2009. 2. 10 – 12

SDSS KSG winter workshop

Gwang-Ho Lee, Changbom Park, & Yun-Young Choi

Properties of Barred Galaxies in SDSS

Introduction

• Understanding the role that environment plays in the

process of galaxy formation and evolution is one of

the most important problems in recent astrophysics.

• Bar structures are believed to be important with

regard to the evolution of late-type galaxies. But, it

remains an open question.

• Our goal is to understand how the properties of

galaxies, like as environment factors, affect the

formation of the bar.

Data Set & Visual Classification

1. Start with D2 sample of 15,414 galaxies drawn from DR4+

with Mr < -19.5, and redshift 0.025 < z < 0.05485

→ 1,267 barred galaxies → bar fraction 8.2%

2. Find 8,689 late-type galaxies (S/Irr) using automated method

(Park & Choi, 2005) and additional visual classification

→ 968 barred galaxies → bar fraction 11.1%

3. Excluding highly inclined (b/a < 0.6) systems,

5,156 Late-type galaxies remain.

→ 792 barred galaxies → bar fraction 15.4%

Dependence of The Bar fraction

1. Physical ParametersNo Dependence

Dependence of The Bar Fraction

2. Local Galaxy Number Density

No Dependence?

Dependence of The Bar Fraction

2. Local Galaxy Number Density

Dependence of The Bar Fraction

3. The Nearest Neighbor Galaxy

Conclusion

• The bar fraction of late-type depends strongly on color of the galaxies. The bar fraction is higher in redder galaxies.

• When color and luminosity are fixed, local galaxy number density seems to affect the bar fraction.

• We also find that the bar fraction depends on environment attributed to the distance of nearest neighbor and also on neighbor’ morphology.

Thanks !!