Travel support for two observers to conduct astronomical observations at the LBT during the LBTB observing block in April 2018

• Applicant: Privatdozent Dr. Dominik Bomans
• Subject Area: Astrophysics and Astronomy
• Term: from 2018 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 408039748

1) Unevolved galaxies should have low-masses, low-metallicities, and a strong radiation fields due to recent starbursts and largely absent older stars. Therefore, they should emit strong UV continuum but very weak continua at longer wavelengths and extremely strong emission lines. At high redshifts these dwarfish galaxies are extremely hard to study, so we need good proxies for a more detailed looks at the involved processes. Such extreme emission line galaxies and extremely blue galaxies have been detected at intermediate redshifts, many have very low metallicity (below 0.1 Z_solar). We therefore have found decent proxies for protogalaxies, allowing detailed analyses. 2) The observation of nebular CIII] and CIV emission lines in z~7 galaxies triggered new interest in the nature of the hard radiation field needed for this emission lines to occur. Since not only very massive, low metallicity stars, but also massive X-ray binaries, accreting supermassive black hole, and even shocks may be possible sources of the hard continuum photons, the definition of a set of very local proxies is imperative, where spatial resolution and sensitivity allow a detailed study of the gas and individual ionization sources. 3) The ionization process of outflows and diffuse ionized gas halos in disk galaxies is still an unsolved puzzle. While a connection to star formation activity seems to be well established (but not fully understood), the ionization mechanism of the observed ionized gas is not well constrained: while photo-ionization certainly contributes, the observed line ratios and their change with distance from the disk require changes in the photon field and the presence of an additional currently unknown heating mechanism. 4) Spitzer and also HERSCHEL revealed a significant number of small bubbles in the Milky Way. In a couple of cases, it was possible to take optical spectra of the apparent central stars, which surprisingly often turned out to be evolved massive stars (Wolf-Rayet stars, candidates for Luminous Blue Variables, and OB supergiants). We target the bubbles and their central stars with LUCI NIR spectroscopy to classify the potentially highly absorbed part of the bubbles and investigate their evolutionary state and their central stars in a more unbiased way.

• DFG Programme: Research Grants