Transcript Document

GeV-TeV prospects & results
Issues:
Origin & diffusion properties
of Galactic CRs:
Main accelerators: SNRs?
Diffusion: measure it?
Massimo Persic
INAF-INFN Trieste
MAGIC Collaboration
 Galaxies: massive SFR
 AGNs: variability, SED, EBL
 GRBs: SED, emission
 pulsars: emission region
 Clusters of galaxies: NT
side of structure formation
 Galaxy halos: DM
Massimo Persic
INAF/INFN-Trieste
MAGIC Collaboration
SNR RX J1713.7-3946
H.E.S.S.
SNR shell  particle acceleration
Resolved shell in VHE-g-rays
g-rays from leptonic or hadronic channels?
leptonic channel fav’d Aharonian+ 2006
3EG J1714-3857
B=100mG
hadronic
channel
favored
Berezhko & Völk 2006
Leptonic:
Ee ~ 20 (Eg )1/2 TeV
~ 110 TeV … but KN sets on ..
 ~100 TeV
Hadronic:
Ep ~ Eg / 0.15 ~ 30 / 0.15 TeV ~
~ 200 TeV
... but: is SN statistics enough to fit CR energy density?
HESS J1813-178
Albert+ 2006
???
ABBA
AGILE
Fermi LAT
IACT
VHE g-rays:
hadronic or leptonic ?
D = 4 kpc
GeV data  solve TeV spectral degeneracy
 CRp normalization
Aharonian + 2006
 index G~2-2.2 (strong shock) GeV+TeV  spatially resolved spectroscopy
 young SNRs (t<tcool (p,e)):
 little variation across SNR
CRp spectrum g = 1+2a + b
 measure k(p) as a function of p
Galaxies
Integrated view of VHE em. from massive SF: acceleration, diffusion, energy loss
Arp 220
M82: most promising candidate
F(>0.1 TeV) ~
~ 2 x10-12 cm-2s-1
MAGIC or VERITAS:
hundreds of hours
F(>100 MeV) ~
~ 10-8 cm-2s-1
Fermi LAT:
first-year scan
MP, Rephaeli & Arieli 2008
diffusion-loss eq. solved
Crab pulsar: detection
First detection of pulsed emission at >25 GeV.
Searches going on for ~35 years!!
EGRET + MAGIC: pl * exp [–E/16.3 GeV)]
pl * exp [–(E/20.7 GeV)2]

at least for Crab pulsar,
polar cap scenario challenged
More psr obs’s:
ms pulsars?
Active Galactic Nuclei
Fermi
AGILE
IACT
Mrk 421
3C454.3
z=0.859
Jul/Aug & Nov/Dec 2007
(S+E)SC model
AGILE trigger
Ghisellini+ 2007
MAGIC
MAGIC
March/April 2008
AGILE
Fermi
First ever simultaneous
HE+VHE g-ray obs of a
blazar!
PG 1553+113
(?)
MAGIC
• Target-of-Opportunity (ToO) obs’s:  high states
• trigger in other l (g: AGILE, Fermi; x: Swift, Suzaku;
optical: KVA)
• simultaneous mwl observations:
• evolution of emitting particle population
– emergy-dependent evolution in time
• Monitoring obs’s:  low states
• in several l
• check quiet emission of blazar
• properties of steady-state particle spectrum
– emergy-dependent evolution in time
 Limitless possibility for
IACT follow-up?
EBL
Hauser & Dwek 2001
Stecker+ 2006
TeV g: E
soft g: e
Cross section (differ.):
Heitler 1960
Optical depth:
x=1+cosq
E ~ 1TeV
 sgg max
for e~0.5 eV
(~2mm, K-band)
g HE g EBL  e e-
Stecker 1999
Slkkkàkàk-lkn
IBL absorption
Franceschini
et al. 2008
Measuring EBL(z).
Tools: sources with sound modeling & minimum number of parameters  BLLacs!?
(l.o.s. orientation, jet-only emission, single-zone SSC).
1) Based on GeV data, set up a list of BLLacs whose predicted VHE flux is detectable with IACTs.
Populate redshift space (out to z ~ 1) as closely as possible.
2) For each BLLac source, obtain simultaneous well-sampled mwl SEDs (at optical, X-ray, HE, and VHE
frequencies) corresponding to different source states (low, high).
This amounts to having several SEDs at each given z.
Since in such SEDs the Compton peak typically occurs in the EBL-unaffected region <100GeV, using HE
data the SSC model can be closed with substantially no EBL-induced bias. Hence, the SSC model in the
VHE region (>100 GeV) is known and can be assumed to represent the intrinsic VHE source spectrum.
Contrasting it with data (measured between photon energies E1 and E2), we obtain nEBL(z) at redshift z and
in the energy interval between, locally at redshift z, 0.5/[E2(1+z)] eV and 0.5/[E1(1+z)] eV.
3) Repeating procedure (2) with different SEDs (i.e.: different sources, or same source in different emission
states) at the same z, in principle we should obtain consistent determinations of the EBL. In practice, we will
reduce the statistic error affecting each determination of nEBL(z).
4) Selecting BLLac objects progressively farther away, we will measure EBL at different z. By repeating
steps (2),(3) we will in principle obtain measures of nEBL(z) -- out to z ~1.
Gamma-Ray Bursts (GRBs)
 Most energetic explosions since Big Bang (1054 erg if isotropic)
 Astrophysical setting unknown (hypernova?)
 Emission mechanism unknown (hadronic vs leptonic, beaming,
size of emitting region, role of environment, … … )
 Cosmological distances (z >> 1)
but ... missed naked-eye GRB 080319B (z=0.937)
Gggg
HESS
MAGIC
HE+VHE data crucial to
constrain/unveil emission
mechanism(s)
----------------------------MAGIC
ST
GRBs
080319B  missed obs of “naked-eye” GRB
Intrinsically:
Nearby: z=0.937
Brightest ever observed in
optical
Exceedingly high isotropicequivalent in soft g-rays
Swift/BAT could have
observed it out to z=4.9
1m-class telescope could
observe out to z=17
Missed by both AGILE
(Earth screening) and
MAGIC (almost dawn)
next BIG ONE awaited !!
Galaxy Clusters
Targets: Draco, Willman-I,
2. DRACO dSph
Milky Way surrounded by small, faint companion galaxies
DRACO dSph
high M/L>200
d~80 kpc
Northern source 
MAGIC ok !!
- dSph’s  very DM-dominated objects.
- Distances, M/L ratios 16<D/kpc<250 kpc, 30<M/L<300
Draco dSph: modeling
total DM
annihil. rate
g-ray flux
upper limit
d~80 kpc
Bergström &
Hooper 2006
<sAv>, mc: WIMP annihil. cross section, mass
Ng: g-rays / annihil.
cusped
profile
cored
profile
g-ray flux
rs = 7 – 0.2 kpc
r0 = 107 – 109 M kpc-3
r02 rs3 = 0.03 – 6 M2 kpc-3
t+t-
bb
tt
min. cored
W+W-
max. cusped
ZZ
Bergström & Hooper 2006
MAGIC
40-h exp.
_
_
Fermi
1-yr exp.
IACT neutralino detection:
<sAv>  10-25 cm3s-1
unid’d GeV sky brightness fluct’s
to be followed up a TeV energies
Stoehr + 2003
Draco dSph obs’d MAGIC
arXiv:0711.2574
7.8 hr
May 2007
m0 > 2 TeV … Wc < (W 2dW ) =0.113
m0 > 2 TeV … Wc < (W -2dW ) =0.09751
DM
DM
DM
DM
WMAP
WMAP
m0  2 TeV … Wc < (WDM2dWDM)WMAP=0.113
m0  2 TeV … Wc < (WDM-2dWDM)WMAP=0.09751
Probing Quantum Gravity
Mrk 501: Jul 9, 2005
Outlook
GeV+TeV: wide spectral coverage to observe Galactic-environment
phenomena useful to solve long-standing issues about CRs.
SNRs, molecular clouds  HE+VHE emission mechanism,
energy-dependent diffusion.
GRBs, star-forming galaxies  SFR(z)
Galaxy clusters  NT side of structure formation
Pulsars  measure magnetosph. emission cutoff
AGNs  solve (S+E)SC model of AGNs
measure EBL(z)
probe short-time variability as function of E
simultaneous mwl monitoring of low-state
ToO obs’s of high states
DM halos  depending on mc, decay channels, central density, distance
Thanks!