Cosmological Evolution of Blazars:

new findings from the Swift/BAT and Fermi/LAT surveys

M. Ajello [KIPAC/SLAC]L. Costamante, R. Sambruna, N. Gehrels, J. Greiner, J. Tueller,

J. Chiang, A. Escala, R. Mushotzky, A. Rau, J. Wall+

On behalf of Fermi/LAT collaboration

M. Ajello 2

Instruments

Swift-BATBand: 15-200 keVFoV: 1.4 srMonitor: 70% sky/dayPos. res.: 1’-5’

Fermi-LATBand: 0.1-300 GeVFoV: 2.4 srMonitor: 100%

sky/3hrPos. res.: 3’-21’

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Why to study blazars at high-E ?Ajello+, 2008, ApJ, 689, 666

@ hard -rays-Blazars are ~15% of extraG. sources-Evolution of blazars unknown -MeV background unexplained(see Inoue+08 and ref. therein)

@ -rays-Blazars are >85% of extraG. sources-Evolution of blazars studied with EGRET: low numbers-GeV background ?(see Chiang+98,Dermer+05,Narumoto+06)

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Ghisellini+99Tagliaferri+00

Pian+98

PKS 0528+134

IBL

HBL

FSRQ

FSRQs and IBL/LBL ‘peak’ in the MeV band

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The BAT 3yr Sample

• 38 blazars (26 FSRQs, 12 BL Lacs) detected up to z~4

• 9 FSRQs and 3 BL Lacs in common with EGRET/LAT

• No blazars at low LX and low redshift

Ajello+09,ApJ 699, 603

Seyferts

blazars

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Test of Evolution

• Luminosity function needed to assess the contribution of a source class to the diffuse background

Seyferts

Blazars

1. Blazars evolve positively at ~3

2. No significant difference between the 2 sub-classes

3. Seyferts ‘do not’ evolve

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Parametric XLF

Luminosity Evolution i.e. objects were more luminous in the past Lx(z)=(1+z)k Lx

Density Evolution i.e. objects were more numerous in the past (L,z)= (L,0) (1+z)k

MethodMaximize Likelihood function based on the product

of Poisson prob. of observing 0 or 1 blazars in a dLxdz element:

(Marshall+83, Borgani+01, Wall+05)

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Best-fit XLF for entire population

Best Fit Model:

PLE with a redshift cutoff coupled to a local double power law XLF

Parameters:

1=-0.871.31 <--beaming?2= 2.730.38k= 3.45 0.44=-0.25 0.07 <--3

(Urry&Schafer84)

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Separating the populations

FSRQs (26) BL Lacs (12)Best fit model:

PLE: k=3.67, =-0.30Local XLF slope: 2.49 ±0.37

Best fit model:

PLE: k=-0.8±2.4 !!

Local XLF slope: 2.61 ±0.36

Claim of negative (Rector+00, Beckmann+03) or no (Caccianiga+02, Padovani+07) evolution not confirmed/denied

BL Lacs ‘produce’ <1% CXB

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The MeV Background

FSRQs

RQ AGN, from Gilli+07

Watanabe+09

•Blazars produce:–10% of CXB @ 2-10 keV–20% of CXB @ 15-55 keV–~100% CXB @ 1 MeV

•FSRQs detected by BAT must peak at ‘MeV’ energy not to violate CXB constraint

•EGRET did not detect high-z BAT blazars. According to Zhang+05, Sambruna+07, Tavecchio+07,

Watanabe+09 they are MeV blazars

FSRQs

RQ AGN, from Gilli+07

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The LAT view of blazars

FSRQBL LacRadio GalaxyUncertain

(Abdo et al. 2009, ApJ 700, 597)

• Aug/Sep/Oct high confidence list: 205 sources with >10 detection

• 132 with |b| > 10 (7 pulsars, 14 unid) – 111/125 are bright, flat spectrum radio sources– 98/111 have optical classifications, 89/111 have redshifts

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Some Key Properties

F

FSRQs

F

BLLacs

BAT LAT

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Blazar Evolution in LAT

FSRQs (59) BL Lacs (29)

Strong Positive EvolutionV/Vm=0.6450.043Power-law slopes: ~2.5

No significant EvolutionV/Vm=0.4220.055

But: 13/42 BL have no z

Power-law slopes: ~2.2

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Anti-hierarchical growth

• Larger structures comes first: tracing the merging history of spheroids (eg. Franceschini+99)

• The bulk of super-massive BHs is formed at z~1 : tracing the SFR of galaxies (eg. Madau+99)

• Beaming allows to study AGNs at large z

Hasinger+05

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Hasinger+05

Galaxy-AGN co-evolution•SMBHs and galaxies co-evolve through the history of the Universe–MBH-relation (e.g.Merrit&Ferrarese01)

–Co-evolution of SFR and

AGN (e.g. Madau99, Hasinger+05)

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AGN-Cluster Interaction

AGNs inflates cavities in the ICM

Total non-thermal pressure in the atmospheres of giant E gal is ~10% (Churazov+09)

Turbulent pressure <5%(Werner+09)

AGN activity

regulate

s the th

ermal s

tate

of the gas b

y injecti

ng energy in

the IC

M Abdo+, ApJ 699, 31

CR pressure <15% (Keith’s talk)

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Conclusions

• Blazars in BAT are 15% of total AGN population– Strong evolution (PLE) with evidence for a

redshift peak– They account for ~100% of the MeV background

• Blazars in LAT are the main population:– FSRQs evolve strongly, evolution is complex– BL Lacs seem not to evolve….but wait for a

larger sample

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Paucity of blazars at low LX: beaming effect ?

Urry & Shafer+84

Beaming alters the intrinsic luminosity function

->(L)dL = P(L|L) (L)dL

where L=p L

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FSRQs

RQ AGN, from Gilli+07

Previous attempts

Comastri+06

Giommi+07

Required to produce ~10% of CXB at 1 keV and not exceed the CXB at ~MeV

Derived from logN-logS of blazar in radio

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In deep surveys

• Deep X-ray surveys ‘must’ contain a fraction of blazars

• Selection of C-thick AGN using hardness ratios becomes dangerous

• Unless the evolution of RQ and RL AGN is different…..

logN- logS [0.5-2.4 keV] Courtesy P.

Giommi

blazars

RQ AGN, Hasinger+05

Looking forward to Astro-H/NuSTAR

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The BAT survey: Deep, all-sky and Unbiased

• All-sky observed down to ~0.5 mCrab (~6e-12 erg/cm2/s)

• No bias against NH up to Compton-thick regime

2-10 keV @ z=0

2-10 keV @ z=1

15-55 keV @ z=0, z=1

• Chandra/XMM much better sensitivity but smaller FOV and biased

• BAT more sensitive than Suzaku/HXD on long exposures