1. Multi-Messenger Astronomy with Subaru II
Myungshin Im
(Seoul National University)
EAO-Subaru Science

2. GW170817: NS-NS merger Multi-Messenger Astronomy
GW event marked the start of MMA using GW and EMW signals
countries, 900+ institutions, 80 facilities ), 59 page ApJL paper

3. Facilities for EM Follow-up: 17+ telescopes
Korea:
SAO 1.0m/0.6m, SOAO 0.6m, BOAO 1.8m, DOAO 1.0m
Maidanak:
1.5m Telescope
US: LOAO 1-m
Gemini-N
UKIRT
Gemini-S
US: McDonald 2.1-m, 0.8m, 0.25m
KMTNet 1.6m
Telescopes
Australia: 0.43m LSGT
+ iTelescope.Net (SSO)

4. First Korean Observation
At , about 21 hours after the GW detection, the GW EM counterpart was detected by LSGT (0.43m telescope!)
Optical counterpart of GW170817
taken with LSGT
GW170817
NGC 4993
서울대학교 초기우주천체연구단
:08:01(UT)
서울대학교 초기우주천체연구단
Lee Sang Gak Telescope
Im et al. 2017, 2019, Abbott et al. 2017

5. KMTNet Image of GW170817 서울대학교/한국천문연구원 KMTNet-SAAO 08-18
Troja et al. 2017, Im et al. 2017, Abbott et al. 2017

6. Several key results
Binary neutron star merger  short GRB-like event? YES
EM counterpart = Kilonova? YES
- blue or red? Both
- Brightness? 17 mag in the beginning
Environment of NS merger? Massive elliptical galaxy
Gold!
(200 ME)
H0 from GW

7. Upcoming Challenges
More events at further distances: Faint counterparts
BH-BH merger: any EM counterpart
BH-NS/BNS merger: general characteristics
Credit: A. Simonnet

8. Event rate & localization area
BNS ~ 13/yr BBH ~ 100/yr NS-BH ~ 1/10 of BNS
Abbott et al. (2016)
Localization: 5 – 20 deg2

9. Light curve prediction
Tanaka et al. (2017)
EM counterpart: Faint (23 – 24 mag): neutrino source too!
How can we identify them? Wide-field, deep image
[Pan-STARRS depths: grizy = 23.3, , 22.3, 21.3]

10. Multi-Messenger Astronomy with Subaru Subaru Hemisphere Survey
Hemisphere wide-field imaging
2 * π ~ 20,000 deg2
3 min (1 min x 3)  r= 25.4 mag (5-σ)
1 night (8 hr)  216 deg2
130 nights (incl. weather loss 30%)  21,600 deg2
Subaru Hemisphere Survey (SHS)
LSST

11. Subaru Hemisphere Survey Science
Faint transient
- GW, GRB, Neutrino counterparts
- Supernovae, novae, ….
Solar system object
Galaxy evolution
Cosmology (cluster identification), etc
Long-lasting archive for the whole world

12. SHS + Transient follow-up
Combination of SHS + another transient follow-up survey (Subaru, Gemini, KMTNet, etc)  GW source EM identification
+ many other projects possible (more targets for PFS)
A great way of EAO collaboration?