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GeV-TeV prospects & results. Issues : Origin & diffusion properties of Galactic CRs: Main accelerators: SNRs? Diffusion: measure it? Galaxies : massive SFR AGNs : variability, SED, EBL GRBs : SED, emission pulsars : emission region Clusters of galaxies : NT
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GeV-TeV prospects & results • Issues: • Origin & diffusion properties • of Galactic CRs: • Main accelerators: SNRs? • Diffusion: measure it? • 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 Massimo PersicINAF/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 hadronic channel favored B=100mG 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?
Albert+ 2006 HESS J1813-178 ??? ABBA MAGIC AGILE Fermi LAT IACT Hadronic: 2MÄ of target gas, exp-cutoff proton distrib: a=2.1, Ec=100 TeV, np=6cm-3, L(0.4-6 TeV)=2.5E+34erg/s Leptonic: B=10mG, exp-cutoff electron distrib: a=2.0, Ec=20TeV 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) · little variation across SNR • GeV+TeV spatially resolved spectroscopy • young SNRs (t<tcool (p,e)): CRp spectrumg = 1+2a+ b measure k(p) as a function of p • = pb…b~0.6 ? from B/CNO ratio from VHE from radio
Galaxies Integrated view of VHE em. from massive SF: acceleration, diffusion, energy loss Arp 220
M82: most promising candidate MP, Rephaeli & Arieli 2008 diffusion-loss eq. solved 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
First detection of pulsed emission at >25 GeV. Searches going on for ~35 years!! Crab pulsar: detection 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 IACT Fermi AGILE
Jul/Aug & Nov/Dec 2007 (S+E)SC model Ghisellini+ 2007 3C454.3 z=0.859 AGILE trigger MAGIC MAGIC
March/April 2008 AGILE MAGIC Fermi First ever simultaneous HE+VHE g-ray obs of a blazar! p r e l i m i n a r y PG 1553+113 (?)
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 Cross section (differ.): Stecker+ 2006 Optical depth: TeV g: E soft g: e E ~ 1TeV sggmax for e~0.5 eV (~2mm, K-band) Heitler 1960 x=1+cosq Slkkkàkàk-lkn Stecker 1999 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 ---------------------------- MAGIC ST HE+VHE data crucial to constrain/unveil emission mechanism(s)
GRBs Intrinsically: Nearby: z=0.937 Brightest ever observed in optical Exceedingly high isotropic-equivalent in soft g-rays 080319B missed obs of “naked-eye” GRB 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 !!
DRACO dSph high M/L>200 d~80 kpc 2. DRACO dSph Milky Way surrounded by small, faint companion galaxies Northern source MAGIC ok !! • dSph’s very DM-dominated objects. • Distances,M/L ratios16<D/kpc<250 kpc, 30<M/L<300
d~80 kpc Bergström & Hooper 2006 Draco dSph: modeling total DM annihil. rate <sAv>, mc: WIMP annihil. cross section, mass g-ray flux Ng: g-rays / annihil. cusped profile upper limit cored profile g-ray flux rs = 7 – 0.2 kpc r0 = 107 – 109 Mž kpc-3 r02 rs3 = 0.03 – 6 Mž2 kpc-3
_ bb t t t+t- _ min. cored W+W- Fermi 1-yr exp. max. cusped MAGIC 40-h exp. ZZ Bergström & Hooper 2006 IACT neutralino detection: <sAv> ³ 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 < (WDM+2dWDM)WMAP=0.113 m0 > 2 TeV … Wc < (WDM-2dWDM)WMAP=0.09751 m0£ 2 TeV … Wc < (WDM+2dWDM)WMAP=0.113 m0£ 2 TeV … Wc< (WDM-2dWDM)WMAP=0.09751
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