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Star Formation in AGN hosts. Evidence from Herschel PACS. Li Shao & PACS Evolutionary Probe (PEP) group. Hangzhou, China April 28, 2011. Linking AGN and Host. BH growth and host star formation both need gas feeding mechanism Empirical relations M BH -sigma M BH -M *

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Star formation in agn hosts
Star Formation in AGN hosts

Evidence from Herschel PACS

Li Shao&PACS Evolutionary Probe (PEP) group

Hangzhou, ChinaApril 28, 2011


Linking agn and host
Linking AGN and Host

  • BH growth and host star formation both need gas feeding mechanism

  • Empirical relations

    • MBH-sigma

    • MBH-M*

      imply strong link between BH growth and host formation

Ferrarese & Ford 05

Marconi & Hunt 03


Our approach
Our approach

  • X-ray selected AGN

    • Deep Chandra or XMM surveys in GOODS and COSMOS

    • Good multi-wavelength coverage, redshifts and identifications are ready

  • Star formation rate estimated from far-IR

    • Greatly improved sensitivity and spatial resolution with Herschel-PACS

    • PACS can measure rest frame 60um out to z~2


Far infrared emission is host dominated
Far-infrared emission is host dominated

Netzer+07


Pacs detection rates
PACS Detection Rates

  • ~20% in GOODS-N of 2Ms Chandra sources

  • For non-detections we use stacking

  • ~40% in GOODS-S with deeper PACS data


Break l z degeneracy
Break L-z Degeneracy

  • We have sufficient statistics to do the analysis in bins of both LX and z simultaneously

  • In each bin, the IR luminosity is weighted average of the detections and the stacking of the non-detections

Shao+10



Merger vs secular1
Merger vs. Secular

Hopkins+06

Merger scenario


Merger vs secular2
Merger vs. Secular

Genzel+06,08

BzK-15504 z~2.38 rotating disk with central AGN



Star formation vs obscuration1
Star formation vs. obscuration?

High obscuration (dusty) and high SFR (ULIRG)

Low obscuration (quasar) and low SFR (quenched)

Correlation expected!

Hopkins+08


But…

  • No trend for z~1 moderate luminosity X-ray AGN in GOODS-N

Shao+10


But…

  • No trend for z~1 moderate luminosity X-ray AGN in GOODS-N

Shao+10

  • Still no trend for high luminosity COSMOS AGN, with good statistics


Summary
Summary

  • We use the rest-frame far-infrared luminosity to measure AGN host star formation rates

  • We have enough statistics to break the redshift/luminosity degeneracy

  • We propose two modes of AGN/host co-evolution

    • Merger like scenario for high LAGN

    • Secular evolution for low LAGN

  • No trend of LIR with AGN obscuration, details of the merger model need further understanding

Thanks to PEP team and F. Bauer, D. Alexander, N. Brandt, M. Brusa, V.Mainieri, M. Salvato, G. Hasinger, and many others


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