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