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| Paper: |
Detection of the 3.3μm PAH Feature as well as Water Ice and HAC Absorption in z ~ 2 ULIRGs |
| Volume: |
408, The Starburst−AGN Connection |
| Page: |
417 |
| Authors: |
Sajina, A.; Yan, L.; Spoon, H.; Fadda, D. |
| Abstract: |
We present preliminary results from the highest available signalto- noise rest-frame 2-8 μm spectra of z ~2 ULIRGs. Our 10 targets are selected for their deep silicate absorption features based on previous shallower IRS spectra. The goal of this follow-up program is: 1) allow for a more accurate analysis of inner/hot dust continuum, 2) detecting the 3.3 μm and 6.2 μm PAH features, and 3) detecting molecular absorption features such as due to water ice and hydrocarbons (HACs). We find that the 3.4 μm HAC absorption feature is observed in four sources, while the 3.05 μm water ice feature is observed in three of the sources. The HAC detectability is higher and ice detectability lower than expected from local ULIRGs, but consistent with a more AGN-dominated sample such as this one. Where ice is detected, the ice-to-silicate ratio is somewhat lower than many local ULIRGs implying on average thinner ice mantles. One source shows the highest redshift reported detection of the 3.3 μm PAH feature (along with a previously detected 6.2 μm feature) whose strength is as expected for a starburst-dominated ULIRG. |
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