An investigation of the structural properties of active and normal galaxies in the local universe and at high redshifts

• Applicant: Professorin Dr. Guinevere Kauffmann
• Subject Area: Astrophysics and Astronomy
• Term: from 2005 to 2009
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5448564

• Final Report Year: 2012

Final Report Abstract

We have applied the software package BUDDA on a large sample of local galaxies to study the structural properties of galaxies in the context of galaxy formation and evolution. During the funding period, we have firstly upgraded BUDDA, producing a significantly more reliable and sophisticated software package. BUDDA is designed to produce 2D image decomposition of galaxy images into their different structural components, namely, bulge, disk and bar. It was tested on a small sample of nearby galaxies, allowing us to identify its strengths and limitations, and then applied to a large, representative sample of ≈ 1000 galaxies in the local universe with stellar mass larger than 10^10 M⊙, using multiband images from the Sloan Digital Sky Survey. This yielded a detailed picture of the structural parameters for elliptical galaxies, bulges, disks and bars at z ∼ 0; the results of the fits are publicly available. We find that 32 per cent of the total stellar mass in massive galaxies in the local universe is contained in ellipticals, 36 per cent in disks, 25 per cent in classical bulges, 3 per cent in disk-like bulges and 4 per cent in bars. This has been quoted as “probably the best current accounting of the stellar mass fractions in various [galaxy] components” (Blanton & Moustakas 2009). This accounting is of great importance, as successful models of galaxy formation and evolution must be consistent with it. In addition, we estimate how the mass in central black holes is distributed among elliptical galaxies, classical bulges and disk-like bulges, and investigate the relation between their stellar masses and central stellar velocity dispersion. Furthermore, the modeling of bars in the nearly 300 barred galaxies in the sample is unprecedented in terms of both sample size and level of detail in the analysis. Finally, these results were used to show evidence that the presence of bars affects the mean stellar ages of bulges and help fueling active galactic nuclei. The results from the fits performed in this project are an invaluable source of information for developing our understanding on massive galaxies, and further studies using them are underway.

Publications

• (2008): Image decomposition of barred galaxies and AGN hosts. In: Mon Not R Astron Soc 384 (1), S. 420–439
  Gadotti, D.A.
  
• (2009): Structural properties of pseudo-bulges, classical bulges and elliptical galaxies: a Sloan Digital Sky Survey perspective. In: Mon Not R Astron Soc 393 (4), S. 1531–1552
  Gadotti, D.A.
  
• (2009): The clustering of barred galaxies in the local Universe. In: Mon Not R Astron Soc 397 (2), S. 726–732
  Li, C., Gadotti, D.A., Mao S. & Kauffmann, G.
  
• (2009): The growth of supermassive black holes in pseudo-bulges, classical bulges and elliptical galaxies. In: Mon Not R Astron Soc 399 (2), S. 621–627
  Gadotti, D.A. & Kauffmann, G.
  
• 2009, in: Chaos in Astronomy, proceedings of a conference held in Athens, 2007, G. Contopoulos, P. Patsis, eds., Springer Berlin Heidelberg, pp. 159–172: Barred Galaxies: an Observer’s Perspective
  Gadotti, D.A.
  
• (2010): Radiative transfer in disc galaxies - IV. The effects of dust attenuation on bulge and disc structural parameters. In: Mon Not R Astron Soc 403 (4), S. 2053–2062
  Gadotti, D.A., Baes, M. & Falony, S.
  
• (2011): Secular evolution and structural properties of stellar bars in galaxies. In: Mon Not R Astron Soc 415 (4), S. 3308–3318
  Gadotti, D.A.
  
• (2011). Bars rejuvenating bulges? Evidence from stellar population analysis. The Astrophysical Journal Letters, 743(1), L13.
  Coelho, P. & Gadotti, D.A.
  
• 2012, in: School of Astrophysics “F. Lucchin” – XI Cycle, 4th Course 2011, G. Bono, M.
  Gadotti, D.A.