The electron/positron puzzle in the Fermi and PAMELA era Aldo - - PowerPoint PPT Presentation

▶
the electron positron puzzle in the fermi and pamela era
SMART_READER_LITE
LIVE PREVIEW

The electron/positron puzzle in the Fermi and PAMELA era Aldo - - PowerPoint PPT Presentation

May 20, 2023 296 likes •1.07k views

The electron/positron puzzle in the Fermi and PAMELA era Aldo Morselli INFN Roma Tor Vergata May 18 2010 GGI Conference The Dark Matter connection: Theory & Experiment 1 Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

slide-1
SLIDE 1

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

1

Aldo Morselli

INFN Roma Tor Vergata

The electron/positron puzzle in the Fermi and PAMELA era

May 18 2010 GGI Conference The Dark Matter connection: Theory & Experiment

slide-2
SLIDE 2

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

2

Neutralino WIMPs

Assume χ present in the galactic halo

  • χ is its own antiparticle => can annihilate in galactic halo

producing gamma-rays, antiprotons, positrons….

  • Antimatter not produced in large quantities through standard processes

(secondary production through p + p --> anti p + X)

  • So, any extra contribution from exotic sources (χ χ annihilation) is an

interesting signature

  • ie: χ χ --> anti p + X
  • Produced from (e. g.) χ χ --> q / g / gauge boson / Higgs boson and

subsequent decay and/ or hadronisation.

slide-3
SLIDE 3

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

3

Caprice coll. Astrophysics Journal, 487, 415, 1997

Antiproton/proton ratio 1997

slide-4
SLIDE 4

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

4

MASS Matter Antimatter Space Spectrometer

slide-5
SLIDE 5

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

5

the MASS89 Calorimeter

slide-6
SLIDE 6

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

6

MASS 89 the calorimeter

slide-7
SLIDE 7

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

7

MASS 89

the calorimeter

slide-8
SLIDE 8

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

8

from Las Cruces to Prince Albert

slide-9
SLIDE 9

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

9

slide-10
SLIDE 10

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

10

slide-11
SLIDE 11

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

11

slide-12
SLIDE 12

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

12

slide-13
SLIDE 13

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

13

MASS 89 flight

slide-14
SLIDE 14

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

14

MASS 89 flight

slide-15
SLIDE 15

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

15

MASS 89

slide-16
SLIDE 16

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

16

PAMELA

Payload for Antimatter Matter Exploration and

Light Nuclei Astrophysics In orbit on June 15, 2006, on board of the DK1 satellite by a Soyuz rocket from the Bajkonour launch site.

First switch-on on June 21 2006

From July 11 Pamela is in continuous data taking mode

slide-17
SLIDE 17

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

17

Separating p from e-

Pamela

slide-18
SLIDE 18

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

18

PAMELA detectors

GF: 21.5 cm2 sr Mass: 470 kg Size: 130x70x70 cm3 Power Budget: 360W

Spectrometer microstrip silicon tracking system + permanent magnet It provides:

  • Magnetic rigidity  R = pc/Ze
  • Charge sign
  • Charge value from dE/dx

Time-Of-Flight plastic scintillators + PMT:

  • Trigger
  • Albedo rejection;
  • Mass identification up to 1 GeV;
  • Charge identification from dE/dX.

Electromagnetic calorimeter W/Si sampling (16.3 X0, 0.6 λI)

  • Discrimination e+ / p, anti-p / e-

(shower topology)

  • Direct E measurement for e-

Neutron detector plastic scintillators + PMT:

  • High-energy e/h discrimination

Main requirements  high-sensitivity antiparticle identification and precise momentum measure

+ -

slide-19
SLIDE 19

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

19

  • ~ 4 years from

PAMELA launch

  • Launched in orbit on

June 15, 2006, on board

  • f the DK1 satellite by a

Soyuz rocket from the Bajkonour cosmodrom.

slide-20
SLIDE 20

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

20

Antiproton-Proton Ratio

Diffuse and Convention Propagation Model Upper and lower bounds A.Lionetto, A.Morselli, V.Zdravkovic JCAP09 (2005) 010 [astro-ph/0502406]

  • PAMELA data: Phys. Rev. Lett. 102, 051101-1 (2009) arxiv:0810.4994

The conventional GALPROP model with γ0 = 2.54 ( δ = 0.33 ) gives a satisfactory description of those data

slide-21
SLIDE 21

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

21

Antiproton flux

p r e l i m i n a r y

slide-22
SLIDE 22

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

22

Positron ratio Positron ratio

conventional GALPROP model

γ0 = 2.54 ( δ = 0.33 ) Secondary positrons only !

e+/(e+ + e-) ∝ E - γp + γ0 - δ γp: proton source power-index

It improves only adopting very soft electron spectra (high γ0 ) E< 10 Gev, probably solar modulation effect

Nature 458, 607 2009 [arxiv:0810.4995]

slide-23
SLIDE 23

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

23

Positron ratio Positron ratio

Secondary production Pamela new data (~ 30% more)

July06-December08

and new analysis

Nature 458,607, 2009 [arxiv:0810.4995] arXiv:1001.3522

Pamela Nature paper

July06-February08

slide-24
SLIDE 24

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

24

Pamela Electron Spectrum ( e- )

p r e l i m i n a r y

slide-25
SLIDE 25

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

25

Pamela Electron Spectrum ( e- )

p r e l i m i n a r y

slide-26
SLIDE 26

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

26

Proton Spectrum

p r e l i m i n a r y

slide-27
SLIDE 27

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

27

PAMELA Helium

slide-28
SLIDE 28

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

28

Carbon

slide-29
SLIDE 29

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

29

Boron

slide-30
SLIDE 30

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

30

Li/C

preliminary

Be/C

preliminary

preliminary

B/C

The HEAO-3 sharp peak at ~1 GeV/nucleon seem to be confirmed by PAMELA

slide-31
SLIDE 31

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

31

31

The CAPRICE 94 flight

slide-32
SLIDE 32

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

32

32

The TS93 and CAPRICE silicon-tungsten imaging calorimeter.

48 cm 48 cm

slide-33
SLIDE 33

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

33

~1993

High Energy Gamma Experiments Experiments

slide-34
SLIDE 34

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

34

slide-35
SLIDE 35

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

35

35

Elements of a pair-conversion telescope

  • photons materialize

into matter-antimatter pairs: Eγ --> me+c2 + me-c2

  • electron and positron

carry information about the direction, energy and polarization of the γ-ray (energy measurement)

slide-36
SLIDE 36

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

36 Energy Calorimeter Spark Chamber Trigger Telescope Cerenkov Counter Anti-Coincidence Dome

Cos-B 8/1975-4/1982

SAS-2 11/1972-7/1973

EGRET 4/1991-1999

The gamma-ray missions

slide-37
SLIDE 37

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

37

GILDA

slide-38
SLIDE 38

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

38

New Detector Technology

  • Silicon strip detector

Strip-shaped PN diode 50-500micron wide 300-500micron thick VLSI amplifier

Stable particle tracker that allows micron-level tracking of gamma-rays

Well known technology in Particle Physics experiments. Used by our collaboration in balloon experiments (MASS, TS93, CAPRICE),

  • n MIR Space Station ( SilEye) and on satellite (NINA)
slide-39
SLIDE 39

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

39

GILDA

GLAST

slide-40
SLIDE 40

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

40

Fermi launch 11 June 2008

slide-41
SLIDE 41

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

41

First Fermi LAT Catalogs

1451 sources

Fermi Large Area Telescope First Source Catalog arXiv:1002.2280, 2010 ApJS accepted. (1FGL)contains 1451 sources detected and characterized in the 100 MeV to 100 GeV, first 11 months data. The First Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope arXiv: 1002.0150, includes 671 gamma-ray sources at high Galactic latitudes (|b| > 10 deg), with TS> 25 and associated statistically with AGNs. The First Fermi Large Area Telescope Catalog

  • f Gamma-ray Pulsars

2010ApJS..187..460A . Contains 46 high- confidence pulsed detections using the first six months of data

S i m

  • n

a M u r g i a p r e v i

  • u

s t a l k

slide-42
SLIDE 42

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

42

How Fermi LAT detects gamma rays

4 x 4 array of identical towers with:

  • Precision Si-strip tracker (TKR)

– With W converter foils

  • Hodoscopic CsI calorimeter (CAL)
  • DAQ and Power supply box

An anticoincidence detector around the telescope distinguishes gamma- rays from charged particles

γ e+ e-

Conversion Conversion (γ i in e+/e /e-) in W foils in W foils Incoming Incoming γ Incoming direction Incoming direction reconstruction by reconstruction by tracking the tracking the charged particles charged particles Energy Energy m measurement with e.m. with e.m. calorimeter calorimeter

slide-43
SLIDE 43

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

43

How Fermi LAT detects electrons

Trigger and downlink

  • LAT triggers on (almost)

every particle that crosses the LAT

– ~ 2.2 kHz trigger rate

  • On board processing

removes many charged particles events

– But keeps events with more that 20 GeV of deposited energy in the CAL – ~ 400 Hz downlink rate

  • Only ~1 Hz are good γ-rays

Electron identification

  • The challenge is identifying

the good electrons among the proton background

– Rejection power of 103 – 104 required – Can not separate electrons from positrons

ACD identifies ACD identifies charged particles charged particles Incoming Electron Incoming Electron Main track Main track pointing to the pointing to the hit ACD tile hit ACD tile Same tracking and Same tracking and energy energy reconstruction reconstruction algorithms used algorithms used for for γ-r

  • rays
slide-44
SLIDE 44

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

44

Event topology

  • TKR: clean main track with extra-

clusters very close to the track

  • CAL: clean EM shower profile, not

fully contained

  • ACD: few hits in conjunction with

the track

  • TKR: small number of extra

clusters around main track

  • CAL: large and asymmetric shower

profile

  • ACD: large energy deposit per tile

A candidate electron (recon energy 844 GeV) A candidate hadron (raw energy > 800 GeV)

slide-45
SLIDE 45

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

45

Distribution of the transverse sizes of the showers (above 150 GeV) in the calorimeter

slide-46
SLIDE 46

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

46

Reconstruction of the most probable value for the event energy:

  • based on calibration of the

response of each of 1536 calorimeter crystals

  • energy reconstruction is
  • ptimized for each event
  • calorimeter imaging capability

is heavily used for fitting shower profile -

  • tested at CERN beams up to

280 GeV with the LAT Calibration Unit

Very good agreement between shower profile in beam test data (red) and Monte Carlo (black)

Energy reconstruction

Electrons

slide-47
SLIDE 47

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

47

Energy reconstruction

slide-48
SLIDE 48

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

48

Fermi LAT Energy resolution for electrons

slide-49
SLIDE 49

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

49

Energy Resolution Validation with Beam Test data

slide-50
SLIDE 50

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

50

Comparison of standard and high-X0 spectra

  • Consistent within their own systematics
slide-51
SLIDE 51

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

51

Fermi-LAT CRE data vs the conventional Fermi-LAT CRE data vs the conventional pre-Fermi pre-Fermi model model

Although the feature @~600 GeV measured by ATIC is not confirmed Some changes are still needed respect to the pre-Fermi conventional model

Fermi Coll., PRL 102, 181101 (2009) [arXiv:0905.0025] 4/5/09

GALPROP model with γ0 = 2.54 ( δ = 0.33 ) More than 4M electron/positron (E>20GeV) from 4/08/08 to 31/01/09

slide-52
SLIDE 52

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

52

Models 0 and 1 account for CR re-acceleration in the ISM, while 2 is a plain-diffusion

  • model. All models assume γ0 = 1.6 below 4 GeV.
 γ0 = 2.42 (δ = 0.33 - with reacceleration): red line  γ0 = 2.33 (δ = 0.6 - plain diffusion): blue line
  • γ0 = 2.54 ( δ = 0.33 )

Cosmic Ray Electron propagation models Cosmic Ray Electron propagation models

slide-53
SLIDE 53

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

53

“Conventional” model with injection spectrum 1.60/2.42 (break at 4 GeV)

Problems at low energy

e+ + e- Dahed: LIS Solid: modulated Secondary e+ Dahed: LIS Solid: modulated Secondary e-

D.Grasso et al.,Astrop. Phys. [arXiv:0905.0636]

slide-54
SLIDE 54

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

54 Fermi LAT Coll. in preparation

new : new : Fermi Electron + Positron spectrum (end 2009) Fermi Electron + Positron spectrum (end 2009)

Extended Energy Range (7 GeV - 1 TeV) One year statistics (8M evts)

p r e l i m i n a r y

slide-55
SLIDE 55

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

55

Spettro di Elettroni (e- + e+)

p r e l i m i n a r y

slide-56
SLIDE 56

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

56

New Fermi-LAT data at low energy

Problems at low energy are confirmed!!!

p r e l i m i n a r y

slide-57
SLIDE 57

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

57

An extra-component with injection index = 1.5 and an exponential cutoff at 1 TeV gives a good fit of all datasets!

p r e l i m i n a r y

slide-58
SLIDE 58

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

58

The CRE spectrum accounting for nearby pulsars (d < 1 The CRE spectrum accounting for nearby pulsars (d < 1 kpc kpc) )

This particular model assumes: 40% e± conversion efficiency for each pulsar

 pulsar spectral index Γ = 1.7 Ecut = 1 TeV . Delay = 60 kyr

Rescaled conventional pre- Fermi GCRE model by 0.95 @ 100 GeV

γ0 = 2.54 ( δ = 0.33 )

Analytically computed spectra using the same diffusion param. as for the GCRE model

[arXiv:0905.0636]

slide-59
SLIDE 59

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

59

the positron ratio accounting for nearby pulsars (d < 1 the positron ratio accounting for nearby pulsars (d < 1 kpc kpc) )

[arXiv:0905.0636]

slide-60
SLIDE 60

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

60

Electron spectrum and a conventional GALPROP model Electron spectrum and a conventional GALPROP model

The solar modulation was treated using the force-field approximation with Φ = 550 MV

P R E L I M I N A R Y

injection spectral index Γ = 1.6 below 4 GeV Γ = 2.5 above 4 GeV Γ = 5 above 2 TeV e- spectrum only

Secondary e- and e+ from CR p and HE interactions with interstellar gas

slide-61
SLIDE 61

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

61

Electron spectrum and a conventional GALPROP model +... Electron spectrum and a conventional GALPROP model +...

injection spectral index Γ = 1.6 below 4 GeV Γ = 2.7 above 4 GeV + additional component with Γ = 1.5 and exponential cut-of

P R E L I M I N A R Y

slide-62
SLIDE 62

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

62

  • 1. On purely energetic grounds they work (relatively large

efficiency)

  • 2. On the basis of the spectrum, it is not clear
  • 1. The spectra of PWN show relatively flat spectra of pairs at

Low energies but we do not understand what it is

  • 2. The general spectra (acceleration at the termination shock)

are too steep

The biggest problem is that of escape of particles from the pulsar

  • 1. Even if acceleration works, pairs have to survive losses
  • 2. And in order to escape they have to cross other two shocks

Pulsars

New Fermi data on pulsars will help to constrain the pulsar models

Extensive discussion two week ago @ GGI ( Serpico, Blasi .. )

slide-63
SLIDE 63

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

63

Under reasonable assumptions, electron/positron emission from pulsars

  • ffers a viable interpretation of Fermi CRE data which is

also consistent with the HESS and Pamela results.

[arXiv:0905.0636]

What if we randomly vary the pulsar parameters relevant for e+e- production?

(injection spectrum, e+e- production efficiency, PWN “trapping” time)

slide-64
SLIDE 64

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

64

Pulses ¡at 1/10th ¡true ¡rate

16 Gamma-Ray Pulsars Through Blind Frequency Searches

Science 325 (5942), 840-844

A Population of Gamma-Ray Millisecond Pulsars Seen with Fermi

Science 325 (5942), 848-852 (14 August 2009)

The Pulsing γ-ray Sky

slide-65
SLIDE 65

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

65

Spectral measurements and emission models

Evidence of γ-ray emission in the outer magnetopshere due to absence of super- exponential cutoff – Radio and γ-ray fan beams separated – γ-ray only PSRs

Vela Abdo, A. A. et al. 2009, ApJ, 696, 1084

from GLAST proposal (1999)

slide-66
SLIDE 66

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

66

  • Positrons created as secondary products of hadronic interactions

inside the sources

  • Secondary production takes place in the same region where cosmic

rays are being accelerated

  • > Therefore secondary positron have a very flat spectrum, which is

responsible, after propagation in the Galaxy, for the observed positron excess

Blasi, arXiv:0903.2794

  • ther Astrophysical solution
slide-67
SLIDE 67

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

67 ATIC-­‑2 Panov et al., ICRC 2007

A ¡rise ¡would ¡rule ¡out ¡the ¡DM ¡and ¡pulsar ¡explana9on ¡of ¡the ¡PAMELA ¡positron ¡excess.

spalla9on ¡during ¡propaga9on

  • nly

spalla9on ¡also ¡during accelera9on Mertsh and Sarkar, arXiv:0905.3152

Boron-to-Carbon Ratio

slide-68
SLIDE 68

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

68

electron + positron expected anisotropy in the directions of Monogem and Geminga

slide-69
SLIDE 69

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

69

  • Statistical limit for the integral anisotropy set by
  • The plot includes all the instrument effects:
  • Energy-dependent effective geometry factor;
  • Instrumental dead time and duty cycle, On board filter.
  • Room for improvements with a better event selection!

Measurement of anisotropies: statistics

slide-70
SLIDE 70

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

70

Measurements of anisotropies: systematics

  • ≈ 25% disuniformity in the exposure map induced by the SAA.

Measuring a 0.1% anisotropy requires a knowledge of the exposure map at the ≈ 0.1% level.

Terrestrial coordinates (South Atlantic Anomaly clearly visible). Fermi does not take science data within the SAA polygon. Exposure map For gammas, after three months of mission (used for the bright source list). It will not be very different for the electrons and for longer time periods.

cm2 s

slide-71
SLIDE 71

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

71

New Data is Forthcoming

  • PAMELA & FERMI (GLAST) (taking data in space);
  • ATIC-4 (had successful balloon flight,under analysis);
  • CREST (new balloon payload under development);
  • AMS-02 (launch date TBD);
  • CALET (proposed for ISS);
  • ECAL (proposed balloon experiment).

Electron Spectrum: Positron / Electron Separation: PAMELA & AMS-02

slide-72
SLIDE 72

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

72

the positron ratio the positron ratio

slide-73
SLIDE 73

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

73

slide-74
SLIDE 74

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

74

The Electron+positron spectrum (CRE) measured by Fermi-LAT is significantly harder than previously thought on the basis of previous data

Conclusion:

Adopting the presence of an extra e+ primary component with ~ 1.5 spectral index and Ecut ~ 1 TeV allow to consistently interpret Fermi-LAT CRE data (improving the fit ), HESS and PAMELA Such extra-component can be originated if the secondary production takes place in the same region where cosmic rays are being accelerated (to be tested with future B/C measurements)

  • Improved analysis and complementary observations

(CRE anisotropy, spectrum and angular distribution of diffuse γ, DM sources search in γ) are required to possibly discriminate the right scenario.

  • or by annihilating dark matter for model with MDM ≈ 1 TeV
  • or by pulsars for a reasonable choice of relevant parameters

(to be tested with future Fermi pulsars measurements)

slide-75
SLIDE 75

Florence GGI, May 3 2010 Aldo Morselli, INFN Roma Tor Vergata

75

Announcement for SciNeGHE 2010

Gamma-ray Gamma-ray astrophysics astrophysics in the multimessenger context in the multimessenger context TRIESTE TRIESTE, , 8-10 September 8-10 September 2010 2010

8th Workshop on Science with the New Generation High Energy Gamma-ray Experiments

s e e y

  • u

t h e r e ! ! !