2. Transparency of the Universe to TeV photons
Włodek Kluźniak
Hoża

3. Crab
Crab image

4. Chandra X-ray Observatory

5. Hess spectrum of the Crab nebula (1.9 kpc, 1054 AD)
(Khelifi et al. 2008)
华文仿宋

6. Water maser

7. Amelino Camelia et al. Nature (1998)
Approaches to Quantum Gravity suggest Lorentz Violation, e.g.,
modified dispersion relation for the photon
Speed of light would then be energy dependent, dispersing a flash of photons.
Time of arrival would be proportional to E, and distance.

8. GRB

9. A photon does not decay because of energy and momentum conservation.
TeV photons are usually absorbed on the IR bgnd (pair creation).
A modified dispersion relation would change all that!

11. Similar result for GZK cutoff (Coleman & Glashow 1998)
10^17 GeV -> 30 Tev
Greiser Zatsepin Kuzmin
K 1999a,b
Similar result for GZK cutoff (Coleman & Glashow 1998)

14. See also Stecker 2003
J Phys G 29

16. Jacobson et al 2006

17. Hess spectrum of the Crab nebula (Khelifi et al. 2008)
华文仿宋
Birefrigence constraint comes from UV observations of distant
Galaxies (Gleiser & Kozameh 2001).
The other constraints come from the Crab:
synchrotron up to 100 MeV,
Inverse Compton up to 50 TeV.

18. 1. To test its ideas, physics is returning to its roots: astronomy.
2. Irony:
if the modified dispersion law holds, Newton’s 2nd law does not.
3. TeV astronomy is a mature field.
4. Look to the future: CTA

19. Data assembled by Neil Gehrels
Short GRB Summary Table
Name Redshift Afteglow Host Eiso Duration Temporal Extended Origin
(1050 erg) (s) Lag (ms) ? /Comment
____________________________________________________________________________________
050509B X ~ ±3.2 N low SF region
050709* X, O SF galaxy ±2.0 Y low SF region
X, O, R elliptical ~ ±6 Y low SF region
? 0.7, 1.8 X galaxy ±14? N -
? - ? galaxy 0.001? N BAT only
? late slew 0.9? ±20? Y is it short?
050925# in gal. plane N non-GRB?
051105A ±5.3? N
? X ? 0.1? ±16.0? N -
051221A X, O, R SF galaxy ±0.4 N -
X ±10? Y -
060121* >1.5 X, O galaxy - 2 2±29? N -
X, O ? ±0.6 N -
060502B 0.287? X ? elliptical 0.1? ±3.0 N -
X, O galaxy ~ n.a. ? is it short?
X, O dwarf gal (5) 3±6 Y is it short?
X galaxy? ~ ±8? N -
* HETE GRB
# soft spectrum
@ galaxy in cluster
Data assembled by Neil Gehrels
Presented by John Nousek