Multimessenger Transient Observations
with MAGIC and Prospects for CTA

SusumuInoue(RIKEN)

CTA
Tra
Coo

MA
Tra
Con

Gamma Ray Bursts VHE Neutrinos

Gravitational Waves?
Fast Radio Bursts

AGN Flares

The Unknown

outline
1. introduction
2. gamma-ray burst follow-up- prospects for short GRBs
- short GRB 160821B and implications
3. gravitational wave follow-up
4. neutrino follow-up
5. fast radio bursts
NB: various plots already shown at previous meetings
but still in preparation for publication

Transients with MAGIC, CTA
MAGIC: GRB Physics WG -> Transients PWG
convenors: Susumu Inoue, Francesco Longo, Konstancja Satalecka

Motto: “Expect the unexpected.”
CTA: Transients Science WG

coordinator: Susumu Inoue; deputy: Catherine Boisson-> coordinator: Catherine Boisson; deputy: Daniela Hadasch

References on CTA science prospects:
GRBs: SI+ for CTA 2013, Astropart. Phys. 43, 252
Transients: SI+ Chap. 9, “Science for CTA”,
World Scientific, in press (arXiv:1709.07997)

MAGIC telescopes

Table A.8
Differential sensitivity of the MAGIC telescopes obtained with the medium zenith angle (30°–45

Roque de los Muchachos Observatory
Emin

Emax

γ -rate−1

bkg-rate

[GeV]

[GeV]

[min

]

63
100
158
251
398
631
1000
1585
2512
3981
6310

100
158
251
398
631
1000
1585
2512
3981
6310
10000

0.40 ± 0.12
3.18 ± 0.16
2.67 ± 0.19
2.86 ± 0.13
1.76 ± 0.12
1.44 ± 0.09
0.94 ± 0.08
0.67 ± 0.06
0.32 ± 0.05
0.20 ± 0.04
0.10 ± 0.03

[min

−1

]

SNex/√Nbkg

SLi&[%C.U.][%C

39 ± 164.9 ± 0.4
2.52 ± 0.19
1.76 ± 0.14
1.5 ± 0.2
1.23 ± 0.13
1.36 ± 0.12
1.43 ± 0.16
2.8 ± 0.4
2.9 ± 0.6
6.7 ± 1.9

7
3
2.6
2.4
2.04
2.3
2
5
6

- 2 × 17m IACTs
La Palma, Canary Is.
altitude 2200m- Field of view: ~3.5°- Angular resolution: ~0.1°
Integral sensitivity [% Crab units]- Sensitivity:~ 10% Crab in 1 h >100 GeV vs Observation time [h]- Threshold energy:~50 GeV at zenith angle <20°
- Repointing speed:~30 s for 180°
- Key observing program
Aleksic+ 16
dedicated to GRB follow-up
mono from Apr. 2005
stereo from July 20092.92 ± 0.11
2.89 ± 0.05
0.54 ± 0.04
0.305 ± 0.019
0.088 ± 0.006
0.038 ± 0.002
0.0197 ± 0.0016
0.0111 ± 0.0015
0.0093 ± 0.0012
0.0042 ± 0.0017
0.0052 ± 0.0002

Fig. 19. Dependence of the integral sensitivity of the MAGIC telescopes (computed according to SLi&Ma,3Off prescription, see text for details) on the observation time, obtained

for
fac

sou
era
ser
larg
in t
the
age
ple
it t
≈2
0.4
eve
∼1

view

Gamma-Ray Bursts

Most luminous explosions hig
in the Universe,>telargely unexplored at VHE

via VHE observations:
Clarify physics of GRBs
- prompt: mechanism, jet properties (central engine: NS/BH?)- early afterglow: mechanism (plateau phase),
particle acceleration, B field generation
Probe the Universe- extragalactic background light (deeper than AGN)
- intergalactic magnetic fields
Test UHECR origin,fundamental physics
search forsignatures of:- accelerated hadrons- Lorentz invarianceviolation

Piran 03

GRBs: short vs long

BATSE
4B catalog

Many systematic differences:
MeV spectra, z distribution,
host galaxy type, environment-> likely distinct progenitors-> high-energy properties
may well be different
GW?

~70-80%~20-30%kilonova?

?

TeV?
GeV

GRB

photosphere?

?

supernova Ibc

adapted from
Gomboc 12

UHECR?
UHE ν?

short GRBs: GeV

LAT detections, as of July 2017~120 long GRBs vs.
~11 short GRBs,
only 1 with z

081
090
130
140
(17

Fermi-LAT+ 17

GRB 090510
z=0.903 (DL~6 Gpc)
detected by LAT up toEγ~31 GeV, t~178 s

Human knowledge on high-energy propertiesof short GRBs is sorely lacking

DLshort GRBs: z distribution

nea
GR
061
080
150
160
050
2nd
160f
so
050

short <z>~0.5
long <z>~2.0
Berger 14 ARAA

gamma-ray horizon E(τγγ=1) vs z due to EBL

SGRB
mean
Y. Inoue, SI+ 13�

LGRB
mean

MAGIC GRB observations: time delay, zenith angle

GRB 160821B
As of July 2017:
96 GRBs observed without hardware issues
43 mono, 53 stereoMAGIC GRB observations: redshift distribution

As of July 2017:
39 (of 96) GRBs with z; 19 mono, 20 stereoMAGIC GRB observations: redshift distribution
z<2

GRB 160821B
As of July 2017:
39 (of 96) GRBs with z; 19 mono, 20 stereo(18 with z<2; 8 mono, 10 stereo)

short GRB 160821B

z=0.16 one of nearest ever

GBM: T90~1s, Ep~84 keV, S~1.7×10-6 erg cm-2 -> Eiso~1.2×1050 erg
c.f. 090510: Eiso~1053 erg , 130427A (long): >1054 erg
XRT: “extended emission”+ steep decay t~<500s, “plateau” t~<30ks
Lü+ 17
optical, IR: afterglow, constraints on kilonova
Kasliwal+ 17, Tanvir+ in prep

energyBAT
15-150 keV

XRT
0.3-10 keV

MAGIC:
automatic follow-up
t~24 s - 1.5 hZd~34-40°
poor weather
NSB ~3-5 ×dark
t~1.5 - 4 h
Zd~40-55°
good weather
NSB ~5-9 ×dark(higher Moon)

DL~short GRB 160821B

z=0.16 one of nearest ever

GBM: T90~1s, Ep~84 keV, S~1.7×10-6 erg cm-2 -> Eiso~1.2×1050 erg
c.f. 090510: Eiso~1053 erg , 130427A (long): >1054 erg
XRT: “extended emission”+ steep decay t~<500s, “plateau” t~<30ks
Lü+ 17
LAT:
nodetection
reported,butlikelynotstronglimit
optical, IR: afterglow, constraints on kilonova(outside FoV at t<5 ks, around edge of FoVKasliwal+
at t~5-9 ks)
17, Tanvir+ in prep

energyBAT
15-150 keV

XRT
0.3-10 keV

MAGIC:
automatic follow-up
t~24 s - 1.5 hZd~34-40°
poor weather
NSB ~3-5 ×dark
t~1.5 - 4 h
Zd~40-55°
good weather
NSB ~5-9 ×dark(higher Moon)DL~MAGIC observations of low-z short GRB 160821B

one of nearest
z=0.16 (DL~800 Mpc)
ever SGRBsse
M- Followed up from t~24 s to t~4 h. Fastest ever, nearest everfor MAGIC, but under non-ideal weather, high Moon.
- Dedicated analysis yields >4 sigma (pre-trial), ~3.1 sigma(post-trial) at >600-800 GeV at GRB position.
Possible evidence of gamma-ray signal, but not firm detection.

MAGIC observations of low-z short GRB 160821B

Sta
tal
by
Jul
(th

IF signal is real:- energy flux >500 GeV ~ 2 × energy flux in X-rays at t~104 s- First SGRB seen >500 GeV
First SGRB seen >GeV to t~104s
Only second SGRB with known z seen >GeV-> Advances our knowledge of HE properties of sGRBs

10-6

short GRB 160821B
interpretation
simple impulsive blastwave
uniform ISM
Ekin=1051 erg, n=0.1 cm-3
εe=0.1, εB=0.01, p=2.1, θjet=0.1
EBL Dominguez+ 11

ger
GRB

energy flux (erg cm-2 s-1)

10-7

VHE spectrum
SSC

-12

MAGIC (1.5-4 hr)

-13

10

Preliminary

10-11
-12

10

impulsive

100

Preliminary
101

102

103

104

105

3

4 5 6 7102

2

VHE light curve
SSC

10-9
10-10

MAGIC (>500 GeV)

10-11
10-12
10-13

impulsive

Preliminary

-14

10

10-1

-14
2

photon flux (cm-2 s-1)

E2df/dE (TeV cm-2 s-1)

10-10

10-8

10

101

XRT (0.3-10 keV)time since BAT trigger

10

10

10-9

10-14
10-1

-10

10-11

-8

10

10-13

interesting implications
for GW follow-up

X-ray light curvesync.

BAT (5-150 keV)3

4 5 6 7E (GeV)103

2

3

4 5 6 7

104

100

101

102

103

time since BAT trigger

104

105

factors should be taken into account in such a
comparison. First, detectors in different energy bands
have different relative thresholds. These should becalibrated using the current GRB and afterglow

glows are significantly different (see Fig. 3). How-

current
X-ray Piran:observations
are before
the jetof
break,
when
The
physics
gamma-ray
bursts
2 The
2 Tsvionly on-axis afterglows can be seen.
(−∂t + ∇ )hµν = 0
1

short GRB off-axis afterglow

(11)

1191

!Rossi et al., 2004". Within the structured jet model thepolarization arises due to the gradient in the emissivity.
This gradient has a clear orientation. The emissivity is
maximal at the centeranddecreases monoµνof the jetµν
4tonically outwards. The polarization will be maximal
when the variation in the emissivity within the emitting
beam is maximal. This happens around the jet breakwhen !obs # "−1 and the observed beam just reaches the23
center. The
polarization
expected
in
this
case
is
aroundµνµ νµν
20% !Rossi et al., 2004" and it is slightly larger than the
maximal polarization from a uniform jet. As the direction of the gradient is always the same !relative to agiven observer" there should be no jumps in the direcµνtion of polarization.
µν and PiAccording to the GW
patchy shell model
5 !Kumarran, 2002a" the jet can include variable emitting hot
spots. This could lead to a fluctuation in the light curve
Fig. 2. Off axis orphan afterglow is seen by observers that are not within the initial relativistic jet. This emission is seen onlyFIG.
after the 31.
jet!Color in online edition" Schematic afterglow light
hot expansion
spotsofenter
theobserved
andalso tocorbreak and !asthe sideways
the relativistic
material.
The schematicbeam"
figure depicts
three observers.
Observer
A detects both the GRB
curve.
−3/8
and the afterglow. Observer B does not detect the GRB but detects afterglow that1/8
is similar to the one observed by A. Observer
C detectsWhile the bursts differ before the jet break !due to difresponding fluctuations in the polarization!Granot,
off-axis orphan afterglow that rises and fall and differs from the afterglow detected by observers A and B.
51There is a cleardprediction ferent opening angles, the light curves coincide after the break
2003; Nakar and Oren, 2003".
when the energy per unit solid angle is a constant.
!Nakar and Oren, 2003; Nakar, Piran, and Granot, 2003"
that if the fluctuations are angular and have a typicalThe search for orphan afterglows is an observational
angular scale !f then the first bump in the light curve
challenge. One has to search for a 10−12 ergs/ sec/ cm2
should appear when "−1 # !f !the whole hot spot will besignal in the x-ray region of the spectrum, a 23rd orwithin the observed beam". The later bumps in the lightv in the optical, or a mJy signal in
curve should decrease in amplitude !due to statistical L higher magnitude signal
the radio !at GHz" transients. Unlike afterglow searches
fluctuations". Nakar -13
and Oren !2004"2 show analyticallyνthat are triggered by a well-located GRB, there is noand numerically that the jumps in the polarization direcinformation on where to search for an orphan afterglow
tion should be random, sharp, and accompanied byand confusion with other transients is rather easy. So far
jumps in the amount of polarization.
there have been no detections of any orphan afterglows

! r"
t−
c

2G
h =
Ï
c r
%
# $
1
I (x) = ρ x x − δ r d x
3

G ... ...
L =⟨I I ⟩
Nakar & Piran 03 5c

16

/yr
day

Γ(t) ≃ 4.4(E /n)(t /(1 + z))

(12)
(13)

Piran 04

(14)
(15)

assume top-hat jet structure
acknowledge
valuable discussions
withMpc,
Changhyun
GRB 160821B-likeevent at D ~40
θ ~30 deg
Takahiro
Kudoh,
YutakaYamazaki,-> νf ~10
erg/cm/s at Ohira,t~25 day:Ryopossibly
detectable by CTA
hiro Nagashima,

Newest window onto the Universe,
connection with GRBs, etc- powerful probe of relativistic dynamical phenomena,
especially compact binary mergers- NS-NS/BH
mergers
potential sources of short GRBs;Metzger & Berger
cal Journal,
746:48 (15pp), 2012 February
10
fast ejecta
rich counterpartsin r-process nuclei
tellarpopulations).
Because mergerce
Jet ISM Shock (Afterglow)
to be faint,->
obtainingaspectroscopic
redshiftcoincident
EM-GW
detection(cf.
Rowlinsonetal.
2010),
in
which
case
+ 14
of the host galaxy
is the most promisingmeans
providesnew dimension
Ejecta ISM Shocke event redshift.
ror
ant to distinguish two general strategies for con-Gravitational Waves

nd GW events. One approach is to search for allowing an EM trigger, either in real time or at+ing
13stage (e.g., Finn et al. 1999; Mohanty et al.
particularly promising for counterparts predicted
mporal coincidence with the GW chirp, such as
gamma-ray bursts (SGRBs). Unfortunately, mostng counterparts (none of which have yet been
identified) occur hours to months after coalesthe predicted arrival time of the GW signal willain, in which case the additional sensitivity gained
rmation is significantly reduced. For instance, if
erger is known only to within an uncertainty ofs), as we will show is the case for optical (radio)
hen the number of trial GW templates that mustlarger by a factor ∼104 –106 than if the merger

Optical (hours days)
Radio (weeks years)

Radio (years)

GRB

VHE γ follow-up- test short GRB physics via:
on-beam afterglow
ent off-beam orphan afterglow?
- probe merger physics via
emission due to ejecta +onambient medium interaction

obs(t ~ 0.1 1 s)

Kilonova

Optical (t ~ 1 day)j

Merger Ejecta
Tidal Tail & Disk Windv ~ 0.1 0.3 c

BH

Metzger & Berger 11

Figure 1. Summary of potential electromagnetic counterparts of NS–NS/

local gamma absorption mean free path
τγγ<1 at~<10 TeV~<200 Mpc
Gilmore+ 09
Kneiske+ 08
Stecker+ 06

Venters+ 10�

The MAGIC follow up of GW Status after O1
MAGIC gravitational wave follow-up
 MAGIC signed in 2014 an MoU- GW151226: BH-BH
with Status
LVC to after
join O1
the follow-up
programof
GW
event
upper limits for small part of error region
 MAGIC signed in 2014 an MoU
candidates
with LVC to join the follow-up- GW1708__: potential binary with NS
programof
GW
On thesupernovae)
Dec 28th 2015,
MAGICevent
upper limits for optical transients (likely
candidates
followed up the second GW
discovery(GW28th
151226)
 Oneventthe Dec
2015, MAGIC

c.f. GW170817: NS-NS
GCN #18776
followed up the second GW

Four
2.5
x 2.5
deg region
unobservable due to high ZA(~88 deg) discovery
event (GW 151226)
GCN #18776

GW151226

pointed. No excesses found Four 2.5 x 2.5 deg region
pointed. No excesses found

MAGIC
Pointings
MAGIC
Pointings

A. Carosi – MAGIC Multi Messenger Transient Program – La Thuile, 2017 March 18-25

GW170817 late-time X-ray, radio� rising up to ~100 days

radio
Mooley+ 1711.11573

X-raysRuan+ 1712.02809

simple off-axis (uniform jet) disfavored-> off-axis structured jet or cocoon / merger ejecta(quasi-spherical, mildly relativistic outflow w. energy injection)

Figure 4. Radio light curves arising from quasi-spherical ejecta with a velocity gradientcompared with the 3 GHz light curve (ref. 12 and Extended Data Table 1). Two light curves(red solid and blue dashed) show single power law models with a maximum Lorentz factor
ɣ=3.5, and with a maximum velocity β=v/c=0.8. The former and latter approximately

Hotokezaka
cocoon/merger ejecta: Y , the observed~3-6,
Ee,max~1-100 TeV priv. com.
data is consistent with a profile of E(> βɣ) ∝ ( βɣ) . For n~0.03 cmComp
radio
correspond to the cocoon and dynamical ejecta, respectively. The shallow rise of the radio-5-3

associated HE/VHE emission?

flux at 93 days is produced by an ejecta component with a velocity of ~0.6c and kinetic
49

-4

-3

rch

New window onto the Universe(UHECRs), turned new mystery?
- clear indicators of VHE/UHE cosmic ray production- being detected by IceCube, but no correlation withpromising sources (bright GRBs, bright blazars) until recently
VHE γ follow-up
identify via co-produced γ rays:- neutrino sources (if γ-rays escape + propagate)- VHE/UHECR sources (if γ-rays + CRs escape+propagate)

VHE Neutrinos

s results

MAGIC high-energy neutrino follow-up- IC-160427A HESE
EHE-160731A, FR cuts
HESE-160427A, LE cuts,
- IC-160731A HESE/EHE
0 nA),d MC - IC-170321A EHE- IC-170922A EHE -> TXS 0506+054 / 3FGL J0509.4+0541
with- IC-171106A EHE (PeV)
deg

ved
rt

AliciaAliciaEHE -170321A

to tooCH

00 GeV

Konst.

MicheleKS for Nu Team | NToO summary | 15/06/2017 | Page 15

blazar TXS 0506+054: MAGIC observations
BL Lac (intermediate or low-frequency peaked)
unknown z (upper limit z<1.6)
clearly detected above 100 GeV
interpretation in terms of lepto-hadronic models in progress

TXS 0506+054
archival data from ASDC

- GHz band, ms duration, Jy flux,~6000/sky/day- likely extragalactic (z~<0.2-2.5),
1 confirmed- extreme Tb-> coherent- multiple subclasses?
FRB 110220
1 repeating, rest non-repeat. (so far)Thornton+ 13- repeating FRB 121102:
z=0.19, dwarf host, persistent radio counterpart- origin mysterious!
no. of models >> no. known FRB sources- some predictions for VHE
correlated with FRBs
in pulsar/magnetar models
repeatingsearch for multi-wavelength/FRB 121102
messenger counterparts! Spitler+ 16

Figure 1 | Disof FRB 12110
pointing, the cshown schema(see Extended
indicate the ∼at 1.4 GHz. Da
with multiple
position. The
survey observ
overlap). Beam
detected are ooutlines for th
pointing) andnumbers (Tab

33° 15′33° 12′opti

33° 09′2–5

6–11

33° 06′1

33° 03′33° 00′32° 57′32° 54′

s
in

30

s
in

45

s
in

00

s
in

15

s
in

30

s
45
in

00

s

32° 51′in

Declination, G

Bs
be

Newest mystery objects
in the Universe!

Fast Radio Bursts�

FRB 121102: simultaneous MAGIC (VHE + optical)+ radio campaign
observations simultaneous with Arecibo in 2016-17
during epochs with few FRB detections
upper limits on persistent VHE emission,,
time-correlated VHE + opticalemission
MAGIC cpix – Introduction
not yet sufficiently constraining for models-> observations to be continued in 2018

M

2I

Fo

optical: MAGIC central pixel- ~300-450 nm (~U band), FoV >0.1 deg- sensitive to signals with duration 0.1ms-1s- observable simultaneously with VHE- sensitivity for ~10ms Crab-like pulse ~3 mJy-> comparable to recent dedicated studies, e.g. Hardy+ 17

VH

(O

17

Fo

Op

Fr

GRB light curve: Fermi vs CTA
LAT
>100
MeV�

GRB 080916C

Abdo+ 09�

>1GeV�

SI+ 2013
Astropart. Phys.
43, 252

oto
e
ki
A)

Clarify physics of emission
Test UHECR origin, LIV

CTA>30GeV, 0.1 sec bin�transient survey via divergent pointing with CTA
M. Szanecki et al. / Astroparticle Physics 67 (2015) 33–46[9–11], over a dozen new sources were

Galactic plane survey should be a major
be capable of performing an all-sky survey
t time at high sensitivity; the scientificof both survey types are thoroughly disscussed in [13], such surveys can be perdes of observation, in particular, large
ance IACTs allows for using non-paralleld FOV. The proper adaptation of such acope array can be a non-trivial task. The
ting strategy, taking into account numerarray, e.g. distance between telescopes,c, can significantly reduce the observation
given sensitivity.
der the array of Middle Sized Telescopes, parallel and non-parallel, modes. By perMonte Carlo (MC) simulations of the skyderive for each mode the basic perforth trigger and analysis levels, which thenciencies of the modes. Our study is a partthin the CTA Monte Carlo Work Package
e CTA observation scheme. Whereas we
nt modes with the MST array, independent
tly performed for the divergent mode ofST) sub-array and the full CTA array work-- possibly effective for surveys
of persistent point sources
N- GRBs from onset
N
prompt emission physics(crucial but poorly understood)- Lorentz invariance violation(big improvement over Fermi)- unbiased transient survey
e.g. FRBs

transients occurring in FoV (not necessarily detectable)
GRBs: all sky ~800/yr (BAT+GBM)
FRBs: all sky ~6000/dy
IF FoV~300 deg2 ->~8 GRBs/yr -> ~0.7 GRBs /1000 hr~45 FRBs/dy -> ~2 FRBs / 1 hr

ble modes for a large telescope array usedrallel and divergent configurations were; below we introduce also a novel, convererence between our terminology and thatmode is referred to as convergent).
telescope system operating in the sky sure FOV of the system and the time of obsereve a given significance level, i.e. its

ach, sky surveys may be performed with

Fig. 1. Three modes of configuration of the telescope system used in the sky-survey
scans: (a) normal (parallel) mode; (b) divergent mode; (c) convergent mode.

parison of the performance of the three modes and a related issue,
i.e. an optimal value of the offset angle (giving the amount of thedifference of the pointing directions, as defined below), appears
crucial for planning the most efficient survey strategy.
3. MC simulations

For all three modes, we simulate the response of the telescopearray to the Extensive Air Showers (EAS) induced by gamma rays
and proton background. To simulate the development of EAS wesummary
MAGIC observations of multimessenger transients
GRBs
intriguing hints for nearby short GRB 160821B
interesting implications for GW follow-up
almost there; clearer detection imminent!
neutrinos
first indications for BL Lac TXS 0506+054!
more observations toward solving mystery of their origin
GWs, FRBs
ongoing with interesting prospects

summary
MAGIC observations of multimessenger transients
GRBs
intriguing hints for nearby short GRB 160821B
interesting implications for GW follow-up
almost there; clearer detection imminent!
neutrinos
first indications for BL Lac TXS 0506+054!
more observations toward solving mystery of their origin
GWs, FRBs
ongoing with interesting prospects
CTA: new prospects for transientsadvanced real-time analysis, survey via divergent pointing…

The fun has just begun!
The best is yet to come- let’s look forward to CTA!