Modeling the Spectral Energy Distribution of the radio galaxy IC310

0.76 MB·

by  N. Fraija

DRAFTVERSIONJANUARY24,2017
PreprinttypesetusingLATEXstyleemulateapjv.5/2/11
MODELINGTHESPECTRALENERGYDISTRIBUTIONOFTHERADIOGALAXYIC310
N.FRAIJA1,A.MARINELLI2,A.GALVA´N-GA´MEZ1ANDE.AGUILAR-RUIZ1
1InstitutodeAstronom´ıa,UniversidadNacionalAuto´nomadeMe´xico,CircuitoExterior,C.U.,A.Postal70-264,04510Me´xicoCity,Me´xico
2I.N.F.N.&PhysicsInstitutePoloFibonacciLargoB.Pontecorvo,3-56127Pisa,Italy
DraftversionJanuary24,2017
ABSTRACT
TheradiogalaxyIC310locatedinthePerseusClusterisoneofthebrightestobjectsintheradioandX-ray
bands,andoneoftheclosestactivegalacticnucleiobservedinvery-highenergies.InGeV-TeVγ-rays,IC310
7
wasdetectedinlowandhighfluxstatesbytheMAGICtelescopesfromOctober2009toFebruary2010.Taking
1
intoaccountthatthespectralenergydistribution(SED)uptoafewGeVseemstoexhibitadouble-peakfeature
0
andthatasingle-zonesynchrotronself-Compton(SSC)modelcanexplainallofthemultiwavelengthemission
2
exceptforthenon-simultaneousMAGICemission,weinterpret,inthiswork,themultifrequencydatasetofthe

n radiogalaxyIC310inthecontextofhomogeneoushadronicandleptonicmodels. Intheleptonicframework,
a wepresentamulti-zoneSSCmodelwithtwoelectronpopulationstoexplainthewholeSEDwhereasforthe
J hadronicmodel,weproposethatasingle-zoneSSCmodeldescribestheSEDuptoafewGeVsandneutralpion

2 decayproductsresultingfrompγ interactionscoulddescribetheTeV-GeVγ-rayspectra. Theseinteractions
2 occurwhenFermi-acceleratedprotonsinteractwiththeseedphotonsaroundtheSSCpeaks. Weshowthat,in
the leptonic model the minimum Lorentz factor of second electron population is exceedingly high γ ∼ 105
e
] disfavoringthismodel,andinthehadronicmodeltherequiredprotonluminosityisnotextremelyhigh∼1044
E
erg/s,providedthatchargeneutralitybetweenthenumberofelectronsandprotonsisgiven.CorrelatingtheTeV
H
γ-ray and neutrino spectra through photo-hadronic interactions, we find that the contribution of the emitting
. regionofIC310totheobservedneutrinoandultra-high-energycosmicrayfluxesarenegligible.
h
p Subject headings: Galaxies: active – Galaxies: individual (IC310) – radiation mechanism: nonthermal –
- gammarays: general
o
r
t
s 1. INTRODUCTION
a
[ Activegalacticnuclei(AGN)areoneofthemostextremeastrophysicalsourcesintheUniverse. Thesearecompact,extremely

luminousandoftenmostvariableshortestobservedfrequencies.Perpendiculartotheplaneoftheaccretionmaterial,magnetically
1
drivenandcollimatedrelativisticplasmaoutflowsareejectedawayfromtheAGN(Lovelace&Kronberg2013;Lovelace1987;
v
Lovelaceetal.2002).They,extensivelystudiedfromradiowavelengthstovery-high-energy(VHE)γ-rays,areusuallyexplained
3
by the non-thermal synchrotron self-Compton (SSC) model (Abdo & et al. 2010; Fraija et al. 2012; Tavecchio et al. 1998),
7
although hadronic models in some cases have been required (Abdo et al. 2011; Aharonian 2002; Mu¨cke & Protheroe 2001;
1
Atoyan&Dermer2003).
6
Theradiogalaxies,atypeofAGN,areellipticalgalaxieswithtwogiantlobesandmisleading-bipolarjetsofgasextendingaway
0
fromacentralnucleus. Theradiogalaxiesaregenerallydescribedbythestandardnon-thermalSSCmodel(Abdo&etal.2010;
.
1 Fraijaetal.2012;Tavecchioetal.1998),low-energyemission(fromradiotooptical)fromsynchrotronradiationandHEphotons
0 (from X-rays to γ-rays) from inverse Compton scattering emission. This model with only one electron population, predicts a
7
spectral energy distribution (SED) that can be hardly extended up to higher energies than a few GeVs (Georganopoulos et al.
1
2005; Lenain et al. 2008). Therefore, some authors have claimed that the emission in the GeV - TeV energy range may have
:
v originindifferentphysicalprocesses(Brown&Adams2011;Georganopoulosetal.2005). TheradiogalaxyIC310,alsocalled
i B0313+411andJ0316+4119,locatedinthePerseusClusterataredshiftofz=0.00189(Bernardietal.2002)isoneofbrightest
X
objectsofthePerseusclusterofgalaxiesintheradioandX-raybands. Duetoitskiloparsec-scaleradiomorphology,ithasbeen
r classifiedasahead-tailor,morespecifically,narrow-angletailradiogalaxy(Ferettietal.1998;Sijbring&deBruyn1998). This
a
radio galaxy being one of the fourth closest AGN observed in VHE γ-rays (after Cen A, M87 and NGC1275) is an excellent
sourceforstudyingthephysicsofrelativisticoutflows.Ithasbeendetectedabove30GeVbyLargeAreaTelescope(LAT)-Fermi
(Neronov et al. 2010). They reported the flux in two energy bands, F = 2.3+2.3 ×10−11 erg cm−2 s−1 between 30
30−100 −1.2
and 100 GeV, and F = 1.4+1.1 ×10−11 erg cm−2 s−1 from 100 to 300 GeV. In addition, this source was detected by
100−300 −0.6
MAGICtelescopesatahighstatisticalsignificanceof7.6σin20.6hrofstereodata. TheTeVγ-rayfluxof(3.1±0.5)×10−12
cm−2 s−1 (between2009Octoberand2010February)wasflatwith adifferentialspectralindexof2.00±0.14(Aleksic´ 2010).
The indications for flux variability on times scales of months and years were reported. The variability time scales of years
was confirmed by the non-detection of the source reported in 2010 August - 2011 February (Aleksic´ & et al. 2012). A re-
analysisoftheMAGICstereo-observationtakenduringthesameperiodwasperformed(Aleksic´ etal.2014b). Afterfittingthe
spectraathighandlowstatebetween0.12and8.1TeVwithasimplepowerlaw,theobservedfluxesreportedbyauthorswere
(4.28±0.21±0.73)×10−12 TeV−1 cm−2 s−1 and(0.608±0.037±0.11)×10−12 TeV−1 cm−2 s−1,respectively(Aleksic´
etal.2014b).
[email protected],[email protected],[email protected]@astro.unam.mx
2 Fraijaetal.
Located at the South Pole, the IceCube telescope was designed to detect the interactions of neutrinos. With a volume of one
cubickilometeroficeandalmostfouryearsofdatataking,theIceCubetelescopereportedwiththeHigh-EnergyStartingEvents
(HESE)1catalogasampleof54extraterrestrialneutrinoeventsintheTeV-PeVenergyrange. Arrivaldirectionsoftheseevents
are compatible with an isotropic distribution and possible extragalactic origin (Ahlers & Murase 2014; Gaggero et al. 2015).
HadronicprocessesproducingafractionoftheobservedneutrinoeventsrevealedbytheIceCubeviatheaccelerationofcomic
rays in radio galaxies have been explored (Reynoso et al. 2011; Khiali & de Gouveia Dal Pino 2016; Sahu et al. 2012; Fraija
2014a,b;Marinellietal.2014).
InthisworkweintroduceleptonicandhadronicmodelstodescribethebroadbandSEDobservedintheradiogalaxyIC310.Inthe
leptonicframework,wepresentamulti-zoneSSCmodelwithtwoelectronpopulationstoexplainthewholeSEDwhereasforthe
hadronicmodel,weproposethatasingle-zoneSSCmodeldescribestheSEDuptoafewGeVsandneutralpiondecayproducts
theproton-photon(pγ)interactionscouldmodeltheγ-rayspectra(highandlowstate)attheGeV-TeVenergyrange.Correlating
theTeVγ-rayandneutrinospectrathroughphoto-hadronicinteractions,weestimatetheneutrinoandultra-high-energycosmic
ray(UHECR)fluxes.
2. THEORETICALMODEL
Injected electrons and protons are accelerated in the emitting region which moves at relativistic velocities. These particles
confined at the emitting region by magnetic fields are expected to cool down by synchrotron radiation, Compton scattering
emission and photo-hadronic processes. We hereafter use primes (unprimes) to define the quantities in a comoving (observer)
frame, the universal constants c=(cid:126)=1 in natural units and the values of cosmological parameters H = 71 km s−1 Mpc−1,
0
Ω =0.27,Ω =0.73(Spergeletal.2003).
m Λ
2.1. Synchrotronradiation
Kardashevet al.(1962) showedthat ifthe spectrumof injectedelectrons is ∝ γ−αe, then thespectrum varieswith timeas a
e
result of losses due to emission in the magnetic field. This variation differs for different energy intervals: N (γ ) = N γ−αe
e e 0,e e
for γ < γ < γ and N γ γ−(αe+1) for γ ≤ γ < γ , where N is the proportionality electron constant, α
e,min e e,c 0,e e,c e e,c e e,max 0,e e
is the power index of the electron distribution and γ are the electron Lorentz factors. The index i is min, c or max for
e,i
minimum,coolingandmaximum,respectively. Assumingthatafractionoftotalenergydensityisgiventoaccelerateelectrons
(cid:82)
U = m γ N (γ )dγ (m istheelectronmass),theelectronluminosityandtheminimumelectronLorentzfactorareL =
e e e e e e e e
4πδD2 rd2Ue and γe,min = m(eα(eα−e−2)1) NUee, respectively. Here r√d is the size of the emitting region and δD is Doppler factor. The
electron distribution submerged in a magnetic field B = 8πU cools down following the cooling synchrotron time scale
B
t(cid:48)c = 34mσTe UB−1γe−1, with σT = 6.65×10−25cm2 the Thomson cross-section. Comparing the synchrotron time scale with
thedynamicscalet(cid:48)d (cid:39) rd/δD, wegetthatthecoolingLorentzfactorisγe,c = 34mσTe (1+Y)−1δDUB−1rd−1. HeretheCompton
(cid:16) (cid:17)1/2
parameterisY = ηUe for ηUe (cid:28) 1and ηUe for ηUe (cid:29) 1,withη = (γ /γ )2−αe givenforslowcoolingandη = 1forfast
UB UB UB UB e,c e,min
cooling(Sari&Esin2001). Byconsideringthataccelerationt(cid:48) (cid:39)(cid:112)πm /q U−1/2γ andcoolingtimescalesaresimilar,itispossibleto
acc 2 e e B e
writethemaximumelectronLorentzfactorasγ =(cid:16) 9qe2 (cid:17)1/4 U−1/4whereq istheelectriccharge.Itisworthnotingthatthedirection
e,max 8πσ2 B e
T
oftheaveragemagneticfieldattheshockisshowntohavealargeeffect. Iftheperpendiculardiffusioncoefficientismuchsmallerthanthe
parallelcoefficient,particlescangainmuchmoreenergyiftheshockisquasi-perpendicularthanquasi-parallel. Inthiscase,theacceleration
(cid:113)
timescalecouldbeevenshorter(Jokipii1987). Takingintoaccountthesynchrotronemission(cid:15) (γ )= 8πqe2 δ U1/2γ2 andfromthe
γ e,i m2e D B e,i
electronLorentzfactors,thesynchrotronbreakenergiesare
√
8πq
(cid:15)syn = e δ U1/2γ2 ,
γ,m √me D B e,min
9 2πq m
(cid:15)syn= e e (1+Y)−2δ3 U−3/2r−2,
γ,c 8σ2 D B d
T
3q2
(cid:15)syn = e δ . (1)
γ,max m σ D
e T
Theobservedsynchrotronspectrumcanbewrittenas(Longair1994;Rybicki&Lightman1986)
(cid:2)(cid:15)2γN((cid:15)γ)(cid:3)γ,syn =Aγ,syn((((cid:15)(cid:15)(cid:15)(cid:15)sγsγsγ(cid:15)(cid:15)sγyyyyγγ,,,,nnnmmmnc )))−−43ααee22−−33((cid:15)(cid:15)γγ,c)−αe2−2, (cid:15)(cid:15)(cid:15)γsγsγyy,,mcnn<<<(cid:15)sγ(cid:15)y,(cid:15)γmnγ,<<(cid:15)(cid:15)sγsγy,y,mncna,x, (2)
where
4σ
A = T d2δ3 U r3N γ2 , (3)
γ,syn 9 z D B d e e,min
istheproportionalityconstantofsynchrotronandd isthedistancebetweenIC310andEarth.
z
1http://icecube.wisc.edu/science/data/HE-nu-2010-2014
TheradiogalaxyIC310 3
2.2. Comptonscatteringemission
Fermi-acceleratedelectronsintheemittingregioncanupscattersynchrotronphotonsuptohigherenergiesas(cid:15)ssc (cid:39)γ2 (cid:15)syn .
γ,(m,c,max) e,(min,c,max) γ,(m,c,max)
FromtheelectronLorentzfactorsandthesynchrotronbreakenergies(eq. 1),wegetthattheComptonscatteringbreakenergiesaregivenin
theform
√
8πq
(cid:15)ssc = e δ U1/2γ4 ,
γ,m m√e D B e,min
81 2πq m3
(cid:15)ssc= e e (1+Y)−4δ5 U−7/2r−4,
γ,c 128σ4 D B d
T
9q3
(cid:15)ssc = √ e δ U−1/2. (4)
γ,max 2 2πm σ2 D B
e T
TheComptonscatteringspectrumobtainedasafunctionofthesynchrotronspectrum(eq.2)is
(cid:2)(cid:15)2γN((cid:15)γ)(cid:3)γ,ssc =Aγ,ssc((((cid:15)(cid:15)(cid:15)(cid:15)sγsγsγ(cid:15)(cid:15)sγsssγγ,,,scc,mmmccc)))−−43ααee22−−33((cid:15)(cid:15)sγγs,cc)−αe2−2 (cid:15)(cid:15)(cid:15)γsγsγss,,ccmc<<<(cid:15)sγ(cid:15)s,(cid:15)γmcγ<,<(cid:15)(cid:15)sγsγs,scm,cca,x,
(5)
whereA =Y [(cid:15)2N ((cid:15) )]syn istheproportionalityconstantofinverseComptonscatteringspectrum.
γ,ssc γ γ γ max
2.3. Photo-hadronicInteractions
RadiogalaxieshavebeenproposedaspowerfulacceleratorsofchargedparticlesthroughtheFermiaccelerationmechanism(Dermeretal.
2009), magnetic reconnection (Khiali et al. 2015; Lovelace et al. 2005) and the magnetized accretion disk working as an electric dynamo
(Lovelace1976;Lovelaceetal.1987,1994).Weconsideraprotonpopulationdescribedasasimplepowerlawgivenby
(cid:18) (cid:19)
dN
=A E−αp, (6)
dE p p
p
withA theproportionalityconstantandα thespectralpowerindexoftheprotonpopulation.Fromeq.(6),theprotondensitycanbewritten
p p
as U = Lp with the proton luminosity given by L = 4πd2A (cid:82) E E−αpdE . Fermi-accelerated protons lose their energies by
p 4πδ2 r2 p z p p p p
D d
electromagneticchannelsandhadronicinteractions. ElectromagneticchannelssuchasprotonsynchrotronradiationandinverseComptonwill
notbeconsideredhere,wewillonlyassumethatprotonscooldownbypγinteractionsattheemittingregionoftheinnerjet.Charged(π+)and
neutral(π0)pionsareobtainedfrompγinteractionwithafractionof2/3and1/3forpπ0andnπ+,respectively.Afterthatneutralpiondecays
intophotons,π0 → γγ,carrying20%(ξ = 0.2)oftheproton’senergyE . Theefficiencyofthephoto-pionproductionis(Stecker1968;
π0 p
Waxman&Bahcall1997)
t r (cid:90) (cid:90) dn
f (cid:39) dyn = d d(cid:15) σ ((cid:15) )ξ (cid:15) dxx−2 γ((cid:15) =x), (7)
π0 t 2γ2 γ π γ π0 γ d(cid:15) γ
π0 p γ
wheredn /d(cid:15) isthespectrumofseedphotons,σ ((cid:15) )isthecrosssectionofpionproductionandγ istheprotonLorentzfactor. Solving
γ γ π γ p
theintegralsweobtain
σ ∆(cid:15) ξ L (cid:18)(cid:15)πγ,0c(cid:19)−1(cid:18)(cid:15)πγ0(cid:19) (cid:15) <(cid:15)π0
fπ0 (cid:39) 4pπγδ2 rres(cid:15)π0 (cid:15)γ,IC (cid:15)0 (cid:15)0 γ γ,c (8)
D d pk,ic res 1 (cid:15)π0 <(cid:15) ,
γ,c γ
where ∆(cid:15) =0.2 GeV, (cid:15) (cid:39) 0.3 GeV, (cid:15) is the energy of the second SSC peak, (cid:15) is the normalization energy and (cid:15)π0 is the break
res res pk,ic 0 γ,c
photon-pionenergyis(cid:15)π0 (cid:39) 31.87GeVδ2 (cid:0)(cid:15)pk,ic(cid:1)−1. Itisworthnotingthatthetargetphotondensityisn (cid:39) Lγ,IC andtheoptical
γ,c D MeV γ 4πrd2(cid:15)pk,ic
depthisτ (cid:39) Lγ,ICσT . Takingintoaccountthatphotonsreleasedintherange(cid:15) to(cid:15) +d(cid:15) byprotonsintherangeE andE +dE
γ 4πrdδD(cid:15)pk,ic γ γ γ p p p
aref E (dN/dE) dE =(cid:15) (dN/d(cid:15)) d(cid:15) ,thenphoto-pionspectrumisgivenby
π0 p p p π0,γ π0,γ π0,γ
(cid:2)(cid:15)2N((cid:15) )(cid:3) =A (cid:18)(cid:15)(cid:15)πγ0,0c(cid:19)−1(cid:16)(cid:15)(cid:15)γ0(cid:17)−αp+3 (cid:15)γ <(cid:15)πγ,0c (9)
γ γ γ,π0 pγ(cid:16)(cid:15)(cid:15)γ0(cid:17)−αp+2 (cid:15)πγ,0c <(cid:15)γ,
wheretheproportionalityconstantA isintheform
pγ
L σ ∆(cid:15) (cid:15)2 (cid:16) 2 (cid:17)1−αp
A = γ,IC pγ res 0 ξπ0 A . (10)
pγ 4πδ2 r (cid:15) (cid:15) p
D d pk,ic res
ThepreviousequationsindicatethatthevalueofA isnormalizedusingtheTeVγ-rayflux.
p
4 Fraijaetal.
3. HIGHENERGYNEUTRINOEXPECTATION
Photo-hadronic interactions in the emitting region (see subsection 3.2) also generate neutrinos through the charged pion decay products
(π± → µ±+ν /ν¯ → e±+ν /ν¯ +ν¯ /ν +ν /ν¯ ). TakingintoaccountthedistanceofIC310,theneutrinofluxratiocreatedonthe
µ µ µ µ µ µ e e
source(1: 2: 0)willarriveonthestandardratio(1: 1: 1;e.g. seeBecker2008). Theneutrinospectrumproducedbythephoto-hadronic
interactionsis
(cid:16) (cid:17)2
(cid:2)E2N((cid:15) )(cid:3) =A (cid:15)2 E(cid:15)0ν Eν <Eν,c (11)
ν ν ν ν 0(cid:16)E(cid:15)0ν(cid:17)2−αν Eν,c <Eν,
withtheproportionalityfactorgivenby,A =A (cid:15)−22−αp (seeHalzen2007,andreferencetherein). Theneutrinofluxisdetectedwhenit
ν pγ 0
interactsinsidetheinstrumentedvolume. ConsideringtheprobabilityofinteractionforaneutrinowithenergyE inaneffectivevolumewith
ν
density(ρ ),thenumberofexpectedneutrinoeventsafteraperiodoftimeT is
ice
(cid:90) (cid:18)E (cid:19)−αp
N ≈ Tρ N (cid:15) V (E )σ (E )A ν dE , (12)
ev ice A 0 eff ν νN ν ν (cid:15) ν
Eν,th 0
whereN istheAvogadronumber,σ (E )isthethechargedcurrentcrosssection,E istheenergythresholdandV istheeffective
A νN ν ν,th eff
volumeofIceCube.
4. ULTRA-HIGH-ENERGYCOSMICRAYS
RadiogalaxieshavebeenproposedaspotentialsourceswhereparticlescouldbeaccelerateduptoUHEs(Ginzburg&Syrovatskii1963;
Shklovskii1963). Weconsiderthattheprotonspectrumgivenbyasimplepowerlawisspreadoutashighascanbeconfinedintheemitting
region.
4.1. HillasCondition
Requiringthatsupermassiveblack holes(BHs)havethepowertoaccelerateparticlesup toUHEsthroughFermiprocesses, protonsac-
celeratedintheemittingregionareconfinedbytheHillascondition(Hillas1984). Althoughthisrequirementisanecessaryconditionand
accelerationofUHECRsinAGNjets(Muraseetal.2012;Razzaqueetal.2012;Jiangetal.2010),itisfarfromtrivial(seee.g.,Lemoine&
Waxman(2009)foramoredetailedenergeticlimits).TheHillascriterionisdefinedby
Zq
E (cid:39) e Br Γ, (13)
p,max φ d
√
1± 1−(1−cos2θ)(1+δ2 cos2θ)
whereZistheatomicnumber,φ(cid:39)1istheaccelerationefficiencyfactorandΓ= D isthebulkLorentzfactorwith
δD(1−cos2θ)
θistheviewingangle.Similarly,supposingthattheBHjethasthepoweralsotoaccelerateparticlesuptoUHEsthroughFermiprocesses,then
duringflaringintervalsforwhichtheapparentisotropicluminositycanreach≈1045ergs−1andfromtheequipartitionmagneticfield(cid:15) the
B
maximumparticleenergyofacceleratedUHECRscanachievevaluesashighas(Dermeretal.2009)
Zq (cid:15)1/2 (cid:18) L (cid:19)1/2
E ≈1020 e B p eV (14)
max φΓ 1045erg/s
4.2. Deflections
UHECRstravelingfromsourcetoEartharerandomlydeviatedbygalactic(B )andextragalactic(B )magneticfieldswhichplayim-
G EG
portant roles on cosmic rays. Requiring that magnetic fields are homogeneous and quasi-constant, the deflection angle due to the B is
G
ψ (cid:39) 4◦(cid:16)57EeV(cid:17)(cid:82)LG| dl × BG |andduetoB isψ (cid:39) 4◦(cid:16)57EeV(cid:17) (cid:16) LEG (cid:17)21 (cid:16) lc (cid:17)12 (cid:16)BEG(cid:17)(Stanev1997),whereL
G Ep,th 0 kpc 4µG EG EG Ep,th 100Mpc 1Mpc 1nG G
correspondstothedistanceofourGalaxy(20kpc),l isthecoherencelengthandE isthethresholdprotonenergy. Duetothestrengthof
c p,th
extragalactic(B (cid:39)1nG)andgalactic(B (cid:39)4µG)magneticfields,UHECRsaredeflected;firstly,ψ (cid:39)4◦andafterψ (cid:39)4◦,between
EG G EG G
thetruedirectiontothesourceandtheobservedarrivaldirection,respectively.Estimationofthedeflectionanglescouldassociatethetransient
UHECRsourceswiththeHEneutrinoandγ-rayfluxes.
4.3. UHECRFlux
TelescopeArrayexperiment— . Withanareaof∼700km2,TelescopeArray(TA)experimentatMillardCountry(Utah)studyUHECRs
withenergiesabove57EeV(fordetailsseeAbu-Zayyad&etal.2012). TheTAexposureis Ξtopω(δs)=(5)7 ×102km2yr,withω(δ )the
Ω π s
exposurecorrectionfactor(Sommers2001).
Pierre Auger observatory— . Designed to determine the arrival directions and energies of cosmic rays above 57 EeV, the Pierre Auger
observatory(PAO)ismadebyfourfluorescencetelescopearraysand1600surfacedetectors(fordetailsseePierreAugerCollaboration&etal.
2008).Theexposureofthisobservatoryis 9×103ω(δs)km2yr(PierreAugerCollaboration&etal.2007,2008).
π
TheradiogalaxyIC310 5
TheHighResolutionFly’seyeobservatory— .TheHiResobservatorywithanexposureof(3.2-3.4)×103km2yearsrmeasuredthefluxof
UHECRsusingthestereoscopicairfluorescencetechniquefrom1997to2006(fordetailsseeAbbasietal.2005;HighResolutionFly’SEye
Collaborationetal.2009).
TheexpectednumberandthefluxofUHECRsaboveanenergyE aregivenby
p,th
Ξt ω(δ ) (cid:90)
N = op s A E−αpdE , (15)
UHECR (α −1)Ω p p p
p Ep,th
and
(cid:90)
F =A E E−αpdE , (16)
UHECR p p p p
Ep,th
respectively,wherethevalueofA isnormalizedwiththeTeVγ-rayfluxes(eq.10).
p
5. DISCUSSIONANDRESULTS
Consideringthattheone-zonehomogeneousmodelsarethemostsuccessfulmodelstodescribetheSEDofradiogalaxiesandtakinginto
accountthatSSCmodelswithonlyoneelectronpopulationhardlyexplainstheTeVγ-rayfluxes(Georganopoulosetal.2005;Lenainetal.
2008),weanalyzethemultifrequencydatasetoftheradiogalaxyIC310inthecontextofhomogeneoushadronicandleptonicmodels. Inthe
leptonicmodel,wetakeintoaccounttwoelectronpopulationstomodelthebroadbandSEDwhereasinthehadronicmodels,weconsiderthat
electromagneticspectrumcomesfromelectronsandprotonsco-acceleratedatthesameemittingregionofthejet.
5.1. Twoelectronpopulations
Thesimplestleptonicmodeltypicallyrequiredtodescribetheemissionfromradiogalaxysourcesistheone-zoneSSC.Withinthispicture,
fromradiotoopticalemissionisproducedbysynchrotronradiationfromelectronsinahomogeneous,randomly-orientedmagneticfield(B)
andfromX- toγ-raysareproduced byinverseComptonscatteringof thesynchrotronphotonsbythe sameelectronswhichproducethem.
However,theone-zoneSSCmodelisnotsufficienttoexplaintheTeVemissionfromthecore(Georganopoulosetal.2005;Lenainetal.2008).
Therefore,weintroduceasecondelectronpopulationtodescribetheMAGICemissionandapossibleexplanationfortheMAGICobservations
is that the TeV emission is produced by another emitting region. Using the method of Chi-square χ2 minimization as implemented in the
ROOTsoftwarepackage(Brun&Rademakers1997),wefittheSEDofIC310,asshowninFigure12.
Fromeqs. (1)and(4),wereportinTable1thevaluesobtainedofelectrondensity,magneticfield,Dopplerfactorandsizeofemittingregion,
thatdescribethebroadbandSEDofIC310. Inthisfit,werequiretheeffectoftheextragalacticbackgroundlight(EBL)absorption(Frances-
chinietal.2008)andadoptedthetypicalvaluesreportedintheliteraturesuchasthedistanceofIC310(d =80Mpc)andtheviewingangle
z
(θ = 16◦) (Sitarek et al. 2015; Aleksic´ et al. 2014a; Ackermann et al. 2013). Derived quantities such as the electron luminosities and the
electrondensities,themagneticfields,etc,arealsoreported.Table1showsalltheparametervaluesobtained,usedandderivedinandfromthe
fit.
Firstpopulation Secondpopulation Secondpopulation
Lowstate Highstate
Obtainedquantities
δd 1.8 3.9 4.9
B(G) 0.12 0.15 0.125
rd(cm) 3.98×1016 2.29×1015 2.38×1015
Ne(cm−3) 3.61×102 1.58×104 2.51×104
αe 3.03 3.14 3.16
Usedquantities
γe,min 7.1×102 3.2×105 3.3×105
Derivedquatities
γe,max 1.34×108 1.20×108 1.31×108
UB (erg/cm3) 5.73×10−4 8.95×10−4 6.21×10−4
Ue (erg/cm3) 1.75 71.14 109.07
Le (erg/s) 3.38×1044 1.02×1044 9.85×1044
Table1.Parametersobtained,derivedandusedofleptonicmodeltofitthespectrumofIC310.
As shown in Table 1, the second electron population that describes the TeV-γ-ray fluxes in high and low states is confined in one emitting
region,andthefirstelectronpopulationthatexplaintheSEDuptoafewGeVisconfinedinanemittingregionlargerthanthatwhichconfines
tothesecondpopulation. Fromthedifferentvaluesobtainedofemittingradiusforthefirstandsecondelectronpopulationcanbeconcluded
thatamulti-zoneSSCemissionisrequiredtoexplainthebroadbandSED.ToobtainagooddescriptionoftheTeV-γ-rayfluxes,theelectron
densityrequiredtomodelthehighstatemustbehigherthanthatusedtodescribethelowstate. Althoughthelargevalueoftheminimum
LorentzfactorusedforthefirstpopulationimpliesthatelectronsareefficientlyacceleratedbytheFermimechanism,thevaluerequiredforthe
secondpopulationisunrealistic.
2ThefittingprocesswasintegratedintoapythonscriptthatcalledtheROOTroutinesviathepyrootmodule.TheIC310datawerereadfromafileandwritten
intoanarraywhichwasthenfittedwithpyroot.Thecurvesaresmoothedusingthesmoothsbezierfunctiongiveninthegnuplotsoftware(gnuplot.sourceforge.net)
6 Fraijaetal.
5.2. Oneelectronandprotonpopulation
IfrelativisticprotonsarepresentedinthejetofIC310,hadronicinteractionsmustbeconsideredformodelingthesourceemission. Here,
theultra-relativisticelectronsinjectedinthemagnetizedemittingregionloseenergypredominantlythroughsynchrotronemission, thatturn
onservingastargetphotonfieldforinverseComptonscatteringwiththesameelectronpopulation. Theinstantaneouslyinjectedrelativistic
protonsinteractwiththesecondSSCpeak.TheresultingGeV-TeVphotonsfrompiondecayproductscorrespondtotheenergybandobserved
by the MAGIC telescopes. Again, using the method of Chi-square χ2 minimization as implemented in the ROOT software package (Brun
& Rademakers 1997), we fit the SED of IC310, as shown in Figure 23. From both panels in Fig. 2 can be seen that pion decay products
comingfromphoto-hadronicinteractionscanreproducetheMAGICemissionforhighandlowactivitystateswithoutdescribingotherdata.
Forthesefits,wehaveconsideredagaintheeffectoftheEBLabsorption(Franceschinietal.2008)andadoptedthetypicalvaluesreportedin
theliteraturesuchasatheviewingangle(θ = 16◦),theobservedluminosities,thedistanceofIC310(d = 80Mpc),theminimumLorentz
z
factors and the energy normalizations (Sitarek et al. 2015; Aleksic´ et al. 2014a; Ackermann et al. 2013; Aleksic´ et al. 2014b; Eisenacher
et al. 2013). Additionally, we have required similar values of power indexes for the injected relativistic electron and protons (α = α ;
e p
2011ApJ...736..131A).Table2showsalltheparametervaluesobtained,usedandderivedinandfromthefits.
AsshowninTable2,theprotonluminosityobtainedwithourmodelcorrespondstoasmallfraction(∼ 10−2)oftheEddingtonluminosity
L ∼ 3.77×1046 erg/s, which was obtained taking into account the BH mass reported in IC310 (3×108M ; Aleksic´ et al. 2014a).
Edd (cid:12)
Byconsideringthataccelerationt(cid:48) (cid:39) (cid:112)πm /q U−1/2γ andcoolingtimescalesforprotonsaresimilar,themaximumprotonLorentz
acc 2 p e B p
(cid:18) (cid:19)1/4
factorisγ = 9qe2 U−1/4 whereσ = m2e σ . Bell(1978)discussedtheparticledistributionaccelerationproducedbya
p,max 8πσT2,p B T,p m2p T
shockfront. Consideringthatparticlesneedtobeabletopassthroughtheshockwithoutbeingstronglydeflected,authorfoundtheresulting
energyspectrumforprotonsandelectrons. Althoughthiscalculationwasperformedforaccelerationofnon-relativisticparticles,canbeseen
thatasthevelocityoftheshockincreases,theratioofprotonandelectronsdensitiesdecreases,tendingtobesimilar(seetable1,Bell1978).
Due to the fact that the minimum Lorentz factor cannot be determined just assuming the standard scenario of injection and acceleration, it
isreasonabletousechargeneutralitytojustifyacomparablenumberofelectronandprotons(Bo¨ttcheretal.2013;Sikoraetal.2009;Abdo
etal.2011;Petropoulouetal.2014). Requiringthatelectronandprotonnumberdensitiesaresimilar(N (cid:39)N ),wehavecalculatedthatthe
e p
minimumprotonLorentzfactorsusedtodescribetheTeVγ-rayfluxesinhighandlowstatesareγ =8×103and5×104,respectively.
p,min
Itisworthmentioningthatthevalueofγ =1isexcludedduetotheprotonluminositiesbecomemuchhigherthanEddingtonluminosity
p,min
(L (cid:28)L ).Thelargevalueofγ providedbyourmodelimpliesthatelectronsareefficientlyacceleratedbytheFermimechanismonly
Edd p e,min
abovethisenergyandthatbelowthisenergytheyareacceleratedbyadifferentmechanismthatproducesthehardelectrondistribution.
Highstate Lowstate
Obtainedquantities
δd 1.9 1.8
B(G) 1.3 1.2
rd(cm) 4.5×1015 5.0×1015
Ne(cm−3) 2.1×104 1.9×104
αe 3.05 3.07
Usedquantities
αp 3.05 3.07
(cid:15)0(TeV) 1 1
γe,min 1×103 1×103
LIC (erg/s) 1×1043 1×1043
Derivedquatities
γe,max 4.25×107 4.25×107
γp,min 5.0×104 8.0×103
γp,max 2.8×1010 2.8×1010
(cid:15)peak (MeV) 0.2 0.2
(cid:15)π0,γ,c (TeV) 0.52 0.52
UB (erg/cm3) 5.7×10−2 5.7×10−2
Ue (erg/cm3) 16.3 16.3
Up (erg/cm3) 17.1 27.58
Lp (erg/s) 3.65×1044 4.3×1044
Le (erg/s) 2.95×1044 2.95×1044
Ep,max (EeV) 24.1 24.2
NUHECRs 0.28 0.09
Nev 0.16 0.02
Table2.Parametersobtained,derivedandusedoflepton-hadronicmodeltofitthespectrumofIC310.
AfterfittingtheTeVγ-rayspectraoftheradiogalaxyIC310withtheneutralpiondecayproducts,fromeq.(12)wehaveobtainedtheneutrino
fluxesandeventsexpectedfromIC310. Figure3showsasky-mapwiththe54neutrinoeventsreportedbytheIceCubecollaboration,the72
and27UHECRscollectedbyTAandPAOexperiments,respectively. Inaddition,wehaveincludedacircularregionof5◦aroundIC310. As
canbeseen,thereareneitherneutrinotrackeventsnorUHECRsassociatedaroundIC310.
ByassumingthattheBHintheradiogalaxyIC310hasthepotentialtoaccelerateparticlesuptoUHEs,themaximumenergyachievedis24.1
3Thefittingprocesswasperformedsimilarlytoreportedwiththeleptonicmodel
TheradiogalaxyIC310 7
(24.2)EeVwhentheTeVγ-rayfluxinhigh(low)activityisconsidered. Thepreviousresultindicatesthatitisimprobablethatprotonscan
beacceleratedtoenergiesashighas57EeV,althoughplausibleforheavieracceleratedions. Fromeq. 13canbeseenthatanyfluctuationin
thestrengthofmagneticfieldand/orsizeofemittingregioncouldconfineprotonsabove57EeV.InterpretingtheTeVgamma-rayspectraas
pγinteractionsandextrapolatingtheacceleratedprotonspectrumuptoenergieshigherthan1EeV,theUHEprotonspectraexpectednotonly
forIC310butalsoforCenAandM87areplottedwiththeUHECRspectracollectedwithPAO(ThePierreAugerCollaborationetal.2011),
HiRes(HighResolutionFly’SEyeCollaborationetal.2009)andTA(Abu-Zayyadetal.2013)experimentasshowninFigure4.Leftpanelin
thisfigureshowsthattheUHECRfluxfromthehighstateofIC310islower(higher)thantheCenA(M87)andtherightpaneldisplaysthat
theUHECRfluxfromthelowstateofIC310isthelowestflux. Inbothpanelsareexhibitedthatthecontributionsoftheemittingregionsto
theUHECRfluxesarenegligible. TakingintoaccounttheexposureofTAexperiment,wehaveestimatedthatthenumberofUHECRsabove
57EeVis0.09(0.28)whentheTeVγ-rayfluxinthelow(high)stateofactivityisconsidered.DuetothelargescaleoftheUniverseaswellas
strengthsandgeometriesofmagneticfields: extragalacticandgalactic(Dasetal.2008;Ryuetal.2010),Galacticwinds(Heesenetal.2016;
Lietal.2016;Wiegertetal.2016),magneticwinds(Parker1958;Everett&Zweibel2011),magneticturbulence(Federrath2013;Ryuetal.
2008), UHECRs are deflected between the true direction to the source, and the observed arrival direction. Ryu et al. (2010) estimated that
thedeflexionanglebetweenthearrivaldirectionofUHEprotonsandtheskypositionisquitelargewithameanvalueof< θ >(cid:39) 15◦. In
T
addition,Dasetal.(2008)foundthatforobserverssituatedwithingroupsofgalaxieslikeours,about70%(35%)ofUHECRswithenergies
above60EeVemergeinside∼15◦(5◦),oftheastrophysicalobjectposition. WecanseethatnumberofUHECRscalculatedwithourmodel
isconsistentwiththosereportedbytheTAand/orPAOcollaborations. ItisworthnotingthatthelatterresultsreportedbyPAOsuggestedthat
UHECRsareheavynucleiinsteadofprotons(Abrahametal.2010).IfUHECRshaveaheavycomposition,thenasignificantfractionofnuclei
mustsurvivephotodisintegrationsintheirsources. Inthiscase,ultra-relativisticprotonscanbeconfinedbytheemittingregionssothatthese
particlescanachievemaximumenergiesof(cid:38)54EeVforZ(cid:38)2.
InterpretingtheTeVγ-rayfluxesfromIC310asπ0decayproductsfromthepγinteractions,thenthenumberofneutrinoeventsare0.16and
0.02whenthesefluxesinhighandlowstatesareconsidered,respectively. Asneutrinofluxeswereobtainedfromthepγinteractionsbetween
acceleratedprotonsandtheseedphotonsattheSSCpeaks,thenfluctuationsinthemagneticfield,Dopplerfactorand/oremittingradiuswould
change the seed photon density and finally the neutrino fluxes. These fluxes for IC310, Cen A and M87 were computed from relativistic
protonsinteractingwiththeseedphotonsaroundtheSSCpeaks,asshowninFigure5. Inthisfigurecanbeseentheneutrinospectrapeaking
aroundafewEeV,asexpectedfromtheinteractionswithseedphotonsaroundthesynchrotronpeak(thefirstSSCpeak)(Cuoco&Hannestad
2008). NeutrinofluxesatTeVenergiesareobtainedfromtheinteractionswithseedphotonsaroundtheinverseComptonscatteringpeak(the
secondSSCpeak). ConsideringtheneutrinoIceCubedata(Aartsenetal.2014)andtheupperlimitsatUHEssetbyIceCube(IC40;Abbasi
etal.(2011)), PAO(Abreuetal.2011), RICE(Kravchenkoetal.2012)andANITA(Gorhametal.2010)weconfirm, withourmodel, the
impossibilitytoobservenorTeVneitherEeVneutrinoeventsfromIC310. Itisworthnotingthatifheavynucleiwouldhavebeenconsidered
insteadofprotons,HEneutrinosfromUHEnucleiaresignificantlowerthantheneutrinofluxobtainedbyprotons.
IC310 CenA M87
Highstate Lowstate
δd 1.9 1.8 1.0 2.8
B(G) 1.3 1.2 3.6 1.61
rd(cm) 4.5×1015 5.0×1015 5.2×1015 2.1×1015
αp 3.05 3.07 2.81 2.80
γp,min 5.0×104 8.0×103 1.0×105 7.0×106
γp,max 2.8×1010 2.8×1010 6.73×1010 6.76×1010
(cid:15)peak (MeV) 0.2 0.2 0.1 0.5
(cid:15)π0,γ,c (TeV) 0.52 0.52 0.32 0.54
UB (erg/cm3) 5.7×10−2 5.7×10−2 0.52 0.10
Up (erg/cm3) 17.1 27.58 2.55 2.69
Lp (erg/s) 3.65×1044 4.3×1044 3.74×1043 4.89×1043
Ep,max (EeV) 24.1 24.2 40.1 6.55
NUHECRs 0.28 0.09 1.52 0.41
Table3.ComparisonofthevaluesfoundwiththehadronicmodelusedtodescribetheradiogalaxiesIC310,CenAandM87.
Inordertocomparetheparametersderivedwithourlepto-hadronicmodelforIC310,CenAandM87(Fraija&Marinelli2016),wesummarize
thesevaluesinTable3.Inthistablecanbenoticedseveralfeatures:i)althoughprotonluminositiesobtainedinIC310presentthelargestvalues,
thenumbersexpectedofUHECRsarethesmallest.ItisduetoIC310exhibitsthesoftestspectralindexes,ii)asexpected,thevaluesofDoppler
factors of IC 310 are in the range of Cen A and M87, which classify to IC310 as radio galaxy in stead of blazar and iii) the values of the
maximumenergiesthatprotonscanachieveintheaccelerationregionindicatethatonlyheavyionscanbeexpectedfromtheseradiogalaxies.
6. SUMMARYANDCONCLUSIONS
WehaveproposedleptonicandhadronicmodelstoexplainthebroadbandSEDobservedinIC310. Takingintoaccountthatoneelectron
populationthroughtheone-zoneSSCmodelcanexplainthemultiwavelengthemissionexceptforthenon-simultaneousMAGICemission,we
haverequiredadditionalelectronandprotonpopulations.Intheleptonicframework,theadditionalelectronpopulationisconfinedinadifferent
emittingregion,requiringaminimumLorentzfactorexceedinglyhighγ ∼105whichdisfavorsthismodel.Inthehadronicmodel,relativistic
e
protons co-accelerated with the electrons that explain the SED up to a few GeV interact with seed photons at the second SSC peak. The
requiredprotonluminositiesarenotextremelyhigh1044erg/s,providedthatthechargeneutralityconditionbetweenthenumberofelectrons
andprotonsisgiven.
CorrelatingtheTeVγ-rayandneutrinospectrathroughphoto-hadronicinteractions,wehaveestimatedthefluxesandnumberofeventsexpected
inIceCubetelescope,respectively. Wefoundthattheneutrinofluxproducedbypγ interactionscannotexplaintheastrophysicalfluxandthe
expectedν eventsintheIceCubetelescopeareconsistentwiththenonneutrinotrack-likeassociatedwiththelocationofIC310(Aartsenetal.
µ
8 Fraijaetal.
2013;IceCubeCollaboration2013;Aartsenetal.2014).
ByconsideringthattheprotonspectrumgivenbyasimplepowerlawcanbeextendeduptoUHEs,wehaveshownthatintheradiogalaxy
IC310neitherfromtheemittingregionnorotherregions(inflaringintervals)UHECRscouldbeexpected,whichisinagreementwiththeTA
andPAOobservations. Consideringtheflaringactivities,cosmicrayswouldneedaprotonluminosityhigherthantheEddingtonluminosity
whichisimplausible.
Ontheotherhand,IfUHECRshaveaheavycompositionassuggestedbyPAO(Abrahametal.2010),UHEheavynucleiinIC310couldbe
acceleratedatenergiesbelow∼57EeV,althoughthenumberofeventexpectedwouldbelessthanone.Itisworthnotingthatifradiogalaxies
arethesourcesofUHECRs,theiron-axiscounterparts(i.e. blazars,andflat-spectrumradioquasars)shouldbeconsideredamorepowerful
neutrinoemitters(Atoyan&Dermer2001;Dermeretal.2014). Infact,aPeVneutrinoshower-likewasrecentlyassociatedwiththeflaring
activityoftheblazarPKSB1424-418(Kadleretal.2016).
Severalluminousblazarswhicharerelatedwithquasar-typeAGNexhibitadouble-humpedshapecharacterizedbyalargeluminosityratio
betweenlowandhighenergyhumps. Sikoraetal.(2009)studiedthoseblazarswithluminosityratiobetween10-100whichposechallenges
tothestandardSSCandhadronicmodels. TheseauthorsconcludedthathadronicmodelscannotaccountfortheveryhardX-rayspectraand
alsorequireextremelyefficientaccelerationofrelativisticprotonstothehighestenergies,surpassingtheEddingtonluminosity.
Bo¨ttcheretal.(2013)proposedleptonicandhadronicmodelstodescribesomeofFermi-LAT-detectedblazars.Theyfoundthateitherleptonic
orhadronicmodelsprovideacceptablefittotheSEDsofmostoftheblazars, althoughinthehadroniccasetheprotonluminositydemands
valuesintherangeL ∼ 1047 −1049 erg/s. Recently, Zdziarski&Bo¨ttcher(2015)reviewedthehadronicmodelinradio-loudAGN,and
p
theimplicationsfortheaccretioninthosesources. Authorsfoundthatthemajorprobleminthehadronicmodelsisrelatedwithhighlysuper-
EddingtonjetpowerrequiredtointerprettheSEDspresentedinAGNs.Thisproblem,inturnwoulddemandhighlysuper-Eddingtonaccretion
ratesandthen,highluminositieswhichhavenotbeenobserved. Inourmodel,theprotonluminosityislowerthantheEddingtonluminosity,
similar to other hadronicmodels whichhave beensuccessful inexplaining, a PeVneutrino shower-like recently associated with theflaring
activity of the blazar PKS B1424-418 (Kadler et al. 2016), the SED of BL Lac Mrk421 in low state activity (Abdo et al. 2011) and radio
galaxiessuchasCenAandM87(Fraija2014a,b;Khialietal.2015;Fraija&Marinelli2016;Petropoulouetal.2014).
The basic discrepancy between our model and those shown in Sikora et al. (2009) and Bo¨ttcher et al. (2013) lies in the distinct radiative
processesusedtodescribethehigh-energyγ-raypeakintheSED.WhereasBo¨ttcheretal.(2013)fittedthehigh-energyγ-raypeakwitha
substantial contribution of proton synchrotron radiation, we have used SSC emission, which is a more efficient process than that generated
by proton synchrotron. As pointed out by Sikora et al. (2009), given the characteristic proton- and electron-related synchrotron energies
(cid:15)syn (γ = γ ) = m /m (cid:15)syn andtherelationbetweenthecorrespondingcoolingrates| γ˙ | (γ = γ ) = (m /m ) | γ˙ | ,the
γ,c,p p e e p γ,c,e p syn p e e p e syn
resultingefficiencyofsynchrotronprotonemissionbecomesverylowincomparisonwithsynchrotronelectron,althoughthisefficiencycanbe
increasedbyconsideringalargestrengthofmagneticfieldintheemittingregion(Aharonian2000). Bymeansofeq. 3,wecanestimatethe
contributionofprotonsynchrotronradiationtotheSEDandalsocompareitwiththeelectronsynchrotronradiation. Inthiscase,therelation
ofproton-andelectron-synchrotronproportionalityconstantsis Aγ,syn,p (cid:39) σT,pUB,pNp , whereσ = m2e σ andU isthemagnetic
Aγ,syn σTUBNe T,p m2p T B,p
fieldenergydensityassociatedwiththeproton-synchrotronradiationusedtofitthebroadbandSED.Here,thevaluesofDopplerandminimum
Lorentzfactorshavebeenconsideredofthesameorder(Abdoetal.2011). TakingintoaccountthechargeneutralityconditionN =N ,the
p e
contributionofprotonsynchrotronemissionisanalyzedintwocases:
1. Inourmodel,relativisticprotonswillradiatebysynchrotronemissionproportionaltothemagneticfieldobtainedafterfittingtheSED
up to GeV energies. In this case, U = U and then the contribution of proton synchrotron emission in our model is very low
B,p B
Aγ,syn,p ∼ 10−6. Since the SED has been described successfully up to a few GeV with one-zone SSC model, proton synchrotron
Aγ,syn
emission is not taken into account and then the proton luminosity normalized by photo-hadronic interactions does not increase. As
reportedinthiswork,moderateprotonluminositiesarerequired(∼1044erg/s)andweaklyaccretingdisksareexpectedforIC310.
2. Inothermodels,someauthorshavereportedthatthetypicalvaluesofmagneticfieldfoundafterfittingthehigh-energyγ-raypeakof
theSEDwithprotonsynchrotronemissionliesintherangeofB =(10-100)B(e.g. seeBo¨ttcheretal.2013;Sikoraetal.2009),with
p
BthemagneticfieldobtainedwhenaleptonicmodelisusedtodescribetheSED.Inotherwords,themagneticfieldobtainedforproton
synchrotronradiationis10-100timeslargerthanthatobtainedforelectronsynchrotronradiation.Inthiscase,theprotonandelectron-
relatedsynchrotroncontributionbecomes Aγ,syn,p ∼(10−5−10−3).Normalizingtheprotonluminositiesthroughproton-synchrotron
Aγ,syn
emission,theprotonluminositiesisincreased∼(103-105)timesmorethantheelectronluminosity,achievingvaluesof∼1047−1049
erg/s.Inthiscase,ahighlysuper-EddingtonjetpowerisrequiredtointerpretthebroadbandSEDs,asdiscussedbyZdziarski&Bo¨ttcher
(2015).
Basedonthepreviousanalysis, wecanconcludethatamixedmodel, withahigh-energyγ-raypeakbeingleptonicismorerealisticthana
hadronicmodelwithasubstantialcontributionofprotonsynchrotronemissiontothehigh-energypeak.Itisworthnotingthatthismodelcould
besuccessfullyusedforthegeneralpopulationofblazarsandradiogalaxies.
Wethanktheanonymousrefereeforacriticalreadingofthepaperandvaluablesuggestionsthathelpedtoimprovethequalityofthiswork.
WealsothankMariaPetropoulou,WilliamLeeandFabiodeColleforusefuldiscussions. ThisworkwassupportedbyUNAMPAPIITgrant
IA102917.
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1x10-4 ChandraRSS 2TSSa0odCC0tia5o12l FFeerrmmii--LLAATT s3e yceoanMrds a sdgXoaiucMt raHcM e(ig1- Nch0ae SGtwateatlooVtgen) 1x10-4 ChandraSS 2TSS0oCC0ta512l Fermi-LAT seconMd asXoguiMcr cMLeo- Nwcae RStwaattaldootigone
1x10-5 1x10-5
2-2-1E dN/dE (MeV cm s)11xx1100--76 2-2-1E dN/dE (MeV cm s)11xx1100--76
1x10-8 1x10-8
1x10-9 1x10-5 1x100 1x105 1x1010 1x1015 1x10-9 1x10-5 1x100 1x105 1x1010 1x1015
Energy (eV) Energy (eV)
FIG.1.—SEDoftheIC310describedwithamulti-zoneSSCmodelgivenbytwoelectronpopulations.ThefirstelectronpopulationisusedtomodeltheSED
uptoafewGeVwhereasthesecondoneisrequiredtofittheMAGICobservation.
1x10-4 1x10-4
1x10-5 1x10-5
2-2-1E dN/dE (MeV cm s)11xx1100--76 2-2-1E dN/dE (MeV cm s)11xx1100--76
1x10-8 1x10-8
Total XMM-Newton
SSC Fermi-LAT second source catalog Total Chandra 2005
1x10-9 1x10-5 1x100 pC-(cid:97)h IanntedrraaRc 2tai0od0ni5os 1x105Fermi-LAT 3 yeaMrsa dgaict aH (ig1h0 SGteaVte) 1x1010 1x1015 1x10-9 1x10-5 1x100 p-(cid:97) InteraRctSaioSdniCos 1x105Fermi-LAT seconMd asXoguiMcr cMLeo- Nwcae Stwattalootgne 1x1010 1x1015
Energy (eV) Energy (eV)
FIG.2.—SEDoftheIC310describedwithasingle-zoneSSCmodelgivenbyelectronandprotonpopulations. Theelectronpopulationisrequiredtofitthe
SEDuptoafewGeVandneutralpiondecayproductsresultingfrompγinteractionsisusedtointerprettheTeV-GeVγ-rayspectra.
90
UHECRs (PAO)
75 75 UHECR's (TA)
Neutrinos
60 60
45 45
30 30
15 15
180 150 120 90 0 60 30 0 330 300 0270 240 210 180
-15 -15
-30 -30
-45 -45
-60 -60
-75 -75
-90
FIG.3.—SkymapinequatorialcoordinatesofUHECRs,neutrinoeventsandIC310.BlueandredpointsaretheUHECRsreportedbyTAandPAOcollabora-
tions,respectively.IngreenaretheneutrinoeventsreportedbyIceCubeCollaboration.