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Astronomy Tea Talks at Caltech

Mondays, Robinson 106
Tea:  4.00pm
Talk: 4.15pm

Organized by:

2008 - 2009 season:
22 September 2008 Mark Ammons (UCSC)

"Detection of Distributed Young Stellar Populations in Strong AGN at z~1 with Keck AO."

I present a pilot study of the stellar populations of 8 AGN hosts at z ~ 1 as well
as laboratory experiments supporting the feasibility of wide-field AO on 5-10
meter telescopes. Our team utilizes K' images in the GOODS South field obtained
with the laser guide star AO system at Keck, combining this data with B, V, I, and
z imaging from the ACS on HST to give multi-color photometry at a matched spatial
resolution. SED fitting of the colors reveals a correlation between the presence
of younger stellar populations and the strength of the AGN, as measured with [OIII]
line luminosity. This finding is consistent with similar studies at lower redshift,
indicating that the timescales for AGN feedback are similar to those of today, if
this is the principal means of quenching. We confirm these findings with a larger
sample of 60 AGN hosts for which deep J,H,K imaging with excellent resolution
(0.3-0.5") is available.

I look to future AO instrumentation that will provide spatial resolution of 15-20
milliarcseconds on the sky, which will enable study of AGN feedback at z~1 on
100-150 pc scales. Toward this end, we have demonstrated hybrid MOAO-type
compensation on a 10 meter telescope at visible wavelengths with the UCO/Lick
MCAO/MOAO testbed in the Laboratory for Adaptive Optics at UCSC. We report Strehls
of ~20% in R band (658 nm) on-axis and Strehls of ~15% off-axis 25" for a 3D
atmosphere with r0 = 16 cm.

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