2015"The extreme Universe viewed in very-high-energy gamma-rays 2015"

A multi-messenger search for the originof cosmic-raysHidetoshi SANO (Nagoya Univ.)Radio (CO, HI)

HS+165in5prep.

Infrared

X-raysWilliams+11

Gamma-rays

Broersen+14

haronian+07

The extreme Universe viewed in very-high-energy gamma-rays 2015, January 13–14, 2015, ICRR

Revealing the origin of cosmic rays! Cosmic rays: relativistic protons (90%), He (10%), electrons + nuclei (<1%)" They have a significant influence on the interstellar space© NASA/J. Hester, P. ScowenHeating the interstellar gas© Kagaya

Galaxy evolution© NSF/J.Yang

Earth environment" Revealing the origin of cosmic-rays is essential to understand the universeSNRs are thought to be the primary sources for the bulk of Galactic cosmic-raysHowever, the acceleration site of protons is still being debated…
The extreme Universe viewed in very-high-energy gamma-rays 2015, January 13–14, 2015, ICRR

Outstanding issues

solutions[1] Origin of gamma-rays (hadronic and/or leptonic)"Spatial comparison between the ISM and gamma-rays[2] Acceleration models including more realistic conditions"Shock-cloud interaction model"Other acceleration mechanisms ?
(non-liner, 2nd order Fermi, magnetic reconnection etc…)[3] Gamma-ray obs. with high sensitivity + angular resolution"Cherenkov Telescope Array (CTA)[4] To reveal an universality"Extend to the distant sources including the LMC SNRsThe extreme Universe viewed in very-high-energy gamma-rays 2015, January 13–14, 2015, ICRRIC stars

Fermi/LATFermi/LAT

ICRXTEstarsRXTEIC stars00πdecay10Fermi/LATπ decayFermi/LAT

E2 Flux

10

E2 Flux [E2 Flu

E2 Flux

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1010[1] Origin of gamma-rays (hadronic and/orleptonic)0π decay

H.E.S.S.
H.E.S.S.

11CR protons

γ-ray-1Interstellar10 10 1010 10 1010 10 1010protons

102-66-6411CR electrons

Hadronic process

10-1 10-4-48-2-210

1

H.E.S.S.
H.E.S.S.

Leptonic process-110-1 10624
61 12 102 10101014 104 10 10 10E [eV]π081081010 1010 10 -61012 -61012 -41014 -41014 -2-210 10 10 E10E10[eV]10[eV]1124
6102 10 104 10 10 104.
Spectralenergydistributionof RCW86a leptonicscenario.
Thesolidredlinesdenotethetotalbroadbandemissionfromtheone-zonescenario. The red solidc.pectralscenario.
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emissionThe fromredthe solidone-zonelinesdenotethetotalbroadbandemissionfromtheone-zoneFig.
4. Spectralenergydistributionof RCW86a leptonic4.
Spectralenergydistributionof RCW86 fora forleptonicscenario.
The red solid line
00 the IC-contributions and Fig.
0delingdiscussedintheSect.
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Theradiodatagcontributionsdiscussedin andSect.
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and theThedashedradiodatalineisthatofthe⇡-decaycontribution.
TheradiodataIC-contributionsmodelingdiscussedin Sect.
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1975;Lemoine-Goumardet2012).
al. 2012).
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(CaswellX-raydataet al.arefromLemoine-GoumardASCAandetal.
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1975;LeLowenergyphotonpointsarefromMolongloat 408MHzandParkesdataat 5areGHz(Caswellet al. 1975; Lemoin0TE datafromLemoine-Goumardet(2012).
al. (2012).
The Fermi-LATdatapointsaretakenfromYuanet(2014)al. (2014)andtheH.E.S.S.
fromthis dataATromLemoine-Goumardpointsare taken etfromal.
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(2012).
TheFermi-LATpointsaretaken+RXTE from Lemoine-Goumardal. (2012). The Fermi-LAT dataICpointsare taken fromscatteringCMB, infraredet etc.
.lysis.
analysis.
analysis.
H.E.S.S. Collaboration et al.: Detailed analysis of the shell type SNR RCW 86

γ-ray

γ-rayπMOST MOST102

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10

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H.E.S.S.

11Hadronic ModelMOSTIC0 ATCAπ decay

Fermi/LATH.E.S.S.

E2 Flux [cm-2 s-1 eV]

10

RCW$86$(H.E.S.S.$Col.+15)

102

E2 Flux [cm-2 s-1 eV]

2

E2 Flux [cm-2 s-1 eV]

E2 Flux [cm-2 s-1 eV]

E2 Flux [cm-2 s-1 eV]

π2Hadronic102 10HadronicModel ModelIC102-6104 10-6B~22 µG

ATCAπ0 decayATCAπ0 decay-2Γ p = ASCA-2Γ p = ASCARXTE RXTE

1010Fermi/LATFermi/LAT

Leptonic ModelICIC CMBIC dustIC starsπ0 decay

H.E.S.S.
H.E.S.S.

1

1

110-110-1 10-110-1 10MOSTMOSTIC-16-48-210214664 104101 12 102 -41010 10-4 1010 10-2 101010 1 10110-6 1010 10 1010-2E [eV]8101481012 -61012610102 10 1010410 -610101014 8-410 -2 101010-21010-4E1010E[eV] [eV]121 101

10142 104 104 106 10102 10E [eV]

[1] Origin of gamma-rays (hadronic and/or leptonic)CR protons

Hadronic process

CR electrons

Leptonic process

γ-rayInterstellarprotons

π0γ-rayπ+π-(π0 decay)

γ-rayLow energy photonCMB, infrared etc.

IC scattering

energy in acceleratedWp n W : totalprotonF ∝ 2 n: ISM gas densityd: distance to the SNRdp

Gamma-rays distributionISM gas distributionThe extreme Universe viewed in very-high-energy gamma-rays 2015, January 13–14, 2015, ICRREvidence for the CR proton accelerations (Fukui+)
TeV5GammaJrays555555555Total5ISM

AcceleraBon5eﬃciency5~0.15%(upper5panels)5Fukui,5HS+12,5(lower5panels)5Fukui,5HS+165in5prep.

The extreme Universe viewed in very-high-energy gamma-rays 2015, January 13–14, 2015, ICRR

[2] Acceleration models including more realistic conditions

15pc

Image Suzaku5XJrays5(RXJ1713)5Contours:5NANTEN25CO5HS+10, 13, 15a! Synchrotron X-rays are enhanced around CO clumps in 0.1 pc scaleThe extreme Universe viewed in very-high-energy gamma-rays 2015, January 13–14, 2015, ICRR

Shock cloud interaction model: schematic viewBefore

shock front

Aftershock front

Eddy (turbulence)vclouddensity n0shock speed v0ISM clump(density ncloud)vcloud = v0 × n0 ncloudVcloud$will$be$decreased…

# Shock cloud interaction generates turbulence around the ISM clumps!
[1] rotational current + dynamo effect " magnetic field amplification!
[2] Synchrotron X-rays are enhanced around the ISM clumpsThe extreme Universe viewed in very-high-energy gamma-rays 2015, January 13–14, 2015, ICRR

Shock cloud interaction model: HMD simulation (Inoue+12)
ISM5density

MagneBc5ﬁeld5strength

Inoue+12

The extreme Universe viewed in very-high-energy gamma-rays 2015, January 13–14, 2015, ICRR

Shock cloud interaction model: HMD simulation (Inoue+12)
ISM5density

MagneBc5ﬁeld5strength

Inoue+12

Gas5clumps5are5rimJbrightened5in5synchrotron5XJrays.5"5strong5turbulence5+5B5ﬁeld5may5accelerate5the5CRs5(e.g.,5HS+15)
The extreme Universe viewed in very-high-energy gamma-rays 2015, January 13–14, 2015, ICRR

Shock cloud interaction model: Gamma-ray spectrumInoue et al.

Leptonic5model5Hadronic5model5and F. A. Aharonianmodel, (Abdo+11)
asL72 S. Gabicispeed,the penetration length of the(Gabici5&5Aharonian514)
shockInouewaveetintoal.the cloud inate from1000 years is evaluated to be ∼0.01 pc (where we have assumedB ~10µGBinto~100µGockspeed,stallthe densitylengthratio betweenthe wavecloudsandthediffusegas to be 105the penetrationof the shockcloud inGas5clumpsed shockasevaluatedwe discussedin Section4.3) thatis muchsmaller thanthe1000 years isto be ∼0.01pc (wherewe haveassumedcouldof the molecularcloud!0.1Thus,the bedensity scaleratio betweenthe cloudsandcoresdiffusegaspc.
to be105 we can stillThe ashighassumeminimumscaleisofmuchcloudsto be 0.1pc,theeven if cloudswe discussedin theSection4.3) thatsmallerthanpenetrateapparentlyembeddedin SNR.
scale of thearemolecularcloudcores !0.1pc. Thus, we can stillunt ofthe the minimumSince thediffusioncoefficientthe high-energyassumescaleof cloudsto be 0.1 forpc, evenif clouds particlesceleratedcanembeddedbe writteninasSNR.
κd = 4 η lg c/3π (Skilling 1975), where lg isare apparentlyecay andgyroradiusof relativisticthe penetrationSince thethediffusioncoefficientfor theparticles,high-energyparticles depth dueAmbient5gasTakaharato theof theparticlescan bewrittencan be writtenas randomκd = 4 ηwalklg c/3π(Skilling1975),wherelg isasass ofthethegyroradius of relativistic particles, the penetration depth due1/2Sincelpd walk≃ (κdoft)theto the randomparticles can be written asFigure 2. Gamma-rays%from RX J1713.7−3946.
emissionfrom the$dashed lineTherefers%a1/2 $%to 1/21. Spectrum of CRs in the SNR shell $(dotted line) and insideenergy ofFigure−1/2clumpsisshownas
asolidline,whilethetheemissionclump that entered the shock at t = 1400, 1500 and 1550 yrE(solid lines 1,t refer to Fermi and HESS
B1/2from the diffuse gas in the shell. Data points age1/22and3,respectively).
m canlpd be≃ (κd t) = 0.1 ηpc,observations.
310100$enteredµGthe SNR%earlier10 yr$ TeV%Clumpsg uniformwhere B = 100 B $µG is the magnetic%field1/2−1/2that1/2 either are disrupted by plasmain the turbulent layer,Inoue+12E and E = E TeV the particle
BL = 0.05 L1/2 pc its thicknessage discontinuity or, if they survive,instabilities at thetcontactenter a(13)=0.1pc,energy.
Forηa given clump, the minimum energy of the particles thatregion characterized by a low density ofCRs and quickly becomeThe extreme Universe viewed in very-high-energy gamma-rays 2015,January 13–14, 2015, ICRR3ctr−4tr,−1.312

can penetrate is given by the equation τd = tage − tc . A significantly

themselves devoid of CRs due to their diffusive escape.

[3] Gamma-ray obs. with high sensitivity + angular resolutionsBy S. Funk (modified)

Young SNRs(age ~2000 yrs)?
15

Current5observaBons5could5not5determine5the5spectra5shape5E5>51005TeV5The extreme Universe viewed in very-high-energy gamma-rays 2015, January 13–14, 2015, ICRR

現行望遠鏡に比べCherenkov感度 10倍Telescope Array (CTA) エネルギー帯域 10 倍

HS+15XJray5photon5index5map5(RXJ1713)

20 GeV-300 TeV

 角度分解能 2 倍（2分角@1TeV）

e5will5be5able5to5determine the spectral shape > 100 TeV by using CTA!
The extreme Universe viewed in very-high-energy gamma-rays 2015, January 13–14, 2015, ICRRCherenkov Telescope Array (CTA): imaging simulationsLeptonic origin

Hadronic origin

Nakamori,$Katagiri,$HS+15$(ICRC)

The origin of gamma-rays can be distinguished by morphological studiesThe extreme Universe viewed in very-high-energy gamma-rays 2015, January 13–14, 2015, ICRR

[4] To reveal an universality

ournal Supplement Series, 209:8 (13pp), 2013 NovemberDempsey,

We are extending our comparative studies (ISM, X-rays, Gamma-rays)for the distant SNRs by using high-angular resolution CO data (Δθ~20”)
Survey!by!Boston/FCRAO;!Jackson!et!al.!2006)

NRO545Jm5GalacBc5plane5survey5(FUGIN):512CO,513CO,5C18O5J$=51–05Coverage:510°5<5l$<550°,|b|5<51°5+5outer5rim55

R51.25

JCMT5GalacBc5plane5survey:512CO5J$=53–2Coverage:510°5<5l$<565°,5|b|5<50.5°5

The extreme Universe viewed in very-high-energy gamma-rays 2015, January 13–14, 2015, ICRRSNR distributions toward the survey area

Image:5NANTEN5GPS5(Mizuno5&5Fukui52004),5Red:5SNR5boundary,5Green:5FUGIN5area! 67 SNRs are located within the FUGIN survey area!
" 40 % of SNRs are emitted by diffuse X-raysThe extreme Universe viewed in very-high-energy gamma-rays 2015, January 13–14, 2015, ICRR

Preliminary results of 12CO J = 3–2

Preliminary5Result…

Preliminary5Result…

Image JCMT512CO5J5=53–25integrated5intensity,55Contours:5Chandra5broad5band5XJrays5! These SNRs are ~10 times smaller than RX J1713 (size ~ 60 arcmin), !
while we could identify the interacting molecular cloudsThe extreme Universe viewed in very-high-energy gamma-rays 2015, January 13–14, 2015, ICRR◥ASTROPHYSICSThe exceptionally powerfulTeV g-ray emitters in the LargeMagellanic CloudThe H.E.S.S. Collaboration*†The Large Magellanic Cloud, a satellite galaxy of the Milky Way, has been observed with theHigh Energy Stereoscopic System (H.E.S.S.) above an energy of 100 billion electron voltsfor a deep exposure of 210 hours. Three sources of different types were detected: thepulsar wind nebula of the most energetic pulsar known, N 157B; the radio-loud supernovaremnant N 132D; and the largest nonthermal x-ray shell, the superbubble 30 Dor C. Theunique object SN 1987A is, unexpectedly, not detected, which constrains the theoreticalframework of particle acceleration in very young supernova remnants. These detectionsreveal the most energetic tip of a g-ray source population in an external galaxy and providevia 30 Dor C the unambiguous detection of g-ray emission from a superbubble.

Next5targets5Magellanic5SNRs5&5Superbubbles

The origin of cosmic rays (CRs), the veryhigh energy (VHE) (≳1011 eV) and ultrahighenergy (≳1018 eV) particles that bombardEarth, has puzzled us for more than a century. Much progress has been made duringthe past decade due to the advent of VHE g-raytelescopes. These telescopes detect ∼1011 to1014 eV g rays from atomic nuclei (hadronic CRs)collisions with local gas or from ultrarelativisticelectrons/positrons (leptonic CRs), which produceg-ray emission by upscattering low-energy background photons (1). Indeed, a survey of the innerpart of the Milky Way with the High Energy Stereoscopic System (H.E.S.S.), an array of imagingatmospheric Cherenkov telescopes (2), revealed apopulation of supernova remnants (SNRs) andN157B

pulsar wind nebulae (PWNe) emitting g rays withenergies in excess of 100 GeV (3).
Here, we report on VHE g-ray sources detectedoutside the Milky Way, namely in the Large Magellanic Cloud (LMC). This satellite galaxy of theMilky Way has a stellar mass of about 4% of theMilky Way (4, 5). Located at a distance of ~50 kpc(6), it is an irregular galaxy seen almost face-on(7). Consequently, source confusion is much lessof a problem than for the inner Milky Way, andthere is less uncertainty in the distances of thesources. The LMC stands out among nearby galaxies for its high star formation rate per unitmass, which is about a factor of five higher thanin the Milky Way (8, 9), and contains the bestexample of a local starburst, the Tarantula Nebula.

ment Telescope (EGRET) (11) and, more recently,by the Fermi Large Area Telescope (LAT) (12),which revealed diffuse emission with an extension of several degrees in diameter, tracingmassive star-forming regions. VHE g-ray telescopes, like H.E.S.S., besides providing information on much higher energy CRs, have anangular resolution of a few arcminutes, whichis substantially better than Fermi-LAT’s resolution at g-ray energies <10 GeV. The goodangular resolution allows H.E.S.S. to identifyindividual sources in the LMC. As we will detailbelow, a deep H.E.S.S. observation revealed threeluminous sources in the LMC: the superbubble30 Dor C, the energetic PWN N 157B, and theradio-loud SNR N 132D. Of these sources, onlyN 157B was detected previously in a 47-hourexposure (13). The observations extend the scopeof VHE g-ray astronomy by providing examplesof sources from a population outside the MilkyWay. N 157B and N 132D belong to known g-raysource classes, but both have distinguishing characteristics, N 157B being powered by the mostenergetic young pulsar, and N 132D being one ofthe oldest VHE g-ray emitting SNRs. The superbubble 30 Dor C, however, provides an unambiguous detection of a superbubble in VHE grays. Conspicuously absent from our list of threesources is SN 1987A, despite predictions that itshould be a bright g-ray source (14, 15).

N132D

H.E.S.S. observationsWe report on a deep, 210-hour H.E.S.S. exposure,targeted at the region of the Tarantula nebula—corresponding to 30 Doradus (30 Dor)—the largeststar-forming region in the Local Group of galaxies.
We reconstructed g-ray showers with an imagefitting analysis (16) and cross-checked with a multivariate analysis based on image parameterization(17, 18), with consistent results. In both analyses,a cut on the uncertainty of the reconstructed g-raydirection indicated an angular resolution of ~0.05°.

305Dor5C

Downloaded from www.sciencemag.org on January 23, 20

REPORTSChandra5XJray535color5Images

Preliminary5Results…

Images:5Mopra5CO51J055Contours:5Chandra5XJray5

Magellanic SNR N132D Mopra CO1-0, HS+15b

ano+15b5Image:5(a)5Chandra5XJrays,5(b)5Mopra5CO51J05(MAGMA:5Wong+11)5Contours:5Chandra5XJrays5(0.5J7.05keV)
The extreme Universe viewed in very-high-energy gamma-rays 2015, January 13–14, 2015, ICRR

30 Dor CJ5Superbubble5in5305Dor55J5NonJthermal5XJrays5J5TeV5GammaJrays5J5Containing5young5SNR555(Age:52.2−4.95kyr,5Kavanagh+14)5HS+16 in prep.

30 Dor CJ5Superbubble5in5305Dor55J5NonJthermal5XJrays5J5TeV5GammaJrays5J5Containing5young5SNR555(Age:52.2−4.95kyr,5Kavanagh+14)5HS+16 in prep.

Image:5CO5Contours5:5XJrays5(0.5J7.05keV)

30 Dor CJ5Superbubble5in5305Dor55J5NonJthermal5XJrays5J5TeV5GammaJrays5J5Containing5young5SNR555(Age:52.2−4.95kyr,5Kavanagh+14)5HS+16 in prep.

Image:5HI5(Kim+03)5Contours5:5XJrays5(0.5J7.05keV)

ISM5associated5superbubbles

Preliminary5Result…

Preliminary5Result…

Summary outstanding issues

solutions[1] Origin of gamma-rays (hadronic and/or leptonic)"Spatial comparison between the ISM and gamma-rays[2] Acceleration models including more realistic conditions"Shock-cloud interaction model"Other acceleration mechanisms ?
(non-liner, 2nd order Fermi, magnetic reconnection etc…)[3] Gamma-ray obs. with high sensitivity + angular resolutions"Cherenkov Telescope Array (CTA)[4] To reveal an universality"Extend to the distant sources including the LMC SNRs

MulBJmessenger5search5plays5an5essenBal5role5in5understanding5the5origin5of5galacBc5cosmicJrays!