Transcript Document

Examples of Science
• Generic fluxes associated with
cosmic rays
• Astrophysics: gamma ray
bursts
• Particle physics: cold dark
matter search
Nature’s Particle Accelerators
• Electromagnetic Processes:
– Synchrotron Emission
• Eg a (Ee/mec2)3 B
– Inverse Compton Scattering
• Ef ~ (Ee/mec2)2 Ei
– Bremmstrahlung
• Eg ~ 0.5 Ee
• Hadronic Cascades
– p + g -> p± +po +… -> e ± + n + g +…
– p + p -> p± +po +… -> e ± + n + g +…
High Energy Gamma-Ray Astrophysics
Typical Multiwavelength Spectrum
from High Energy g-ray source
E2 dN/dE
or
n Fn
[ Energy
Emitted]
Radio
Optical
X-ray
[ Photon Energy]
GeV
TeV
Spinning Neutron Star Fills Nebula with Energetic Electrons
=> Synchrotron Radiation and Inverse Compton Scattering
Active Galactic Nuclei
•Massive Black Hole Accelerates Jet of Particles to Relativistic Velocities
=> Synchrotron Emission and Inverse Compton and/or Proton Cascades
Challenge I: Acceleration
shock velocity n
R
n
1  1 BR2
V  ~
  BRE p   eBR
c
c R/v
(V = e ;  = v/c)
B
2
2


E
B2
B
1
L  dE /dt  { 4pR2dR}/dt  4pR2
v >  p c
8p
8p
2  e 

= boosted energy 
from cosmic accelerator

L>2
2

2
E p,20
1045 erg/s
Energy in extra-galactic cosmic rays ~
3x1037 erg/s or 1044 erg/yr per (Mpc)3
3x1039 erg/s per galaxy
3x1044 erg/s per active galaxy
2x1052 erg per gamma ray burst
1 TeV = 1.6 erg
brightest known sources match IF
equal energy in protons and electrons (photons)
• AGN (steady):
~ few requires L>1047 erg/s
Few, brightest AGN
• GRBs (transient):
~ 300 requires L>1051 erg/s
Average Lg~1052 erg/s
equal energy in neutrinos?
some definitions
flux
F = dN/dE (particles cm-2 s-1)
fluency
f = E dN/dE (erg cm-2 s-1)
luminosity L = f x 4pd2 (erg s-1)

Point Sources
a
1 for En 100T eV,



E
-4
n
Pn 
10 
 ,a  
100T eV
0.5 o.w.
n

a -1


 En   AT 
fn
Signal:  event # 1 event -11
 

2 
2


10
erg/cm
s
100T
eV
1km
yr





Background (atmos. n’s):

 -1  En 0.8 AT 1/ 2
fn
3 events  -12

 

2  deg
 300T eV 1km2yr 
10 erg/cm s 
For 10 -- 1000 TeV:

-1
2
fn  10-11 Akm
erg/cm
s
2
-1
2
fn t /100s)  310-5 Akm
erg/cm
2
Cosmological sources:
d  1028 cm
-1

Ln  1046 Akm
2 erg/s
 
52.5 -1

)
L

t
/
100
s

10
Akm2 erg
 n
Most Powerful Cosmological sources:
AGN (Steady)
fg 10-11erg/cm2s
GRBs (~100s transient)
Fg  10-5 erg/cm2

1. ~1 km2 detector
2. Same UHE CR “suspects”
Challenge II: Propagation (GZK)
• >1020eV proton: E<100 Mpc
• Bright AGN (Radio galaxies)- too far 
• GRBs 
Does the spectrum support GZK?
Model
[EW 95]
• Fly’s Eye fit for Galactic heavy (<1019eV):
JG~E-3.50
• X-Galactic protons:
Generation spectrum (shock acceleration):
dnp / d p   p-n
, n  2;
Generation rate:
 10 21 eV
dn p 
erg
44


R   19 d p  p
 3 10
;
3
 10 eV

d p 
Mpc yr

z 0
Redshift evolution ~ SFR
Model vs. Data
X-G Model:
[Bahcall & EW 03]
R  3.0  1044 erg/Mpc3yr; n  2.1
Ruled out
7s
5s
Conclusions are Robust
R  3.5  1044 erg/Mpc3yr; n  2.0
CR Conclusions
• Yakutsk, Fly’s Eye, HiRes: Consistent with
dn p
erg
 0.8 10
XG protons: E
+ GZK
3
dEp
Mpc yr
2
p
44
Robust; Consistent with GRB model predictions
• AGASA (25% of total exposure):
Consistent below 1020eV
Excess above 1020eV: 2.2+/-0.8
8 observed
New source/ New physics/ ?? 25% energy
Local inhomogeneity
over-estimate
• Stay tuned for Auger (Hybrid)
diffuse flux
flux = velocity x density
flux = c/4p x density, for isotropic flux
--> in energy density
E dN/dE dE = c/4p x rE
-g
E dN/dE = A E cm-2 s-1
sr-1 (g = -1)
diffuse background
Signal:
a -1

 n
n2n


 event #  1 -9

2
 100 TeV 
10
GeV/cm
s
sr



 AT 


2
 1km yr 
Background (atmos. n’s):

 n
 


Ns  3 -8 n n 2

10
GeV/cm
s
sr
300
T
eV



2
0.8
 AT 


2
 1km yr 
Waxman-Bahcall bound
n2n  5 10-8 GeV/cm2s sr

1/ 2
~ 1km2 detector --> 50 events/yr
n Flux Bound
• Observed JCR(>1019eV)
dncr
E
dE
 1044 erg/Mpc3 yr
2
z 0
• For Sources with tgp < 1:
cr
c
GeV
2 dn
-8
E n 
E
  z tH  5 10  z
4p
dE
cm2ssr
2
• Strongest know z evolution (QSO, SFR): collect n’s beyond
GZK
ncr  (1  z)3
 Z  3
[EW & Bahcall 99, Bahcall & EW 01]
tgp for known sources
’g
g
p+ e+
n
e-
p
 p 'g  m p mp 
g
2me2
-6



4

10
 g  'g  2me2 
 p m p mp
 tgg g  1TeV)  2 103t gp  p  2 1017 eV)
Antares
Nemo
Neutrinos from GRB: an example
11
22
1m released
inside 10 2km
(opaque)
44
g’s produces by
electron synchrotron
33
Fireball n’s
 100MeV
Relativistic shock
g = 102 - 103
electron - proton
acceleration
Gamma-ray Bursts
M on ~1 Solar Mass BH
Relativistic Outflow
~300
e- acceleration in
Collisionless shocks
e- Synchrotron
Lg~1052erg/s
[Meszaros, ARA&A 02]
MeV g’s
Gamma
Ray
Burst
• Photons and protons
coexist in internal
shocks
• External shocks
1969
1997
BATSE: 1991- May 2000
NUMEROLOGY
Lg = 1052 erg/s
R0 = 100 km
Eg = 1 MeV
t = 1-10 msec
g= 300
tH = 1010 years
dE/dt = 4x1044 erg Mpc-3yr-1
Pdetected = 10-6 En0.8 (in TeV)
spg = 10-28cm2 for p+gn+p
< xp  p > = 0.2
GRB1
FRAMES
Fireball Frame
Observer Frame
R
R'
R
v
c
g ~ 102 - 103
E = g E' ~ 1 MeV
R = g R'
d
R = ct = R0
with R0 = R' (t = 0)
observed 1 msec
grb kinematics

R
c
• tobs

v
• R0 ~- 100 km
• cos  = v/c
v__2 -1/2
g = [1- 2 ]
c
~
- 102 - 103
1_
R
__
t =
= c (R - Rcos)
c
2
v
v
R
R
__
__ ) ~ __ ( 1 - )
1__
R
__
(1__
- 2c
=
~
c2
c
- 2c g2
c
• Eobs ~
- gE
GRB3
Pion (neutrino) production when
protons and photons coexist
pg
np+
neutrinos
np0
gamma rays
2 - m2
m

p
_________
E'p >
4E'g
En = 1/4 < xp
p > Ep
Ep > 1.4 x 104 TeV
~
_
1/20 Ep
~
_
0.7 PeV
GRB4
Fraction of GRB energy converted
into pion (neutrino) production
fp=
R'
___
pg
xp
p
> ~_ 15%
-1pg = ng spg
e
fireball
synchro/ICompton
p
(LCR)
g (Lg)
pions
n
GRB2
Photon Density in the Fireball
Lgt/g
______
2R'
U'
4pR'
g
___
ng =
=
E'
E'g
g
___
R' = g2ct
g
R' = gct
note: for g = 1 (no fireball) optical depth of
photons is
R
0
__
topt =
= R0ngsTh ~ 1015
Th
GRB 5
Neutrino flux from GRB fireballs
U
1
c
c
dE
n
___
___
__
fn =
= __
(
1/2 fp tH __ )
4p En
dt
4p En
charged p only
Nevents = Psurvived Pdetected fn
~
_ 20 km -2 yr -1
LCR ~_ Lg
GRB 6
NUMEROLOGY
Lg = 1052 erg/s
R0 = 100 km
Eg = 1 MeV
t = 1-10 msec
g = 300
<xp -> p> = 1/5
spg = 10-28cm2
tH = 1010 years
dE/dt = 4x1044 erg Mpc-3yr-1
Pdetected = 10-6 En0.8 (in TeV)
Search for HE n from GRB
GRB search bin
Off source
GRB Position
1 hour
BKG - off time
GRB burst
16 s
1 hour
on time BKG - off time
GRB search bin
Correlations
to GRB
Off source
GRB Position
1 hour
BKG - off time
GRB burst
16 s
1 hour
on time BKG - off time
Background cuts can be
loosened considerably
 high signal efficiency
88 BATSE bursts in 1997
Combined
data give
sensitivity
~ prediction!
Marriage of Astronomy and Physics
• Astronomy: new window on the Universe!
“You can see a lot by looking”
• Physics:
search for dark matter
search for topological defects and cosmological remnants
search for monopoles
measure the high-energy neutrino cross section
(TeV-scale gravity?)
cosmic ray physics: 150 atmospheric nus/day
array with EeV sensitivity
test special and general relativity with new precision
Relic density – simple approach
Decoupling occurs when
<H
We have
  s ann v n 
 m T 
eq
n  g 
 2p 
H(T )  1.66g
3 /2
1/ 2
*
e
- m / T
T2
mP lanck
m
20
3  10-27 cm3 s-1
2
  h 
s ann v
  H  Tf 
s annv  s annv WIMP   1
The MSSM – general
The Lightest Supersymmetric
Particle (LSP)
Usually the neutralino. If
R-parity is conserved, it is
stable.
The Neutralino – 
˜ 3  N13 H
˜ 10  N14 H
˜ 20
˜ 10  N11 B˜  N12 W
1. Select MSSM parameters
2. Calculate masses, etc
3. Check accelerator constraints
4. Calculate relic density
5. 0.05 < h2 < 0.5 ?
6. Calculate fluxes, rates,...
Calculation done with
Gaugino fraction
2
Zg  N11  N12
2
http://www.physto.se/~edsjo/darksusy/
The m-Zg parameter space
Gauginos
Mixed
Higgsinos
Low sampling
WIMP search strategies
• Direct detection
• Indirect detection:
– neutrinos from the Earth/Sun
– antiprotons from the galactic halo
– positrons from the galactic halo
– gamma rays from the galactic halo
– gamma rays from external galaxies/halos
– synchrotron radiation from the galactic center /
galaxy clusters
– ...
Direct detection - general
principles
• WIMP + nucleus 
WIMP + nucleus
• Measure the nuclear recoil
energy
• Suppress backgrounds
enough to be sensitive to a
signal, or...
• Search for an annual
modulation due to the
Earth’s motion around
the Sun
Edelweiss
June 2002
Most likely DAMA
point. Excluded at 99.8% CL
Direct detection – current limits
Spin-independent scattering
Spin-dependent scattering
Direct detection experiments have started exploring the MSSM parameter space!
Neutralino capture and annihilation
r 
Sun
velocity
distribution
Earth
n interactions
sscatt
n
n int.
 int.
capture
annihilation
qq
ll
 
 n

Detector


W , Z,H
interactions
hadronization

-


 cc ,bb ,tt , t t ,W , Z , H H
Silk, Olive and Srednicki, ’85
Gaisser, Steigman & Tilav, ’86
0
0
Freese, ’86; Krauss, Srednicki & Wilczek, ’86
Gaisser, Steigman & Tilav, ’86
Indirect detection for cyclists
e.g. 104 m2 n-telescope searches for 500 GeV WIMP
300 km/s
> LHC limit
1.  - flux
500
GeV
________
4
f = rv = 2.4 x 10 [
]cm-2s-1
mz
500
GeV
________
-3
-4
0.4 GeV cm = 8 x 10 [
] cm-3
mz
2. Solar cross section
M
__
S = ns = m s (N) = [1.2x10]57 10-41cm2
N
GF2
MZ2
___
(GF mN2)2 ___4 ~
2
m
Z
mH
N = capture rate = annihilation rate
_

500 GeV
WW
n
250 GeV
3. Capture rate by the sun
N = f S= 3 x 1020 s-1
4. Number of muon-neutrinos
Leptonic BR~0.1
Nn = 2 x 0.1 N 
N
n
____
-8 cm-2 s-1
5. fn =
=
2
x
10
4pd2 1 A.U.
5.5 x 1023 cm-3
6. # events = area x fn x rice x sn

x R
104 m2
E
n
___
-38
2
• sn  = 10 cm
= 2.5 x 10-36 cm2
GeV
E

___
• R = 5m
= 625m (E ~_ 0.5 En)
GeV
# events = 10 per year
Baikal
AMANDA limit
– 10 strings only
Limits:  flux from the Earth/Sun
Earth
Sun
Flux from Earth/Sun and future
GENIUS/CRESST limits
Earth
Sun