The role of environment in galaxy evolution

The Seyfert's sextet, a compact group located at z=0.014 and composed by four bounded galaxies, a background one located z=0.066, and a tidal tail.
Credit: NASA, English (Manitoba), Hunsberger, Zonak, Charlton, Gallagher (PSU) and Frattare(STScI)

The Seyfert's sextet, a compact group located at z=0.014 and composed by four bounded galaxies, a background one located z=0.066, and a tidal tail. Credit: NASA, English (Manitoba), Hunsberger, Zonak, Charlton, Gallagher (PSU) and Frattare(STScI)

Galaxies are not alone in the Universe and they gather together to form larger structures such as groups and clusters. The properties of the galaxies belonging to dense structures are different that those of isolated galaxies, highlighting the importance of environment and galaxy interactions in the evolution of galaxies.

Thanks to its large (~ 8500 deg²) and contiguous sky coverage, J-PLUS is an excellent survey to study the role of environment in galaxy evolution and, in particular, in the spatially resolved 2D properties of the nearby galaxies. Some of the topics that will be addressed with J-PLUS are:

  • The impact of close interactions in the star formation. Previous studies based on fiber and/or long-slit spectroscopy show that the star formation is enhanced in interacting paired galaxies (Figure 1). Moreover, the closer the two galaxies, the larger the increase in the star formation. Thanks to the star formation rates (SFR) derived with the J-PLUS photometry, we will study the impact of close companions in the 2D properties of paired galaxies: Is the SFR enhanced in all the galaxy or only in the central parts? Does the SFR increase depend on the orbital parameters of the interaction (e. g., position angle or ellipticity)?
  • The properties of merger remnants. Several paired galaxies finally merge and the properties of the merger remnants (Figure 2) are important to understand the fate of merging systems and the impact of mergers in galaxy evolution. In this context, J-PLUS will permit the study of the tidal tails and shells of nearby merger remnants.
  • The properties of galaxies in different environments. The cores of clusters are dominated by elliptical galaxies with old stellar populations, while their outskirts and isolated galaxies are usually star-forming spirals. This is the so called color / morphology – density relation. The processes acting in dense environments that quench the star formation and lead to the color – density relation are well understood (e. g., starvation, ram-pressure stripping, close encounters, etc.), but their relative role and importance in galaxy evolution is still matter of debate. These processes have different impact in the 2D properties of galaxies and, thanks to J-PLUS, we will trace the environmental dependence on the SFR and the stellar populations of galaxies.
Mosaic of paired galaxies

Figure 1. Mosaic of paired galaxies. The closer the two galaxies in the pair, the lager the increase in the star formation with respect to isolated galaxies. Credit: Sloan Digital Sky Survey

The merger remnant NGC 520

Figure 2. The merger remnant NGC 520. Credit : NASA, ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration, and B. Whitmore (STScI)