De_Angelis_Alessandro.pdf

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Cluster of very bright stars, Omega Centauri,
as observed from the space:
60,000 K
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Accretion Disk 3- 10 r s Black Hole Diameter = 2r s ~ 4 AU
~ parsecs
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hadronic cascades
p + (>>TeV)
matter
0
- +
(TeV)
In the VHE region,
dN/dE ~ E - (: spectral index)
To distinguish between had/leptonic origin
study Spectral Energy Distribution (SED):
(differential flux) . E 2
e.m. processes
e - (TeV)
E 2 dN/dE
B
(eV)
Synchrotron
(eV-keV)
(TeV)
Inverse Compton
0 decay
energy E
VHE
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edshift z
30 GeV
100 GeV
> 1
region of opacity
= 1 (GRH)
De Angelis, Galanti, Roncadelli 2011
with Franceschini EBL modeling
ray energy (TeV)
() ~
VHE bck e + e -
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e + e -
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c ~ 1º
e Threshold @
sl: 21 MeV
Maximum of a 1 TeV
shower
~ 8 Km asl
~ 200 photons/m 2 in
the visible
Angular spread ~ 0.5º
Incoming
-ray
~ 120 m
~ 1 o
The Cherenkov technique
~ 10 km
Image intensity
Shower energy
Image orientation
Shower direction
Image shape
Primary particle 10

c ~ 1º
e Threshold @
sl: 21 MeV
Maximum of a 1 TeV
shower
~ 8 Km asl
~ 200 photons/m 2 in
the visible
Angular spread ~ 0.5º
Incoming
-ray
~ 120 m
~ 1 o
The Cherenkov technique
~ 10 km
Image intensity
Shower energy
Image orientation
Shower direction
Image shape
Primary particle 10

VERITAS: 4 telescopes (~12m) in Arizona operational since 2006
VERITAS: 4 telescopes (~12m) in Arizona operational since 2006
Major upgrade expected ~end 2011:
Very large (28m) central telescope in construction
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Fermi,
Egret
Magic,
Veritas
Alessandro De Angelis
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W51: gamma rays come from a
molecular cloud separated from the
pulsar
[Albert et al. ApJ RX J1713.7-3946
664L 87A 2007

x
x
x
() ~
Heitler 1960
VHEbck e + e-
e -
Mean free path
e +
Measurement of spectral features permits 18 to
constrain EBL models

Alessandro De Angelis
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edshift z
~ E -2
De Angelis, Galanti, Roncadelli 2011
with Franceschini EBL modeling
ray energy (TeV)
Alessandro De Angelis
Selection bias?
New physics ?
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Alessandro De Angelis
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E P = hc G 1.2 1019
H 2 = m 2 + p 2 H 2 = m 2 + p 2 1+ E
p 1+ m2
2 p
H p>>
v = H
p
2 + p
2E P
m2 p
1 + 2
2p E P
+…
E P
v 1+ E
E P
+…
t TE
E P

Alessandro De Angelis
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astro-ph/0702008
arXiv:0708.2889
H.E.S.S.
arXiV:0706.0797
Alessandro De Angelis
MAGIC, Mkn 501
Doubling time ~ 2 min
HESS PKS 2155
z = 0.116
July 2006
Peak flux ~15 x Crab
~50 x average
Doubling times
1-3 min
R BH /c ~ 1...2 . 10 4 s
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(t) obs 3
2
E
E s2
2
1
H0
0
dz'
(1 + z') 2
M (1 + z') 3 +
E s2 > 6 10 10 GeV (~10 -9 M P) (HESS, MAGIC)
z
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= ()
() ~
r
Begelman/
Navarro
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Alessandro De Angelis
los
2
dl
from particle physics
Look to the closest point with M

All-sky map of
simulated gamma ray
signal from DM
annihilation
(Pieri et al 2006)
Satellites
Galactic Center
Good statistics but source
confusion/diffuse background
Low background and good source id,
but low statistics, astrophysical background
Milky Way Halo
Large statistics but diffuse
background
Spectral Features
Lines, endpoint Bremsstrahlung,…
No astrophysical uncertainties, good
source Id, but low sensitivity
because of expected small BR
Extra-galactic
Large statistics, but astrophysics, galactic
diffuse backgrounds
Plus data-driven searches
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Alessandro De Angelis
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Alessandro De Angelis
MAGIC ICRC
2011
all e + e -
Preliminary
e + /e + +e -
probe e+/e- ratio at 300-700 GeV
?
MAGIC

• LHC may find candidates but cannot prove that
they are the observed Dark Matter, nor localize it
• Direct searches (nuclear recoil) may recognize
local halo WIMPs but cannot prove the nature and
composition of Dark Matter in the sky
• LHC reach limited to some 200-600 GeV; IACT
sensitivity starts at some ~200 GeV (should
improve)
Alessandro De Angelis
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Alessandro De Angelis
• extend E range beyond 50 TeV
• better angular resolution
• larger FOV
• monitor many objects simult.
• extend E range under 50 GeV
•10x sources
• better flux sensitivity
• lower threshold
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2 arrays: north+south
all-sky coverage
low energy section
E thresh ~ 10 GeV
4 23 m telescopes
Alessandro De Angelis
core array
100 GeV-10 TeV
~ 23 12 m telescopes
high energy section
~35 tel.
on 10 km 2 area
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E*F(>E) [ TeV/cm2s] Agile, Fermi, Argo, Hawk: 1 year
Magic, Hess, Veritas, CTA: 50h
Agile
Fermi
Far universe
Pulsars
Fundamental physics
Magic-II
CTA
Argo
Hawc
Crab
10% Crab
Hess/Veritas
Cosmic rays
at the knee
1% Crab
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Alessandro De Angelis

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Marvel 1961
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dN dE dN p
dE p
D x = E
E
p
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Alessandro De Angelis
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Colours: 0.2 - 6 keV (Chandra)
Contours: 8 GHz radio (VLA)
HST-1
Core
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Knot D
Knot A
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Alessandro De Angelis
VHE
X-ray
Radio
nucleus
nucleus
Peak flux
jet
Chandra
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Alessandro De Angelis
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dN
dE
1
2
dN
dE
Alessandro De Angelis
Very accurate input for
neutrino detectors
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Over 350 publications in high-impact journals:
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Results from HESS, MAGIC and VERITAS
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Alessandro De Angelis
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Alessandro De Angelis
Chandra
Hubble
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World-wide Collaboration
25 countries
132 institutes
>800 scientists
10 fold sensitivity of current instruments
10 fold energy range
improved angular resolution
two sites (North / South)
operated as observatory
The future in
VHE gamma ray
astronomy:

Design study phase concluded in Fall 2010
Design Concepts for the Cherenkov Telescope Array
(arXiv:1008.3703)
FP7-supported Preparatory Phase: Fall 2010 – Fall 2013
Technical design, sites, construction and operation cost
Legal, governance and finance schemes
Small + medium-sized telescope prototypes
Aim for
start of deployment in early 2014
first data in 2016/17
base arrays complete in late 2018
expanded mid-energy array driven by US
total cost below 200 M

Carbon-fibre
structure
27.8 m focal length
4.5 o field of view
0.1 o pixels
400 m 2 dish area
1.5 m sandwich
mirror facets
On (GRB) target
in < 20 sec.

100 m 2 dish area
1.2 m mirror
facets
16 m focal length
7-8 o field of view
0.18 o pixels

Multi-Anode PMT camera option
Under study:
dual-mirror optics with compact photo sensor arrays
single-mirror optics
PMT-based and silicon-based sensors
Not yet conclusive which solution is most cost-effective
One of four
options for
telescope
structure

Wavelenght range
300 – 600 nm
Mirror PSF
O(1’) on axis, worse off axis
Pixel size
0.1 o – 0.2 o
Source localization
5” – 10” for source centroid
Image rate
kHz
Exposure time
single image: O(10 ns)
typical source: 10 – 50 h

+30
-30
Warning: map not quite accurate
proposals for sites due 6/2011 (S) and 12/2011 (N)
evaluation and downselection to few sites
final selection

Hardware key elements:
- O(100) Telescope structures/drives: very resistant, reliable,
accurate, light-weight (LST)
- O(10.000) m 2 Mirrors: good quality, stable in extreme
conditions, cheap, light-weight
- O(2-3 x10.000) camera channels:
* Photosensors: PMT (and eventually SiPMs)

* Readout Electronics: fast, low dissipation, compact,
reliable, cheap
- Timing/Synchronization: comparable to LHC machine
requirements
- Trigger/Data: comparable to LHC experiments

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Fermi
Alessandro De Angelis
HAWC
MILAGRO
HESS
CTA
factor 3
improvement
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HESS map of the Gal.plane, total exp ~500 hours
Alessandro De Angelis
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2008 2009 2010 2011 2012 2013 2014 2015
Alessandro De Angelis

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La = ga E
( B )a
*
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• 10 1
a
*
P a NP 1
P1 g 2 2 2
a
BT s
4
a a
…
*
*
2 10 3 BT s ga
2

DARMA
3C279
Note: if conversion “a la
Simet-Hooper-Serpico”,
=> the effect could be directional
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Alessandro De Angelis
HESS, PKS 2155
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1st order
(t) obs E
H0
E s1
v c 1+ E
MAGIC Mkn 501, PLB08
(with J. Ellis et al.)
E s1 ~ 0.04 M P ( ~ -25)
E s1 > 0.02 M P
HESS PKS 2155, PRL08
E s1 > 0.06 M P
GRB X-ray limits:
E s1 > 0.11 M P (Fermi, but…)
1
z
0
dz'
M P
2 E
+ 2 2
MP (1 + z')
+ ...
M (1 + z') 3 +
< 5 MeV
> 1 GeV
0.15-0.25 TeV
0.25-0.6 TeV
0.6-1.2 TeV
1.2-10 TeV
4 min lag
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(t) obs E
H0
E s1
1
z
0
dz'
(1+ z')
M (1+ z') 3 +
~ -12
K(z)~z
t
E
M P
H0
1 K(z)
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• z = 0.903 ± 0.003
• prompt spectrum detected,
significant deviation from Band
function at high E
• High energy photon detected:
31 GeV at T o + 0.83 s
[expected from Ellis & al. (12 ± 5) s]
• tight constraint on Lorentz
Invariance Violation:
– E s1 = M QG > several M Planck
• z = 1.8 ± 0.4
• one of the brightest GRBs
observed by LAT
• after prompt phase, power-low
emission persists in the LAT data as
late as 1 ks post trigger:
highest E photon so far detected:
33.4 GeV, 82 s after GBM trigger
[expected from Ellis & al. (26 ± 13) s]
• much weaker constraints on LIV E s
=> Fermi rules, and 1 st order violations appear unlikely
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Better bkgd reduction
Better angular resolution
Better energy resolution

v = H
p
1 m2
2p 2 + p
E P
c
2 p 2 = E 2 1 E
E s
+ O E
E s
= 1
2
= -1
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1. If c e < c => decay -> e + e - kinematically allowed for gamma with
energies above
E max = m e sqrt(2/abs())
- E > 100 TeV => abs() < 5 x 10 -17
2. If >0 => c e > c => electrons become superluminal for energies larger than
E max /sqrt(2) => Vacuum Cherenkov Radiation.
- E e > 2 TeV from cosmic electron radiation => abs() < 2 x 10 -14
- Modification of -> e+e- threshold. Using Mkn 501 and Mkn 421
spectra observations up to E g > 20 TeV
=> abs() < 1.3 x 10 -15
From MAGIC Mkn501 (taken as a LIV signal): || ~ 2 10 -15

GRH depends on the –ray path and there the Hubble constant and
the cosmological densities enter => if EBL density and intrinsic
spectra are known, the GRH might be used as a distance estimator
GRH behaves differently than other observables already used for cosmology measurements.
EBL constraints are paving
the way for the use of AGN
to fit M and …
PKS2005-489 PKS 2155-304 H2356-309
1ES1959+650 H1426+428
1ES1218+304
Mkn 180
1ES 2344+514
1ES1101-232
Mkn 421
Mkn 501
Blanch & Martinez 2004
Simulated
measurements
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( E,z)=
dz
dl
z
dz
0
2
0
dx x
2
d n( , z )2xE 1+ z
Using the foreseen precision on the
GRH (distance at which (E,z)=1)
measurements of 20 extrapolated
AGN at z>0.2, cosmological
parameters can be fitted.
=> The 2 =2.3 2-parameter
contour might improve by a
factor 2 the 2004’ Supernovae
combined result !
2m 2 c 2
( ) 2
Ex 1+z
( ) 2
[ ]
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detection of -rays from GC by Cangaroo,
Whipple, HESS, MAGIC
hard E -2.2 spectrum
fit to -annihilation continuum
spectrum leads to: M > 14 TeV
other interpretations possible (probable)
Galactic Center: very crowded sky region, strong exp.
evidence against cuspy profile
Whipple
(95%)
CANGAROO (80%)
H.E.S.S.
Chandra GC survey
NASA/UMass/D.Wang et al.
from W.Hofmann, Heidelberg 2004
no real indication of DM…
The spectrum is featurless!!!
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BOOTES
FORNAX
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Alessandro De Angelis
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