Highlights from MAGIC
observations
Ievgen Vovk on behalf of MAGIC collaboration
Max Planck Institute for Physics,Munich, Germany
The extreme Universe viewed in very-high-energy gamma rays 2018
La Palma, Spain, 12.10.2018

Main VHE instruments

Ie. Vovk

H.E.S.S.

VERITAS

MAGIC

HAWC
MAGIC highlights

2

Main VHE instruments
VERITAS

H.E.S.S.
CTA – the future

HAWC

MAGIC
Ie. Vovk

MAGIC highlights

2

Main VHE instruments
VERITAS

H.E.S.S.
CTA – the future

HAWC

MAGIC
Ie. Vovk

VHE astronomy highlights

2

MAGIC telescope system
Stereoscopic system of 2 IACTs,located at La Palma, Spain
Telescopes: two D=17m
Site:
La Palma (Canary Islands)
Energy range: 40 GeV – above 50 TeVResolution: 0.07º-0.14º (0.1-1 TeV)
Sensitivity: 0.6% Crab units (integral)
Field of view: 3.5 deg

Recent improvements:- at lower energies: new trigger system (SumTrigger-II);- at higher energies: new observational strategy (Very Large Zenith angles).

Ie. Vovk

MAGIC highlights

3Galactic sources

Galactic PeVatrons

Main argument: spectrum at low energies

10-1010-1110-121081010
Energy (eV)1012

E2 dN/dE (erg cm-2 s-1)

Supernovae remnants were foundaccelerating (low-energy) protons

E2 dN/dE (erg cm-2 s-1)

Sources of the galactic cosmic rays are not known.
But there are already first identifications of cosmic ray accelerators.
10-10
10-11
10-12
1081010
Energy (eV)1012

Main argument: morphology of emission

+0.4
+0.0
-0.4
01.0
00.0
359.0
Galactic Longitude (deg.)

WCR(≥10 TeV) (10-3 eV cm-3)

Cosmic ray acceleration up to PeV
energies in the Galactic CenterGalactic Latitude (deg.)

Fermi-LAT collaboration '133020102040 80 120 160 200
Projected distance (pc)

H.E.S.S. collaboration '16Ie. Vovk

MAGIC highlights

4Searching for sources of Galactic CR:
Cas A supernova remnant
Are supernovae remants PeVatrons?
Cas A: MAGIC + Fermi/LAT view
Cas A – young (~400 years old) andwell-studied SNR.
Young SNRs were expected to be able toprovide PeV cosmic rays.

Intrinsic cut-off

Analysis of the deep MAGIC
observations suggests the γ-ray emission
is mostly hadronic.
But reveals a high-energy cut-off
at ~0.01 PeV.

π0 decay cut-off

Challenging the assumptionthat young SNRs are PeVatrons
Ie. Vovk

MAGIC Collaboration (2017)
MAGIC highlights

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A PeVatron in the Galactic Center
Recently the interest to the Galactic Center has increased with the discovery of apotential PeVatron there, likely associated with the SMBH.
H.E.S.S. (Abramowski+ ‘16)

If confirmed, this provides animportant milestone to the1) identification of the galactic
pevatrons2) investigation of the CR
propagation in the Galaxy

Consistent with thepoint-like source

Alternative explanations proposed(Gaggero+ ‘17) underline theimportance of the large scale CR“sea” for the firm interpretation.

No cut-off

However, one of the main ingredients is the gas distribution in the central ~200 pc
from the black hole.
And it is particularly difficult to get.
Ie. Vovk

MAGIC highlights

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A PeVatron in the Galactic Center
Recent MAGIC re-observations also find a similar w~1/r CR profile,confirming H.E.S.S. results

Still, the poorly know gas (target material) distribution close to the Gal. Centerquestions the w~r-1 form – other indices are also possible.
More accurate radio measurements are needed tosupport γ-ray data.
Ie. Vovk

MAGIC highlights

7Detection of the >100 TeV emission> 100 TeV emission – a signature of a PeVatron.
Main obstacle – low expected count rates.
Expected counts for Aeff = 1 km2 and Tobs=50 hr

To keep observation time short,Aeff > 1 km2 is required.
Case for CTA, but also achievablewith current generation IACTs
through a special observational
setup.

Large zenith angle observations

Ie. Vovk

MAGIC highlights

8Larger zenith angle observations
Vertical observations

Large zenith angle
observations(typical observationalmode of IACTs)(proposed setup)

ZenithZenithdd ~ 10 km
dr ~ 120 mr
ZAd ~ 100 kmr ~ 1200 mr

d ~ 10 km /cos(ZA)
ZA > 70⁰
shower distance d > 50 km

Usually ZA ~ [0⁰; 60⁰] and shower
distance d ~ 10-20 km
Ie. Vovk

MAGIC highlights

9Crab Nebula detection
at highest energies
Approximately 50 hr of exposure (after cuts) inZA range 70-80⁰.
Angular event distribution> 30 TeV estimated energy

Reconstructed collection area

Time = 52.33 hSignificance (Li&Ma) = 6.47σPreliminary

intsoBoce ctlloiorenaaPreliminary

Significant signal above the highest
source energy, previously measured
by MAGIC (Aleksic+ ‘15)

LZA MAGIC collection area @100 TeV
is comparable to
CTA predictions (at 20° zenith angle).
http://www.cta-observatory.org/science/cta-performance/ (version prod3b-v1)

Ie. Vovk

MAGIC highlights

10Crab Nebula detection
at highest energies
Approximately 50 hr of exposure (after cuts) in ZA range 70-80⁰.
Unfolded Crab Nebula SED
Preliminary

ints
BooIe. Vovkmma xialgyreen

Reconstructed LZA spectrum
extends to ~100 TeV – comparable
to HEGRA measurements,
but in 8x less time.
LZA SED is consistent with earlier
MAGIC measurements at lower
zenith angles.

MAGIC highlights

11Lowering the energy threshold:detecting pulsars with MAGIC
Pulsars (rotating neutron stars) typically have cut-off
spectra, quenching at too low energies.
Only 2 pulsars are detected with IACTs untill recently!
Crab pulsar spectrum
MAGIC Collaboration (2016)

Vela pulsar
H.E.S.S. Collaboration (2018)

Ie. Vovk

MAGIC highlights

12Lowering the energy threshold:detecting pulsars with MAGICNew SumTrigger-II system: stacking PMT signals.
Yields a ~30 GeV energy threshold.
More efficient pulsar observations.

Ie. Vovk

MAGIC highlights

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Lowering the energy threshold:detecting pulsars with MAGICA new MAGIC detected pulsar: Geminga~30 h of Sum-Trigger-II observations,winter 2017●
Rotational parameters derived from 10
years of Fermi/LAT data
●Clear detection of P2 (5.2σ)●No detection of P1●IACT-observed pulsar family
is growing.

Ie. Vovk

MAGIC highlights

14Extragalactic sources

Gravitational (micro)lensing
Gravitational lensing – bending of the light due to the gravity of theintervening galaxy.
Image deformation / flux magnification

Gravitational microlensing – bending of the light due to the gravityof the stars and small-scale structures in the intervening galaxy.
Short-time scale flux magnification of small (!) objects onlyIe. Vovk

MAGIC highlights

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Gravitational (micro)lensing
The lens and the source aremoving with respect to each otherat v~1000 km/s, leading to a
constant change in magnification.

Magnification amplitude andduration depends on the sourcesize:
μmicro~(RE/R)0.5 and Δt = R/vt = R/v
R~5x1015 cm
R~5x1014 cm

−0.5R
μ≈10
3 x 1014 cm(Δ t ≈100Ie. Vovk

MAGIC highlights(R3 x 1014 cm)

)(

−1v
days
300km /s)16

Gravitational (micro)lensing
Regular observations of microlensing opens a new way
to learn about the nature of AGNs:✔ energy dependence of Rγ✔ its variations with time✔ gamma vs radio location estimates
Rγ~1015 cmcm

β cm< cmcdγ=(10-100)RRg

This gives a completely unique opotunity to study thedetails of the structure of the acceleration sites in AGNs,
effectively improving the angular resolution of gammaray telescopes by 1011 times.
...AGN emission region angularsize is that of an ant at the Moon

Neronov, Vovk, Malyshev ‘15Ie. Vovk

MAGIC highlights

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B0218+358: a bright lensed AGN

Flaring period 1

Flaring period 2

Redshift z=0.94 – very distant source (Universe‘s middle-age).
Microlensing is observed at GeV energies, MAGIC data at ~100 GeV
may be also indicative of a magnification phenomenon.

Vovk & Neronov ‘16
MAGIC collaboration ‘16

Very compact emission source, likely close to the central
supermassive black hole.
Ie. Vovk

MAGIC highlights

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AGN emission region problem
Emission scenario:
close to central engine
ORoutside the so-called
Broad Line Region?
Close to central engine: fastvariability most naturally explained, but
BLR should absorb the VHE photons.
Outside BLR: where do the seedphotons for inverse Compton scattering
come from? How to produce the smallemission region?

Ie. Vovk

Cartoon of the possible locations of theemitting region

MAGIC highlights

19AGN emission region problem
In 2015 MAGIC has observed anotherrecord-breaking source (z=0.94)
PKS 1441+25 in a campaign with othertelescopes.
Delivers unique measurements ofExtragalactic Background Light fromthe middle-age Universe.
Modelling suggests the emission regionis outside of BLR (otherwise a strong
absorption occurs).

MAGIC Collaboration + (2017)
So...

Distant emission region insome sources(absorption constraints)

Nearby emission region inother sources(microlensing detection)

Seems there is no common location
Ie. Vovk

MAGIC highlights

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MAGIC detection ofthe neutrino source
TXS 0506+056 observations triggered by the IceCube alert EHE-170922A

VHE emission (MAGIC)TXS 0506+056 shows asynchrotron peak around 1014 Hz→ classified as LBL/IBL
VHE gamma-ray observations
allowed computation of redshift
upper limits with between z=0.61
and z=0.98 at 95% CL(depending on EBL model used,Paiano+ ‘18)

IceCube+Fermi/LAT+MAGIC+…, Science, (2018)

Ie. VovkMAGIC highlights

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MAGIC observations ofthe neutrino source
Deep (40 hr) exposure following the original event
MAGIC Collaboration (2018)
Two flares● Daily time scale variabily● No spectral changes●Conclusions (overall):✔ AGNs are responsible at least for afraction of the observed astrophysicalneutrino flux.
✔ AGNs do accelerate CRs to 1014-1018 eV.

Ie. Vovk

MAGIC highlights

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Intergalactic Magnetic Field
Physics beyond the Standard Modellarge energies

astrophysics/cosmology

Suitable conditions: Early Universe.

lack of messengers

IGMF

Cosmological IGMF may originate
from different epochs:✔ QCD phase transitions: ~10-12✔ electroweak phase transitions: 10-11 G✔ recombination: ~10-9 G
Neronov & Semikoz, '09

Detection of a cosmological IGMF may allow to learn about the conditions
well before the recombination
Currently there is no other way to do thisIe. Vovk

MAGIC highlights

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Intergalactic Magnetic Field“Smoking gun”: extended halo
Size and shape depend on IGMF strength andsource parameters (jet opening and orientation).
Delayed emission
The delay is set by IGMF, but light curve shapemay also depend on the jet parameters.
New spectral components
Depend on IGMF, source spectrum, jetorientation.
Taylor+ ‘11

Neronov & Vovk ‘10, Tavecchio+ '10, Dermer+ ;11, Dolag+ ‘11, Taylor+ ‘11,Vovk+ ‘12, Finke+ ‘15, Aharonian+ ‘01, Aleksic+ ‘10, Abramowski+ ‘14,Archambault+ ‘17
Ie. Vovk

MAGIC highlights

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Intergalactic Magnetic Field
Recent MAGIC observations strongly constrain the IGMF parameter space
MAGIC Collaboration (in prep.)

Adapted from Durrer & Neronov ‘13
MHD cmturbulance cmdecay

Supernovae

AGN

PreliminaryIACTCR

LAT

Ongoing debate on the role of plasma instabilities (Chang+ ‘12, Broderick+ ‘12, Miniati &Elyiv ‘12, Schlickeizer+ ‘12, ...)
Ie. Vovk

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Summary
MAGIC now lives its golden age:- advances in hardware / analysis,- new sources discovered,- synergies with other wavelengths / domains.
A number of prominent discoveries were not covered here due to lack of time:- GRB detection with an IACT
- sharp spectral features in AGN gamma-ray emission- dark matter searches- gamma-ray binaries- spatially-resolved supernova remnants and pulsar wind nebulaeand so on...
We are looking forward to joint observations with CTA/LST and synergies with
upgraded LIGO/VIRGO/IceCube and others...

Ie. Vovk

MAGIC highlights

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Gravitational microlensing: dynamics
of the magnification map
This magnification pattern is changing in time as the separate stars-lenses
are moving with respect to each other.

However, the peculiar velocities of the stars in galaxies are typicly ~10-100 km/s andtypical time scale for a change is ~10 years.
On shorter time scales the pattern can be considered stable.

Gravitational (micro)lensing
γ cm cmrays

PKS cm1830-211

10-6 cmarcsec

1 cmarcsec
Radio cm(Patnaik cmet cmal. cm1994)R