AGN Content of the mJy Population

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AGN Content of the mJy Population Through X-ray
stacking
Franz Bauer (Columbia), Glenn Morrison (Hawaii)
FOR CDF/GOODS Teams
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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

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X-ray Emission as SFR tracer
(Lehmer et al. 2007, Persic Rephaeli 2007)
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X-ray Emission as SFR tracer
Uh Oh?
(Barger, Cowie, Wang 2007)
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FOCUS on DATA RICH Chandra Deep Fields
Dozens of bands from NUV to 8um with extremely
deep limits HST imaging Deepest X-ray coverage in
entire Sky Deep MIPS 24um/70um imaging Deep
1.4GHz imaging 1000s of speczs 100k photzs
(Morrison et al. 2009)
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S1.4GHz vs. S24um
(Morrison et al. 2009)
(Miller et al. 2008)
S1.4GHz 20 mJy (5s) , S24mm 20 mJy (3s)
S1.4GHz 45 mJy (5s) , S24mm 14 mJy (3s)
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.
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S1.4GHz vs. S24um
S1.4GHz 20 mJy (5s) , S24mm 20 mJy (3s)
S1.4GHz 45 mJy (5s) , S24mm 14 mJy (3s)
Spec zs for 60 (only good quality z chosen if
flag provided). (numerous
refs) High quality phot zs typically sNMAD lt
0.06 with 5 outliers.
(Rafferty/Xue in prep) A disproportionate of
radio sources lacking z are radio-loud and likely
at zgt1-2.
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q24mm vs. z
SEDs locked to local q24 values and evolved using
MIR spectrum convolved with MIPS 24um bandpass
and radio spectral index a-0.7. This appears to
fit faint GOODS-N spike sources.
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q24mm vs. z
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qcor24mm vs. z
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qcor24 vs. L1.4GHz
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L0.5-8 keV vs. L1.4GHz
X-ray/radio SFR relations
X-ray AGN
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L0.5-8 keV limits vs. L1.4GHz
X-ray/radio SFR relations
X-ray AGN
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L0.5-8 keV Stack vs. L1.4GHz
X-ray/radio SFR relations
X-ray AGN
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qcor24 vs. L1.4GHz
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DISCUSSION/CONCLUSIONS
Radio 20-40uJy populationAGN/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/MIRUV
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
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Prospects for EVLA and future instruments to
constrain AGN constrain of uJy population
Spectral indices? Comparison of 2-5 and lt0.2
beams? Variability? Push comparisons to 24um to
higher redshift, lower luminosities?