Galaxies 09: Assembly, Gas Content and Star Formation History of Galaxies
Lin Yan
Caltech
Detection of Cold Molecular Gas in Spitzer Selected $z\sim$2 ULIRGs
I will present CO interferometric observations of 9 $z\sim$2 ULIRGs using PdBI. The CO
observations are in low-medium spatial resolution. The targets are bright in 24$\mu$m~with
flux density greater than 1~mJy, and initially discovered by the mid-IR spectroscopy. Eight
of the 9 sources show significant CO detections, with integrated CO luminosities of
(1-5)x10$^7~L_{\odot}$, and cold molecular gas of (1.3-3.8)x10$^{10}M_{\odot}$. Of the 8 detections,
four sources show double peak CO line profiles. The CO velocity width of the 8 sources
range from (150-300)~km~s$^{-1}$, similar to that of QSOs, much smaller than the averaged value
of SMGs. With analysis combining all of the available data from spectroscopy in optical,
mid-IR and CO, and multi-wavelength photometry, we compare these bright 24$\mu$m~$z\sim$2
ULIRGs with SMGs and high-$z$, CO emitting QSOs. I will show what we learn about the history
of the black hole growth and stellar assembly of these Spitzer ULIRGs, and discuss
the implication to the understanding of galaxy and black hole co-evolution.
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