Exploring Multi-messenger Transients with MAGIC
Susumu Inoue (RIKEN)
for the Transients
Physics Working Group,
MAGIC Collaboration

Gamma Ray Bursts VHE Neutrinos

Gravitational Waves?
Fast Radio Bursts

AGN Flares

The Unknown

CTATraCooMATraCon

outline
1. introduction
2. high-energy neutrinos- IC-170922A / TXS 0506+056, interpretation
3. gamma-ray bursts- short GRB 160821B
4. gravitational waves

VHEDetection
gamma-rayby Cherenkov
telescopes
g-raysof detection
E>100 GeV
g ray
100 GeVGammarayParticleshowerProton,300 GeV~ 10 km~1o~ 120 mg showers

hadronic showers• Narrow images• Spread images• Aligned towards
source direction• Isotropic arrival
direction• Cherenkov light is emitted byrelativistic particles in the shower• number of hadron/gamma
more than 1000 times-> need to reject hadron events
Masaaki Hayashida (ICRR)
from M. Hayashida2017/02/23

6

Transient astronomy with Cherenkov telescopes
Pros:- Large effective area (~few 104-105 m2)- Relatively large field of view (>~3.5-5 deg)
- Relatively fast repointing (>30 sec)
Cons:
- Limited duty cycle (~15%)- Limited zenith angle range (~<70 deg)
- EBL attenuation for high-z extragalactic sources

for transients/variables�
CTA (IACTs) vs Fermi�
Funk & Hinton 2013

big advantange over satellites for transients/variables:
effec. area ~104 x LAT@30GeV�MAGIC telescopes

Table A.8
Differential sensitivity of the MAGIC telescopes obtained with the medium zenith angle (30°–45Roque de los Muchachos Observatory
Emin

Emax

γ -rate−1

bkg-rate

[GeV]

[GeV]

[min]

63100
158
251
398
631
1000
1585
2512
3981
6310

100
158
2513986311000
15852512
39816310
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

732.6
2.4
2.04
2.3
256- 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°
2.92 ± 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

Aleksic+ 16
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, obtainedforfacsouera
serlarg
in t
theageple
it t≈20.4eve∼1view

rch

New window onto the Universe(UHECR origin), 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 (either leptonic or hadronic):- 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/EHE0 nA),d MC - IC-170321A EHE- IC-170922A EHE -> TXS 0506+056 / 3FGL J0509.4+0541
with- IC-171106A EHE (PeV)
degvedrt

AliciaAliciaEHE -170321A

to tooCH00 GeV

Konst.

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

blazars

relativistic jet viewed near-axis
electron sync.+ICLE - sync.

HE - IC?
ext ICSSC?

blazar sequence
Fossati+ 98

GeV TeVnhadronic (proton-induced) emission in blazars
e-+B→e-+γLE
p+γLE→N+ π0, π+- photo-meson�
π0→2γ π+-→µ+-+ν→e+-+3ν
µ+-+B→µ+-+γ muon synchrotronp+γLE→p+ e+e- photo-pair (Bethe-Heitler)�
γ+γLE→e+eelectron-positron
e+e-+B→e+e-+γ sync. cascade
p+B→p+γ

proton synchrotron

Potential issues asdominant component
1. Low radiative efficiency
generally high Lp required
2. Poor fit to broadband spectra?
3. tpγ, tpB too long to explain<day timescale X-TeV correlations
in HBLs

Mannheim 93
Ep~
Aharonian 00
Mücke+ 02,03…
also
if dEp~Rom

Böttcher+ 09

3C279

p syn
µ syn
γπ casblazar TXS 0506+056
BL Lac (intermediate or low-frequency peaked)
z=0.03365+-0.0010
Paiano+ 18
MAGIC
Collaboration
apparently “typical” SED -> leptonic dominant?

MAGIC: >6σofdetection
above 100 GeV
GIC detectionTXS 0506+056
TSTXS 0506+056
archival data from ASDC
time: more than 12h between September 24 th and October 4thSignal → more than 6 sigma

Gamma-Ray Bursts

Most luminous explosions higin 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 longBATSE
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

081090130140(17Fermi-LAT+ 17GRB 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 lackingDL

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~<30ksLü+ 17optical, IR: afterglow, constraints on kilonova
Kasliwal+ 17, Tanvir+ in prepenergy

BAT
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 SGRBs

seM- 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

StatalbyJul(thIF 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+ 11ger
GRB

energy flux (erg cm-2 s-1)

10-7

VHE spectrum
SSC-12MAGIC (1.5-4 hr)

-13

10

Preliminary

10-11-1210

impulsive

100

Preliminary101102

103

104

105

34 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

1010

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

/yrdayshort GRB off-axis afterglow
10-7energy flux (erg cm-2 s-1)

>500 GeV
orphan afterglows (see Fig. 2) are the ‘traditional’
d=40
orphan Mpc
afterglows (Rhoads, 1997; Perna and Loeb,1998; Dalal et al., 2002; Granot et al., 2002; Nakar et
z=0.16
al., 2002; Totani and Panaitescu, 2002) that are

E. Nakar, T. Piran / New Astronomy 8 (2003) 141–153

10-8

θv=010-9

observed outside the initial jet. Off-axis orphan
afterglows can be seen only after the jet break when
the jet expands sideway. Their light curve rises
initially reaching a maximal flux (that depends on
the observing angle) and then decays following thepost-jet-break light curves of a standard GRB afterglow. To study the initial opening angles of therelativistic jets we must consider the on-axis orphan
afterglows.
A direct way to determine the beaming ratios is tocompare the rates of detection of transients indifferent energy bands. However, several confusing
factors should be taken into account in such acomparison. First, detectors in different energy bands
have different relative thresholds. These should becalibrated using the current GRB and afterglow

10-10
10-11

HESS
GW170817

θv=0.1 (5.7º)

-12

10

0.2 (12º)0.3 (17º)
0.4 (23º)

10-13
10-14

143

observations. Second, there are numerous background transients and we have to identify specifictransients as afterglows. We show in Section 3 that
this problem may not be severe for the X-ray band.
Even assuming that all observed transients (aftersome basic filtering) are afterglows we find a tightconstraint on the ratio of X-ray to g-ray beaming.
Optical background transients (e.g. AGNs, stellarflares, etc.) are more numerous. Here, we should use
the temporal and spectral observations of the afterglows, observed so far, as templates for identification.
A third problem that is unique to afterglows is thepossible confusion between the optical and radio 1
on-axis and off-axis orphan afterglows. The overall
light curves of on-axis and off-axis orphan afterglows are significantly different (see Fig. 3). How1

The current X-ray observations are before the jet break, when
only on-axis afterglows can be seen.

0.5 (29º)
10-15
110

210

310

410

510

610710time since BAT trigger

c.f. Granot+ 2002

Nakar & Piran 03
Fig. 2. Off axis orphan afterglow is seen by observers that are not within the initial relativistic jet. This emission is seen only after the jet

Gravitational Waves Newest window onto the Universe,

connection with GRBs, etc- powerful probe of relativistic dynamical phenomena,
especially compact binary mergers- NS-NS/BHmergers
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.
Rowlinson
etal.
2010),
inwhichcase+ 14of the host galaxy
is the most promisingmeans
providesnew dimension
Ejecta ISM Shocke event redshift.
ror
ant to distinguish two general strategies for con-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, iferger 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 interactionobs(t ~ 0.1 1 s)

Kilonova

Optical (t ~ 1 day)jMerger Ejecta
Tidal Tail & Disk Windv ~ 0.1 0.3 c

BHMetzger & Berger 11

Figure 1. Summary of potential electromagnetic counterparts of NS–NS/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 afterjoin O1
the follow-up
programofGW
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
programofGW
On thesupernovae)
Dec 28th 2015,
MAGICevent
upper limits for optical transients (likelycandidates
followed up the second GWdiscovery(GW28th151226)
 Oneventthe Dec
2015, MAGIC

c.f. GW170817: NS-NS
GCN #18776
followed up the second GWFour2.5x 2.5deg 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 approximatelycorrespond to the cocoon and dynamical ejecta, respectively. The shallow rise of the radio

cocoon/merger ejecta: Ycomp~a few, Ee,max~1-100 TeVHotokezaka
associated HE/VHE emission?
priv. com.

data is consistent with a profile of E(> βɣ) ∝ ( βɣ) -5 . For n~0.03 cm-3, the observed radio
flux at 93 days is produced by an ejecta component with a velocity of ~0.6c and kinetic
49-4-3future: MAGIC+CTA

CTA LST1
Real photo from Feb 2017

summary
MAGIC observations of multi-messenger transientsneutrinos
first indications for BL Lac TXS 0506+056!
more observations toward solving mystery of their origin
GRBs
intriguing hints for nearby short GRB 160821B
interesting implications for GW follow-up
almost there; clearer detection imminent!
GWs, FRBs
ongoing with interesting prospects
Future: off-line joint observations with CTA LST1