Blazar Physics in the GLAST Era: Eduardo's Talk Continued…
P. Coppi,
Yale


General comments: the astrophysics-particle physics connection
Astronomical observations + detailed understanding of astronomical objects and processes provides access to physical conditions and length scales not accessible in the laboratory.
E.g., supernovas + CMB + galaxy and cluster surveys => dark energy, #1 problem for many helioseismology + solar model + neutrino observatory => neutrino oscillations galaxy rotation curves + cluster X-rays/gravitational lensing => dark matter MeV-GeV gamma-ray background + WMAP + BBN => measure baryon asymmetry + no significant antimatter domains w/in our horizon + baryogenesis at T> MeV (BBN scale) + probably not via GUT scale relicts that decay late in "old days," cosmic rays => new particles Pendulum has swung back and forth between accelerator and non-accelerator science. In US, at least, DOE non-accelerator science has grown dramatically in last 5-10 years. Until LHC and we get out of the desert, will probably continue to do so.
Probing the high-energy Universe: pick your messenger particle!
Photons - Radio: mainly non-thermal, relatively good at penetrating intervening matter [currently highest spatial resolution, .g., VLBA, ] Infrared: see energy absorbed and re-emitted by dust [Spitzer, ALMA] Optical/UV: characteristic (z=0) stellar energy, worst in terms of obscuration, but do see lots of useful atomic features Soft X-Ray: hot gas, atomic features still available but not completely understood, still easily obscured hard X-ray (>10 keV): very little gas/stellar contamination, very penetrating, lose atomic features, hard to focus Soft Gamma-Ray (>500 keV): pair annihilation line, nuclear lines, but start being subject to obscuration again due to photon-photon pair production, even harder to stop in detector and image, lots of background Gamma-Ray (>GeV): obscuration in source and during propagation big worry, but clearly indicates presence of very energetic particles and "extreme" processes All, straight line propagation from source!

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