1. The 3rd Fermi Catalog
arXiv:
Zhang Xiao
2015/03/10

2. Content 1. Introduction 2. Instrument and background
3. construction of the catalog
4. The 3FGL catalog
5. source association and identification
6. Galactic source numbers counts
7. Conclusions

3. 1. Introduction The existing Fermi catalog:
the LAT Bright source list (0FGL):
Abdo et al. 2009, 3 months
the 1st Fermi LAT catalog (1FGL):
Abdo et al. 2010, 11 months
the 2nd Fermi LAT catalog (2FGL):
Nolan et al. 2012, 2 years
the 1st Fermi LAT Catalog of sources above 10 GeV (1FHL):
Ackermann et al. 2013, 3 years
the 3rd catalog of AGN (3LAC):
Ackermann et al. 2015
FGL: Fermi Gamma-ray LAT

4. Improvement more data Pass 7 reprocessed data
4 years: 2008/08/04 15:43 UTC /06/31 22:46 UTC
Pass 7 reprocessed data
new model of the diffuse Galactic and isotropic emissions

5. 2. Instrument and background

6. 2.1 Fermi Gamma-ray Space Telescope
Austria
France
Germany
Iceland
Italy
Japan
South Africa
Spain
Sweden
USA
launched on a Delta II rocket from Cape Canaveral on June 11, 2008 at 12:05 pm EDT

7. The construction and principles
Converter-tracker
Calorimeter
Anticoincidence detector (ACD)
Data acquisition system (DAQ)
Fermi LAT
...
12 thin layers, 'Front' events
4 thin layers,
'back' events
2 layers without tungsten foils
tungsten (钨)
silicon
CsI

8. size: 1.8m x 1.8m x 0.72m; mass: ~2800 kg; power: 650 W

9. performance
energy range
from 20 MeV to more than 300 GeV
effective colleting area
~ GeV
live time
76%
field of view
2.4 1 GeV
PSF (68%)
~5 100 MeV
~0.8 1 GeV
Timing accuracy
< 10 μs

10. 2.3. Diffuse Gamma-ray background
the diffusive emission of the Milky Way
isotropic backgound
...
solar and lunar
residual earth limb

11. 3. Construction of the catalog
3.1. detection and location
3.2. significance and thresholding
3.3. spectral shapes
3.4. extended sources
3.5. flux determination
3.6. variability
3.6. limitations and systematic uncertainties
3.7. sources toward local interstellar clouds and the Galactic ridge
3.8. analysis flags

12. 4. The 3FGL Catalog 4.1. catalog description
4.2. comparison with 0FGL, 1FGL, 2FGL and 1FHL

13. the spactial distribution of 3033 sources

14. Catalog Description Name: 3FGL JHHMM.m+DDMM(c/i/s/e) Flags (78+572)：
c (78): pay more attentions to them
e (25): extended sources
i/s: the IC/SYN component of the Crab
Flags (78+572)：
1, 3, 4, 5, 6, 7, 9, 10, 11, 12

16. total: = 3033

20. Statistics of sources in LAT Catalogs
Comparison with 0FGL, 1FGL, 2FGL and 1FHL

22. Possible causes for losing sources
Properties:
general equally distributed over all latitudes
most are the unassociated sources
most of the associated sources are AGN
Possible reasons
centroid has shifted
"..., allowed us to obtain better localizations of the sources at positions that might be outside the 95% confidence error regions reported in the 0FGL, 1FGL, or 2FGL catalogs."
statistical threshold effects, i.e. TS < 25

24. step-by-step from 2FGL to 3FGL
The Front/Back handling
larger TS values, higher photon fluxes, softer spectra (+0.05)
Data from Pass 7 (2FGL) to Pass 7 reprocessed (3FGL)
larger TS, harder sources (-0.03)
Changing the model for Galactic diffuse emission
In conclusion, to first order the resulting net changes are not very large.

25. Source identification
Periodic Variability
PSR, binaries
Spatial Morphology
SNR, PWN
Correlated Variability
AGN
137 PSRs, 66 AGNs, 12 SNRs, 3 binaries, 9 PWNe,
2 normal galaxies, 1 massive SFR, 1 nova

26. Source Associations
1809 in total

27. SNRs Associations (11): Identifications (12 extended sources):
2FGL (6): IC 443, W28, W30, W44, W51C, Cygnus Loop (W78)
new (6): S147, Puppis A, Vela Jr., RX J , Gamma Cygni (W66), HB21
Associations (11):
Tycho, Cas A, Kes 17, CTB 33 (G ), CTB 37A,
G , MSH 17-39, W41, 3C 391, W49B, CTB 109
Araya
G , G , HB9 (G )
Auchettl, K.
Kes 79
Xing, Yi
RCW 103, Kes 27
Yuan, Qiang
RCW 86
Liu, Bing
Kes 41
Lemoine-Goumard
G , G

28. High Mass Binaries Identification (3) Association (0) HMB 3FGL TeV
LS I +61
3FGL J
YES
1FGL J
3FGL J
LS 5039
3FGL J
LS 2883
miss
HESS J

29. Summary total: 3033 sources with TS > 25
flaged: 78 (2.6%) (18.9%)
identified: 232 (7.6%)
associated: 1809 (59.6%)
unassociated: 992 (32.7%)