Active Galactic Nuclei &

High Energy Neutrino Astronomy

黎卓 北京大学

>TeV

JUNO Workshop, IHEP, 2015/7/10

Outline

• Background: neutrino detection; sources

• AGN phenomena

• AGN neutrino models

• constraint by gamma-ray

• Conclusion

HE neutrino flux implied by UHE cosmic ray

• Neutrinos from production

• If all p energy converted to

• Waxman-Bahcall Bound from detected >1019eV CR flux :

c

H

j

j

p /

/1

2

1

2

1

GZK

0

Waxman & Bahcall 1999

ee

Npp )(

sr scm

GeV10

d

d2

82

j

CR spectrum

IceCube: KM scale •KM3 size to detect GZK neutrino, as well as SNR, AGN & GRB•DUMAND, 1976-1995•AMANDA, operation 2000•IceCube, completed 2010

10s evts/yr for WB bound

High energy neutrino discovery

3yr IC86, 37 evts, 5.7sigma(8.4 atm muon, 6.6 atm neutrino)30TeV-2PeVE-2 PL, 1:1:1, isotropic

2010/5-2012/5 data:1. EeV GZK neutrino search

• found two at 1 PeV2. Follow-up search: 28 evts

1. Lower E2. Interaction vertices within

detector volumeVeto entering tracks

South

North

HE tracks?

Diffuse neutrinos

Harder than atmospheric eventsUncertainty: charm meson decay

Consistent with isotropicDisfavor charm component–which expect south 50% smaller than north

per flavor

Diffuse neutrinos

Spectrum: best fit E-2.3

Or E-2 spectrum + PeV cutoff•unbroken unlikely

Sky map, no significant spotAlso no clustering in time,no correlation with GRB

PeV neutrino source?

• Galactic origin– CR propagation: diffuse– point sources (isotropic?!)

• Pulsar, SNR, PWN, micro-quasar, …

• Extragalactic origin– p-p: CR propagation

• Star forming/starburst galaxies• Galaxy clusters• …

– p-in-source• Gamma ray bursts• Active galactic nuclei: jets & core

• …

upper limit

~200 GRBs

Null results…

Stacking search

Gamma – neutrino connection

Connection:I. neutrino -- secondary electronII. neutrino -- secondary gamma-rayIII. neutrino -- primary proton/electron

radiation Comp rsesynch/inve

radiation cascade

)(

0

0

e

N

e

e

Npp

e

Fermi-LAT probes neutrino origin

Whether various candidates can produce the IceCube neutrino flux?

Galactic diffuse emission: unlikely

• Pi0 gamma-neutrino

• Extrapolation: GeV to PeV– Galactic CR spectral index

-2.75– p-p neutrino spectrum

follows CR

IC

MW diff. emis.

Fermi-LAT

[Wang, LZ, Zhao 2014]

AGN property • Compact and strong nuclear emission– luminosity 10^43-48 erg/s; size

<0.1pc (1pc=3.08E18cm)• Broad band radiation spectra

– primarily non-thermal, F∝-α (polarized)

– thermal in some bands (but not from stars)

• Strong emission lines– Widths suggest velocity up to

1E4 km/s• Variability

– in continuum and emission line flux, as well as line profile and polarization

• Stronger X- and Gamma-ray (than normal galaxies)

FSRQ

BL Lac

Unified model

• BH – 1E6~1E10 Msun

• Disk• Torus• Jet• BLR• NLR• …

• Viewing angle effect

Blazar spectrum: two bumps

• Low energy bump– Electron synchrotron

• Gamma origin– Leptonic model

• electron IC

– Hadronic model• Pi decay• P-synchrtron

BL Lac 3C 66A

AGN CRneutrino

• Jet model– CR accelerated at Jet– Target photon:

jet+disk+BLR+torus– Relativistic beaming;

bright

• Core model– CR accelerated at core

region: disk or near BH– Target: disk photon– Isotropic emission; high

pion production efficiency

Accretion disk(UV, X)

Dust torus(IR)

Broad line region(optical, UV)

CR

CR

Model uncertainty

• L~LCR*f(n,r…)

• Assumption:– Murase+14 (jet

model)

LCR=CRLrad; ;need CR>100-1000

– Stecker 91,92,05,13 (core model)

L=Lx, 10%LMeV, …

Blazars in IC neutrino fields

• Blazars in the error box of IC’s neutrinos (three 0.1-1PeV neutrinos): – six resolved +

unresolved• can produce IC’s

neutrinos– assuming

• ANTARES does not see neutrinos in those fields

Integration

[TANAMI, Krauß et al. 2014]

[ANTARES+TNAMI 2015]

!!

Gamma – neutrino connection

Connection:I. neutrino -- secondary electronII. neutrino -- secondary gamma-rayIII. neutrino -- primary proton/electron

radiation Comp rsesynch/inve

radiation cascade

)(

0

0

e

N

e

e

Npp

e

Flat spectrum radio quasar (FSRQ) jets

• Assume – neutrino flux proportional to

gamma flux

– FSRQs can account for IC neutrinos

• Neutrino/gamma flux ratio– (20TeV-2PeV)/(0.1-

100GeV)=3.8%

• gamma (>0.1GeV) is not from hadronic model with cascade emission– where the flux ratio=O(1)

– (p-synch still OK)

[Fermi-LAT, Ajello+ 2012]

Diffuse gamma-ray from FSRQsderived from Fermi-LAT survey

Gamma>>neutrino flux

[Wang & LZ 15]

neutrino

gamma

Candidate FSRQs

• apply the ratio to individual FSRQs

• predict neutrino flux • comparison with IC limit • several sources in

northern sky overpredicted

[Wang & LZ, 2015]

Stacking search

• 33 bright FSRQs– selected based on gamma

flux

• Prediction/limit>10– >30 @ northern sky

• So FSRQs can only account for <10% (<3%) IC neutrinos

prediction

upper limit

sensitivity

[Wang & LZ, 2015]

Conclusion & discussion

• IceCube neutrino origin– Fermi-LAT observations disfavor

• disfavor Galactic origin (diffuse emission & point sources), GRB, & AGN (FSRQ & BL Lac) jet

• favor star forming/starburst galaxies

– Current stacking limit cannot constrain AGN core model yet• Stack more AGN (how many?)

• AGN jet still possible to be UHE CR sources– AGN neutrinos is a few% diffuse neutrinos; and f~a few%,

CR power maybe consistent with observed UHECR flux

Starburst galaxies: II

Fermi-LAT, Ackermann+12

Starburst galaxies: II

• Local-universe gamma-ray emissivity

• Redshift-integrated gamma-ray intensity

• Neutrino flux and spectrum: – if CRs injected with ~Ep

-2.2 as observed in MW

– if <100PeV CRs lose energy significantly as expected in SBs

Match both flux and spectrum by IC

IC flux = WB bound?

• Simply coincident?

• The same sources for both >1019eV CR and IceCube neutrinos?– GRBs in starbursts

Wang, Zhao & Li, 2014