Star Formation in AGN hostsStar Formation in AGN hosts

Li Shao&

PACS Evolutionary Probe (PEP) group

Hangzhou, ChinaApril 28, 2011

Evidence from Herschel PACSEvidence from Herschel PACS

Linking AGN and HostLinking 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 approachOur 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 isFar-infrared emission is host dominated host dominated

Netzer+07

PACS Detection RatesPACS 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 DegeneracyBreak 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. SecularMerger vs. Secular

Merger vs. SecularMerger vs. Secular

Hopkins+06

Merger scenario

Merger vs. SecularMerger vs. Secular

Genzel+06,08

BzK-15504 z~2.38 rotating disk with central AGN

Star formation vs. obscuration?Star formation vs. obscuration?

Hopkins+08

Star formation vs. obscuration?Star formation vs. obscuration?

Hopkins+08

High obscuration (dusty) and high SFR (ULIRG)

Low obscuration (quasar) and low SFR (quenched)

Correlation expected!

But…But…

Shao+10

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

But…But…• No trend for z~1

moderate luminosity X-ray AGN in GOODS-N

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

Shao+10

SummarySummary

• 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