active galactic nuclei & high energy neutrino astronomy 黎卓 北京大学 >tev juno...
TRANSCRIPT
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