PI: Nadia L. Zakamska, Institute for Advanced Study, firstname.lastname@example.org
Address: School of Natural Sciences, Einstein Dr., Princeton, NJ 08540, USA
CoI: Jenny E. Greene, Princeton University
CoI: Bruce T. Draine, Princeton University
Title: Anomalous molecular hydrogen emission in ultraluminous infrared galaxies
Abstract: Ultraluminous Infrared Galaxies are thought to be powered by starbursts embedded in clouds of dust and gas that are optically thick even at mid-IR wavelengths. Recent \spi Space Telescope observations of rotational lines of molecular hydrogen demonstrate that \molh\ emission in these objects is not affected by absorption. This suggests that \molh emission in ULIRGs cannot be explained by processes directly powered by the embedded star formation, in marked contrast with local low-luminosity star-forming galaxies where \molh and star formation indicators are strongly correlated. The anomalous \molh emission in ULIRGs is an interesting puzzle, all the more so because excitation and cooling of \molh is of significant importance in many areas of astrophysics. We propose to explore the origin of this emission using Gemini NIFS AO observations. We will study the spatial distribution and kinematics of NIR ro-vibrational lines of \molh in a z=0.08 ULIRG. We will use the maps of \molh line ratios to constrain \molh\ excitation mechanisms in different parts of the galaxy. We will also compare \molh emission with HI, FeII and other emission features that trace photoionization by young stars or supernova remnant shocks, as well as CO absorption features that trace stellar ages and stellar kinematics. At the 160 pc resolution provided by the AO system, we will be able to distinguish \molh excited in compact SNRs from that in filaments due to superwinds or intergalactic shocks and from the diffuse emission excited by turbulence or cosmic ray deposition.
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