|PaLARS -- PACS spectroscopy of the Lyman-alpha Reference Sample
|In observational studies of the high-redshift universe, the potential of the HI Lyman-alpha (Lya) to answer open cosmological questions is well established. This potential, however, is hampered by the fact that Lya is a resonant line, scatters in HI, and undergoes a complicated radiative transport. It has recently been suggested that certain structural geometries of the multiphase ISM could be even more important than the overall dust content in regulating the Lya visibility. The simplest scenario to unify the requirements for Lya with what we know about the phases of the ISM in galaxies is that these scattering surfaces must be the typical photodissociation regions (PDR), surrounding dusty molecular clouds within. Currently there is no observational test of this theory. We propose here to obtain unresolved PACS spectroscopy of the [C II] and [O I] lines, and photometric observations in all three channels, of 10 galaxies in the local LARS (Lyman Alpha Reference Sample) sample. These data will allow us to 1) Measure the total mass of PDR gas and contrast it against the total HI mass (already obtained). We will test the hypothesis that when more of the HI is condensed around high-density clumps, the ISM is more conducive to the transmission of Lya photons. 2) We will use the [O I]-[C II] ratio and the total ratio of ([O I]+[C II])-FIR in conjunction with PDR modelling, to constrain the HI density in PDRs. 3) From the PACS photometric points we will model the IR SED, compute dust masses, gas-to-dust ratios, attenuation from UV-FIR, and contrast them all against Lya properties.
|The Lyman Alpha Reference Sample. XI. Efficient turbulence-driven Lyα escape and an analysis of IR, CO, and [C II]158 μm . Puschnig J. et al. . Astronomy and Astrophysics . null . null . 2020A&A...644A..10P ,
|Herschel was launched on 14 May 2009! It is the fourth 'cornerstone' mission in the ESA science programme. With a 3.5 m Cassegrain telescope it is the largest space telescope ever launched. It is performing photometry and spectroscopy in approximately the 55-671 µm range, bridging the gap between earlier infrared space missions and groundbased facilities.
|Publisher And Registrant
|European Space Agency
|European Space Agency, 2013, OT2_mhayes_4, SPG v14.2.0. https://doi.org/10.5270/esa-wpy5b9p