Sky Model for DC2:

1
Sky Model for DC2 Extragalactic Miscellaneous
Sources
2
Credits

• Advice from Diego Torres on galaxies and galaxy
  clusters.
• Paolo Giommi and Jim Chiang for AGN populations
  (luminosity/redshift distributions)
• Gino Tosti for blazar lightcurves.
• Nicola Omodei for GRB simulation code
• Luis Reyes for implementing EBL attenuation
  models.
• Valerie Connaughton GBM simulations

3
Extragalactic Gamma-ray sources

• Galaxy Clusters
• Galaxies
• Active Galactic Nuclei
• Gamma-Ray Bursts
• Hard transient (PBH)
• Extragalactic background light

4
Galaxy clusters

• Motivated by Reimer etc al. (2003, ApJ, 588, 155)
• Fluxes are chosen to be near the EGRET limits
• Modeled as point sources with power law index of
  -2.1.
• The redshifts are small, and assumed to be zero
  in the DC2 simulation.
• Coma, flux 3.177e-08 cm-2 s-1
• Oph, flux 1.383e-08 cm-2 s-1
• Perseus, flux 3.177e-08 cm-2 s-1
• Virgo, flux 3.972e-08 cm-2 s-1

5
Galaxies

• LMC - extended source using spatial model
  developed by Sreekumar (Private communication).
  Flux was 1.42e-7 cm-2 s-1
• SMC - from Pavlidou and Fields 2001, ApJ, 558, 63
  
• M31 with EGRET upper limit (1.0e-8, Pavlidou
  and Fields 2001)
• M82 Using most optimistic prediction from Blom
  et al. 1999, ApJ, 516, 744, spectral shape is
  from fig 1 of that paper.
• NGC 253 Using the most optimistic prediction
  from Blom et al 1999.

6
AGN

• AGN 104 high confidence blazar identifications
  of 3EG sources from 2003 and 2004 papers by
  Soward-Emmerd, Romani etc al and high confidence
  3EG blazars from the 3rd catalog.
• 1005 AGN generated using package developed by
  Paolo Giommi (see Jim Chiangs talk for details
  on redshift and flux distributions).
• All 104 EGRET blazars and the brightest 100
  Giommi blazars were defined as variable sources,
  the remaining 905 Giommi blazars were steady
  sources.
• 20 of the Giommi blazars were moved to locations
  and assigned the redshift of known AGN.
• B3 1428422 (z4.72) was 42 away from 1ES
  1426428.

7
AGN

• 204 blazars were assigned lightcurves (see Gino
  Tostis talk for details).
• Each blazar was fit as a broken power-law
• There were two classes
• Highly variable, low break energy assigned to
  FSRQs and LBL
• Less variable, higher break energy assigned to
  HBLs.
• The break energy, and gamma-gamma2 (the
  difference between the two power-law indices) did
  not vary with time for a given blazar.

8
AGN

• Some examples

0210-5055, Ebreak 181 MeV
Mrk 421, Ebreak 1047 MeV
9
Gamma-Ray Bursts

• 132 GRB simulated over 4 pi
• 64 triggered the GBM, the remainder did not
  trigger due to
• Earth occultation
• SAA passages
• Threshold cut of 6e-8 erg cm-2.
• Small bug in GRB simulation software which caused
  input files for GBM simulation to not be produced
  for some bursts (5 GRB).
• GBM statistical uncertainty
• Inversely proportional to the maximum intensity
  of the burst as measured on a 0.25 sec timescale
  in the 2 brightest detectors and cosine
  corrected. It was a Gaussian distribution.
• GBM systematic uncertainty
• 2 degree (1 sigma) assumed to be independent of
  statistical error/brightness and distributed as a
  Gaussian.

10
Gamma-Ray Bursts

• GRB080125657 an intriguing burst!
• Theta 132 deg (i.e. below the LAT horizon)
• 104 photons triggered and passed OBF (but OBF
  filtered out all but the lowest energy events).
• 70 events had a fit track but the reconstructed
  directions were essentially random.

11
GRB afterglows

• Two basic types
• Power-law decay (soft)
• Broken power-law, gamma-1.9 and gamma2-2.7
• Ebreak sweeps from 5 GeV down to 1 GeV as the
  afterglow ages.
• Bright steady, hard component (hard)
• Broken power-law, gamma-1.1 and gamma2-2.0,
  Ebreak1000.
• Afterglows were generated for 9 GRB using one or
  both of the above models (but with varying flux
  and duration normalizations).

12
GRB Afterglows

• GRB080101283 hard duration 5 mins
• GRB080104514 - soft hard duration 5 hrs, 5
  mins
• GRB080105885 hard duration 400s
• GRB080107334 - soft duration 5 hrs
• GRB080118175 soft duration 5 hrs
• GRB080127553 soft duration 5 hrs
• GRB080131904 hard duration 5 mins
• GRB080213493 soft duration 5 hrs
• GRB080217126 soft duration 5 hrs
• Fluxes were fairly low these would be hard to
  find!

13
PBH

• A short very hard transient event.
• Flux increases exponentially, spectra gets harder
  and cutoff moves to higher energies as a function
  of time.
• This was designated GRB080106074 by Nukri Komin
  and David Band (from their blind searches)

14
EBL Model

• Kneiske High UV

15
Extragalactic diffuse

• Modeled as a power-law with -2.1 spectrum
  (Sreekumar 1998).
• Cillis and Hartman (2005, ApJ, 621, 291) source
  subtracted map has average 5.1e-5 cm-2 s-1 sr-2
  (gt100MeV). The flux normalisation for the DC2
  extragalactic diffuse was obtained by subtracting
  the galactic diffuse and sum of the 997 DC2
  blazars below 5e-8 cm-2 s-1 (approx flux
  detection limit of EGRET).

16
Residual background
Energy distribution of residual background events
(classA/GoodEvent3) The excess at large energies
(gt10 GeV) would have been greatly lessened if we
had implemented Bills ACD ribbon cuts (c.f.
performance plots shown by Bill at the kickoff
meeting.
17
Accounting of sources
18
Delving more deeply

• In the DC2 sky there were 1719 discrete,
  persistent sources, 134 transient sources, 6
  diffuse source (4 dark matter components,
  galactic diffuse and extragalactic diffuse).
• We have collected information about the DC2 sky
  model on http//www-glast.slac.stanford.edu/softwa
  re/DataChallenges/DC2/SkyModel/simulated_data.html
  
• The DC2 data servers which serve root files, will
  now return data which contains the MC information
  (see the merittuple documentation for details).
• The MC variable you probably care most about is
  McSourceId. This tells you which source produced
  the event.
• The DC2 FT1 fits data have been reprocessed to
  add an additional variable MC_SRC_ID (this is
  the same as McSourceId).
• You can download an all-sky fits file containing
  this variable from the website above.
• The GSSC data server will be updated sometime
  next week.

19
Webpages
RA sorted table of DC2 sources
FT1 data including MC_SRC_ID
Tables of DC2 sources by source class
20
Webpages
Pulsars
21
Webpages
Variable blazars
22
Webpages
Gamma-ray bursts
23
Conclusions

• What has been presented in these talks is an
  overview of the DC2 sky.
• We encourage everyone to visit the website and
  compare the details of their analysis against the
  DC2 truth.
• Have fun!