... and a few words about Cosmic Rays and Climate CRs and Climate - - PowerPoint PPT Presentation

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and a few words about cosmic rays and climate
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... and a few words about Cosmic Rays and Climate CRs and Climate - - PowerPoint PPT Presentation

Nov 01, 2022 263 likes •621 views

Vulcano 2010 Inhomogeneity in the SN Remnant Distribution as the Origin of the PAMELA Anomaly, and the B/C ratio (i.e., a mundane solution to PAMELA, while abiding to stringent CR constraints) Nir J. Shaviv (Hebrew U.) with Tsvi Piran (Hebrew

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Vulcano 2010 Inhomogeneity in the SN Remnant Distribution as the Origin of the PAMELA Anomaly, and the B/C ratio (i.e., a mundane solution to PAMELA, while abiding to stringent CR constraints)

Nir J. Shaviv (Hebrew U.) with Tsvi Piran (Hebrew U.), Ehud Nakar (TAU) & David Binyamin (Hebrew U.)

... and a few words about Cosmic Rays and Climate

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  • CRs and Climate
  • Solar activity and Climate
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SLIDE 3

Forbush decreases

  • Carefully select Forbush decreases which large

atmospheric ionization effect

AERONET

  • 15 -10 -5

5 10 15 20 days 1.10 1.15 1.20 1.25 1.30 1.35 Aangstroem 340-440nm

SSM/I

  • 15 -10 -5

5 10 15 20 days 0.084 0.086 0.088 0.090 0.092 CWC (kg/m2)

MODIS

  • 15 -10 -5

5 10 15 20 days 0.340 0.345 0.350 0.355 0.360 0.365 Liquid Water CF

ISCCP

  • 15 -10 -5

5 10 15 20 days 0.310 0.315 0.320 0.325 0.330 0.335 Low IR CF

  • 15
  • 10
  • 5

5 CLIMAX (%)

Svensmark et al. GRL 2009 5 strongest forbush decreases (1987-2007)

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SLIDE 4

Experimental Results

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Cloud Experiment @ CERN

  • Positive Results soon to come!
  • Fig. 6: The CLOUD experiment, showing the 0.5m cloud
condensation particle counters (CPC) differential mobility particle sizers (DMPS) mass spectrometers ion mobility spectrometers piston actuator external analysers piston control system trace gas analysers vacuum system CCD cameras Mie scattering detector liquid FC cooling inspection video camera gas & aerosol systems cooling /temperature control synthetic air/ argon water vapour aerosols trace gases ice particle detector cryogenics expansion system retractable probe refractive index gas thermometer lasers beam telescope scintillation counter roof (GCR monitor) aerosol /trace gas analysers in situ analysers temperature & pressure mixing chamber field cage voltage UV illumination

Kirkby et al.

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SLIDE 6

Sea Level change rate Solar Flux

Sea Level Variations

Shaviv, JGR 2008

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Synopsis

❖ The Standard Picture of

CR Acceleration & Diffusion

❖ The PAMELA anomaly ❖ New Type of sources?? ❖ A SN Remnant Solution: ✴ Distribution of SNe ✴ Implications (e.g., B/C)

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SLIDE 8

Standard View

  • Electrons and Protons

are mostly accelerated by supernova/ interstellar medium (ISM) shocks.

  • Pairs are produced by

the protons interacting with the ISM

  • Positron / Electron ratio

should decrease with energy! C, p, e- spectrum at source C, p, e- spectrum in galaxy

faster diffusion EVEN faster diffusion

B, e+ e- spectrum in galaxy

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SLIDE 9

These models fit the data well

Typical parameter values

D(E>E0) = D0 (E/E0)!

"

D0 = 3-5 ! 1028 cm2/s E0 ~ 3 GeV ! = 0.3-0.6 lH =2-4 kpc

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PAMELA results:

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1st Type of Solutions: Astrophysical Sources of Pairs: Pulsars

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2nd Type of Solutions: Decay of exotic particles (WIMPs)

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Source distribution: Most SNe

  • ccur in the spiral arms
  • In the Milky Way: Almost all

SNe are non-Type Ia, and

  • ccur where almost all star

formation takes place: In the Spiral Arms

  • Meteorites: Show that

density changes by a factor

  • f > 2.5
  • Deconvolved Synchrotron:

Shows arm to inter-arm ratio of ~ 3

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SLIDE 14

DECLINATION (B1950) RIGHT ASCENSION (B1950) 20 34 15 00 33 45 30 60 03 02 01 00 59 59 58 57 56 55 54 0.5 1.0 1.5 2.0

3rd Type of Solution: Source Distribution

NGC6946

Lacey & Duric 2003

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Meteoritic and Terrestrial Evidence

Shaviv & Veizer 2003

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So?

  • If CRs primarily come from the

spiral arms, it takes them time!

  • Along the way, electrons cool

though Synchrotron & Compton (on CMB, IR background and starlight).

  • Above some energy, they don’t

have enough time to reach us.

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So?

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This means that...

  • Above Eb ~ 20 GeV, the electrons

will start cooling.

  • Positrons however, form along the

way from proton-ISM interactions, therefore the positron/electron ratio will increase

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  • Primary electrons cool and

disappear before reaching earth

  • Secondary electrons/positrons

form nearer and can reach earth before cooling

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  • Electrons from Sprial

arms above ~ 20 GeV cool (synchrotron and inverse-Compton) before reaching the solar system!

  • Protons do not cool, so

positron production near us does not care (too much) about cooling.

What does it mean?

p, e- spectrum at source p spectrum in galaxy faster diffusion

  • ut of the galaxy!

e+ e- spectrum in galaxy e

  • s

p e c t r u m i n g a l a x y

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SLIDE 21
  • Electrons from Sprial

arms above ~ 20 GeV cool (synchrotron and inverse-Compton) before reaching the solar system!

  • Protons do not cool, so

positron production near us does not care (too much) about cooling. p, e- spectrum at source p spectrum in galaxy faster diffusion

  • ut of the galaxy!

e+ e- spectrum in galaxy e- s p e c t r u m i n g a l a x y

What does it mean?

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Monte Carlo Model

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Results

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e+/(e++e-) ratio and e- spectrum

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e+/(e++e-) ratio and e- spectrum

Contribution from nearby KNOWN young SNRs: Geminga, Monogem, Vela LoopI and Cygnus Loop

A comaprison with Pamela/Fermi/ HESS data

?

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e+/(e++e-) ratio and e- spectrum

Contribution from nearby KNOWN young SNRs: Geminga, Monogem, Vela LoopI and Cygnus Loop Exact CR diffusivity effects high E behavior (effect of singular SNRs)

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e+/(e++e-) ratio and e- spectrum

Preliminary results (Bruno, here) are consistent with a spectral break at ~50 GeV This is naturally interpreted as the contribution from disk +local SNR Break

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Does this disturbe the protons?

  • Arm + non-truncated

disk - dotted line

  • Arm + truncated disk
  • dashed line
  • Arm + truncated disk

+ nearby sources - full line

  • Nearby sources -

dot-dashed line

Break due to the solar wind

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More detailed modeling

  • All the galaxy.
  • Allowing arm dynamics (important for B/C):

★ CR age at high energy: Diffusion time

(smaller for larger E)

★ CR age at low energies: Time from last

arm passage (tp ~ few 10^7 yr)

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More detailed modeling

  • All the galaxy.
  • Allowing arm dynamics (important for B/C):

★ CR age at high energy: Diffusion time

(smaller for larger E)

★ CR age at low energies: Time from last

arm passage (tp ~ few 10^7 yr) second./prim. ~ d2/κ c ~ E-1/3 d

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SLIDE 31

More detailed modeling

  • All the galaxy.
  • Allowing arm dynamics (important for B/C):

★ CR age at high energy: Diffusion time

(smaller for larger E)

★ CR age at low energies: Time from last

arm passage (tp ~ few 10^7 yr) second./prim. ~ tp v ~ E+1/2 tp

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Results for B/C

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Conclusions

➡

Taking the real distribution of SNRs gives the correct positron/electron energy behavior.

➡

NO Free parameters give the correct break energy (constrained by cosmic ray age).

➡

Nearby young known SNRs dominate around 800

  • GeV. e+/e- @ high E depends on exact κ.

➡

Predictions:

❖

e+/etot ratio should saturate < 50%

❖

At higher energies the ratio should decrease! (due to fresh electrons)

➡

B/C ratio naturally explained once including the arm dynamics. No need for ad hoc assumptions (break in diffusivity, wind, reacceleration)

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That’s it!