While much of what we have gleaned of the details of dust and gas properties and the processes of dust recycling and heating and cooling in galaxies has been limited to Galactic studies, with Herschel we will be able to explore these issues in low metallicity dwarf galaxies which are known by now to exhibit dust and gas properties different from more metal-rich galaxies. Because these objects are relatively nearby, it is possible to relate the observed variations in the SEDs to the actual physical phenomena occuring within the ISM of the galaxy, allowing the construction of a rich interpretative framework for unresolved, more distant galaxies in the early universe.
Using the SPIRE and PACS instruments on Herschel, we propose to map the dust and gas in a 51 dwarf galaxies, sampling a broad metallicity range of 1/50 to 1/3 solar. These data, in conjunction with other ancillary data, will be used to construct the emission spectrum of the dust plus that of the gas in the most important cooling lines. The combination of these instruments onboard Herschel will provide the first opportunity to study the dust and gas in extremely low metallicity environments that have not yet experienced repeated recycling through the ISM. The interpretation of this data will open the door to comprehending primordial ISM conditions and star formation in the young universe.
Publication
Using dust, gas and stellar mass-selected samples to probe dust sources and sinks in low-metallicity galaxies . De Vis P. et al. . Monthly Notices of the Royal Astronomical Society, Volume 471, Issue 2, p.1743-1765 . 471 . 10.1093\/mnras\/stx981 . 2017MNRAS.471.1743D , An Overview of the Dwarf Galaxy Survey . Madden S. C. et al. . Publications of the Astronomical Society of the Pacific, Volume 125, Issue 928, pp. 600 (2013). . 125 . 10.1086\/671138 . 2013PASP..125..600M , Diversity of dwarf galaxy IR-submm emission patterns: CLUES from hydrodynamical simulations . Santos-Santos Isabel M. E. et al. . Astronomy & Astrophysics, Volume 603, id.A4, 22 pp. . 603 . 10.1051\/0004-6361\/201629426 . 2017A&A...603A...4S , Dust emission in star-forming dwarf galaxies: General properties and the nature of the submm excess . Izotov Y. I. et al. . Astronomy & Astrophysics, Volume 570, id.A97, 21 pp. . 570 . 10.1051\/0004-6361\/201423539 . 2014A&A...570A..97I , Dust grain size evolution in local galaxies: a comparison between observations and simulations . Relaño M. et al. . Monthly Notices of the Royal Astronomical Society . null . null . 2022MNRAS.515.5306R , The Herschel Virgo Cluster Survey. XVIII. Star-forming dwarf galaxies in a cluster environment . Grossi M. et al. . Astronomy & Astrophysics, Volume 574, id.A126, 30 pp. . 574 . 10.1051\/0004-6361\/201424866 . 2015A&A...574A.126G , Revealing the cold dust in low-metallicity environments. I. Photometry analysis of the Dwarf Galaxy Survey with Herschel . Rémy-Ruyer A. et al. . Astr...onomy & Astrophysics, Volume 557, id.A95, 32 pp. . 557 . 10.1051\/0004-6361\/201321602 . 2013A&A...557A..95R , Tracing the total molecular gas in galaxies: [CII] and the CO-dark gas . Madden S. C. et al. . Astronomy and Astrophysics . null . null . 2020A&A...643A.141M , Linking dust emission to fundamental properties in galaxies: the low-metallicity picture . Rémy-Ruyer A. et al. . Astronomy & Astrophysics, Volume 582, id.A121, 42 pp. . 582 . 10.1051\/0004-6361\/201526067 . 2015A&A...582A.121R , The Herschel Dwarf Galaxy Survey. II. Physical conditions, origin of [C II] emission, and porosity of the multiphase low-metallicity ISM . Cormier D. et al. . Astronomy and Astrophysics . null . null . 2019A&A...626A..23C , Inferring the HII region escape fraction of ionizing photons from infrared emission lines in metal-poor star-forming dwarf galaxies . Ramambason L. et al. . Astronomy and Astrophysics . null . null . 2022A&A...667A..35R ,
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.
