Dwarf Galaxy Research Group

Thorsten Lisker   –   ZAH

Posters and talks presenting our group's research at the conference "Galaxy Clusters Across Cosmic Time"

10-13 July 2017


How can we decide which galaxy properties were set at birth and which by environmental transformation?


The Evolution of the Galaxy Cluster Red Sequence at Intermediate Redshift


Properties in llustris Galaxies in Observer's Phase Space


Young, metal-enriched cores in early-type dwarf galaxies in Virgo

Thorsten Lisker

We doubt that the present-day environment alone yielded the morphology-density relation and set the properties of dwarf galaxies. Instead, we propose that more quantitative comparisons of simulations and observations be done and that all possible hypotheses be explored for when and why the dwarfs acquired their characteristics.
Josefina Michea

Under the ΛCDM paradigm of hierarchical structure formation, galaxy clusters progressively build-up as the Universe ages. This assembly process is imprinted in the evolving properties of the galaxy cluster red sequence across redshift space.
Christoph Engler

Characteristics such as age, metallicity and time of infall are reflected in the kinematic properties of galaxies.
Linda Urich

Ram pressure stripping models predict colour gradients that are similar to those we observe in early-type dwarf galaxies. A fraction of them includes a young central stellar population, while almost all of them have a non-zero metallicity gradient.
Urich et al. 2017

Were the most compact and most diffuse stellar systems in galaxy clusters both formed by stripping?

Carolin Wittmann

Wittmann et al. 2016:
Spatial distribution of spectroscopically confirmed compact stellar systems (grey and red dots) in the Fornax cluster. Compact objects with an asymmetric or elongated outer structure are preferentially located at larger cluster-centric distances, similar to low-mass galaxies (blue crosses). This might be an indication that some of these are the remnant nuclei of tidally stripped galaxies.

Wittmann et al. 2017:
Faint low surface brightness galaxy candidates in the Perseus cluster core (red dots and left side panels). The majority of the sample does not show obvious signs of ongoing tidal distuption. The sample is superimposed on our deep V-band mosaic (WHT/PFIP) that we used for their identification.


Related papers of our group

Urich et al. 2017: Young, metal-enriched cores in early-type dwarf galaxies in the Virgo cluster based on colour gradients

Wittmann et al. 2017: A population of faint low surface brightness galaxies in the Perseus cluster core

Sybliska et al. 2017: The hELENa project - I. Stellar populations of early-type galaxies linked with local environment and galaxy mass

Wittmann et al. 2016: Peculiar compact stellar systems in the Fornax cluster

Mentz et al 2016: Abundance ratios and IMF slopes in the dwarf elliptical galaxy NGC 1396 with MUSE

Bialas et al. 2015: On the occurrence of galaxy harassment

Smith et al. 2015: The sensitivity of harassment to orbit: mass loss from early-type dwarfs in galaxy clusters

Pak et al. 2014: The properties of early-type galaxies in the Ursa Major cluster

Lisker et al. 2013: Dwarf galaxy populations in present-day galaxy clusters - II. The history of early-type and late-type dwarfs

Additional information related to the posters above

Poster by L. Urich: Young, metal-enriched cores in early-type dwarf galaxies in Virgo



Correlations between age/metallicity colours and colour gradients:
A young stellar population in the galaxies centres leads to a stronger age gradient, while a metal-enriched central region does not necessarily imply a metallicity gradient.
See also Urich et al. 2017

Poster by T. Lisker: How can we decide which galaxy properties were set at birth and which by environmental transformation?

Sybilska et al. 2017:
SAURON IFU-study of 20 dEs.
The figure shows SSP-derived stellar population parameters (age, [M/H] and [Mg/Fe]) versus velocity dispersion.

Bialas et al. 2015:
N-body simulations of galaxy harassment.
The figure shows how much energy (colour scale) is approximately injected into the stellar component of the galaxy by a close
approach of a massive cluster galaxy, depending on the distance of closest approach (x-axis) and the relative velocity (y-axis).