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Analysis of the Effect of Bars on Environmental Dependence of Disc Galaxies with MaNGA Survey Data

Pius Privatus, Umananda Dev Goswami

TL;DR

This work addresses how bars influence the environmental dependence of disc galaxies by analyzing a volume-limited MaNGA sample with Galaxy Zoo 2 bar classifications and GEMA-VAC environmental labels. It compares barred and unbarred galaxies in isolated versus non-isolated environments across $M_\star$, $SFR$, $g-r$, $ci$, and $12+\log(O/H)_{N2}$, using mass-matched samples to control confounding factors. The key finding is that environmental trends are strong for unbarred discs but substantially weakened in barred discs, suggesting bars act as internal regulators that decouple disc evolution from environment. This has implications for interpreting galaxy evolution, highlighting the role of secular processes in shaping structural and chemical properties alongside external influences.

Abstract

Bars are fundamental structures in disc galaxies, although their role in galaxy evolution is still not fully known. This study investigates the effect of the presence of bars on the environmental dependence of disc galaxies' properties using the volume-limited sample from Mapping Nearby Galaxies at APO (MaNGA) survey. The disc galaxies with and without bars samples were obtained using the Galaxy Zoo 2 project then assigned into isolated and non-isolated sub-samples. These sub-samples were used to compare the stellar mass, star formation rate, $g-r$ colour, concentration index and gas phase metallicity, and their relationships between isolated and non-isolated environments. Then these are used to investigate if there is an existence of any difference between galaxies with and without bars. A one-to-one correspondence between isolated and non-isolated galaxy properties was observed, and a strong dependence on the environment for properties of unbarred galaxies was observed when compared to barred. The stellar mass against star formation rate, $g-r$ colour against concentration index and stellar mass against gas phase metallicity of unbarred galaxies strongly depend on environment while for barred these relations weakly depend on environment. The study concludes that bars in disc galaxies decrease the dependence of analysed properties and their relations on the environment.

Analysis of the Effect of Bars on Environmental Dependence of Disc Galaxies with MaNGA Survey Data

TL;DR

This work addresses how bars influence the environmental dependence of disc galaxies by analyzing a volume-limited MaNGA sample with Galaxy Zoo 2 bar classifications and GEMA-VAC environmental labels. It compares barred and unbarred galaxies in isolated versus non-isolated environments across , , , , and , using mass-matched samples to control confounding factors. The key finding is that environmental trends are strong for unbarred discs but substantially weakened in barred discs, suggesting bars act as internal regulators that decouple disc evolution from environment. This has implications for interpreting galaxy evolution, highlighting the role of secular processes in shaping structural and chemical properties alongside external influences.

Abstract

Bars are fundamental structures in disc galaxies, although their role in galaxy evolution is still not fully known. This study investigates the effect of the presence of bars on the environmental dependence of disc galaxies' properties using the volume-limited sample from Mapping Nearby Galaxies at APO (MaNGA) survey. The disc galaxies with and without bars samples were obtained using the Galaxy Zoo 2 project then assigned into isolated and non-isolated sub-samples. These sub-samples were used to compare the stellar mass, star formation rate, colour, concentration index and gas phase metallicity, and their relationships between isolated and non-isolated environments. Then these are used to investigate if there is an existence of any difference between galaxies with and without bars. A one-to-one correspondence between isolated and non-isolated galaxy properties was observed, and a strong dependence on the environment for properties of unbarred galaxies was observed when compared to barred. The stellar mass against star formation rate, colour against concentration index and stellar mass against gas phase metallicity of unbarred galaxies strongly depend on environment while for barred these relations weakly depend on environment. The study concludes that bars in disc galaxies decrease the dependence of analysed properties and their relations on the environment.

Paper Structure

This paper contains 10 sections, 10 equations, 10 figures.

Table of Contents

  1. Introduction
  2. Data
  3. MaNGA survey
  4. Barred and unbarred galaxy samples
  5. Galaxy environment
  6. Results
  7. Galaxy properties
  8. Galaxy properties relationship
  9. Discussion
  10. Summary and Conclusion

Figures (10)

  • Figure 1: The images for $6$ out of $356$ barred galaxies denoted by their MaNGA plate and IFU, MaNGA$10226-3704$ (top left), MaNGA$9873-3701$ (top middle), MaNGA$10222-6103$ (top right), MaNGA$9876-6101$ (bottom left), MaNGA$9881-12705$ (bottom middle) and MaNGA$9513-3703$ (bottom right). The pink hexagon covers the spatial extent of the MaNGA Integral Field Unit.
  • Figure 2: The images for $6$ out of $1180$ unbarred galaxies denoted by their MaNGA plate and IFU, MaNGA$10213-9101$ (top left), MaNGA$9879-9101$ (top middle), MaNGA$9890-6102$ (top right), MaNGA$8951-12705$ (bottom left), MaNGA$11939-12705$ (bottom middle) and MaNGA$9894-6104$ (bottom right). The pink hexagon covers the spatial extent of the MaNGA Integral Field Unit.
  • Figure 3: Comparison between stellar mass distributions of barred (left panel) and unbarred (right panel) isolated (x-axis) and non-isolated (y-axis) galaxies. In plots, GB stands for barred non-isolated galaxies, GNB for unbarred non-isolated galaxies, FB for barred isolated galaxies, FNB for unbarred isolated galaxies and AD for Anderson-Darling. The orange upper left inset plot represents the distribution of the differences between the isolated and non-isolated samples, where the x-axis is in dex while the y-axis shows the probability density, which is unitless. These terminologies and representations are used for the rest of the similar figures.
  • Figure 4: Comparison between SFR of barred (left panel) and unbarred (right panel) isolated (x-axis) and non-isolated (y-axis) galaxies.
  • Figure 5: Comparison between $g-r$ colour distributions of barred (left panel) and unbarred (right panel) isolated (x-axis) and non-isolated (y-axis) galaxies.
  • ...and 5 more figures