Presentation on theme: "Star Formation in AGN hosts Li Shao & PACS Evolutionary Probe (PEP) group Hangzhou, China April 28, 2011 Evidence from Herschel PACS."— Presentation transcript:
Star Formation in AGN hosts Li Shao & PACS Evolutionary Probe (PEP) group Hangzhou, China April 28, 2011 Evidence from Herschel PACS
Outline Motivation Relation of AGN luminosity and host star formation Relation of AGN obscuration and host star formation Summary
Linking AGN and Host BH growth and host star formation both need gas feeding mechanism Empirical relations –M BH -sigma –M BH -M * imply strong link between BH growth and host formation Ferrarese & Ford 05 Marconi & Hunt 03
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 Netzer+07
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 We have sufficient statistics to do the analysis in bins of both L X and z simultaneously In each bin, the IR luminosity is weighted average of the detections and the stacking of the non- detections Shao+10
Star formation vs. obscuration? Hopkins+08 High obscuration (dusty) and high SFR (ULIRG) Low obscuration (quasar) and low SFR (quenched) Correlation expected!
But… Shao+10 No trend for z~1 moderate luminosity X-ray AGN in GOODS-N
But… Still no trend for high luminosity COSMOS AGN, with good statistics Shao+10
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 L AGN –Secular evolution for low L AGN No trend of L IR 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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