Searches for FastTransients with MAGIC

Koji Noda (ICRR, U. Tokyo)
S. Inoue, F. Longo, K. Satalecka, MAGIC Transient WG,
on behalf of the MAGIC Collaboration
29 June 2018
Astrophysics + MAGIC @ La Palma

MAGIC Transient Physics•

MAGIC Telescopes•

MAGIC Transients Programs••

Gamma-Ray Bursts•

Gravitational Wave follow-up•

Neutrino ToO•Fast Radio Bursts•

TDE, novae, etc.

Summary & Future2

MAGIC Telescopes•

Stereo system since 2009•

Field of view: 3.5 deg•

Energy threshold: 50 GeV(30 GeV with Sum-Trig)•Sensitivity:0.7% Crab > 220 GeV in 50 h
(10% Crab > 100 GeV in 1 h)

•Energy resolution:
15% (@1 TeV), 24% (@100 GeV)

•Angular resolution:
0.06 deg (@1 TeV), 0.1 deg (@100 GeV)

•Light-weight structure: 70 t•

Fast repositioning: 7 deg/s(4 deg/s in std mode)

MAGIC for transients3

Automatic alert system•

Automatic repointing and DAQ. Active for GCN alerts since 2003.

•Multi-messenger: Adapted to neutrino and GW alerts.
New VOEvent protocol is being implemented.
4

GRB follow-up obs.
•101 GRBs observed since 2005•8-10 / yr (50 h allocated)•late time obs. since 2013•

39 with z, 14 with z<1.5•

14 with < 100 s delay & stereo,out of which 4 with z < 1.5,
1 with z < 0.5 : GRB160821B

Delay vs.
Zenith angle

5

Highlight: GRB 160821B(ICRC 2017, Texas Symposium, etc., MAGIC Coll. in prep. (2018))•Short GRB (T90 ~= 0.5 s) at z = 0.16, triggered by Swift-BAT•

Swift-XRT: t < 300 s extended emission + steep decay, t < 30 ks plateau?

•No LAT detection. HST: hint of a kilonova? (Tanvir+, in prep. Gompertz+ 17)•

MAGIC: 24 s - 4 hr. Bright moon (3-9 x dark), adverse weather up to 1.5 hr

Preliminary•

3.1 sigma (post-trial) in >600-800 GeV. Not firm, but a hint of a detection•No other potential γ-ray emitter in FoV. Unknown steady source excluded(by an observations ~1 year later)6

If the signal is real
Swift-XRT

Fermi-LATMAGICainmiler
Pyr

Fermi-LAT ULsPreliminary

Intrinsic spectrum(EBL de-absorbed)

Good weatheronly (1.5-4 hr)

MAGIC SED

• compatible with a relatively flat LC coinciding with a possible X-ray shallow
decay (though not constraining much)• Suggested flat SED is OK with the EBL attenuation (Intrinsic PWL spectrumwith index 0.8 +/- 0.6). Beyond synchrotron?
7

Implications for VHE from NS-NS(By S. Inoue)•NS mergers favoured as progenitors of short GRBs•

However, GW170817 may or may not have produced a short GRB. Even if it
did, the observed afterglow is inconsistent with the simple top-hat structure•Thus, this implies rather a potential detection for a future nearby NS merger

8

GW follow-up: ex. GW151226•MAGIC plans to improve strategy for O3 from Feb 20199

Neutrino programs•Since 2012, MAGIC participates the Gamma-ray Follow-Up (GFU) program•

Archival tracks: 2 HESE (37 & 38) and a 2-PeV track observed•

Real-time alerts (HESE+EHE): all the 4 visible for MAGIC were observed. > 30 h obs.

10

Archival / realtime HESEs(Gora+ Neutrino 2016; Satalecka+ Gamma 2016; Noda+ TeVPA 2016; Santander+ ICRC 2017)•No signal found•

UL map for alerts with alarge localization error•

HESE/EHE-160731A

HESE-160427•

Shared analysis toolwith the GW group

All-IACT paper in prepIC-170922A / TXS 0506+056•IC neutrino event on 22 Sep 2017, 20:54:30.43 UT•

EHE Notice: t0 + 43 s, GCN Circular on 23 Sep•

Immediate follow-up by other instruments. Bad weather at the MAGIC site•

Within the error circle of the event,a blazar TXS 0506+056 was flaring,in GeV, and also in opt/IR.

•MAGIC observation from 28 Sep.
12 hr data until 3 Oct: 5 σ detection•Redshift by GTC: 0.3365 (Paiano+ 2018)•First time VHE gamma rays detectedfrom a direction consistent with a HEneutrino

Paper drafting, modelling, revising, etc. 99.9% done
Stay tuned (<1 month!)
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Fast Radio Burst: 121102•

MAGIC can observe VHE & optical, using the central pixel•

FRB121102: only known repeating, detected in opt & radio, z=0.193•MAGIC obs.: Sep 2016, simultaneously with Arecibo and Effelsberg.
Sep 2017, with INTEGRAL, Effelsberg, GBT, and Nancay. 20 h in total.

•No detection. Publication submitted.
Additional obs. in 2018.

Preliminary

Preliminary

Sensitivity for optical pulses(mU~13.4 for msec - sec pulses)

13

Summary & Future•

MAGIC is an excellent IACT for transient physics•

GRB: A hint of a detection. Short GRB implication on the near-future
GW observations.

•GW follow-up: lessons learned for O3•

Neutrino follow-up: HESEs & TXS 0506+056 detection, excitingprospects for multi-messenger modelling•

FRB: optical and VHE signals explored at the shortest time scales
Fruitful results in the ORM... We should collaborate with CTA LST!

14Backup

GRB160821B models
By S. Inoue. MAGIC Coll. in prep (2018)

10-6

Implusive:
single pulse injection with single Γ
Not too bad, but marginal with VHE UL.
Not nice in X-ray (? Jin et al. 2017）

10-8

•

Energy injection: “Refreshed shock”

energy flux (erg cm-2 s-1)

•

10-7

•

•

Anyway, need another explanation for theX-ray extended emission.
Transient ms pulsar?
Both models work also for SED (backup)-1010

Impulsive

XRT (0.3-10 keV)

-111010-12

Energy injection-1310-14

impulsive
energy injection

Preliminary

-15
10 -6

1010-1

100

101

-10

10103

104105

VHE light curve
SSC

10-8
10-9102

time since BAT trigger

10-7energy flux (erg cm-2 s-1)

multiple Γ
Slightly better both in VHE and in X, but
inconclusive-91010(Sari & Meszaros 01, Veres & Meszaros 14)
Additional injection after the main, with

X-ray light curve
Sync.

BAT (5-150 keV)

Impulsive
MAGIC (>500 GeV)

-11

10

Energy injection-121010-13

impulsive
energy injection

Preliminary

-14

10

10-1

100

101

102

103

time since BAT trigger

104

105

16