Search for Dark Matter in Space
Aldo Morselli
INFN Roma Tor Vergata
XII ROMA TRE TOPICAL SEMINAR ON SUBNUCLEAR PHYSICS
Università
degli
Studi Roma Tre
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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.
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Antiproton/proton ratio 1997
Caprice coll.
Astrophysics Journal,
487, 415, 1997
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MASS
Matter Antimatter Space Spectrometer
5 September 2009, marks twenty (!)
years since the launch of MASS 89 !!!
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the MASS89
Calorimeter
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MASS 89 the calorimeter
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from Las Cruces to
Prince Albert
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MASS 89 flight
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MASS 89 flight
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MASS 89
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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
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Pamela
Separating p
from e-
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• ~ 4 years from
PAMELA launch
• Launched in orbit on
June 15, 2006, on board
of the DK1 satellite by a
Soyuz rocket from the
Bajkonour cosmodrom.
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Antiproton-Proton Ratio
The conventional
GALPROP model with
γ0 = 2.54 ( δ = 0.33 )
gives a satisfactory
description of those data
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,
• PAMELA
051101-1 (2009)
data arxiv:0810.4994
arxiv:0810.4994
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2009: PAMELA results
conventional GALPROP model
γ0 = 2.54 ( δ = 0.33 )
Secondary positrons only !
Nature 458, 607 2009
e+/(e+ + e-) ∝ E - γp
E< 10 Gev, probably solar modulation effect
+ γ0 - δ
γp: proton source power-index
It improves only adopting very soft electron spectra (high γ0 )
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The CAPRICE 94
flight
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The TS93 and CAPRICE silicon-tungsten imaging calorimeter.
48 cm
48 cm
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High Energy Gamma Experiments Experiments
~1993
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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)
25
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Anti-Coincidence Dome
Spark Chamber
Trigger Telescope
Cerenkov Counter
SAS-2
11/1972-7/1973
Energy Calorimeter
Cos-B
8/1975-4/1982
The gamma-ray
missions
EGRET
4/1991-1999
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GILDA
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New Detector Technology
• Silicon strip detector
Strip-shaped
PN diode
300-500micron thick
50-500micron wide
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),
on MIR Space Station ( SilEye) and on satellite (NINA)
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GILDA
GLAST
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The GLAST Participating Institutions
American Institutions
SU-HEPL Stanford University, Hanson Experimental Physics Laboratory ,
,
SU-SLAC Stanford Linear Accelerator Center, Particle Astrophysics group
GSFC-NASA-LHEA Goddard Space Flight Center, Laboratory for High Energy Astrophysics
NRL - U. S. Naval Research Laboratory, E. O. Hulburt Center for Space Research, X-ray and gamma-ray branches
UCSC- SCIPP University of California at Santa Cruz, Santa Cruz Institute of Particle Physics
SSU- California State University at Sonoma, Department of Physics & Astronomy , WUStL-Washington University, St. Louis
UW- University of Washington , TAMUK- Texas A&M University-Kingsville, Ohio State University
Italian Institutions
INFN - Istituto Nazionale di Fisica Nucleare and Univ. of Bari, Padova, Perugia, Pisa, Roma Tor Vergata,
Trieste, Udine
ASI - Italian Space Agency
IASF- Milano, Roma
Japanese Institutions
University of Tokyo
ICRR - Institute for Cosmic-Ray Research
ISAS- Institute for Space and Astronautical Science
Hiroshima University
French Institutions
CEA/DAPNIA Commissariat à l'Energie Atomique, Département d'Astrophysique, de physique des Particules,
de physique Nucliaire et de l'Instrumentation Associée, CEA, Saclay
IN2P3 Institut National de Physique Nucléaire et de Physique des Particules, IN2P3
IN2P3/LPNHE-X Laboratoire de Physique Nucléaire des Hautes Energies de l'École Polytechnique
IN2P3/PCC Laboratoire de Physique Corpusculaire et Cosmologie, Collège de France
IN2P3/CENBG Centre d'études nucléaires de Bordeaux Gradignan
IN2P3/LPTA Laboratoire de Physique Theorique et Astroparticules, Montpellier
Swedish Institutions
KTH Royal Institute of Technology
Collaboration members:
~390
Stockholms Universitet
Members:
121
Affiliated Scientists
~96
Postdocs:
68
Graduate
105
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Vergata Students
Tracker Production Overview
Module Structure (walls, flexures,
thermal-gasket, fasteners)
Engineering: SLAC, Italy (Hytec)
Procurement: SLAC, Italy
SSD Procurement, Testing
Japan, Italy, SLAC
SSD Ladder Assembly
Italy (G&A, Mipot)
10,368
Tracker Module
Assembly and Test
Italy
2592
18
Tray Assembly and
Test
Italy (G&A, Mipot)
342
Electronics Design,
Fabrication & Test
UCSC, SLAC (Teledyne)
648
Readout Cables
UCSC, SLAC
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Aldo Morselli, INFN Roma Tor Vergata
Composite Panel & Converters
Engineering:
SLAC, Italy (Hytec, COI)
Procurement: Italy (Plyform)
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Tray assembly in G&A
Tray positioning
Ladder positioning
•160 bare panels produced
•100 tested and qualified for integration
with ladders
•completed trays for 3.3 towers
•6 assembly chain ready
•Max assembly rate : 3 trays/day/shift
Microbonding
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228 µm
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Encapsulation
Dam & Fill encapsulation
Dam Nusil 1142
Fill Nusil 15-2500
Requirements:
1. Height <0.5mm
2. Lateral overflow <0.05mm
3. Coverage of all the bondings and pads
228 µm pitch
Fast system to check
encapsulation height
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Ladders testing
Ladders probe station: 5 probes are used to measure body and
single strip I, C to check sanity of each single channel
Measured
Expected
160
140
Expected
Average
65.888
65.759
Min
25
35
Max
115
117.5
RMS
18.788
17.765
120
100
80
60
40
150
140
130
120
90
80
70
60
50
40
30
0
110
20
20


Depletion voltage
10



Completed and tested (INFN BA/RM2/PG)
1900
Under construction
800
rejected
~ 1%
0.016% bad chans caused by bonding or
probing
2µm RMS alignment spread
All results in good agreement with what
expected from SSDs
Measured
180
0

200
100
Flight ladders production status:
Depletion voltage (V)
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Tray Test at INFN Roma 2
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GLAST @ SLAC
1.6 m
16/16 Towers
in the GRID
on 20/10/05
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The LAT Tracker numbers
11500 sensors
360 trays
18 towers
~ 1M channels
83 m2 Si surface
> 240K functional test
recorded in DB
~ 30M strip tested
(30 test/strip on average)
> 60 physicist and engineers involved
in the italian teams from INFN
(Trieste, Udine,
Udine, Padova,
Padova, Pisa, Perugia,
Perugia,
Roma2, Bari)
Bari) in partnership with ASI
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Celebrations for the end of Tracker construction
52 attendees from INFN, ASI, SLAC, NASA,
italian industrial partners
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DoE – NASA – international partnership
GLAST renamed Fermi by
NASA on August 26, 2008
http://fermi.gsfc.nasa.gov/
“ Enrico Fermi (1901-1954) was an
Italian physicist who immigrated to
the United States. He was the first
to suggest a viable way to produce
high-energy particles in cosmic
sources. Since gamma-rays are
produced by interactions of such
energetic particles, his work is the
foundation for many of the studies
being done with the Fermi Gammaray Space Telescope, formerly
GLAST.
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Fermi Prior to Fairing Installation
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Fermi
paper Model
http://people.roma2.infn.it/~aldo/GLASTpaperModel.pdf
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Fermi
inside the Delta 2
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11 June 2008
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11 June 2008
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11 June 2008
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11 June 2008
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11 June 2008
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11 June 2008
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Fermi in orbit
• Track the satellite:
http://observatory.tamu.edu:8080/Trakker
• Watch Fermi as it orbits over you home town:
http://www.nasa.gov/mission pages/GLAST/news/glast online.html
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EGRET(Spark Chamber) VS. GLAST(Silicon Strip Detector)
EGRET on Compton GRO
(1991-2000)
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GLAST Large Area Telescope
(2006-2015)
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GRB 090902B - Autonomous Repoint Request
•
LAT pointing in celestial coordinates from -120 s to 2000 s
– Red cross = GRB 090902B
– Dark region = occulted by Earth (θz>113°)‫‏‬
– White line = LAT FoV (±66°)‫‏‬
– Blue lines = 20° (Earth avoidance angle) / 50° above horizon
– White points = LAT transient events (no cut on zenith angle)
Public data  GRB090902B paper submitted to ApjL, arXiv:0909.2470
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Simulated Fermi LAT exposure for five years of all-sky scanning at 100 GeV
cm2 s
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Sensitivity of γ-ray detectors
Aldo Morselli V.1-09
High galactic latitudes (background Φb=2 10-5 γ cm-2 s-1 sr -1 (100 MeV/E)1.1). Cerenkov telescopes sensitivities (Veritas, MAGIC,
Whipple, Hess, Celeste, Stacee, Hegra) are for 50 hours of observations. Large field of view detectors sensitivities (AGILE, GLAST,
Milagro, ARGO) are for 1 year of observation.
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Sensitivity of γ-ray detectors
A.M.1-09
High galactic latitudes (background Φb=2 10-5 γ cm-2 s-1 sr -1 (100 MeV/E)1.1). Cerenkov telescopes sensitivities (Veritas, MAGIC,
Whipple, Hess, Celeste, Stacee, Hegra) are for 50 hours of observations. Large field of view detectors sensitivities (AGILE, GLAST,
Milagro, ARGO) are for 1 year of observation.
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Fermi Science After ~ 1.5 Years
Approximately 80 Papers (AGN, Pulsars, Starburst Galaxies, GRB, diffuse
background, electrons, dark matter searches ...)
• Fermi Catalog, 1FGL – Public data release, Pass 6V3 arXiv:1002.2280
Dark matter search publications (CAT I)
• Measurement of the Cosmic Ray e+ + e- spectrum from 20 GeV to 1 TeV with
the Fermi Large Area Telescope; PRL; arXiv:0905.0025
• Observations of Milky Way Dwarf Spheroidal galaxies with the Fermi LAT
detector and constraints on Dark Matter models; ApJ; arXiv:1001.4531
• Constraints on Dark Matter Annihilation in Clusters of Galaxies with the
Fermi Large Area Telescope; Submitted to JCAP; arXiv:1002.2239
• Fermi Large Area Telescope search for photon lines from 30 to 200 GeV and
dark matter implications; PRL; arXiv:1001.4836
• Constraints on Cosmological Dark Matter Annihilation from the Fermi LAT
Isotropic Diffuse Gamma-Ray Measurement ; JCAP; arXiv:1002.4415
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How many gammas?
1967
1972
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1975
1991
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195 M
2008
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How many gammas?
109
195 M
108
107
106
105
104
103
102
101
100
1967
1972
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1975
1991
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2008
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First Fermi LAT Catalog (11 month)
1451 sources
arXiv:1002.2280
http://fermi.gsfc.nasa.gov/ssc/data/access/lat/1yr_catalog/
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First Fermi LAT Catalog
1451 sources
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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
of Gamma-ray Pulsars
2010ApJS..187..460A .
Contains 46 highconfidence pulsed
detections using the first
six months of data
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First Fermi LAT Catalog (11 month)
1451 sources
•Typical 95% error radius is 10’.
•Absolute accuracy is better than 1’
• 241 sources show evidence of variability
• ~ Half the sources are associated positionally,
mostly with blazars (~ 680) and pulsars ( 56)
• Other classes of sources exist in small
numbers (XRB, PWN, SNR, starbursts, globular
clusters, radio galaxies, narrow-line Seyferts)
Fermi Coll., ApJS submitted [arXiv:1002.2280]
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Fermi-LAT CRE data vs the conventional pre-Fermi model
Fermi Coll., PRL 102, 181101 (2009) [arXiv:0905.0025] 4/5/09
More than 4M electron/positron
(E>20GeV) from 4/08/08 to 31/01/09
GALPROP model with γ0 = 2.54 ( δ = 0.33 )
~130 citation ~ > 1/day average
Although the feature @~600 GeV measured by ATIC is not confirmed
Some changes are still needed respect to the pre-Fermi conventional model
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Cosmic Ray Electron propagation models
• γ0 = 2.54 ( δ = 0.33 )


γ0 = 2.42 (δ = 0.33 - with reacceleration): red line
γ0 = 2.33 (δ = 0.6 - plain diffusion):
blue line
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.
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“Conventional” model with injection spectrum
1.60/2.42 (break at 4 GeV)
e+ + e- Dahed: LIS
Solid: modulated
Problems at
low energy
Secondary e+ Dahed:
LIS Solid: modulated
Secondary eD.Grasso et al.,Astrop. Phys. [arXiv:0905.0636]
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new : Fermi Electron + Positron spectrum (end 2009)
Extended Energy Range (7 GeV - 1 TeV) One year statistics (8M evts)
Fermi LAT Coll. in preparation
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New Fermi-LAT data at low energy
Problems at
low energy are
confirmed!!!
PRELIMINARY
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An extra-component with injection index = 1.5 and
an exponential cutoff at 1 TeV gives a good fit of all
datasets!
PRELIMINARY
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Primary electrons in Cosmic Rays
• Now, ~45 years later
PAMELA excess in
positron fraction
and Fermi results on the
electron+positron
spectrum
unavoidably testifies
the presence of primary
positrons in CRs
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which are the sources of
the primary positrons ?
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Pulsars as sources of e-/+ pairs
e± pairs are produced in the
magnetosphere and accelerated by the
electric fields and/or the pulsar wind.
Crab Pulsar Wind Nebula (PWN)
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The CRE spectrum accounting for nearby pulsars (d < 1 kpc)
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]
This particular model assumes: 40% e± conversion efficiency for each pulsar
 pulsar spectral index Γ = 1.7 E
cut = 1 TeV . Delay = 60 kyr
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the positron ratio accounting for nearby pulsars (d < 1 kpc)
[arXiv:0905.0636]
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What if we randomly vary the pulsar parameters
relevant for e+e- production?
(injection spectrum, e+e- production efficiency, PWN “trapping” time)
Under reasonable assumptions, electron/positron emission from pulsars
offers a viable interpretation of Fermi CRE data which is
also consistent with the HESS and Pamela results.
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[arXiv:0905.0636]
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Pulsars
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
New Fermi data on pulsars will help to constrain the pulsar models
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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
The Pulsing γ-ray Sky
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(14 August 2009)
Pulses at
1/10th true rate
86
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Spectral measurements and emission models
Vela
Abdo, A. A. et al. 2009,
ApJ, 696, 1084
from GLAST proposal (1999)
Evidence of γ-ray emission in
the outer magnetopshere
due to absence of superexponential cutoff
– Radio and γ-ray fan
beams separated
– γ-ray only PSRs
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other Astrophysical solution
• 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
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Boron-to-Carbon Ratio
Mertsh and Sarkar, arXiv:0905.3152
ATIC-­‐2
Panov et al., ICRC 2007
spalla9on during propaga9on
only
spalla9on also during
accelera9on
A rise would rule out the DM and pulsar explana9on of the PAMELA positron excess.
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Predictions for the CRE spectrum from two specific dark matter models
( spectrum should be folded with
the Fermi energy resolution)
[arXiv:0905.0636]
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Pure
e+eModels
the dark matter
pair annihilation
always yields a
pair of
monochromatic
e+e-, with
injection energies
equal to the mass
of the
annihilating dark
matter particle
[arXiv:0905.0636]
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electron + positron expected anisotropy in the
directions of Monogem and Geminga
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Measurement of anisotropies: statistics
• 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!
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94
Measurements of anisotropies: systematics
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.
•
≈ 25% disuniformity in the exposure map induced by the SAA.
cm2 s
Measuring a 0.1% anisotropy requires a knowledge of the exposure map at the ≈ 0.1% level.
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95
Search Strategies
Satellites:
Low background and
good source id, but low
statistics
Galactic center:
Good statistics but source
confusion/diffuse background
Milky Way halo:
Large statistics but
diffuse background
And
electrons!
and
Anisotropies
Spectral lines:
No astrophysical
uncertainties, good
source id, but low
statistics
Galaxy
clusters:
Extra-galactic:
Large statistics, but
astrophysics,galactic
diffuse background
Low background but
low statistics
Pre-launch sensitivities published in Baltz et al., 2008, JCAP 0807:013 [astro-ph/0806.2911]
Roma Tre, April 15 2010
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96
Milky Way Dark
Matter Profiles
All profiles are
normalized to the local
density 0.3 GeV cm−3
at the Sun’s location
r ≈ 8.5 kpc
A.Lapi et al. arXiv:0912.1766
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97
Differential
yield for each
annihilation
channel
WIMP mass=200GeV
A.Cesarini, F.Fucito, A.Lionetto, A.Morselli,
P.Ullio, Astroparticle
Physics, 21, 267, 2004 [astro-ph/0305075]
Roma Tre, April 15 2010
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98
Differential yield
for b bar
neutralino mass
A.Cesarini, F.Fucito, A.Lionetto, A.Morselli,
P.Ullio, Astroparticle
Physics, 21, 267-285, 2004 [astro-ph/0305075]
Roma Tre, April 15 2010
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99
Fermi LAT Observations of the GC
+3°
LAT >1 GeV
LAT Observation of the GC region
ry
a
n
i
m
i
prel
–3° 5°
355°
12-month data set, Diffuse class,
Front only
smoothed with σ = 0.1°
BSL source location circles overlaid
S.Digel,
Symp.
Fermi LAT Fermi
Coll. in preparation
Roma Tre, April 15 2010
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100
Spetrum
(E> 400 MeV, 7°x7° region centered on the Galactic
Center analyzed with binned likelihood analysis )
ry
a
n
i
m
preli
data (stat. error)
best diffuse model and
isotropic emission
12 Fermi 1 year
catalog sources
Fermi LAT Coll. in preparation, Fermi
Symp. arXiv:0912.3828
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INFN Roma Tor Vergata
101
GC Residuals
7°x7° region centered on the Galactic Center
11 months of data, E >400 MeV, front-converting events
analyzed with binned likelihood analysis )
• The systematic uncertainty of the effective area (blue area) of the LAT is ~10%
at 100 MeV, decreasing to 5% at 560 MeV and increasing to 20% at 10 GeV
Fermi LAT Coll. in preparation, Fermi
Symp. arXiv:0912.3828
Roma Tre, April 15 2010
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INFN Roma Tor Vergata
102
Data Analysis of the Galactic Center Data
Full modeling of 7degﾗ7deg region centered in RA =266.46, Dec=-28.97
Region size selected to minimize the background
11 months of data(8/2008-7/2009)
Events selected to have 400 MeV < Energy < 100 GeV;
Events classified of diffuse class and front-converted
Best event quality and reconstructed incoming direction and energy
Data binned into a 100ﾗ100 bins map;
P6V3 IRF and software version
All the sources with and around the studied region
Galactic Diffuse gamma-ray background: GALPROP realization
gll_iem_54_87Xexph7S (e.g.physically motivated and the status of art of the
galactic diff. Emission modeling )
Isotropic Background: EGB as measured with Fermi, plus a spectral template to
account the residual charged particles.
Vitale & Morselli arxiv0912.3828v1
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103
Search for DM in the GC
➡Model generally reproduces data well within uncertainties. The
model somewhat under-predicts the data in the few GeV range
(spatial residuals under investigation)
➡Any attempt to disentangle a potential dark matter signal from
the galactic center region requires a detailed understanding of
the conventional astrophysics
More prosaic explanations must be ruled out before invoking a
contribution from dark matter if an excess is found (e.g.
modeling of the diffuse emission, unresolved sources, ....)
Analysis in progress to updated constraints on annihilation cross
section
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104
A galactic dark matter halo
Detecting dark matter
substructure
with Fermi
Roma Tre, April 15 2010
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105
Roma Tre, April 15 2010
A galactic dark matter halo
Aldo Morselli, INFN Roma Tor Vergata
106
Dwarf spheroidal galaxies (dSph) :
promising targets for DM detection
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107
Dwarf spheroidal galaxies (dSph) :
promising targets for DM detection
➢ dSphs are the most DM dominated systems known in the
Universe with very high M/L ratios (M/L ~ 10- 2000).
➢ Many of them (at least 6) closer than 100 kpc to the GC (e.g.
Draco, Umi, Sagittarius and new SDSS dwarfs).
➢ SDSS [only ¼ of the sky covered] already double the number of
dSphs these last years
➢ Most of them are expected to be free from any other
astrophysical gamma source.
✔ Low content in gas and dust.
Roma Tre, April 15 2010
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108
Dwarf Spheroidal Galaxies upper-limits
No detection by Fermi
with 11 months of data.
95% flux upper limits
are placed for several
possible annihilation
final states.
Flux upper limits are
combined with the DM
density inferred by the
stellar data(*)for a
subset of 8 dSph (based
on quality of stellar data)
to extract constraints on
<σv> vs WIMP mass for
specific DM models
(*)
stellar data from the Keck observatory
(by Martinez, Bullock, Kaplinghat)
Fermi Coll. arXiv:1001.4531
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109
Dwarf Spheroidal Galaxies upper-limits
No detection by Fermi
with 11 months of data.
95% flux upper limits
are placed for several
possible annihilation
final states.
Flux upper limits are
combined with the DM
density inferred by the
stellar data(*)for a
subset of 8 dSph (based
on quality of stellar data)
to extract constraints on
<σv> vs WIMP mass for
specific DM models
(*)
stellar data from the Keck observatory
(by Martinez, Bullock, Kaplinghat)
Fermi Coll. arXiv:1001.4531
Roma Tre, April 15 2010
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110
Dwarf Spheroidal Galaxies upper-limits
No detection by Fermi
with 11 months of data.
95% flux upper limits
are placed for several
possible annihilation
final states.
Flux upper limits are
combined with the DM
density inferred by the
stellar data(*)for a
subset of 8 dSph (based
on quality of stellar data)
to extract constraints on
<σv> vs WIMP mass for
specific DM models
(*)
stellar data from the Keck observatory
(by Martinez, Bullock, Kaplinghat)
Fermi Coll. arXiv:1001.4531
Roma Tre, April 15 2010
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111
Dwarf Spheroidal Galaxies upper-limits
No detection by Fermi
with 11 months of data.
95% flux upper limits
are placed for several
possible annihilation
final states.
Flux upper limits are
combined with the DM
density inferred by the
stellar data(*)for a
subset of 8 dSph (based
on quality of stellar data)
to extract constraints on
<σv> vs WIMP mass for
specific DM models
(*)
stellar data from the Keck observatory
(by Martinez, Bullock, Kaplinghat)
Fermi Coll. arXiv:1001.4531
Roma Tre, April 15 2010
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112
Inverse Compton Emission and Diffusion in Dwarfs
 
We expect significant IC gamma-ray emission for high
mass WIMP models annihilating to leptonic final states.
 
The IC flux depends strongly on the uncertain/unknown
diffusion of cosmic rays in dwarfs.
 
We assume a simple diffusion model similar to what is
found for the Milky Way
D(E) = D0 E1/3 with D0 = 1028 cm2/s
(only galaxy with measurements, scaling to dwarfs ?? )
Roma Tre, April 15 2010
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113
Dwarf Spheroidal Galaxies upper-limits
Exclusion regions
already cutting into
interesting parameter
space for some WIMP
models
Stronger constraints can
be derived if IC of
electrons and positrons
from DM
annihilation off of the
CMB is included, however
diffusion in dwarfs is not
known ⇒ use bracketing
values of
diffusion coefficients
from cosmic rays in the
Milky Way
(*)
stellar data from the Keck observatory
(by Martinez, Bullock, Kaplinghat)
Fermi Coll. arXiv:1001.4531
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114
Galaxy Clusters upper-limits
PRELIMINARY
Fermi Coll. arXiv: 1002.2239
Flux upper limits as a function of particle mass for an assumed μ+μ- final
state, including the contributions of both FSR and IC gamma-ray emission
Roma Tre, April 15 2010
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115
Galaxy Clusters upper-limits
Stronger constraints
on leptophilic DM
models can be
derived with galaxy
clusters when the
IC contribution off
the CMB of
secondary
electrons (from DM
annihilation) is
included
PRELIMINARY
Fermi Coll. arXiv: 1002.2239
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116
Galaxy Clusters upper-limits
PRELIMINARY
Constraints for a
b-bbar final state
are weaker than or
comparable to
(depending on the
assumption on
substructures) the
ones obtained with
dSph
Fermi Coll. arXiv:1002.2239
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117
SED of the isotropic diffuse emission (1 keV–100 GeV)
arXiv:1002.3603
Roma Tre, April 15 2010
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118
SED of the isotropic diffuse emission (1 keV–100 GeV)
arXiv:1002.3603
Flux, E>100 MeV
spectral index
Fermi LAT
1.03 +/- 0.17
2.41 +/- 0.05
EGRET (Sreekumar et al., 1998)
1.45 +/- 0.05
2.13 +/- 0.03
EGRET (Strong et al. 2004)
1.11 +/- 0.10
LAT + resolved sources below EGRET sensitivity
1.19 +/- 0.18
2.37 +/- 0.05
x 10-5 cm-2 s-1 sr-1
Roma Tre, April 15 2010
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119
extragalactic gamma-ray spectrum
600 GeV gravitino decay
Buchmuller et al, arXiv:0906.1187
Roma Tre, April 15 2010
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120
extragalactic gamma-ray spectrum
Fermi Coll.arXiv:1002.4415
others possible contributions to the extragalactic gamma-ray spectrum
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121
The Galactic Diffuse Emission
•Spectra shown for
mid-latitude range
→ GeV excess in
this region of the
sky is not
confirmed.
•Sources are not
subtracted but are
a minor component.
•LAT errors are
dominated by
systematic
uncertainties and
are currently
estimated to be
~10% → this is
preliminary.
Fermi LAT
Fermi Coll. , to appear soon
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122
2009: Fermi-LAT diffuse gamma-ray spectrum first measurements
Fermi LAT data
Total
π0 decay
Isotropic component
IC
Sources
Bremsstrahlung
Fermi Coll. , to appear soon
PREL
IMINA
RY
Roma Tre, April 15 2010
EGRET GeV excess was
not observed ⇒
Conventional models
(based on the locally
measured CR fluxes) can
be used
The conventional model
with
γ0 = 2.54 ( δ = 0.33 )
gives a satisfactory
description of Fermi-LAT
gamma-ray data
Conventional model are
weakly affected by small
changes in the electron
spectrum.
Aldo Morselli, INFN Roma Tor Vergata
123
2009: Fermi-LAT diffuse gamma-ray spectrum first measurements
Roma Tre, April 15 2010
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124
gamma-ray spectrum for an example of gravitino dark matter
decay in the mid-latitude range
• 100≤ |b| ≤ 200
Gamma-ray detection from gravitino dark matter decay in the µνSSM arXiv:0906.368
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125
The LAT isotropic diffuse flux (200 MeV – 100 GeV)
|b| > 60º
20º < |b| < 60º
10º < |b| < 20º
galactic diffuse
isotropic diffuse
data
sources
Roma Tre, April 15 2010
galactic diffuse
isotropic diffuse
data
sources
Aldo Morselli, INFN Roma Tor Vergata
galactic diffuse
isotropic diffuse
data
sources
126
Wimp lines search
Roma Tre, April 15 2010
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127
Search for Spectral Gamma Lines
DM annihilation
No line detection, 95% CL flux
upper limits are placed
Fermi LAT Coll. PRL,arXiv:1001.4836
Roma Tre, April 15 2010
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128
Search for Spectral Gamma Lines
decaying DM particles
No line detection, 95% CL flux
upper limits are placed
Fermi LAT Coll. PRL,arXiv:1001.4836
Roma Tre, April 15 2010
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129
Latest on Wino Models
Kane, DM10
Data from Fermi Coll. arXiv:1001.4836
Roma Tre, April 15 2010
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130
Conclusion:
The Electron+positron spectrum (CRE) measured by Fermi-LAT
is significantly harder than previously thought on the basis of
previous data
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)
• or by pulsars for a reasonable choice of relevant parameters
(to be tested with future Fermi pulsars measurements)
•or by annihilating dark matter for model with MDM ≈ 1 TeV
•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.
Roma Tre, April 15 2010
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131
2nd Conclusion : Gamma
No discovery (yet)....
.... however promising constraints on the nature of
DM have been placed
In addition to increased statistics, better
understanding of the astrophysical and instrumental
background will improve our ability to reliably extract
a potential signal of new physics or set stronger
constraints
Further improvements are anticipated for analysis
that benefits from multi-wavelength observations (for
example galactic center, dwarf spheroidal galaxies and
DM satellites)
Roma Tre, April 15 2010
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132
Announcement for SciNeGHE 2010
8th Workshop on Science with the New Generation High Energy Gamma-ray Experiments
Gamma-ray astrophysics
in the multimessenger context
TRIESTE, 8-10 September 2010
Roma Tre, April 15 2010
Aldo Morselli, INFN Roma Tor Vergata
se
o
y
e
t
u
r
e
h
!!
!
e
133
RICAP’11
3rd
MAY 25 -27, 2011
All of you are invited
to the third edition of
RICAP in 2011 that
will be hosted in INFN
& Roma TRE
University
http://ricap09.roma2.infn.it/
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134