Kohta Murase

1
High-energy neutrinos from extragalactic
cosmic-ray sources

• Kohta Murase
• (Center for Cosmology and AstroParticle Physics,
  
• Ohio State University, USA)

NOW 2010
2
Outline

• Overview of HE ns from extragalactic sources
• Gamma-ray bursts
• Active galactic nuclei clusters of galaxies
• Newly born magnetars
• n emission from sources of UHE nuclei

3
Neutrinos as a Messenger

• Purposes
• Origin of cosmic rays (CRs)
• Source properties (jet contents, magnetic field
  etc.)
• Clues to acceleration mechanisms
• GeV-TeV gamma-ray obs.
• attenuation in sources and/or CMB/CIB
• contamination by leptonic emission
• HE-neutrino obs. (gt0.1TeV)
• more direct probe
• neutrino physics (e.g., oscillation)

• Neutrinos produced outside a source (e.g.,
  cosmogenic) (-gtStanev, Olinto)
• Neutrinos produced inside a source
• In this talk, we focus on the latter

4
Extragalactic Cosmic-Ray Accelerators
magentars
UHECR source candidates The most extreme objects!
Magnetars
GRB
The strongest mag. fields B 1015 G
B
AGN jet
GRBs
The brightest explosion EGRB1051ergs
clusters
AGN
The most massive BH MBH106-9Msun
r
Hillas condition E lt e B r b Egt1020eV, Z1 ?
LBeBL gt 1047.5 erg/s G12 b-1
Clusters
The largest grav. obj. rvir a few Mpc
5
Gamma-Ray Bursts
6
(Long) Gamma-Ray Bursts

• The most violent phenomena in the universe
  (Lg1051-52 ergs s-1)
• Cosmological events (z1-3)
• 1000 per year (? 5 yr-1 Gpc-3 _at_ z1)
• Relativistic jet (G300 Eg 1051 ergs 0.01
  Eg,iso, qjet 0.1 rad)
• Related to the death of massive stars
  (association with SNe Ic)

variability ms
Luminosity
Afterglow
Prompt (GRB)
X-ray?optical?radio
Gamma-ray300 keV Duration10-103s
Time
10-102s
103-104s
7
Meszaros (2001)

• Prompt emission
• PeV ?, GeV-TeV ?
• (Waxman Bahcall 97 PRL)
• (KM et al. 06 ApJL)

Orphan emission TeV ?, no ? (Meszaros Waxman
01 PRL) (Razzaque et al. 03 PRL) (Ando Beacom
95 PRL)

• emission radius 1013-1015.5 cm
• mildly relativistic shocks
• magnetic field 102-105G

8
Basics of Neutrino Emission
Photon Spectrum (observed)
CR Spectrum (Fermi mechanism)
Key parameter CR loading
e?2N(e?)
ep2N(ep)
2-ß-0
2-p0
EHECRep2N(ep) e?,pk2N(e?,pk)
2-a1.0
total ECR20EHECR
ep
e?
1018.5eV
1020.5eV
e?,pk300 keV
emax
GGeV
Photomeson Production
?-resonance
at ?-resonance ep e? 0.3 G2 GeV2 epb 0.15
GeV mpc2 G2/e?,pk 50 PeV
multi-pion production
Photomeson production efficiency effective
optical depth for p? process fp? 0.2
n?sp? (r/G)
(in proton rest frame)
9
Meson Spectrum
pion energy ep 0.2 ep break energy epb 0.07
GeV2 G2/e?,pk 10 PeV
ep2N(ep)
a-10
fp?EHECR
ß-11
meson cooling before decay (meson cooling time)
(meson life time) ? break energy in neutrino
spectra
a-3-2.0
ep
epb
epsyn
meson muon decay
Neutrino Spectrum
Waxman-Bahcall type spectrum (Waxman Bahcall
97 PRL)
e?2N(e?)
a-10
ß-11
a-3-2.0

• neutrino energy e? 0.25 ep 0.05 ep
• ? lower break energy e?b 2.5 PeV
• ? higher break energy e?psyn 25 PeV

e?
e?b
e?µsyn
e?psyn
Neutrino oscillation
No loss
pg process
(Kashti Waxman 05 PRL)
High e? Loss limit
10
GRB Prompt
Event rates by IceCube for 1 GRB _at_ z1
10-4-10-2 ? Cumulation of many GRBs (time and
space coincidence)
see also Dermer Atoyan 03 PRL
Guetta et al. 04 APh Becker et al.
06 APh
KM Nagataki, PRD, 73, 063002 (2006)
G102.5, UgUB
CR loading parameter ?HECR ep2 N(ep)
high CR loading EHECR 2.5 EGRBg (Up50Ug)
Set A - r1013-14.5cm
moderate CR loading EHECR 0.5 EGRBg (Up10Ug)
Set B - r1014-15.5cm

• ?Meson production efficiency is rather uncertain
  mainly due to r and G
• ?0.1-10 events/yr by IceCube (w. moderate CR
  loading)
• ?Testable case GRB-UHECR hypothesis/Hadronic
  model for Fermi GRBsIceCube is constraining
  optimistic cases (Beckers talk, Kappes
  arXiv1007.4629)

11
Alternative Scenario?

• Internal shock model has problems in explaining
  observations
• Prompt emission may be quasi-thermal rather than
  nonthermal
• (e.g., Thompson 94, Rees Meszaros 05,
  Ioka, KM 07)
• g-ray emission from tTnesT(r/G)1-10 ? tpp 0.1-1

KM, PRD(R), 78, 101302 (2008) Wang Dai, ApJL,
691, L67 (2009)
G102.5, UgUB

• GeV-TeV neutrinos due to pp
• Efficiency is almost fixed
• Detectable for smaller EHECR
• Detectable even if proton
• acceleration is inefficient
• UHECRs are not produced

pp
pg
EHECR1051 erg
12
Early AfterglowsEeV ?, GeV-TeV ?(KM Nagataki
06 PRL)(Dermer 07 ApJ)(KM 07 PRD)
Meszaros (2001)
Classical AfterglowsExternal Shock ModelEeV ?,
GeV-TeV ? (Waxman Bahcall 00 ApJ)(Dai Lu 01
AA)(Dermer 02 ApJ)

• emission radius 1016-1017cm
• mildly relativistic reverse shock
• ultra-relativistic forward shock
• magnetic field 0.1-100 G

13
GRB Early Afterglow

• Afterglows are explained by the external shock
  model
• Proton acceleration is possible during afterglows
  analogous to in SNRs
• Many GRBs accompany energetic flares during
  afterglows

KM, PRD, 76, 123001 (2007)
KM Nagataki, PRL, 97, 051101 (2006)
Late IS protons flare x rays (normalized by 10
of UHECR budget)
ES protons ES opt-x rays Stellar Wind
Medium (normalized by UHECR budget)
ES protons ES opt-x rays Inter Stellar
Medium (normalized by UHECR budget)

• Flares efficient for meson production (fpg
  1-10) and detectable
• ES not easy to be seen by both neutrinos and
  gamma rays

14
Active Galactic NucleiandClusters of Galaxies
15
Active Galactic Nuclei

• Super-massive black holes (M106-9 Msun)
• Accretion onto a BH (accretion disk) and
  relativistic jets (G3-30)
• Beamed nonthermal emission from inner jets -gt
  blazar emission
• AGN w. powerful jets -gt radio galaxies
  (Fanaroff-Riley III)
• 1 of AGN have hot spots as well as lobes
  (Fanaroff Riley II)

jet
BH
accretion disk
dust torus
16
CR and n Production in AGN
Inner jet (blazar FRI/II) (c.f. prompt) r
1016-1017 cm B 0.1-100 G
Emax Epg lt 1017-20 eV
neutron conversion?
e.g., Biermann Stritmatter 87 ApJ
Mannheim 92 AA Atoyan Dermer 01 PRL
Hot spot, Cocoon (FRII) (c.f. afterglow) r
1021 cm B 1 mG r 1022 cm B 0.1 mG??
Emax Eesc 1020-21 eV
e.g., Biermann Stritmatter 87 ApJ
Takahara 90 PTP Rachen Biermann 93 AA
Berezhko 08 ApJL
Core (disc/vicinity of BH) (c.f. orphan)
optimistic cases (no UHECRs) Stecker 91 PRL,
Protheroe Szabo 92 PRL
17
Neutrinos and Gamma Rays from Blazars
Neutrino spectrum
Observed Photon Spectrum
X-ray
IR,optical
GeV ?
TeV ?
Low-peak BL Lac
Low-peak
High-peak BL Lac
High-peak
Mucke et al. 02
Mucke 03 APh
HE

• Lower-peak blazars tend to have larger
  luminosities
• Lower-peak blazars ? efficient ? (and g)
  production ( EeV neutrinos) (On the other hand,
  UHECR survival is more difficult due to pg)

18
Contd.
HE emission can be explained by the hadronic
model as well as leptonic model
(e.g., Mannheim 93, Aharonian 02, Mucke 03) This
scenario requires high CR loading, LCR gt Lrad
JetDisk
jet
Jet only
Nm 10-3
Nm 0.1-0.4
Atoyan Dermer 01 PRL Atoyan Dermer 03 ApJ
ns from blazars may be seen by seed photons from
acc. disc(but UHECRs are depleted c.f. GRB
flares)
19
AGN Jet
Becker 06 PhR
KM 08 AIPC
Blazar-max. jet (Mannheim 01)
FRII jet (Becker05)
Core (Stecker 05)
BL Lac jet (Mucke 03)

• Various models from different motivations
• Core/Blazar-max. (norm. _at_ MeV/gt0.1GeV) are being
  constrained
• Norm. by UHECRs for typical BL Lacs ? lt 0.1-1
  events/yr
• But we will be in the interesting stage

20
Cen A (Non-Blazar)

• Cen A nearest AGN (FRI) _at_ 3 Mpc
• Apparently correlated with UHECRs observed by
  Auger
• UHECR source? (e.g., Gorbunov 08, Sigl 09,
  Hardcastle 09, Gopal-Krishna 10)

(Biermanns talk)

• Acc. sites
• Core/inner jet
• Possible hot spots
• Lobes
• But ns from inner jets are off-axis emission
• pg in core
• pp in extended high-density region
• ? lt a few events/yr
• (CuocoHannestad 08 PRD
• Kachelriess 09 NJP 09)
• But, then Cen A should be particular
• (Koers Tinyakov 08 PRD )

Kachelriess, NJP, 76, 123001 (2009)
21
AGN and Clusters of Galaxies

• Clusters of galaxies contain AGN
• The largest gravitationally bounded objects
• (M1014-15 Msun, r Mpc)
• Cosmic-ray storage room (AGN, Galaxies)
• Structure formation shocks (matter accretion,
  cluster mergers)

CRs interact with intracluster gas via
pp (Berezinsky97 ApJ, Colafransesco Blasi 98
APh) CRs interact with rad. field via pg (De
Marco 06 PRD, Kotera, Allard, KM 09 ApJ) gt30
PeV CRs lead to gtPeV ns
22
AGN and Clusters
KM, Inoue, Nagataki, ApJL, 689, L105 (2008)
Kotera, ApJ, 892, 391 (2009)
pp
pg
all the flavors Eb1017.5 eV

• Norm. by HECRs above 1017.5 eV ? a few events/yr
  (gt0.1PeV)
• gs are cascaded ? can be consistent with Fermi
  g-ray bkg.

23
Newly Born Magnetars
24
Magnetars

• Neutron stars with the strongest magnetic fields
  (B1015 Ggt1012G)
• Giant flares (Eflare1044-46 erg)
• Slow rotation at present (period 5-10 s) but
  maybe fast rotation at birth (period ms)
• Birth rate may be 10 of core-collapse SN rate

Corr. w. spiral galaxies ? magnetar or GRB?
Ghisellini 08 MNRAS, Takami09 JCAP
25
n Production in Fast-Rotating Magnetars

• UHECR acc. may occur in a cavity hrs after the
  birth (Arons 03 ApJ)
• Surrounded by stellar envelope
• Accelerated CRs interact with envelope and rad.
  Field
• ? meson production
• Escape of UHECRs?
• e.g., puncturing envelope by jets
• ? A fraction of CRs may produce mesons in
  jets as in GRBs

(possible) jet
envelope
shock
cavity
wind
NS
naturally expected in the magnetar-UHECR scenario
26
Fast-Rotating Magnetars
KM, Meszaros, Zhang, PRD, 79, 103001 (2009)
Detectable for Dlt5Mpc Time scale
day soft-hard-soft time-evolution Probe of the
magnetar birth

• Expected muon-event rate 1-10 events/yr
• Rate detecting gt1 ns ? 0.1 yr-1 (useful for n
  alerts)

27
Neutrinos from Sources of UHE Nuclei
28
Proton or Nuclei?

• HiRes/TA -gt proton composition Auger -gt UHECRs
  are largely nuclei
• Hillas cond., Egt1020 eV, Z26 ? LB gt 1043.5 erg/s
  (G/3)2 b-1
• Much dimmer sources are allowed as UHECR sources
• Survival from photodisintegration (tAgng sAg
  (r/G) lt 1)
• Photon and matter density should be small
  enough
• One can build scenarios where UHE nuclei can
  survive
• GRB
• AGN
• Clusters
• Then, what is the consequence for detectability
  of neutrinos?

(KM 08 PRD, Wang 08 ApJ)
(e.g., Peer, KM, Meszaros 09 PRD,
Gopal-Krishna 10 ApJ)
(Inoue 07, see also Kotera, Allard, KM 09, ApJ)
29
Landmarks from UHE Proton Sources

• Waxman-Bahcall landmarks (Waxman Bahcall 98
  PRD)
• reasonable bounds of cumulative ns from UHECR
  sources
• assumption UHECR spectrum N(ep) ?ep-2
• meson production efficiency fpg (lt 1) ? 1
  formal limit
• (fpg 0.2 n?sp? (r/G))
• n flux en2 N (en) 0.25 fpg ep2 N(ep)
• ? (0.6-3)10-8 GeV cm-2 s-1 sr-1
• Most theoretical predictions lieunder WB
  landmarks
• IceCube reaches WB landmarks
• below MPR landmarks

30
Landmarks from UHE Nuclei Sources

• Nucleus-survival requirement tAg ng sAg (r/G) lt
  1
• res. approx. ? fmes (0.2/A) ng A spg (r/G)
  tAg (0.2 spg/sAg) lt 10-3

KM Beacom, PRD, 81, 123001 (2010)
fAgkAgtAg lt 1 (most conservative)

• en2 N (en)0.25 fmes e2 N(e)
• lt (0.4-2)10-9 GeV cm-2 s-1 sr-1

non-applicable to non-UHECR sources (e.g., KM
08 for exception)
31
Summary

• ns are expected for very powerful extragalactic
  CR sources
• Various possibilities, of course many
  uncertainties
• Sources may be seen if we are lucky -gt big
  impacts!
• Some of the scenarios seem testable in the near
  future
• GRB prompt w. UHECR hypothesis (?CR loading must
  be large)Hadronic models for Fermi GRBs, flares
• AGNblazars in the hadronic model, flares of GeV
  blazars, clusters of galaxies, specific models
  for Cen A
• Magnetar
• Especially for UHECR sources, if UHE nuclei such
  as UHE iron ubiquitously survive in sources, Ag
  ns would be difficult to see by IceCube

32
Grazie!Thanks for organizers