Galactic Neutrinos Michael Kachelrieß NTNU, Trondheim []
Introduction Outline of the talk 1 Introduction Observations Cascade limit and implications 2 Neutrinos from the Galactic CR sea Galactic plane 3 Neutrinos from Galactic CR sources 4 Neutrinos from extended sources TeV γ-ray excess in Fermi-LAT Interpretations 5 Conclusions Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 2 / 30
Introduction IceCube events: Soft low-energy spectrum? Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 3 / 30
Introduction IceCube events: power-law fit of energy spectrum Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 4 / 30
Introduction IceCube events: power-law fit of energy spectrum Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 4 / 30
Introduction Cascade limit The photon horizon 22 radio 20 18 log(e/ev) 16 photon horizon γγ e + e CMB 14 IR 12 kpc kpc 0kpc Mpc Mpc 0Mpc Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 5 / 30 Gpc
Introduction Cascade limit Cascade limit: α = 21 E 2 J(E) [ev/cm 2 s sr] 000 00 0 gamma nu Fermi EGRB 1 1e+ 1e+11 1e+12 1e+13 1e+14 1e+15 1e+16 1e+17 E/eV Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 6 / 30
Introduction Cascade limit Cascade limit: α = 23 E 2 J(E) [ev/cm 2 s sr] 000 00 0 gamma nu Fermi EGRB 1 1e+ 1e+11 1e+12 1e+13 1e+14 1e+15 1e+16 1e+17 E/eV Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 6 / 30
Introduction Cascade limit Cascade limit: α = 25 E 2 J(E) [ev/cm 2 s sr] 000 00 0 gamma nu Fermi EGRB 1 1e+ 1e+11 1e+12 1e+13 1e+14 1e+15 1e+16 1e+17 E/eV Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 6 / 30
Introduction Cascade limit Cascade limit: E 2 J(E) [ev/cm 2 s sr] 000 00 0 gamma nu Fermi EGRB 1 1e+ 1e+11 1e+12 1e+13 1e+14 1e+15 1e+16 1e+17 Slope α > 22 E/eV requires hidden sources or Galactic origin Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 6 / 30
Introduction Cascade limit (Isotropic) photon limits [Ahlers, Murase 13 ] GRAPES-3 UMC HEGRA EAS-TOP IC-40 (γ) KASCADE GAMMA CASA-MIA 4 E 2 Jγ [GeV cm 2 s 1 sr 1 ] 5 6 7 8 9 85kpc 20kpc 30kpc 1 2 3 4 E γ [TeV] Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 7 / 30
Introduction Cascade limit (Isotropic) photon limits [Ahlers, Murase 13 ] GRAPES-3 HEGRA IC-40 (γ) GAMMA UMC EAS-TOP KASCADE CASA-MIA 4 E 2 Jγ [GeV cm 2 s 1 sr 1 ] 5 6 7 8 9 85kpc 20kpc 30kpc 1 2 3 4 Eγ [TeV] KASCADE limits reanalysed 17 and increased Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 7 / 30
Neutrinos from the Galactic CR sea Galactic plane Hints for a Galactic plane contribution? [Neronov, Semikoz 14, 15 ] Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 8 / 30
Neutrinos from the Galactic CR sea Galactic plane Hints for a Galactic plane contribution? [Neronov, Semikoz 14, 15 ] Neronov & Semikoz 15: Galactic latitude distribution of 4yr IceCube data with > 0 TeV inconsistent at 3σ with isotropy Palladino & Vissani 15: Two component fit, soft Galactic E 24 25% Galactic contribution Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 8 / 30
Neutrinos from the Galactic CR sea Galactic plane Expectation: CR interactions with gas in Galactic plane give guaranteed ν flux [Berezinsky, Smirnov 75 ] [Gaggero et al 15, Pagliaroli, Evoli, Villante 17, ] agreement: -20% Galactic contribution at 0 TeV Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 9 / 30
Neutrinos from the Galactic CR sea Galactic plane Expectation: CR interactions with gas in Galactic plane give guaranteed ν flux [Berezinsky, Smirnov 75 ] [Gaggero et al 15, Pagliaroli, Evoli, Villante 17, ] agreement: -20% Galactic contribution at 0 TeV However, uncertainties are very large: elemental composition unclear, but Z ν A 1 γ CRs locally measured close to knee diffusion may be unreliable gas density Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 9 / 30
Neutrinos from the Galactic CR sea Galactic plane Uncertainties: CR composition Kascade-Grande: dependenc on interaction model Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 / 30
Neutrinos from the Galactic CR sea Galactic plane Uncertainties: CR composition Kascade-Grande: dependenc on interaction model Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 / 30
Neutrinos from the Galactic CR sea Galactic plane Uncertainties: CR composition [Gaisser, Stanev & Tilav 13 ] E 26 I(E) [GeV 16 m -2 sr -1 s -1 ] 000 00 0 p He C O Fe total 11 12 13 14 15 16 17 18 19 20 E/eV Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 11 / 30
Neutrinos from the Galactic CR sea Galactic plane Uncertainties: CR composition [Hörandel 0? ] τ E 26 I(E) [GeV 16 m -2 sr -1 s -1 ] 000 00 p He Li-Fl Ne-Cr Mn-Co total 0 11 12 13 14 15 16 17 18 19 E/eV Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 11 / 30
Neutrinos from the Galactic CR sea Galactic plane Resulting ν fluxes (τ = 1 at PeV) [MK, Ostapchenko 14 ] E 26 I(E) [GeV 16 m -2 sr -1 s -1 ] 00 0 1 01 Hillas Polygonato Escape 001 11 12 13 14 15 16 17 18 E/eV Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 12 / 30
act Neutrinos from the Galactic CR sea Galactic plane power-law spectrum corresponds to a deficit with a del statistical significance of 42 standard deviations To see vy Uncertainties: if any artificial CRfeature composition could have been produced in our in ARGO-YBJ: position of p+he knee 700 TeV ing we ent: 6% 6% 1% 1% ev ev 7% 2% 165 (GeV) -1 ssr) 2 (m 265 Flux E 4 3 H+He This work ARGO/WFCTA-02 ARGO-YBJ CREAM KASCADE SIBYLL KASCADE QGSJET-II 02 Tibet-Phase II QGSJET Tibet-Phase II SIBYLL 4 5 Energy (GeV) FIG (color online) H&He spectrum obtained by the hybrid Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 13 / 30 6 7
Neutrinos from the Galactic CR sea Galactic plane Uncertainties: CR composition ARGO-YBJ: position of p+he knee 700 TeV ] 16 s -1 sr -1 GeV -2 [m 26 Flux E 4 3 2 ARGO-YBJ all-particle (unfolding) ARGO-YBJ P+He (unfolding) ARGO-YBJ P+He (Hybrid) ARGO-YBJ all-particle (NP8Max) ARGO-YBJ P+He (NP8Max) ARGO-YBJ P+He (Digital) Horandel 2003 - ALL Gaisser-Stanev-Tilav 2013 - ALL Horandel 2003 - P+He Gaisser-Stanev-Tilav 2013 - P+He 4 5 Energy [GeV] Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 13 / 30 6 7 8
Neutrinos from the Galactic CR sea Galactic plane Uncertainties: CR composition ARGO-YBJ: position of p+he knee 700 TeV ] 16 s -1 sr -1 GeV 4-2 [m 26 E Flux 3 2 ARGO-YBJ all-particle (unfolding) ARGO-YBJ P+He (unfolding) ARGO-YBJ P+He (Hybrid) ARGO-YBJ all-particle (NP8Max) ARGO-YBJ P+He (NP8Max) ARGO-YBJ P+He (Digital) Horandel 2003 - ALL Gaisser-Stanev-Tilav 2013 - ALL Horandel 2003 - P+He Gaisser-Stanev-Tilav 2013 - P+He 4 5 neutrino knee at 20 40 TeV 6 Energy [GeV] Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 13 / 30 7 8
Neutrinos from the Galactic CR sea Galactic plane Uncertainties: diffusion approach diffusion picture requires R L (E ) L coh /(2π) for L coh 50 pc and B fewµg: E 16 ev Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 14 / 30
Neutrinos from the Galactic CR sea Galactic plane Uncertainties: diffusion approach diffusion picture requires R L (E ) L coh /(2π) for L coh 50 pc and B fewµg: E 16 ev LOFAR: l coh < pc in disc diffusion has to be anisotropic [Giacinti, MK, Semikoz 18 ] grammage X(E) in the escape model [Giacinti, MK, Semikoz 14, 15 ] X(E) in g/cm 2 1 01 β=1, L=pc β=01, L=pc 001 β=1/8, L=25pc δ=1/3 AMS-02 (a) AMS-02 (b) 0001 Jones 11 12 13 14 15 16 17 E/Z in ev Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 14 / 30
Neutrinos from the Galactic CR sea Galactic plane Uncertainties: diffusion approach diffusion picture requires R L (E ) L coh /(2π) for L coh 50 pc and B fewµg: E 16 ev LOFAR: l coh < pc in disc diffusion has to be anisotropic [Giacinti, MK, Semikoz 18 ] grammage X(E) in the escape model [Giacinti, MK, Semikoz 14, 15 ] X(E) in g/cm 2 1 01 β=1, L=pc β=01, L=pc 001 β=1/8, L=25pc δ=1/3 AMS-02 (a) AMS-02 (b) Jones 0001 11 12 13 14 15 16 17 E/Z in ev reduced τ above few 15 ev Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 14 / 30
Neutrinos from the Galactic CR sea Galactic plane Uncertainties: deviations from local spectrum CR slope from molecular clouds: α 24 [Neronov, Malyshev, Semikoz 17 ] 26 χ 2 /NDF=20/8 25 24 i1 23 22 21 Galactic LMC Cygnus RCrA Rho Oph Chameleon Cepheus Mon R2 Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 15 / 30 Orion A Orion B Perseus Taurus
Neutrinos from the Galactic CR sea Galactic plane Uncertainties: deviations from local spectrum CR slope from molecular clouds: α 24 [Neronov, Malyshev, Semikoz 17 ] 26 χ 2 /NDF=20/8 25 24 23 22 21 RCrA Rho Oph Chameleon Cepheus Mon R2 Orion A Orion B Perseus i1 Galactic LMC Taurus Cygnus agrees with local slope of nuclei (and δ = 1/3) deviation of α p 27 vs α nuc 25 local effect? Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 15 / 30
Neutrinos from the Galactic CR sea Galactic plane Uncertainties: deviation from local spectrum explanations: local source [MK, Neronov, Semikoz 15 ] Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 16 / 30
Neutrinos from the Galactic CR sea Galactic plane Uncertainties: deviation from local spectrum explanations: local source [MK, Neronov, Semikoz 15 ] diffusion depends on ρ, D = D(ρ) [Yang, Aharonian, Evoli 16 ] Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 16 / 30
Neutrinos from the Galactic CR sea Galactic plane Detection prospects: [Pagliaroli, Evoli, Villante 16 ] φν( ) ( - - - - - ) b = 0 C B A Isotropic - - - ( ) A: local; B: n sources,c: E δ(r) Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 17 / 30
Neutrinos from the Galactic CR sea Galactic plane Detection prospects: [Pagliaroli, Evoli, Villante 16 ] φν( ) ( - - - - - ) l = 0 C B A Isotropic - - - ( ) Close to GC: always an excess rel extragal detectability requires good angular resolution Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 17 / 30
Neutrinos from Galactic CR sources Galactic sources at low energies: many sources, large confinement times average CR sea plus few recent sources Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 18 / 30
Neutrinos from Galactic CR sources Galactic sources at low energies: many sources, large confinement times average CR sea plus few recent sources close to the knee: CRs in PeV range spread fast few extreme sources inhomogenous CR sea, extended sources no clear distinction between point sources vs Galactic bulge + plane cases Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 18 / 30
Neutrinos from Galactic CR sources Galactic sources at low energies: many sources, large confinement times average CR sea plus few recent sources close to the knee: CRs in PeV range spread fast few extreme sources inhomogenous CR sea, extended sources no clear distinction between point sources vs Galactic bulge + plane cases connection to γ rays: sources transparent: φγ (E) φ ν (E) but requires extrapolation above TeV young SNRs, Cygnus region, Fermi bubbles, Galactic center Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 18 / 30
Neutrinos from Galactic CR sources Galactic center E 2 dφ/deγ/dω [GeVcm 2 s 1 sr 1 ] 3 4 5 Galactic ridge Conventional diffusion Base model Gamma model Fermi Data PASS8 HESS Data 2006 Best Fit Fermi + HESS data Hard diffusion 6 2 1 0 1 E [T ev ] [Gaggero et al 17 ] Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 19 / 30
Neutrinos from Galactic CR sources Galactic center E 2 dφ/deγ/dω [GeVcm 2 s 1 sr 1 ] 3 4 5 Pacman region Conventional diffusion Base model Gamma model Fermi Data PASS8 HESS Data 2016 Best Fit HESS+Fermi Hard diffusion 6 2 1 0 1 E [T ev ] [Gaggero et al 17 ] Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 19 / 30
Neutrinos from Galactic CR sources Antares IceCube limit 7 E 2 dφ/dedω [GeV cm 2 s 1 sr 1 ] 8 KRAγ model Combined UL KRAγ 5 Combined UL KRAγ 50 ANTARES UL KRAγ 5 IceCube UL KRAγ 50 IceCube starting events IceCube up-going ν µ 5 PeV CR cutoff 50 PeV CR cutoff 9 1 0 1 2 3 E [TeV] Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 20 / 30
Neutrinos from Galactic CR sources Slow diffusion around sources: Geminga D(0 TeV) [cm 2 /s] 28 HAWC (3 µg) B rms = 3 µg 2 µg 4 µg 5 µg 27 01 1 L c [pc] possible explanations: weak regular field, smallish Lcoh [López-Coto, Giacinti 17 ] Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 21 / 30
Neutrinos from Galactic CR sources Slow diffusion around sources: Geminga D(0 TeV) [cm 2 /s] 28 HAWC (3 µg) B rms = 3 µg 2 µg 4 µg 5 µg 27 01 1 L c [pc] possible explanations: weak regular field, smallish Lcoh [López-Coto, Giacinti 17 ] self-generated turbulence by CRs [ Evoli, Linden, Morlino 18 ] Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 21 / 30
Neutrinos from extended sources Sources in Local & Loop I superbubble [Andersen, MK, Semikoz 17 ] Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 22 / 30
Neutrinos from extended sources Sources in Local & Loop I superbubble [Andersen, MK, Semikoz 17 ] Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 22 / 30
Neutrinos from extended sources Sources in Local & Loop I superbubble [Andersen, MK, Semikoz 17 ] 2 IceCube all flavors IceCube muon*3 local flux EG 1/E 21 total E 2 F(E) [ev/cm 2 /s/sr] 1 0 12 13 14 15 16 E [ev] Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 22 / 30
Neutrinos from extended sources Sources in Local & Loop I superbubble [Andersen, MK, Semikoz 17 ] -11-12 KASCADE I(>E)/(cm 2 s sr) -13-14 -15-16 -17 14 15 16 E/eV Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 22 / 30
Neutrinos from extended sources TeV γ-ray excess Are multi-tev photons in the Fermi data? [Neronov, MK, Semikoz 18 ] Caveats Analyzing LAT Pass 8 Data: because the validation process was hampered by lack of statistics, using data below 30 MeV or above 1 TeV is discouraged gtlike tool has limit 850 GeV Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 23 / 30
Neutrinos from extended sources TeV γ-ray excess Are multi-tev photons in the Fermi data? [Neronov, MK, Semikoz 18 ] Caveats Analyzing LAT Pass 8 Data: because the validation process was hampered by lack of statistics, using data below 30 MeV or above 1 TeV is discouraged gtlike tool has limit 850 GeV eff area & energy resolution up to 32 TeV: 15% at 1 TeV & 25% at 3 TeV aperture photometry possible Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 23 / 30
Neutrinos from extended sources TeV γ-ray excess Cross calibration test: Galactic plane Galactic plane ( b < 5 and 40 < l < 0 ) spectrum from ARGO-YBJ and Milagro 40 < l < 0 5 < b < 5 E 2 dn/de, GeV/(cm 2 s sr) 5 6 Fermi/LAT Argo-YBJ MILAGRO 0 1 2 3 4 E, GeV Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 24 / 30
Neutrinos from extended sources TeV γ-ray excess Extension to 3 TeV for b > 20 : 6 residual CR IGRB b > 20, total counts b > 20, PS, IGRB & CR subtracted E 2 dn/de, GeV/(cm 2 s sr) 7 8 0 1 2 3 E, GeV Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 25 / 30
Neutrinos from extended sources TeV γ-ray excess Extension to 3 TeV for b > 20 : 6 residual CR IGRB b > 20, total counts b > 20, PS, IGRB & CR subtracted E 2 dn/de, GeV/(cm 2 s sr) 7 8 0 1 2 3 E, GeV bin 1 17 TeV: expected 14 (185) for nominal (renormalised) exposure observed (after subtr CR): 47 bin 17 3 TeV: expected 24 (355), observed 17 Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 25 / 30
Neutrinos from extended sources TeV γ-ray excess Adding neutrinos: 4 5 6 IGRB LAT 0 decay model Fermi/LAT all sky IceCube HESE, 6 yr IceCube HESE, 4 yr 7 ) 8 4 ANTARES IceCube Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 26 / 30
Neutrinos from extended sources Intepretation Possible explanations: interface Loop I/local superbubble: strong dipole? Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 27 / 30
Neutrinos from extended sources Intepretation Possible explanations: interface Loop I/local superbubble: strong dipole? extended CR halo [Taylor, Gabici, Aharonian 14 ] [Dolag 02 ] Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 27 / 30
Neutrinos from extended sources Intepretation Possible explanations: interface Loop I/local superbubble: strong dipole? extended CR halo for B 001µ G and L coh 0 pc: CR with E = 0 TeV is in large-angle scattering regime D(E ) 29 cm 2 /s escape time τ = H 2 /2D t 0 [Dolag 02 ] Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 27 / 30
Neutrinos from extended sources Intepretation Possible explanations: interface Loop I/local superbubble: strong dipole? extended CR halo PeV dark matter: re-incarnation of SHDM idea for AGASA excess: non-hermal DM avoids cascacde limit Galactic anisotropy Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 27 / 30
Neutrinos from extended sources Intepretation PeV dark matter E Ν 2 dj de Ν TeV cm 2 s 1 sr 1 11 DM Ν e Ν e 15, bb 85 DM Ν e Ν e 12, cc 88 DM e e 40, qq 60 1 2 3 E Ν TeV [Kusenko et al 13, Esmaili, Serpico 13 ] Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 28 / 30
Neutrinos from extended sources Intepretation Possible explanations: heavy dark matter 00000000 nu tot gam gal gam gal ICS gam ex casc gam tot IceCube Fermi 00000000 00000000 0000000001 1x 1x 11 1x 12 1x 13 1x 14 1x 15 1x 16 Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 29 / 30
Summary Summary 1 EGRB constrains stronly neutrino sources: slope of extragal neutrino α < 22 neutrino sources are not main source class of EGRB 2 Standard Galactic neutrinos: northern km 3 telescope very useful important info on propagation and acceleration 3 Soft neutrino signal in IceCube: isotropy: extragalactic or large Galactic halo TeV γ-ray excess consistent with neutrino flux Michael Kachelrieß (NTNU Trondheim) Galactic neutrinos VLVNT, 2 October 18 30 / 30