Moriond 04/02/09 Benoit Lott

New insight into Gamma-ray New insight into Gamma-ray Blazars from the Fermi-LAT Blazars from the Fermi-LAT

Benoît Lott CEN Bordeaux-Gradignan

on behalf of the Fermi-LAT collaboration

Moriond 04/02/09 Benoit Lott

Fermi-LAT as an all-sky monitor

OR103FSRQz=1.83

ATEL #1650S.Ciprini et al.

Moriond 04/02/09 Benoit Lott

3-month sky survey

TS=100, photon index=2.2

Flux(E>100 MeV) ph cm-2s-1

Moriond 04/02/09 Benoit Lott

Two flavors of blazars: FSRQs and BLLacs

• Defining property: strong emission lines intense radiation field (disk, clouds) outside the jet • High power (~1046-48 erg/s)

• Parent population: FRII • Low synchrotron peak (IR) in SED

• 46 FSRQs in EGRET all-sky survey (18 months)

• high redshift 0.1 < z < 2.3

Moriond 04/02/09 Benoit Lott

Two flavors of blazars: FSRQs and BLLacs

• from the “BL Lacerta” archetype

• Defining property: nearly lineless

Low ambient radiation field

• “Low” power (~1045-46 erg/s)

• Parent population: FR I

• Low peak (Opt/IR): LBL

High peak (UV/X-rays): HBL (TeV)

• 14 BLLacs in EGRET all-sky survey

• Low redshift 0< z < 0.9

Moriond 04/02/09 Benoit Lott

BZCat (Massaro et al. 08)Compilation of 2500 known blazars association based on spatial coincidence (Mattox et al., 01)

102 high-conf. (P>90%) associations 4 low-conf. (40%<P<90%) associations

CGRaBS (Healey et al. 08) 1627 radio sources from CRATESassociation based on Figure-of-Merit (spatial, radio and X spectrum) established from EGRET

101 high-conf. (P>90%) associations 14 low-conf. (40%<P<90%) associations

0FGL: 132 sources with TS>100, |b|>10° 7 pulsars, 125 AGN candidates

associations

celestialgalactic

Moriond 04/02/09 Benoit Lott

LAT Bright AGN Sample (LBAS) • 125 non-pulsar sources at |b|>10°

• 106 high-confidence (P>90%) associations with AGNs: (LBAS)

• 10 lower-confidence associations

• FSRQs: 57

• BLLacs: 42

• Uncertain class: 5

• Radiogalaxies: Cen A, NGC1275

• 40% BLLacs (23% for EGRET)

• 7 HBLs (3+1 for EGRET)

• 9 unidentified (3EG: 96/181 at |b|>10°)

Preliminary57 FSRQ42 BLLac6 of Uncertain class2 Radio Galaxies

95% ~0.14° (EGRET sample ~0.62°)

Moriond 04/02/09 Benoit Lott

Flux vs index

FSRQBLLacUncertainRadio Galaxies

TS=100b=20, 80 deg.

TS=100b= 20 deg.E< 3 GeV

Preliminary

Moriond 04/02/09 Benoit Lott

FermiEGRET

EGRET mean flux « 1234 VP»

EGRET peak flux:maximum in 2-w VPs

Fermi mean flux:3-m averaged

Fermi peak flux:maximum in 1-w periods

meanflux

weekly peakflux

mean vs peak flux

peak/mean flux ratio

Flux distributions

Preliminary

Moriond 04/02/09 Benoit Lott

3C454.3 (FSRQ) AO 0235+165 (Int. BL) Mkn501 (HBL)

SED at LAT energies

Preliminary

Significant departures from pure power-law distributions for bright blazars!

Moriond 04/02/09 Benoit Lott

Photon index distributions

Preliminary

all

BL Lacs

FSRQs

<>= 2.33±0.01

<>=1.99±0.01

Photon index

Nu

mb

er

of

so

urc

es

FSRQs

F

BLLacs

Moriond 04/02/09 Benoit Lott

EGRET vs FERMI photon index

FSRQBLLacUncertainRadio galaxies

33 AGNs/116 LAT-sources (30%)

in 3EG catalog with a comparable

flux → duty cycle

Others are found at lower fluxes

FSRQs: 20

BLLacs: 11

Uncertain: 3

Radio galaxy:1

Preliminary

LBAS Sources in 3EG

Moriond 04/02/09 Benoit Lott

Mukherjee et al. 1999

Redshift distributions

Preliminary

EGRET

FSRQBLLacUncertainRadio galaxies

Preliminary

FSRQsBZCatLAT

BL LacsBZCatLAT

Moriond 04/02/09 Benoit Lott

Preliminary

Blazar class slope

All 2.50±0.12

FSRQs 2.55 ±0.12

BLLacs 2.32 ±0.15

• « sky coverage » enables the log N-LogS to be computed

• Euclidian space: slope=2.5

Preliminary

Log N - Log S

FSRQs

BL Lacs

Marco Ajello

Moriond 04/02/09 Benoit Lott

Luminosity vs redshift

Preliminary

FSRQBLLacUncertainRadio galaxies

Moriond 04/02/09 Benoit Lott

Preliminary

<V/Vmax>: ratio between the comoving volume within which the source wasdetected and the maximum volume available for its detection

Population uniformly distributed in Euclidian space, non evolving: <V/Vmax> ~ 0.5

<V/Vmax> test

Sample #objects <V/Vmax>

FSRQs 57 0.645±0.043

BLLacs 42 0.473±0.046

All with z>0 92 0.512±0.031

Positive evolution for FSRQs (more FSRQs in the past)Compatible with no evolution for BLLacs

Moriond 04/02/09 Benoit Lott

Perspectives

• Luminosity function• Contribution of unresolved blazars to

Extragalactic Diffuse Background• Variability on different timescales• Duty cycle of blazars• Existence of a blazar sequence ? (evolutionary link between FSRQs and BLLacs?)

• Gamma-ray radio connection• …