Review of Interpretation of Multi-Messenger Data

Transcrição

Review of Interpretation of
Multi-Messenger Data
1. Sources of Highest Energy Cosmic Rays
2. Gamma-Rays and Neutrinos
3. Magnetic Fields and three-dimensional simulations
Günter Sigl
II. Institut theoretische Physik, Universität Hamburg
http://www2.iap.fr/users/sigl/homepage.html
1
Mittwoch, 15. Februar 12
Some general Requirements for Sources
Accelerating particles of charge eZ to energy Emax requires induction
ε > Emax/eZ. With Z0 ~ 100Ω the vacuum impedance, this requires
dissipation of minimum power of
2
Lmin
✏
45
⇠
' 10 Z
Z0
2
✓
Emax
1020 eV
◆2
erg s
1
This „Poynting“ luminosity can also be obtained from Lmin ~ (BR)2 where BR is
given by the „Hillas criterium“:
17
BR > 3 ⇥ 10
1
✓
Emax /Z
1020 eV
◆
Gauss cm
where Γ is a possible beaming factor.
If most of this goes into electromagnetic channel, only AGNs and maybe
gamma-ray bursts could be consistent with this.
2
1st Order Fermi Shock Acceleration
synchrotron iron, proton
Fractional energy gain per shock crossing ～ u1 - u2 on a time scale rL/u2 .
-q
Together with downstream losses this leads to a spectrum E with q > 2 typically.
Confinement, gyroradius < shock size, and energy loss times define maximal energy
3
Relation to Radio Emission
In MNRAS 105 (2010) 2810, Hardcastle estimates a corresponding lower limit on
the radio luminosity:
24
L108 MHz > 2 ⇥ 10
✏
✓
E/Z
1020 eV
◆7/2 ✓
rlobe
100 kpc
◆
1/2
W Hz
1
for an E-2 electron spectrum
with ε = energy in electrons / energy in magnetic field
He concludes: for proton dominated flux, very few sources which should be known
and spectrum should cut off steeply at observed highest energies
For heavier nuclei dominated flux there are many radio galaxy sources but only
Cen A may be identifiable
4
Multi-Messenger Astrophysics with
Discrete Sources: Centaurus A
∼1044 erg/sec bolometric luminosity
∼1042 erg/sec luminosity in MeV γ-rays
5
Centaurus A is a UHECR source candidate
Pierre Auger sees a clear excess
in the direction of Centaurus A
Pierre Auger Collaboration, Astropart.Phys. 34 (2010) 314
6
But even for iron primaries Centaurus A can not be the
only UHECR source
Including an extreme choice for the turbulent
Galactic field component with strength 10 µG,
coherence length 50 pc, 10 kpc halo extension
Iron Image of Cen A in the Prouza-Smida Galactic
magnetic field model
simulation
data
isotropic
Giacinti, Kachelriess, Semikoz, Sigl, Astropart.Phys. 35 (2011) 192
7
Lobes of Centaurus A seen by Fermi-LAT
Radio observations
> 200 MeV γ-rays
Abdo et al., Science Express 1184656, April 1, 2010
8
Low energy bump = synchrotron
high energy bump = inverse Compton on CMB in ~0.85µG field
Abdo et al., Science Express 1184656, April 1, 2010 9
Core of Centaurus A seen by Fermi-LAT
Can be explained by synchrotron self
Compton except for HESS observation
Abdo et al., (Fermi LAT collaboration), arXiv:1006.5463
10
Centaurus A as Multimessenger Source:
A Mixed hadronic+leptonic Model
Sahu, Zhang, Fraija, arXiv:1201.4191
Low energy bump = synchrotron
high energy bump = synchrotron self-Compton
TeV-γ-rays: pγ interactions of shock-accelerated protons
11
Centaurus A as Multimessenger Source: Hadronic Model
current IceCube40 limit
acceleration of protons around the core: pγ dominated
and secondary γ-rays cascade in infrared field of the source
Kachelriess, Ostapchenko, Tomas, NJP 11 12(2009) 065017
Newest Limits Pierre Auger limits for Centaurus A
Y. Guardincerri [Pierre Auger Collaboration], arXiv:1107.4805
13
Electromagnetic Cascades and TeV Ɣ-Rays
Solution 1:
magnetic fields > 10-17 G sufficiently
disperse the GeV Ɣ-ray cascades
[Neronov et al.]
Solution 2:
cascade absorption by plasma beam
instabilities
[Broderick et al.]
Essey et al., Astrophys. J. 731 (2011) 51
Pure Ɣ-ray injection tends to underproduce
“prompt” TeV Ɣ-rays (observed by IACT) and
overproduce GeV Ɣ-ray cascades (not observed
by Fermi LAT)
14
Solution 3:
Primary cosmic rays produce TeV
Ɣ-rays continuously during
propagation
[Essey et al.]
Very High High Energy Neutrinos
The „grand unified“ differential neutrino number spectrum
From Physics Today
15
dNν /dEν GeV cm s-1 sr-1
Current Neutrino Flux Upper Limits at TeV-EeV energies
10-3
-2
1
10-4
5
-5
10
-6
10
1)
AMANDA-II Atmospheric ν µ 1387 d
Bartol + Naumov RQPM
(8
2)
AMANDA-II ν µ unfolding (2000-2003)
Honda + Enberg Min
(9
3)
AMANDA-II ν µ 807 d
Waxman Bahcall Prompt GRB(10
4)
ANTARES ν µ 07-09
Blazars Stecker
(11
5)
IC40 Atmospheric ν µ
Waxman Bahcall 1998 x 1/2
(12
6)
IC40 Atmo. ν µ Unfolding
Becker AGN
(13
7)
IC40 ν µ 375.5 d
Mannheim AGNs
(14
6
14
2
3
2
Eν
10-7
13
4
12
10-8
7
10-9
9
10
2
3
4
5
8
6
7
8
9
10
log Eν [GeV]
Gaisser, arXiv:1201.5637
10
16
11
Discrete Extragalactic High Energy Neutrino Sources
Pro g e nitor
50⌧53
E~10 erg
Pre burst
Burst
lo c al
m e dium
Sho c k
n~10 c m
form ation
(photons)
n e utrinos ?
T=
R=
active galaxies
6
~100 s
10 c m
12
~3*10 c m
soft photons
(X⌧ra ys)
n e utrinos?
3
~3*10 s
14
~10 c m
⌧3
X⌧ra ys, o pt,
ra dio, ...
n e utrinos?
6
~10 s
16
~3*10 c m
gamma ray bursts
Figures from J. Becker, Phys.Rep. 458 (2008) 173
17
0s
Afterglow
Chemical Composition and Source Contributions to the
Ultra-High Energy Neutrino Flux
In AGN sources, nuclei are disintegrated above ~1019 eV
In GRB sources, all nuclei are practically disintegrated (compact source)‫‏‬
In starburst galaxy sources, very few nuclei are disintegrated
Anchordoqui, Hooper, Sarkar, Taylor, Astropart. Phys. 29 (2008) 1
18
Neutrino Fluxes from Gamma-Ray Bursts
GRBs are optically thick to charged cosmic rays and nuclei are disintegrated
=> only neutrons escape and contribute to the UHECR flux by decaying back
into protons
Diffuse neutrino flux from GRBs can thus be linked to UHECR flux (if it is
dominantly produced by GRBs)
1
⌫ (E⌫ ) ⇠
⌘⌫
p
✓
E
⌘⌫
◆
,
where ⌘⌫ ' 0.1 is average neutrino energy in units of the parent proton energy.
Above ~ 1017 eV neutrino spectrum is steepened by one power of E ν because pions/
muons interact before decaying
19
GRB origin of cosmic
rays challenged
gamma rays after
cascading in the
microwave background
0
Halzen, NUSKY2011
+ neutrinos
20
Physics with Diffuse Cosmogenic Neutrino Fluxes
Cosmogenic neutrino fluxes depend on number of nucleons produced
above GZK threshold which is proportional to Emax/A
Further suppressed for heavy nuclei due to increased pair production
Pure protons, Emax=3 1021 eV,
strong evolution
current Auger limit on
Earth-skimming neutrinos
Pure iron, Emax= 1020/26 eV,
no evolution
Kotera, Allard, Olinto, JCAP 1010 (2010) 013
21
1D: Secondary gamma-rays and
neutrinos in mixed composition Scenario
Fermi LAT
Auger sensitivity
gamma-rays
full IceCube sensitivity
Pierre Auger data
neutrinos
simulated cosmic rays
comoving injection rate scaling as
(1+z)4 up to z=2
injection spectral slope α=2.2
up to Emax = Zx1021 eV
22
Sensitivities to and Predictions for UHE neutrino fluxes
Gaisser, arXiv:1201.6651
Rates for intermediate flux estimates
Kotera, Allard, Olinto, JCAP 1010 (2010) 013
23
TeV γ-ray fluxes also constrain cosmogenic neutrino fluxes
sensitive to redshift evolution; complementary to UHE γ-ray fluxes
Ahlers and Salvado, arXiv:1105.5113; also Aharonian, Berezinsky, Kachelriess, ...
jp (E)
jFe (E)
/
/
⇥(2
⇥(2
z) (1 + z)5 E
z) E
2.3
⇥ 1020.5 eV
⇥ 26 ⇥ 10
24
2.3
20.5
eV
E ,
E .
Physics with Diffuse Secondary Gamma-Ray Fluxes
UHE gamma-ray fluxes depend on number of nucleons locally produced
above GZK threshold which is proportional to Emax/A
Further suppressed for heavy nuclei due to increased pair production
complementary to cosmogenic neutrinos: does not depend on redshift evolution
Hooper, Taylor, Sarkar, Astropart.Phys. 34 (2011) 340
25
Current upper limits on the photon fraction are of order 2% above 1019 eV
from latest results of the Pierre Auger experiments (ICRC) and order 30%
above 1020 eV.
Pierre Auger Collaboration, Astropart. Phys. 31 (2009) 399
Pierre Auger Collaboration, Astropart.Phys.29 (2008) 243
26
Future data will allow to probe smaller photon fractions and the GZK
photons
Pierre Auger Collaboration, Astropart.Phys.29 (2008) 243
Risse, Homola, Mod.Phys.Lett. A22 (2007) 749.
27
Lorentz Symmetry Violation in the Photon Sector
For a photon dispersion relation
2
!±
2
=k +
⇠n± k 2
✓
k
MPl
◆n
,n
1,
pair production may become inhibited, increasing GZK photon fluxes
above observed upper limits: In the absence of LIV for electrons/positrons
for n=1 this yields:
⇠1  10
12
Such strong limits may indicate that Lorentz invariance violations are
completely absent !
28
3-Dimensional Effects in
Propagation
Kotera, Olinto, Ann.Rev.Astron.Astrophys. 49 (2011) 119
29
CRPropa 2.0
CRPropa is a public code for UHE cosmic rays, neutrinos and γ-rays being extended
to heavy nuclei and hadronic interactions
Eric Armengaud, Tristan Beau, Günter Sigl, Francesco Miniati,
Astropart.Phys.28 (2007) 463.
Version 1.4 at http://apcauger.in2p3.fr/CRPropa/index.php
Now including: Jörg Kulbartz, Luca Maccione,
Nils Nierstenhoefer, Karl-Heinz Kampert, Peter Schiffer, Arjen van Vliet
ask for beta version CRPropa 2.0 !
30
The main part of the code is written in C++ and calls some Fortran routines
(mainly SOPHIA for interactions photo-pion production of nucleons)
Electromagnetic cascades are treated by solving one-dimensional transport
equations
The set-up (source distributions, environment, magnetic fields, low energy
photon backgrounds, injection spectrum, arbitrary composition at fixed energy per
nucleon, which interactions/secondaries to take into account)
can be provided with xml files.
Output can be in form of whole trajectories or events; possible output formats are
ASCII, FITS or ROOT.
Presented are two examples for 1D and 3D simulations
31
Structured Extragalactic
Magnetic Fields
Miniati
Kotera, Olinto, Ann.Rev.Astron.Astrophys. 49 (2011) 119
Filling factors of extragalactic magnetic fields are not well known and come out different in
different large scale structure simulations
32
Extragalactic iron propagation produces nuclear cascades in structured magnetic fields:
Initial energy 1.2 x 1021 eV, magnetic field range 10-15 to 10-6 G. Color-coded is
the mass number of secondary nuclei
33
Discrete Sources in
nearby galaxy clusters
Earth
Earth
10 sources per (75 Mpc)3 box, concentrated in a galaxy cluster at ≃30 Mpc, injecting
E-2.5 spectra up to 200xZ EeV with 10 x galactic abundance;
+ one source @ 4Mpc of 0.002 relative strength injecting E-2 spectrum up to 10xZ EeV.
34
Results: Spectra and Composition
proton fraction
35
Results: Sky Distributions and Anisotropies
deflection angles
deflection angles
above 1 EeV
above 55 EeV
36
Composition and energy dependence
of excess from nearby source
In the absence of interactions Lemoine and Waxman
2009 (JCAP 11, 009) relate significance of anisotropy
in a given sky patch at energies E and E/Z by
p (>
E/Z) =
qp (E/Z) s
Z
Z (> E)
qZ (E)
( +1)/2
provided an E-s spectrum from a nearby source is
dominated by protons and Z-nuclei at E/Z and E,
respectively, where E-α observed spectrum, qZ(E) =
injection composition of nearby source at energy E
37
Composition and energy dependence
of excess from nearby source:
simulation results
significance of excess within 18 degrees
around nearby source
Lemoine/Waxman estimate
simulations including energy losses
with relatively strong fields do not
necessarily show strong correlations
between anisotropies at different
energies
=> anisotropy may not directly
constrain composition
38
Possible Explanations of
anisotropy results
interactions break the E/Z degeneracy
mixed composition washes out anisotropies
nearby and background source fluxes may
not be independent since a nearby
magnetized source can shield the background
flux at low energy thus reducing the
excess. Shielding at high energy irrelevant
due to GZK effect
39
UHECR Deflection in
Galactic Magnetic Fields
Deflection in galactic magnetic field is rather
model dependent, here for E/Z=4 1019 eV for
Models of
Tinyakov, Tkachev (top)
Harrari, Mollerach, Roulet (middle)
Prouza, Smida (bottom)
Deflection in extragalactic fields is even more
uncertain
Kachelriess, Serpico, Teshima, Astropart. Phys. 26 (2006) 378
40
Mapping the Sky at Earth to the Sky outside the Galaxy by
backtracing anti-nuclei
contour plot of amplification
factor for 60 EeV iron nuclei
due to Galactic magnetic
field: Prouza-Smida
model, no turbulence
including a turbulent
component of strength 4 µG,
50 pc coherence length,
extending 3 kpc into halo
Giacinti, Kachelriess, Semikoz, Sigl, Astropart.Phys. 35 (2011) 192
41
Composition and the Transition Galactic/Extragalactic
Cosmic Rays
turbulent coherence length varied
turbulent field strength varied
Giacinti, Kachelriess, Semikoz, Sigl, arXiv:1112.5599
Light Galactic Nuclei produce too much anisotropy above ≃ 1018 eV. This implies:
1.) if composition around 1018 eV is light => probably extragalactic (and ankle may be due
to pair production by protons)
2.) if composition around 1018 eV is heavy => transition could be at the ankle if
Galactic nuclei are produced by sufficiently frequent transients, e.g. magnetars
42
Distribution of Galactic Sources Contributing to
Observed Flux
E/Z=1018 eV
19
E/Z=3x10
Giacinti, Kachelriess, Semikoz, Sigl, arXiv:1112.5599
43
eV
Physics Conclusions
1.) Both diffuse cosmogenic neutrino and photon fluxes mostly
depend on chemical composition, maximal acceleration energy
and redshift evolution of sources
2.) Multi-messenger modeling sources including gamma-rays and
neutrinos start to constrain the source and acceleration
mechanisms
3.) It is surprisingly difficult to construct simple scenarios
with structured sources and magnetic fields that reproduce all
observations: spectra, energy dependent composition and
anisotropy; to explain them separately is quite easy
44
Conclusions
Multimessenger Simulations with CRPropa 2.0:
1.Nuclei propagation through ambient photon fields with all
relevant interactions
2.Deflections in magnetic fields (3D)
3.1D version with cosmological evolution
4.Secondary electromagnetic cascades and neutrino
propagation (rectilinear approximation)
Currently we are β testing the full nuclei code.
If you want to use or test the code, please contact us.
45

Review of Interpretation of Multi-Messenger Data

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