Navigating in low-metallicity starbursts

• Applicant: Professorin Dr. Lida Oskinova
• Subject Area: Astrophysics and Astronomy
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 529885128

Stars which are much more massive than our Sun are hot, luminous, and drive strong stellar winds. At the end of their evolution, massive stars suffer a gravitational collapse, often accompanied by a supernova explosion. Neutron stars or black holes are the remnants of such collapse. Sometimes, these compact objects are in a binary orbit with a normal stars from which they accrete matter. Such accreting neutron stars or black holes shine brightly in X-rays. The most luminous objects among such X-ray binaries are called "ultra-luminous X-ray sources" (ULXs). They emit more than a million times more radiation energy than our Sun, but predominantly in the X-ray part of the electromagnetic spectrum. The energy released by massive stars, supernovae, X-ray binaries, and ULXs strongly influence the physical conditions in their host galaxies; this process is called "stellar feedback". In the proposed project we aim at understanding this stellar feedback in galaxies, in particular under conditions which resemble earlier cosmic epochs. Specifically, we will study two galaxies, NGC 3109 and ESO 338. These galaxies are exceptionally suitable for such investigation, because they are close enough to study individual objects, while their chemical composition is rather typical for galaxies in the much more distant, younger Universe when yet much less elements heavier than helium existed. The empirical basis of this proposal are our new observations of the galaxies NGC 3109 and ESO 338 with the powerful X-ray space telescopes Chandra (NASA) and XMM-Newton (ESA). These data are augmented by existing observations in the optical and ultra-violet light with the Hubble Space Telescope. We will consistently analyze these data using our models to establish the links between massive stars, X-ray binaries, ULXs, their local environment and the global properties of the respective host galaxies. Among other fundamental aspects, we will empirically constrain the evolutionary channels which lead to the formation of compact-object binaries that eventually will emit gravitational waves when merging. Our work will quantitatively describe stellar feedback in NGC 3109 and ESO 338, and advance our general understanding of the role which massive stars, X-Ray binaries and ULXs have played in galaxies of the young Universe.

• DFG Programme: Research Grants