BARS REJUVENATING BULGES? EVIDENCE FROM STELLAR POPULATION ANALYSIS
- Nucleo de Astrofisica Teorica, Universidade Cruzeiro do Sul, R. Galvao Bueno 868, Liberdade 01506-000, Sao Paulo (Brazil)
We obtained stellar ages and metallicities via spectrum fitting for a sample of 575 bulges with spectra available from the Sloan Digital Sky Survey. The structural properties of the galaxies have been studied in detail in 2009 by Gadotti and the sample contains 251 bulges in galaxies with bars. Using the whole sample, where galaxy stellar mass distributions for barred and unbarred galaxies are similar, we find that bulges in barred and unbarred galaxies occupy similar loci in the age versus metallicity plane. However, the distribution of bulge ages in barred galaxies shows an excess of populations younger than {approx}4 Gyr, when compared to bulges in unbarred galaxies. Kolmogorov-Smirnov statistics confirm that the age distributions are different with a significance of 99.94%. If we select sub-samples for which the bulge stellar mass distributions are similar for barred and unbarred galaxies, this excess vanishes for galaxies with bulge mass log M < 10.1 M{sub Sun }, while for more massive galaxies we find a bimodal bulge age distribution for barred galaxies only, corresponding to two normal distributions with mean ages of 10.4 and 4.7 Gyr. We also find twice as much active galactic nuclei among barred galaxies, as compared to unbarred galaxies, for low-mass bulges. By combining a large sample of high-quality data with sophisticated image and spectral analysis, we are able to find evidence that the presence of bars affects the mean stellar ages of bulges. This lends strong support to models in which bars trigger star formation activity in the centers of galaxies.
- OSTI ID:
- 22047309
- Journal Information:
- Astrophysical Journal Letters, Vol. 743, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
Similar Records
THE STELLAR AGES AND MASSES OF SHORT GAMMA-RAY BURST HOST GALAXIES: INVESTIGATING THE PROGENITOR DELAY TIME DISTRIBUTION AND THE ROLE OF MASS AND STAR FORMATION IN THE SHORT GAMMA-RAY BURST RATE
The Milky Way’s bulge star formation history as constrained from its bimodal chemical abundance distribution