Red galaxies with pseudo-bulges in the SDSS: closer to disc galaxies or to classical bulges?

Pseudo-bulges are expected to markedly differ from classical quasi-monolithically forming bulges in their star formation history (SFH) and chemical abundance patterns. To test this simple expectation, we carry out a comparative structural and spectral synthesis analysis of 106 red massive galaxies i...

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Veröffentlicht in:Monthly notices of the Royal Astronomical Society 2016-03, Vol.456 (4), p.3899-3914
Hauptverfasser: Ribeiro, B., Lobo, C., Antón, S., Gomes, J. M., Papaderos, P.
Format: Artikel
Sprache:eng
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Zusammenfassung:Pseudo-bulges are expected to markedly differ from classical quasi-monolithically forming bulges in their star formation history (SFH) and chemical abundance patterns. To test this simple expectation, we carry out a comparative structural and spectral synthesis analysis of 106 red massive galaxies issued from the Sloan Digital Sky Survey (SDSS), sub-divided into bulgeless, pseudo-bulge and classical bulge galaxies according to their photometric characteristics, and further obeying a specific selection to minimize uncertainties in the analysis and ensure an unbiased derivation and comparison of SFHs. Our 2D photometry analysis suggests that discs underlying pseudo-bulges typically have larger exponential scalelengths than bulgeless galaxies, despite similar integral disc luminosities. Spectral synthesis models of the stellar emission within the 3-arcsec SDSS fibre aperture reveal a clear segregation of bulgeless and pseudo-bulge galaxies from classical bulges on the luminosity-weighted planes of age–metallicity and mass–metallicity, though a large dispersion is observed within the two former classes. The secular growth of pseudo-bulges is also reflected upon their cumulative stellar mass as a function of time, which is shallower than that for classical bulges. Such results suggest that the centres of bulgeless and pseudo-bulge galaxies substantially differ from those of bulgy galaxies with respect to their SFH and chemical enrichment history, which likely points to different formation/assembly mechanisms.
ISSN:0035-8711
1365-2966
DOI:10.1093/mnras/stv2872