1. Recent Highlights from the Fermi-LAT
Benoît Lott
CEN Bordeaux-Gradignan
on behalf of the Fermi-LAT collaboration

2. LAT performance energy range: 30 MeV - 300 GeV large FOV: 2.4 sr
energy range: 30 MeV GeV
large FOV: 2.4 sr
Aeff:~8000 cm2 at 1 GeV
PSF: q68%~0.8° at 1 GeV
altitude: 565 km
inclination: 25.6°
orbital period: 91 min
whole sky covered in 2 orbits
in survey mode (rocking angle 50°)
public data, available within 12 h
Pass 8 data released soon
operation garanteed until 2018

4. 3FGL (arXiv:1501.02003) Acero et al. (2015, in press)
• 4 years, P7REP_SOURCE_V15, improved PSF
• Front/Back handled separately (different isotropic and Earth limb)
• Energy range 100 MeV GeV
3033 sources (2192 at |b|>10°) >4.1 s

5. Data Interval (months)
LAT Source Catalogs
Catalog
Energy Range (GeV)
Data Interval (months)
Sources
Event Selection
Release
Date
0FGL 3
205
P6V1
DIFFUSE
Feb. 2009
1FGL 11
1451
P6V3 DIFFUSE
Feb. 2010
2FGL 24
1873
P7V6
SOURCE
Aug. 2011
1FHL
10-500 36
511
CLEAN
Jun. 2013
3FGL 48
3033
P7V15
Jan. 2015
The catalogs are analyses over successively deeper data sets, and also represent successive analysis refinements, from event classification on up

6. Associated Source Classes
Blazars and pulsars dominate
Briefer transient classes of LAT sources (GRBs, solar flares) are not represented at all*
The fraction of unassociated sources is about 1/3
This has not decreased appreciably as the FGL catalogs have deepened and counterpart catalogs have grown
* This is by design; time intervals of the brightest flares were excluded from the analysis

7. The Third LAT AGN catalog (3LAC)
Ackermann M. et al., arXiv:
48 month data set
2192 TS>25, |b|>10° sources
3LAC: 1591 counterparts
1563 sources
1444 AGNs in Clean
Sample (no dup., no flags)
Census :
415 FSRQs
602 BLLacs
(~50% with measured z)
162 LSPs, 178 ISPs, 272 HSPs, 20 no class.
413 of unknown type (BCUs)
23 other AGNs
Differences between Northern and Southern Hemispheres: % of BL Lacs in Southern Hemisphere
Preliminary

8. Second Fermi Hard-Source List (2FHL)
6 years of Pass8 data
at E > 50 GeV increase in Aeff of 25%, in PSF of 20% at 50GeV (50% at 500GeV)
51,000 photons E> 50 GeV ~ 1 ph /deg (EGRET: 1500 ph E>10 GeV)
18,000 photons E>100 GeV
2,000 photons E>500 GeV
Fills the gap between Cherenkov ground-based observations and GeV all sky survey
Preliminary

9. Second Fermi Hard-Source List (2FHL)
Preliminary
Detections
320 sources
71 detected by ACTs (TeVCat)
249 not detected by ACTs
206 in 1FHL
60 new sources
Only 10 FSRQs
BL Lacs have softer spectra than
in 3FGL ( GeV) and
1FHL ( GeV)
Should be a valuable resource to establish pointing strategies for
existing ground-based Cherenkov telescopes and CTA.

10. Dark-matter search: Line-like feature near 133 GeV
Spheroidal dwarfs, galaxy clusters, Galactic center
Hint of a signal for a while but feature too narrow and also present in Earth limb
P8_CLEAN R3 5.8 yr
ArXiv , PRD in press

11. Galactic Center data-model
Claims of a potential signal of dark matter annihilation from this region
Set of models for the diffuse emission in the inner 15°x15° of the Milky Way, by fitting GALPROP-derived templates plus point sources.
Foreground/background emission, excluding the 15°x15° region, assessed from all-sky data (CR source distribution, gas intensity and spectral index, and IC intensity across galactocentric rings)
IC emission from inner kpc is higher than predicted and is the dominant interstellar emission component in this region (combination of ISRF and CR leptons)
Enhancement approximately centered the Galactic center with a spectrum that peaks in the GeV range, persisting across all models . Spectral properties vary widely with the modelled interstellar emission.
Foreground/background accounts for most of the emission.
Its determination is crucial in extracting the contribution from the Galactic center region.
data-model

12. LMC: PSR J0540-6919 First «extragalactic» gamma-ray pulsar !
In Large Magellanic Cloud
Power law with exp. cutoff spectrum
• Pulsation search using photon weighting based on model
• Ephemeris from RXTE over 3.5 yrs
• Pulsations at 6.8σ (facilitated by Pass 8)
• The Crab twin, giant spin-down power
• Rare extreme case useful to test emission models
Gamma-ray luminosity erg/s
~10 times more luminous than Crab
(also more luminous in pulsed X-rays)

13. PG 1553+113 HSP BL Lac 0.395 < z < 0.62
one of the brightest BL Lacs
in the X-ray band
TeV source (HESS, MAGIC)
Indication for a periodic
behavior in
the radio (15 GHz)
the optical (R-band)
the LAT band
Autocorrelation gives a
peak at 750 days
Interpretation:
binary black hole?
warped disk?
other?

14. Shortest timescales PKS 1509-089 3C 454.3
model
data
Tr= s
+700
-300
Preliminary
Constraints on size and location
of emitting zone
4 sources show Tmin close to 3 hr:
3C 454.3, 3C 273, 4C+21.35,
PKS
RS/c~104 M9 s
Binned light curves unsuitable to
derive Tmin accurately
Unbinned maximum-likelihood method
Sub-hour variability (<20 min) is found for
3C454.3 and PKS
3C 454.3
3hr
exposure rate
model
data
+ 3hr
+ 6hr
Tr<1000 s

15. Conclusions
The Fermi-LAT has revolutionized our knowledge of the gamma-ray sky,
regarding both galactic and extragalactic sources.
The 4FGL is already in the works.
Operation will continue at least till 2018.
The data reprocessed with the new Pass 8 event selection/data
reconstruction scheme open up new perspectives. They should be
released within a few weeks.