what can we really learn from positron flux 'anomalies'?
DESCRIPTION
What can we really learn from positron flux 'Anomalies'?. Boaz Katz, Kfir Blum, Eli Waxman arXiv:0907.1686. PAMELA. …Our results clearly show an increase in the positron abundance at high energy that cannot be understood by standard models describing the secondary production of cosmic-rays. - PowerPoint PPT PresentationTRANSCRIPT
What can we really learn from positron flux 'Anomalies?'
Boaz Katz, Kfir Blum, Eli Waxman
arXiv:0907.1686
…Our results clearly show an increase in the positron abundance at high energy that cannot be understood by standard models describing
the secondary production of cosmic-rays .
PAMELA
CR positrons:
What do we expect?
What do we know?
• e+ ~ pbar / radiative losses
• pbar understood
• Measure e+ measure losses
• 10Be agrees secondary!
• e+/pbar theoretically clean
Plan:
• e+ `anomaly’ ???
• Propagation models fit grammage.
e+ lose energy radiatively( -ordinarily )steep spectrum, loss suppresses flux.
Ignore energy loss upper bound on flux.
e+ produced in pp and spallation interactions
– similar to , B, Sc, Li,…
e+ ~ pbar / radiative losses
Stable secondaries, no loss
Pbar understood
Pbar understood: Stable secondaries, no loss
In general
…If*:
• Propagation only depends on magnetic rigidity
• Rigidity fixed on propagation
• Homogenous composition*Also used the fact that spallation secondary inherits rigidity of primary
Stable secondaries, with loss
Pbar understood
Pbar understood: Stable secondaries, with loss
nP,out
n’A,out nA,in
nP,in
n’’A,out
nP,out
nA,in
nP,in
nA,out
Equivalently:
Homogenous composition :
Qeff works just the same!
Pbar understood: Stable secondaries, with loss
Pbar understood
Antiprotons
Antiprotons
Pbar understood
Antiprotons
Pbar understood
Why does it work so well??
Why it could work:NGC 891
1.4GHz
NIR
Positrons
Measure e+ measure losses
?
non secondary
(very )probably secondary
Measure e+ measure losses
Cooling vs Decay
10Be agrees e+ secondary!
- ~1
Atomic clocks
Be/B
10Be agrees e+ secondary!
Atomic clocks
10Be agrees e+ secondary!
Factorize out spallation losses:
Agree with e+
Be/B
e+/pbar theoretically clean
e+ anomaly??
Claims of a primary source:
Unknown.2
Unknown.
?
?
Diffusion models fit grammage.
Maurin, Donato, Taillet, Salati
Astrophys.J.555:585-596,2001
()
Diffusion models fit grammage.
Summary & Outlook
• Interpreting e+ data
e+ ~ pbar / radiative losses; pbar understood
Measure e+ measure losses
• `Anomaly’ ? Doesn’t seem so right now10Be agrees secondary!
No tension with model independent estimates
Wait for further data release. PAMELA reach Ee+< 270 GeV
• e+/pbar theoretically clean
define model independent tests for exotics
• Propagation models fit grammage
what does it mean to be conservative?
?
Xtras
Pbar understood: Stable secondaries, no loss
…If:
In general
protons
TeV
slope ~ 2.75 above ~ 20 GeV, ~ 0.1/m^2srs above TeV
ρ Ophiuchi