Ploeckinger et al. (2019)
Recent observations have indicated that faint high-redshift galaxies have smaller sizes than expected. But do we really see the whole galaxy? Or do we only see one bright, very compact star cluster that outshines the rest of the galaxy? Is it possible that one of these bright star cluster shines so bright that it heats up the rest of the gas in the galaxy to temperatures that prohibit star formation elsewhere?
Ploeckinger et al. (2018)
Together with my master student, Kuldeep Sharma, we were looking for tidal dwarf galaxies in the high-resolution box of the EAGLE suite of cosmological simulations. Despite the limited resolution we could - for the first time - identify individual tidal dwarf galaxies forming in a cosmological box. We discuss the selection criteria as well as the properties of the identified objects.
As seen in the simulations presented in Ploeckinger et al. (2015), the tidal field can compress a gas-rich tidal dwarf galaxy close to the peri-centre of its orbit. I compare this additional acceleration from the tidal field to the additional acceleration from a dark matter halos surrounding a dwarf galaxy. Depending on the host galaxy mass as well as the distance between the tidal dwarf galaxy and its host galaxy, the tidal field can be as strong in keeping the gas bound as a dark matter halo.
Ploeckinger et al. (2015)
After establishing in Ploeckinger et al. (2014) that tidal dwarf galaxies can survive their initial star formation, we follow the simulated galaxies for 3 Giga years, as they orbit their host galaxy. We find that if the tidal dwarf galaxy is still gas-rich as it approaches the peri-centre of its orbit, the tidal field can compress the gas and lead to the additional formation of tightly bound stars.
Ploeckinger et al. (2014)
Tidal dwarf galaxies are the only objects labelled "galaxies" that do not form within their own dark matter halo, in the current standard cosmological model for structure formation. Traditionally, tidal dwarf galaxies are observed when they are still young and actively forming stars. Can these low-mass objects survive these initial star formation events? Or do they get disrupted by stellar feedback, without the extra binding energy of a dark matter halo?
Ploeckinger & Hensler (2012)
Compact high velocity clouds are observed in the 21 cm line of neutral hydrogen. As they do not contain any stars it is difficult to estimate their distances. Are they small and close to the Milky Way disc or are they much larger and only look small because they are far away? Where do these gas clouds come from? We experimented with hydrodynamic simulations to find out if they travel through the Milky Way halo embedded in their own dark matter halo and how could we see this from observations?
Hartsuiker & Ploeckinger (accepted)
This paper is based on the master thesis of Len Hartsuiker that I supervised.
Compact groups of galaxies are spectacular systems where three or more galaxies appear very close together on the sky. Are these galaxies really close together or is this in many cases a projection effect? How long does it take these galaxies to merge into one giant galaxy? These questions are difficult to answer with observations, but after constructing a sample of compact groups in the EAGLE cosmological simulation, we can provide some answers.
Forbes et al. (2018)
Review article on globular cluster formation.
Full author list:
Forbes, Duncan A.; Bastian, Nate; Gieles, Mark; Crain, Robert A.; Kruijssen, J. M. Diederik;Larsen, Søren S.; Ploeckinger, Sylvia; Agertz, Oscar; Trenti, Michele; Ferguson, Annette M. N.;Pfeffer, Joel; Gnedin, Oleg Y.
Recchi, Kroupa, Ploeckinger (2015)
Young tidal dwarf galaxies form out of gas that has been previously metal enriched in a more massive galaxy. Comparing to the mass-metallicity relation of all galaxies, their metallicity is therefore too high for their mass. If tidal dwarf galaxies survive for several Giga years, would the metal content of old tidal dwarf galaxies follow the relation of their dark matter dominated dwarf galaxy peers?
Eigenthaler, Ploeckinger et al. (2015)
Compact groups of galaxies show a variety of galaxy interaction features, including tidal arms. Some of those have reported tidal dwarf candidates, but as these previous observations were using broad-band filters, projection effects cannot be excluded. We received observing time at the 4.1-m Southern Astrophysics Research (SOAR) telescope to study seven compact groups of galaxies in detail.