Cosmological Evolution of Blazars: new findings from the SwiftBAT and FermiLAT surveys

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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

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Instruments
Fermi-LAT Band 0.1-300 GeV FoV 2.4 sr Monitor
100 sky/3hr Pos. res. 3-21

• Swift-BAT
• Band 15-200 keV
• FoV 1.4 sr
• Monitor 70 sky/day
• Pos. res. 1-5

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Why to study blazars at high-E ?
_at_ ?-rays -Blazars are gt85 of extraG.
sources -Evolution of blazars studied with EGRET
low numbers -GeV background ? (see
Chiang98,Dermer05,Narumoto06)
_at_ hard -rays -Blazars are 15 of extraG.
sources -Evolution of blazars unknown
-MeV background unexplained (see Inoue08 and
ref. therein)
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PKS 0528134
Ghisellini99
IBL
FSRQ
FSRQs and IBL/LBL peak in the MeV band
HBL
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The BAT 3yr Sample
Ajello09,ApJ 699, 603

• 38 blazars (26 FSRQs, 12 BL Lacs) detected up to
  z4
• 9 FSRQs and 3 BL Lacs in common with EGRET/LAT
• No blazars at low LX and low redshift

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Test of Evolution

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

• Blazars evolve positively at 3?
• No significant difference between the 2
  sub-classes
• Seyferts do not evolve

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Parametric XLF
Density Evolution i.e. objects were more
numerous in the past ?(L,z) ?(L,0) (1z)k
Luminosity Evolution i.e. objects were more
luminous in the past Lx(z)(1z)k Lx

• Method
• Maximize Likelihood function based on the product
  of Poisson prob. of observing 0 or 1 blazars in a
  dLxdz element

(Marshall83, Borgani01, Wall05)
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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 ?1-0.87?1.31 lt--beaming? ?2
2.73?0.38 k 3.45 ?0.44 ?-0.25 ?0.07 lt--3?
(UrrySchafer84)
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Separating the populations
FSRQs (26)
BL Lacs (12)
Best fit model PLE k3.67, ?-0.30 Local XLF
slope 2.49 0.37
Best fit model PLE k-0.82.4 !! Local XLF
slope 2.61 0.36
Claim of negative (Rector00, Beckmann03) or no
(Caccianiga02, Padovani07) evolution not
confirmed/denied BL Lacs produce lt1 CXB
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The MeV Background

• Blazars produce
• 10 of CXB _at_ 2-10 keV
• 20 of CXB _at_ 15-55 keV
• 100 CXB _at_ 1 MeV

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

Watanabe09
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The LAT view of blazars
(Abdo et al. 2009, ApJ 700, 597)

• Aug/Sep/Oct high confidence list 205 sources
  with gt10? detection
• 132 with b gt 10? (7 pulsars, 14 unid)
• 111/125 are bright, flat spectrum radio sources
• 98/111 have optical classifications, 89/111 have
  redshifts

FSRQ BL Lac Radio Galaxy Uncertain
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Some Key Properties
nFn
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Blazar Evolution in LAT
FSRQs (59)
BL Lacs (29)
Strong Positive Evolution V/Vm0.645?0.043 Power-l
aw slopes 2.5
No significant Evolution V/Vm0.422?0.055 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.
  Franceschini99)
• The bulk of super-massive BHs is formed at z1
  tracing the SFR of galaxies (eg. Madau99)
• Beaming allows to study AGNs at large z

Hasinger05
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Galaxy-AGN co-evolution

• SMBHs and galaxies co-evolve through the history
  of the Universe
• MBH-?relation (e.g.MerritFerrarese01)
• Co-evolution of SFR and AGN (e.g. Madau99,
  Hasinger05)

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AGN-Cluster Interaction
AGN activity regulates the thermal state of the
gas by injecting energy in the ICM
Abdo, ApJ 699, 31
AGNs inflates cavities in the ICM
Turbulent pressure lt5(Werner09)
Total non-thermal pressure in the atmospheres of
giant E gal is 10 (Churazov09)
CR pressure lt15 (Keiths 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 ?
Beaming alters the intrinsic luminosity
function -gt?(L)dL P(LL) ?(L)dL where L?p L
Urry Shafer84
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Previous attempts
Comastri06
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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..

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

• Chandra/XMM much better sensitivity but smaller
  FOV and biased
• BAT more sensitive than Suzaku/HXD on long
  exposures