EXPLORING RELATIVITY WITH COSMIC RAY AND g-RAY SPACE OBSERVATIONS

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EXPLORING RELATIVITY WITH COSMIC RAY AND g-RAY
SPACE OBSERVATIONS

• F. W. STECKER
• NASA GODDARD SPACE FLIGHT CENTER

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Beyond Einstein (?)

• Group of Lorentz boosts (just like the group of
  Galilean transformations) is open at the high end
  (Planck scale?) possible modifications by
  quantum gravity, extra dimensions, string theory,
  etc.
• The cosmic background radiation is only isotropic
  in one preferred frame (may not be significant).

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Testing Lorentz Invariance with GLAST

• Some classes of quantum gravity models imply a
  photon velocity dispersion relation which may be
  linear with energy (e.g. , Amelino-Camelia et al.
  1998).
• Using GLAST data for distant g-ray bursts the
  difference in arrival times of g-rays of
  different energies could be gt 100 ms. But ??
  effects intrinsic to bursts?? Look for
  systematic change with distance.

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The GLAST Mission

• Two GLAST instruments
• LAT 20 MeV gt300 GeV
• GBM 10 keV 25 MeV
• Launch 2007
• 5-year mission (10-year goal)

Large Area Telescope (LAT)
GLAST Burst Monitor (GBM)
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GRBs and Instrument Deadtime
Distribution for the 20th brightest burst in a
year (Norris et al)
Time between consecutive arriving photons
Time resolution lt10 microsec Simple deadtime
per eventlt30 microsec
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?-Ray Astrophysics Limit on LIV from Blazar
Absorption Features
Let us characterize Lorentz invariance violation
by the parameter ? such that
(Coleman Glashow 1999). If ? gt 0, the ?-ray
photon propagator in the case of pair production
is changed by the quantity
so that the threshold energy condition is now
given by
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?-Ray Astrophysics Limit on LIV from Blazar
Absorption Features (continued).
Thus, the pair production threshold is raised
significantly if
The existence of electron-positron pair
production for ?-ray energies up to 20 TeV in
the spectrum of Mkn 501 therefore gives an upper
limit on ? at this energy scale of
(Stecker Glashow 2001).
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Limit on the Quantum Gravity Scale
For pair production, ? ?? e e- the electron
( positron) energy Ee E? / 2. For a third
order QG term in the dispersion relation, we find
And the threshold energy from Stecker and Glashow
(2001)
reduces to
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Limit on the Quantum Gravity Scale (continued)
Since pair production occurs for energies of at
least E? 20 TeV, we then find the numerical
constraint on the quantum gravity scale
Arguing against some TeV scale quantum gravity
models involving extra dimensions! Previous
constraints on MQG from limits on an energy
dependent velocity dispersion of ?-rays from a
TeV flare in Mkn 412 (Biller, et al. 1999) and
?-ray bursts (Schaefer 1999) were of order
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AGN What GLAST will do

• EGRET has detected 90 AGN.
• GLAST should expect to see dramatically
  more many thousands
• (Stecker Salamon 1996)

• Probe absorption cutoffs with distance (g-IR/UV
  attenuation).

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Two Telescope Operation
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Mkn 501 Spectrum (Stecker De Jager 1998)
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Mkn 501 Intrinsic with SSC Fit Using X-ray Data
(Konopelko et al. 1999)
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Photomeson Production off the Cosmic
Microwave Background Radiation
?CMB p ? ? ? N p
Produces GZK Cutoff Effect
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Shutting off Interactions with LIV

• With LIV, different particles, i, can have
  different maximum attainable velocities ci.
• Photomeson production interactions of ultrahigh
  energy cosmic rays are disallowed if
  cp cp gt 5
  x 10-24(e/TCBR)2
• Electron-positron pair production interactions of
  ultrahigh energy cosmic rays can be suppressed if
  
  ce cp gt (mp
  me)mp/Ep2

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UHECR Spectra with Photomeson Production Both On
(Dark) and Turned off by LIV (Light)
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High Energy Astrophysics Tests of Lorentz
Invariance Violation (LIV)

• Energy dependent time delay of g-rays from GRBs
  AGN (Amelino-Camelia et al. 1997 Biller et al
  1999).
• Cosmic g-ray decay constraints (Coleman Glashow
  1999, Stecker Glashow 2001).
• Cosmic ray vacuum Cherenkov effect constraints
  (Coleman Glashow 1999 Stecker Glashow 2001).
• Shifted pair production threshold constraints
  from AGN g-rays (Stecker Glashow 2001).
• Long baseline vacuum birefringence constraints
  from GRBs (Jacobson, Liberati, Mattingly
  Stecker 2004).
• Electron velocity constraints from the Crab
  Nebula g-ray spectrum (Jacobson, Liberati
  Mattingly 2003).
• Ultrahigh energy cosmic ray spectrum GZK effect
  (Coleman Glashow 1999 Stecker Scully 2005).

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OWL ORBITING WIDE-ANGLE LIGHT COLLECTORS
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Orbiting Wide-angle Light-collector

• Air fluorescence imagery, night atmosphere
• Stereo viewing unambiguously determines shower
  height and isolates external influences (e.g.,
  cloud effects, surface light sources)
• Large Field-of-View ( 45O ) reflective optics
  at a 1000 km orbit in a stereo configuration
  an asymptotic
• Instantaneous aperture 2.3 x 106 km2-sr

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OWL Deployment
Jiffy-Pop Light Shield
Schmidt Optics Mechanical Configuration
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Capabilities of OWL

• Energy resolution 15 _at_ 1020 eV and improves
  with energy
• Angular resolution 0.2 - 1 degree
• Longitudinal profile Locate shower max within
  50 g cm-2
• Able to statistically identify protons, nuclei,
  and photons
• Perform event by event identification of near
  horizontal and earth skimming neutrinos)
• Instantaneous stereo aperture AI 2.3x106 km2
  sr, duty cycle of
• 11.5 defined by requirement of
  moonless nightside viewing conditions. Cloud
  cover reduces the duty cycle to 3.5.

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OWL Instantaneous Proton ApertureSchmidt Optics,
1000 km Orbits
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UHE Cosmic Rays Status and Prospects
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Crucial Role of Stereo-viewing from
Space Monocular Events Demonstrate Significant
Systematic Errors

• Simulated data of 1021 eV EAS events in an
  atmosphere with clouds
• are reconstructed as either stereo events or
  monocular events.
• The presence of clouds does not bias the stereo
  event reconstruction.
• However, monocular events demonstrate significant
  systematic errors.

Tareq Abu Zayad Astroparticle Phys. 21, (2004) 163
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Ultrahigh Energy Neutrino-Induced Horizontal
Showers Detected via Air Fluorescence
OWL

• Large Detecting Volume (1012 tons of
• atmospheric target atoms) opens the door
• for observing ultra-high energy neutrino
• Interactions.
• Horizontal n-initiated airshowers start
• deep (gt 1500 g/cm2) in the atmosphere,
• providing a unique signature for
• ultrahigh energy neutrinos.

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Instantaneous Electron Neutrino ApertureSchmidt
Optics, 1000 km Orbits OWL
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UHE-Neutrino Physics Status and Prospects
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Reference Material for OWL

• F.W. Stecker, J.F. Krizmanic, L.M. Barbier, E.
  Loh, J.W. Mitchell, P. Sokolsky and R.E.
  Streitmatter
• Nucl. Phys. B 136C, 433 (2004),
• e-print astro-ph/0408162

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THE TRUE CONQUESTS, THE ONLY ONES THAT LEAVE NO
REGRET, ARE THOSE THAT ARE WRESTED FROM
IGNORANCE-----------------------------NAPOLEON
----------------------------
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Backup Slides
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Minimum Source Spectrum Local Power Density
Requirements in W Mpc-3 for E gt 3 EeV

• With source evolution and including pair
  production energy losses 1.5 x 1031
• With source evolution and no pair production
  energy losses 1.2 x 1030
• With no source evolution and including pair
  production energy losses 2.2 x 1031
• With no source evolution and no pair production
  energy losses 7.7 x 1030

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UHECR Spectra with Pair Production Turned Off and
with Photomeson Production both On (Light) and
Off (Dark)
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OWL Major Requirements Overview

• Large Aperture (effective aperture 100,000
  km2-sr)
• Wide-angle optics ( 25 degree half-angle)
• Stereo viewing of EAS
• Photonics (single photoelectron sensitivity,
  large focal plane detector)
• Trigger. space-time pattern recognition
• Ability to handle background light
• Deal with signal distortion by clouds,
  atmospheric conditions, lights

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Observing EAS from Space TWO CRUCIAL POINTS

• THE INSTANTANEOUS APERTURE (AI) IS NOT
• THE TIME-AVERAGED EFFECTIVE APERTURE (AE)
• AE AI D e
• Efficiency, e , involves fractional cloud cover,
  atmospheric conditions. The maximum achievable
  efficiency for space observation of EAS is 0.30
  .
• D e 0.035
• gt AE AI 0.035, general approximation
• AE 80,000 km2-sr for OWL
  specifically
• J.K. Krizmanic et al., Proc. 28th-ICRC (2003),
  2, 639
• (2) For observation from space, stereo viewing is
  essential for good energy resolution and
  neutrino-event characterization.

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• OWL Looking for Neutrinos
• Ability to measure neutrinos from exotic
  processes, statistically distinguish from
  bottom-up photomeson neutrinos. BUT,
  ANITA-LITE results ..
• Double-bang taus in atmosphere Non-viable
• Earth-skimming taus, via air fluorescence
  Edgy
• Strongly-interacting neutrinos getem if
  theyre there
• Upward tau neutrinos via Cherenkov Edgy

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OWL Mission Overview
Launch Delta IV Heavy, dual spacecraft, 5
meter fairing Orbit LEO, 1000 km initial, move
to 500 km before end of mission controlled
re-entry Life 3 years minimum, 5 year goal
Mass / size one satellite 1730 kg / 8 meter
diameter / low density ACS 3-axis stabilized,
2 degree control, 0.01 degree knowledge Power
712 watts, including cloud monitor, 11 m2 solar
panels, flat panel, fixed Data system dual
redundant, 150 kbits / sec average, 110 Gbit
onboard storage,