23
z=0.3
incurves
the early
phase.
limit.The
mag. dasheddarker to lighter colors.
represent
the Ga6days
24 ules. (Color11days
online)Rapid decline
1day

25

unobservablearea

2
corresponding to the 66
observed
area
is
28.9
deg
26
-1
0
1
2
3
GW170817
1). Exposures9 u
ASJ 2023B Meeting (Z1 Session) ible regioni -of
University(figure2023/09/21
z Nagoyaminor planet

Utsumi+2017

in a few days

Optical/Near-Infrared light curves of kilonovae
GW170817 (observation)

al Letters, 851:L21 (12pp), 2017 December 10

Villar et al.

Angular Dependence

Villar+2017-20

opticalAB absolute magnitude

-19

NIR

Model

10

Kawaguchi+2020

-18
-17
-16

g
z
K
°
0 ≤θ<20°35°≤θ<41°55°≤θ<59°86°≤θ<90°

-15
-14
-13
-12

UV

-11

0.5

1

2

3
t [day]

4 5

7

10

14

s from the combined data set (Table 3), along with the spherically symmetric three-component models with the highest likelihood scores.
zations of highest likelihood for each ﬁlter, while shaded regions represent the 1s uncertainty ranges. For some bands there are multiple
ences between ﬁlters. Data originally presented in Andreoni et al. (2017), Arcavi et al. (2017), Coulter et al. (2017),
et al. dependence of the gzK-band light curves forFig. Cowperthwaite
7.— Angularout et al. (2017), Evans et al. (2017), Hu et al. (2017), Kasliwal et al. (2017), Lipunov et al. (2017), Pian the
et al. (2017),
Pozanenko
etfiducial model al.(HMNS YH). The solid, dashed, densely dotted,, Smartt et al. (2017), Tanvir et al. (2017), Troja et al. (2017), Utsumi et al. (2017), and Valenti et al. (2017b).

Is GW170817/SSS17a/AT2017gfo “normal”?
viewing angle dependence?
and sparsely dotted curves denote the light curves observed fromejecta mass, electron fraction,0  ✓ < 20 , 35  ✓  41 , 55  ✓ < 59 , and 86  ✓ < 90 ,log-likelihood isrespectively.
abundance?
⎤
1 n ⎡ (Oi - Mi )2n⎛ L (t ) ⎞1 4
2
ln
ln
2
ln
$
=
ps
⎢
(
)
⎥
(2ps 2) , results indicate that the di↵erence in the
bands.
Theseå
i⎜⎜ etc. ⎟⎟ > Tc
2
2
2 i=1 ⎣ s i + s
2
⎦
2
2 2
⎝ 4ps SB vej t ⎠)⎞1 2 ⎛⎜⎜⎟
4velocity profile is reflected most significantly in the de(6 )
1
4
cline
rates
of
the
light curves particularly in the optical
L (t ) ⎞⎟10- TcASJ 2023Bwhere
si , are the ith of n(andOi, M(Z1observed
magnitudes,
perhaps,also,University
ultraviolet) bands.
We note that the
Meeting
Session)
Nagoya2023/09/21
i, and
2
2 2⎟
.

(5 )

EM counterpart for a Binary Black Hole?
Graham+2020, PRL, 124, 25, 251102
S190521g
binary black hole (BBH)
distance: 3931 +/- 953 [Mpc]
AGN@z=0.438

3FIG. 2. ZTF g-band photometry, r-band photometry, and g r color for J1249+3449 over the
beginning MJD ⇠ 58650 represents a 5 departure from the ZTF baseline for this source. The flto the model described in the text and assuming a linear model for the source continuum behav
vertical line corresponds to the S190521g trigger time.
4

FIG. 1. Left panel: A Mollweide projection of the 50% and 90% LIGO localization regions for S190521g (with 44%/5
the northern/southern hemisphere) and the location of ZTF19abanrhr (within the 78% contour). ZTF covered 48%
FIG. 1. Left panel: Aof the 50%
and 90% LIGO
localization regions
for S190521g(withcovered
44%/56% in by ZTF. Right pane
90% region and contours at declination<Mollweide
30 projection
indicatesouthernhemisphere
regionsnotthe northern/southern hemisphere) and the location of ZTF19abanrhr (within the 78% contour). ZTF covered 48% of themarginal luminosity distance90%distribution
overtheskyhemisphere(dottedblue
line)
forRight
S190521g
region and contours integrated
at declination < 30
indicatesouthern
regions
not covered
by ZTF.
panel: The as well as the cond
marginal luminosity distance distribution integrated over the sky (dotted blue line) for S190521g as well as the conditional
distance distribution (black distanceline) distribution
at the (black
position
ofposition
ZTF19abanrhr.
red lineto thecorrespondsline) at theof ZTF19abanrhr. The The
red line corresponds
luminosity distancetoof the luminosity dista
ZTF19abanrhr, assuming a Planck15 cosmology [36].
ZTF19abanrhr, assuming a Planck15 cosmology [36].
Fig. 3 shows that a decade-long baseline reveals evidence for more significant variability in J1249+3449. Note thatthese data, from the Catalina Real-time Transient Survey [CRTS; 43], are noisier than ZTF (a result of a 0.7-m survey
telescope vs. a 1.2-m survey telescope), and are binned at 15 day intervals for clarity in the plot. Using the DRW
model parameters from the CRTS data, which characterize the overall variability of the source, we simulated theobserved ZTF light curve 250,000 times and find an equivalent flare (i.e., matching the selection criteria describedabove) in four instances. The event is thus very unlikely to arise from AGN activity in this particular source (i.e.,⇠ O(0.002%). Similarly, to address the look-elsewhere e↵ect, we produced 1000 simulations of the full sample of 3255
AGN in the 90% three-dimensional localization region of S190521g using their CRTS DRW parameterizations and
ZTF time sampling. We find a comparable AGN flare in just five simulations, i.e., O(0.5%) chance of a false positive,prior to visual inspection.
Supernovae can occur in AGN [e.g., 44], although the rate is likely small (> 2 ⇥ 10 7 AGN 1 yr 1 in the WISE
sample).Meeting
Even with a O(10erg) energy output, we expect rise times of O(2050) daysand a decay time or plateau
ASJ 2023B(Z1 51Session)
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2023/09/21

Fig. 3 shows that a decade-long baseline reveals evidence for more significant variability in J1249+3449. Not
these data, from the Catalina Real-time Transient Survey [CRTS; 43], are noisier than ZTF (a result of a 0.7-m stelescope vs. a 1.2-m survey telescope), and are binned at 15 day intervals for clarity in the plot. Using themodel parameters from the CRTS data, which characterize the overall variability of the source, we simulate
observed ZTF light curve 250,000 times and find an equivalent flare (i.e., matching the selection criteria desc
11

GW+optical/IR sciences
Pin-down a counterpart
sub-arcsec angular resolution

Kilonova properties
light curve + spectroscopy“explosion” (e.g., supernovae)
ejecta mass
Figure 8. Top panels: distribution of galaxies observed in the GLADE+ K (leelectron fraction Yegalaxy luminosity weights, compared with the GW190814 redshift localizatio
m = 0.3065 (green line) and the predicted redshift distribution for a prior tha
multi-components? polarization (Covino+2017)Ωintended
as representative of the reconstructed galaxy distribution as it is calThis procedure only serves to give a rough idea where the H0 contribution is c
Environment: host galaxy (Im+2017)
without application of the luminosity weighing scheme.
morphology, stellar mass of ~1011 Msun
Domoto+2022
Figure 8. Comparison between the synthetic spectra (blue) and the observed spectra of AT2017gfo (gray, Pian et al. 2017; Smartt et al. 2017)mean stellar age of ~3 Gyrdays after the merger (dark to light colors). Spectra are vertically shifted for visualization. The gray shade shows the regions of strong atmo
similar to sGRB hosts
distance estimate of 37.7+/-8.7 [Mpc]

Hubble constantDistance and Properties of NGC 4993
luminosity distance (GW)<==> redshift (spectroscopy)

3

Figure 9. Synthetic spectra at t = 2.5 days after the merger for different mass fractions of La (left) and Ce (right). Variation of each elementwith the same color used for the spectra. Pink and orange arrows in each panel indicate the position of the notable absorption lines cause
respectively. Line segments above and below the spectra indicate spectral slopes for visualization.

panel of Figure 9, we estimate that the mass fraction ofphotosphere shifts outward compared to tha
La is higher than 1/30 times
that of the L model, i.e., Abbott+2023,
This makes the photospherictemperaturelo
12lineIm+2017
ApJ,
949,
76
Figure9.
Hubbleconstantposteriorforseveralcases.
Gray
dotted−6
ASJ 2023B Meeting (Z1 Session)
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2023/09/21
X(La) > 2 × 10 , which is required to identify the visible
Ce III lines disappear.

GW observing runs

“すばる2”

Rubin/LSST
Subaru/PFS

Subaru/HSC

now

30m-classhttps://observing.docs.ligo.org/plan/

OISTER
J-GEM~50 (100) deg2 at O4/O5 BNS ranges can be surveyed w/ Subaru/HSC (Rubin/LSST)(Tominaga+2018, Ohgami+2021, Andreoni+2022).
All the nearby gals can be observed w/ J-GEM tels. for ~<500 deg2 & <100 Mpc(Sasada+2021).
O(1) deg2 localization ==> Subaru/PFS (1.25 deg2, 2400 fibers) spectroscopy for Rubin/
LSST transients or point sources in nearby galaxies(?) @5-detector era (Nissanke+2013)
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IceCube高エネルギーニュートリノ源に対する光赤外観測

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Optical properties of possible neutrino sources
TDE, 木村さん講演 (Z102r)

©NASA

Had

blazar

GRB, 岩切さん講演ASJ(Z104a)2023B Meeting (Z1 Session)

Figure1. The schematic
picture of the interaction-powered
SN scenario.
interacting
supernova,
Murase+2014

15
NagoyaUniversity
2023/09/21
collision between
the SNejecta with a CSM
shell and found that CRciencemag.org/ on October 20, 2020∗

In the first column, S and M denote “survey” and “monitoring,” respectively.
consistent with a zenith angle 5:7þ0:50"0:30 degrees below the †horizon.

IceCube-170922A/TXS 0506+056: Fermi/LAT

When we took the Tomo-e Gozen data, the instrument was operating with a limited number of sensors (four) before the completion of the 84-sensor
in 2019.

TM+2021

BROS catalog

IceCube Collaboration+2018

TM+2021

Fig. 1. Coadded r-band image of the field taken with KWFC. North is up and east is left. The IceCube 90% containment region (IceCube Co

Blazar Radio and Optical Survey (BROS)
flat-spectrum@radio: NVSS (1.4 GHz) + TGSS
(151 MHz)88,211 sources at Dec.>-40 deg (largest blazar
candidate catalog)
a new faint blazar population in early-typegalaxies?

optical brightness (g)pixel,
using anddetected
with
ofThe
1 to
300flat-spectrum
GeV in a radio
2° bysources
2° in the prelimi
Fig. 2. Fermi-LAT and MAGIC observations of IceCube-170922A’s
2018) is shown by the thickblue ellipse,
its centerphotons
is indicatedas a energy
blue cross.
sevencatalogwhich we observed
first areindicatedby small blue circles,
the TXS
regionofis 0.02°
markedand
as a redregionaroundTXS0506+056.
Theandmap
has0506+056
a pixel size
wasrectangle, close
location. Sky position of IceCube-170922A in J2000 equatorial
coordinates" × 1" view around TXS 0506+056 is also shown in the top right inset. The fields of view of the optical and NIR instrum
cross.
A
zoomed-in
1smoothed with a 0.02°-wide Gaussian kernel. MAGIC data are shown as
overlaying the g-ray counts from Fermi-LAT above 1 GeV (A) and the signal
in this paper are shown in brown. For Tomo-e Gozen, the field of view of one sensor is shown. (Color online)
signal significance for g-rays above 90 GeV. Also shown are the locations ofsignificance as observed by MAGIC (B) in this region. The tan squareby Fermi-LAT
asgiven ininthe
Fermi-LAT Third
indicates the position reported in the initial alert, and the green
squarein figure1 and listedaing-ray
tablesource
2. Fiveobservedof the sevensources
described
sub-subsection
2.2.1. In addition, w
Source Catalog (3FGL) (23) and the Third Catalog of Hard Fermi-LAT
indicates the final best-fitting position from follow-up reconstructions (18).
were detected in the optical archival PS1 DR1 data. Eachout J-, H-, and Ks -band simultaneous imaging wit
Sources (3FHL) (24) source catalogs, including the identified positionally
Gray and red curves show the 50% and 90% neutrino containment regions,(Nagayama et al. 2003; Nagayama 2012) on tof the seven BROS sources was observed basically one bycoincident 3FGL object TXS 0506+056. For Fermi-LAT catalog objects,
respectively, including statistical and systematic errors. Fermi-LAT data are
Infrared Survey Facility (IRSF) and V-band imag
one with Kanata/HONIR and MITSuME, while all sevenmarker sizes indicate the 95% CL positional uncertainty of the source.
shown as a photon counts map in 9.5 years of data in units of counts per
the 0.4 m Kyoto telescope. The exposure times of t
were also covered by two KWFC pointings and two HSC
images were 10 s and 60 s. We also took non-filte
pointings. As described in subsection 3.1, we performed a
The IceCube Collaboration et al., Science 361, eaat1378 (2018)
13 Julydata
2018reduction for the data, and a Kanata/HONIR
2 of(Sako
8 et al. 201
imaging data with Tomo-e Gozen
quick
on the Kiso Schmidt telescope with the 2 fps reado
difference image for TXS 0506+056 revealed that it was
No filters were used; the sensors of Tomo-e Gozen
fading on a time scale of a day.
sitive in ∼350–900 nm (Kojima et al. 2018).

2.2.2 (TM+2021)
Monitoring for TXS 0506+056
7 BROS sources in 170922A region

2.2.3 Data reduction of imaging data
After detecting rapid NIR variability of TXS 0506+056
All the data were reduced in a standard manner, iwith Kanata/HONIR (described in subsection 3.1), we
16 if nbias, overscan,and dark current subtractions
continued monitoring TXS 0506+056Nagoya
with the telescopes
ASJ 2023B Meeting (Z1 Session)
University
2023/09/21

optical color (g-r)

Itoh+2020

g-rays, x-rays, optical, radio, and gravitational
waves, allowing for the potential identificationof even rapidly fading sources.

IceCube-170922A : EM Counterpart Identification
Multimessenger observations of aflaring blazar coincident withnear-infrared variability detected
high-energy neutrino IceCube-170922A
Publications of the Astronomical Society of Japan (2021), Vol. 73, No. 1

NEUTRINO ASTROPHYSICSRESULTS: A high-energy neutrino-induced

muon track was detected on 22 September 2017,
automatically generating an alert that was
distributed worldwide
ON OUR WEBSITE
within 1 min of detection
and prompted follow-up
Read the full article
searches by telescopes overat http://dx.doi.
org/10.1126/
a broad range of waveThe IceCube Collaboration, Fermi-LAT, MAGIC, AGILE, ASAS-SN, HAWC, H.E.S.S.,
science.aat1378
lengths. On 28 September
INTEGRAL, Kanata, Kiso, Kapteyn, Liverpool Telescope, Subaru, Swift/NuSTAR,..................................................
2017, the Fermi Large Area
VERITAS, and VLA/17B-403 teams*†
Telescope Collaboration reported that the direction of the neutrino was coincident with a
INTRODUCTION: Neutrinos are tracers of
mic rays. The discovery of an extraterrestrial
cataloged g-ray source, 0.1° from the neutrino
cosmic-ray acceleration: electrically neutral
diffuse flux of high-energy neutrinos, announced
direction. The source, a blazar known as TXS
and traveling at nearly the speed of light, they
by IceCube in 2013, has characteristic prop0506+056 at a measured redshift of 0.34, wascan escape the densest environments and may
erties that hint at contributions from extrain a flaring state at the time with enhanced
be traced back to their source of origin. Highgalactic sources, although the individual sources
g-ray activity in the GeV range. Follow-up obenergy neutrinos are expected to be produced
remain as yet unidentified. Continuously monservations by imaging atmospheric Cherenkov
in blazars: intense extragalactic radio, optical,
itoring the entire sky for astrophysical neutelescopes, notably the Major Atmospheric
x-ray, and, in some cases, g-ray sources
Gamma Imaging Cherenkov (MAGIC)
characterized by relativistic jets oftelescopes, revealed periods whereplasma pointing close to our line ofthe detected g-ray flux from the blazarsight. Blazars are among the mostreached energies up to 400 GeV. Meapowerful objects in the Universe andsurements of the source have also
are widely speculated to be sources
been completed at x-ray, optical, andof high-energy cosmic rays. These cosradio wavelengths. We have invesmic rays generate high-energy neutritigated models associating neutrino
nos and g-rays, which are produced
and g-ray production and find thatwhen the cosmic rays accelerated incorrelation of the neutrino with thethe jet interact with nearby gas orflare of TXS 0506+056 is statisticallyphotons. On 22 September 2017, thesignificant at the level of 3 standard
cubic-kilometer IceCube Neutrino
deviations (sigma). On the basis of the
Observatory detected a ~290-TeV
redshift of TXS 0506+056, we derive
“The
FAVA
light
curve
at
energies
above
800
MeV
shows
a
neutrino from a direction consistentconstraints for the muon-neutrino
flaringstateg-ray
recently.”
with the flaring
blazar TXS(Y. Tanaka+2017, ATel, #10791, Posted
luminosity for this source and find0506+056.
detailsofthem to be similar2023/09/21
to the luminosity
at10:10 We
onreport
28 theSep.
2017
in UT)ASJ
2023B
Meeting (Z1 Session)
Nagoya University◥

Fermi/LAT

Downloaded from http://science.sciencemag.org/ on October 20, 202

IceCube17
Kanata (1.5m) / HONIR (TM+2021)

IceCube-170922A : redshift determination (spectroscopy)
0.1-0.3 hours
integration
Subaru(8.2m)/FOCAS
S/N~100
1% (S/N=100)

TM+2017, ATel, #10890

10-hour integration
GTC(10m)/OSIRIS
S/N~500
1% (S/N=100)

Paiano+2018
ASJ 2023B Meeting (Z1 Session)

IceCube Collaboration+2018

Nagoya University

2023/09/21

18

Improvements on Follow-Ups for Identification?
IceCube-170922A
TXS 0506+056@z=0.336(TM+2021, blazar)
variability detected
w/ Kanata (1.5m)

200 days

200 days
IceCube-191001A: AT2019dsg@z=0.051 (TDE)
discovered w/ ZTF (1.2m) (Stein+2021)

Previous identifications
lower-z than expectation (<z>~0.5-1)
other origin?: supernovae
suffering from many contaminations“How can we overcome the difficultyin identifying the counterparts?”
better telescopes/instruments
better neutrinos
ASJ 2023B Meeting (Z1 Session)

200 days
IceCube-200530A: AT2019fdr@z=0.267 (TDE)
discovered w/ ZTF (1.2m) (Reusch+2022)

FIG. 1. The bottom plot shows the lightcurve in the optical ZTF g-band, the infrared P200 Ks- and WISE W1-band asas the modeled dust echo (black line, dashdot), with the neutrino arrival time marked with a red dotted vertical line.
SRG/eROSITA X-ray measurements are also included. The shaded gray areas are averaged and their respective SEDs
shown in the top panels, including a fitted blue and a red blackbody (blue dashed and red dotted curve; lab frame), as wethe combined spectrum (black solid curve). The left axes all show ⌫F⌫ , where F⌫ is the spectral flux density at frequenc
while the right axes show ⌫L⌫ , where L⌫ is the luminosity at frequency ⌫. The second epoch (middle plot on top) encompaseveral months to include both WISE and P200 infrared data points. The global values for line-of-sight dust extinction
AV = 0.45+0.14
0.14 mag, assuming RV = 3.1 and the Calzetti attenuation law-2[54]. Note that the X-ray measurements were
included in the blackbody fits. The luminosities are given in the source rest frame.

sourceSNe# [deg ] (z<1)~10trino arrival (corrected for absorption).
~10 if classified“interacting”)
The position of AT2019fdr was also visited bytions for SLSNe. Frederick et al. [45] 2-3
already( disfavored1
the SLSN hypothesis based on the long-lived U-band andthe UV emission, the flare’s longevity, emission at theblue end of the Balmer line profiles as well as its proximity to the nucleus of the galaxy. Here we add a late-time
X-ray detection and the detection of a strong infraredecho, rendering a SLSN interpretation less likely (see below).
After discovery, AT2019fdr was also observed by the
Ultraviolet and Optical Telescope (UVOT) [60] aboard
the Neil Gehrels Swift Observatory (Swift) [45, 61]. Additional observations continued up to 2020, June 7, including one epoch shortly after the neutrino detection.
By that point, the transient had faded by 84% in the
UVW1-band from its peak luminosity of 2.1 ⇥ 1044 erg
s 1 . AT2019fdr was not detected in any of the simultaneous X-ray observations by the Swift X-ray Telescope(XRT) [62], yielding a combined 3 flux upper limit ofBlazars
TDEs

AGNs

Nagoya University

eROSITA telescope [63] aboard the Spectrum-Roentg
Gamma (SRG) mission [64] four times. The first
0-1
visits did not detect an excess, with a mean flux up
limit of 2.7 ⇥ 10 14 erg s 1 cm 2 at the 95% confide
level. However, at the third visit on 2021, March 10–
it detected late time X-ray emission from the trans14with an energy flux of 6.2+2.7
erg s 1 cm
2.1 ⇥ 10
the 0.3–2.0 keV band, thus showing temporal evolu
in the X-ray flux (see Fig. 1). The detection displa
3
a very soft thermal spectrum with a best fit blackb
temperature of 56+32
26 eV.
The softness of the spectrum provides further evide
for AT2019fdr being a TDE rather than regular A
variability, where soft spectra are rare [65]. Tho
NLSy1 galaxies generally exhibit softer X-ray spec
the temperature of AT2019fdr is atypically low even

~10

<1

~10

contamination rate
2023/09/21

19

Telescopes/Instruments: Wide-Field Deep Imaging
How Wide?
“a few deg2” is wide enough. (Subaru/HSC, Rubin/LSST, other smaller tels)
unpredictable location ==> wide-field/all-sky monitoring is favorable.
How Deep?
~25 mag for z~1 sources ==> 8m-class telescopes are necessary.
Subaru/HSC (8.2m, 1.8 deg2 FoV), Rubin/LSST (6.5m, 9.6 deg2 FoV)How to “identify”?
Most of the targets at z~1 are too faint even for 8m-class telescopes.
30m-class telescopes are wanted.
SN Ia@z~1
Subaru/FOCAS, 6.3 hours

Subaruhttp://subarutelescope.org

Rubin/LSST
https://www.lsst.org

ASJ 2023B Meeting (Z1 Session)

NagoyaUniversity
TM+20102023/09/21

20

Subaru/HSC Follow-Up for IceCube neutrino GOLD events = TDE search
Led by S. S. Kimura
How Wide?
“a few deg2” is wide enough. (Subaru/HSC, Rubin/LSST, other smaller tels)
unpredictable location ==> wide-field/all-sky monitoring is favorable.
How Deep?
IC230724A (~0.5 deg radius localization) is inside HSC-SSP field.
~25 mag for z~1 sources ==> 8m-class telescopes are necessary.
Subaru/HSC (8.2m, 1.8 deg2 FoV), Rubin/LSST (6.5m, 9.6 deg2 FoV)
http://subarutelescope.org

Target: tidal disruption events (TDEs)
2 previous successes (discoveries by ZTF)
low contamination rate of unrelated TDEs
We can claim the coincidence of theneutrino event once a TDE is identified.
ASJ 2023B Meeting (Z1 Session)

Nagoya University

2023/09/21

21

larger spheres corresponding
to larger signals.Deep
The total
Telescopes/Instruments: Wide-Field
Spectroscopy
charge recorded is ~5800 photoelectrons. Inset is an overhead

þ0:50
Prime Focus Spectrographonangle8.2m
Telescopeconsistent with (PFS)a zenith
5:7Subaru
degrees
below the horizo"0:30~2,400 science fibers over 1.25 deg2 FoVMost of possible origins can be spectroscopically observed.
Spectroscopy for “transients”(TDEs, interacting SNe etc.)from Rubin/LSST
Operation starts from 2024.

Dec
source# [deg-2] (z<1)

SNe~102-3 (~101 if classified “interacting”)

Blazars~100-1

TDEs

<1

AGNs

~103

contamination rate
ASJ 2023B Meeting (Z1 Session)

Subaru/PFS
IceCube Collaboration 2017

RA

Nagoya University

2023/09/21

22

where no galaxy is registered within 100 Mpc is set to
07 Le Mpc−3 for the conservative estimate determined by the catalog
eness.

candidate following a neutrino multiplet detection.

清水さん講演 (Z103a)

Neutrinos: “Multiplet”

IceCube Collaboration
2017
dentiﬁcationof a Transient
Associatedwith a Neutrino
z=0.1
z=1
Multiplet

described in Section 3.1, the multiplet source is most
located at a relatively small redshift (z < 0.15, with anprobability). Given that most astrophysical neutrino
lets will therefore originate from objects with small
ts, we can construct a follow-up search strategy for
z=0.023
ying the optical counterpart.
Figure 7 shows a ﬂow chart
trate our proposed procedure to ﬁnd a source candidate.
z=0.06st step in this procedure for the follow-up
observations is
if the optical transient counterparts are close enough. We
e z = 0.15 as the threshold for the ﬁrst level selection.
detect emission from transients at z  0.15, the required
vity for optical follow-up observations is about 23 mag.
8 shows the
typicalpeak
opticalmagnitudeof different(strongly
dependingon neutrino
spectralshape)
nts as a function of redshift. The sensitivity of 23 mag is
ent to detect hypernovae and broad-lined, energeticc SNe at z = 0.15. To perform such an optical survey for
wide-ﬁeld
opticalwith a diameter of
g2 area,Muchbetterthantelescopes“singlet”
such as DECam on the 4 m Blonco telescope (Flaugher
closerorigin,localization
2015), HSC
on the8.2 m better
Subaru telescope(Miyazaki018), and==>the much
8.4 m Rubin
observatory
telescope (Ivezić
lowercontamination2019), are required.
==> TDEs, interacting SNe can be
h a deep survey can identify not only the true multiplet
as a neutrino
sourcebut also claimed
unrelated transient
objects (i.e.,
contaminants).
following
we ﬁrst estimate the number of
w/sections,high confidence.
mination sources that may be found with such a survey,
Identified
w/ smaller
telescopes
en discuss
the strategy
to identify(~4m)
the neutrino
multiplet.
ASJ 2023B Meeting (Z1 Session)

Yoshida+2022

Figure 8. Observed magnitude as a function of redshift for target objects after
expected time delays (green: hypernovae
at peak; red: TDEs at 100 days after-2] (z<1)source#[deg
multipletthe event; blue: SNe Ibc at peak).

SNe~102-3 (~101 if classified “interacting”) ~101 (<1)
The light curves of normal SNe are generated with theBlazars
sncosmo package (Barbary
et al. 2016) by using templates~100-1~<1 ofthe available spectral energy distributions and their time
TDEs
<1 the SALT2 model (Guy
<1 et al.
evolutions. For Type Ia SNe,2007) is used as a template. The parameters of the SALT2
3 color parameters, are ~10
1AGNs
model, such as the stretch~10
andrandomly
selected according to the measured distribution (Scolnic &Kessler 2016). The peak luminosity of Type Ia SNe is assigned
23
Nagoya University

2023/09/21

まとめ
光赤外観測の特長
多種多様な放射天体、物理量の推定、赤方偏移決定、広視野深撮像、多数の望遠鏡群
無関係天体の混入不可避 <==> 起源天体は1つ
重力波<50 (100) deg2, <200-300 Mpc: Subaru/HSC (Rubin/LSST)<500 deg2, <100 Mpc: J-GEM望遠鏡群
高エネルギーニュートリノ
IC170922A/TXS 0506+056: 日本貢献大 (IC Collab.+2018, TM+2021)
ニュートリノ放射と無関係な天体の排除がキー
潮汐破壊現象に注目 (Subaru/HSC)、multiplet事象に期待
いずれも「Subaru/HSC撮像」、「Rubin/LSST transientsのSubaru/PFS
分光」が強力 (“すばる2”)
ASJ 2023B Meeting (Z1 Session)

Nagoya University

2023/09/21

24