AGN Content of the m Jy Population Through X-ray stacking

AGN Content of the Jy Population Through X-ray stacking

Franz Bauer (Columbia), Glenn Morrison (Hawaii) FOR CDF/GOODS Teams

Motivation Radio traces massive SF, AGN jets

Characterization of uJy population to understand evolution and interplay to other bands.

As we push deeper, we will have very limited number of diagnostics (even worse for EVLA?)

Easier to detect AGN when they dominate radio, but AGN are predicted to affect and play off of evolving galaxies of all types and could contaminate SFR estimates

X-ray Emission as SFR tracer

(Lehmer et al. 2007, Persic & Rephaeli 2007)

X-ray Emission as SFR tracer

(Barger, Cowie,& Wang 2007)

Uh Oh?

FOCUS on DATA RICH Chandra Deep Fields

Dozens of bands from NUV to 8um with extremely deep limitsHST imagingDeepest X-ray coverage in entire SkyDeep MIPS 24um/70um imagingDeep 1.4GHz imaging1000s of speczs~100k photzs

(Morrison et al. 2009)

S1.4GHz ~20 Jy (5) , S24m ~20 Jy (3)

S1.4GHz ~45 Jy (5) , S24m ~14 Jy (3)

S1.4GHz vs. S24um

GOODS-N probes deep, E-CDF-S probes wide.

MIPS photometry: clustering/blending leads to some overestimated MIR fluxes, while aperture photometry may lead to some underestimated MIR fluxes.

Obviously confused radio/MIR sources rejected.

Will soon triple GOODS-N dataset by merging with GTO MIPS data for full CDF-N field.

(Morrison et al. 2009) (Miller et al. 2008)

S1.4GHz vs. S24um

S1.4GHz ~20 Jy (5) , S24m ~20 Jy (3) S1.4GHz ~45 Jy (5) , S24m ~14 Jy (3)

Spec z’s for ~ 60% (only good quality z chosen if flag provided). (numerous refs)

High quality phot z’s: typically NMAD < 0.06 with ~5% outliers. (Rafferty/Xue in prep)

A disproportionate % of radio sources lacking z are radio-loud and likely at z>1-2.

q24m vs. z

SEDs locked to local q24 values and evolved using MIR spectrum convolved with MIPS 24um bandpass and radio spectral index =-0.7. This appears to fit faint GOODS-N spike sources.

q24m vs. z

qcor24m vs. z

qcor24 vs. L1.4GHz

Starburst?

AGN?

RL/RIAGN

L0.5-8 keV vs. L1.4GHz

X-ray/radioSFR relations

X-rayAGN

L0.5-8 keV limits vs. L1.4GHz

X-ray/radioSFR relations

X-rayAGN

L0.5-8 keV Stack vs. L1.4GHz

X-ray/radioSFR relations

X-rayAGN

X-ray Steep = SF?

X-ray Flat = AGN

qcor24 vs. L1.4GHz

Starburst?

AGN!

RL/RIAGN

eVLA/eMerlin decide SF?

DISCUSSION/CONCLUSIONS

Radio 20-40uJy population…AGN/Starburst? Likely a mix, with a significant AGN component amongst the star-forming disk. How well can we trust radio-derived SFR rates? How well can we constrain evolution? (See Ballantyne poster upstairs)

Local and distant X-ray/MIR+UV correlations suggest X-ray provides a SFR baseline. What is driving the perceived large X-ray/radio dispersion?

q24 thought to be a powerful selection tool, however we may need to take conservative cuts on the radio side in order to limit AGN contamination. More investigation is needed, but appears that even a factor of ~3-10 off the most basic local template may be dominated by obscured AGN activity in radio. Furthermore, even when on template at the radio luminous end, likely to have severe AGN contamination!

Several tweaks still to do with existing data…

Prospects for EVLA and future instrumentsto constrain AGN constrain of uJy population

Spectral indices?

Comparison of ~2-5” and <0.2” beams?

Variability?

Push comparisons to 24um to higher redshift, lower luminosities?