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EXPLORING RELATIVITY WITH COSMIC RAY AND g-RAY SPACE OBSERVATIONS

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Title: EXPLORING RELATIVITY WITH COSMIC RAY AND g-RAY SPACE OBSERVATIONS


1
EXPLORING RELATIVITY WITH COSMIC RAY AND g-RAY
SPACE OBSERVATIONS
  • F. W. STECKER
  • NASA GODDARD SPACE FLIGHT CENTER

2
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).

3
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.

4
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)
5
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
6
?-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
7
?-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).
8
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
9
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
10
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).

11
Two Telescope Operation
12
Mkn 501 Spectrum (Stecker De Jager 1998)
13
Mkn 501 Intrinsic with SSC Fit Using X-ray Data
(Konopelko et al. 1999)
14
Photomeson Production off the Cosmic
Microwave Background Radiation
?CMB p ? ? ? N p
Produces GZK Cutoff Effect
15
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

16
UHECR Spectra with Photomeson Production Both On
(Dark) and Turned off by LIV (Light)
17
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).

18
OWL ORBITING WIDE-ANGLE LIGHT COLLECTORS
19
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

20
OWL Deployment
Jiffy-Pop Light Shield
Schmidt Optics Mechanical Configuration
21
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.

22
OWL Instantaneous Proton ApertureSchmidt Optics,
1000 km Orbits
23
UHE Cosmic Rays Status and Prospects
24
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
25
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.

26
Instantaneous Electron Neutrino ApertureSchmidt
Optics, 1000 km Orbits OWL
27
UHE-Neutrino Physics Status and Prospects
28
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

29
THE TRUE CONQUESTS, THE ONLY ONES THAT LEAVE NO
REGRET, ARE THOSE THAT ARE WRESTED FROM
IGNORANCE-----------------------------NAPOLEON
----------------------------
30
Backup Slides
31
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

32
UHECR Spectra with Pair Production Turned Off and
with Photomeson Production both On (Light) and
Off (Dark)
33
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

34
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.

35
  • 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

36
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,
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