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 >10 19 eV CR flux : Waxman & Bahcall 1999 CR spectrum

IceCube: KM scale KM 3 size to detect GZK neutrino, as well as SNR, AGN & GRB DUMAND, AMANDA, operation 2000 IceCube, completed s evts/yr for WB bound

High energy neutrino discovery 3yr IC86, 37 evts, 5.7sigma (8.4 atm muon, 6.6 atm neutrino) 30TeV-2PeV E -2 PL, 1:1:1, isotropic 2010/5-2012/5 data: 1.EeV GZK neutrino search found two at 1 PeV 2.Follow-up search: 28 evts 1.Lower E 2.Interaction vertices within detector volume Veto entering tracks South North HE tracks?

Diffuse neutrinos Harder than atmospheric events Uncertainty: charm meson decay Consistent with isotropic Disfavor 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 spot Also 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 electron II.neutrino -- secondary gamma-ray III.neutrino -- primary proton/electron

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 –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 M sun 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 CR  neutrino 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

Model uncertainty L ~L CR *f  (n,r…) Assumption: –Murase+14 (jet model) L CR =  CR L rad; ;need  CR > –Stecker 91,92,05,13 (core model) L =L x, 10%L MeV, …

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 electron II.neutrino -- secondary gamma-ray III.neutrino -- primary proton/electron

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)/  ( GeV)=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 FSRQs derived 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 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 ~E p -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 >10 19 eV CR and IceCube neutrinos? –GRBs in starbursts Wang, Zhao & Li, 2014