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Table C.1 is only available at the CDS via anonymous ftp to ( 130.79.128.5) or via These processes, which presumably combine in situ SF in the bulge and inward migration of material from the disk, are expected to lead to a non-homologous radial growth of Σ ⋆ and a trend for an increasing Sérsic index with increasing galaxy mass. Our results are consistent with a picture where bulge growth in LTGs is driven by a superposition of quick-early and slow-secular processes, the relative importance of which increases with ℳ ⋆,T. The continuity both in the properties of LTG bulges themselves and in their age and metallicity contrast to their parent diskssuggests that these components evolve alongside in a concurrent process that leads to a continuum of physical and evolutionary characteristics. The coexistence of Seyfert and SF activity in ~20% of higher-ℳ ⋆, high-Σ ⋆ bulges being spectroscopically classified as Composites suggests that the onset of AGN-driven feedback does not necessarily lead to an abrupt termination of SF in LTG nuclei.Ĭonclusions.
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This is in agreement with previous work and consistent with the notion that the Eddington ratio or the black hole-to-bulge mass ratio scale with ℳ ⋆. Whereas gas excitation in lower-mass (≲ 10 9.7 M ⊙) bulges is invariably dominated by star formation (SF), LINER- and Seyfert-specific emission-line ratios were exclusively documented in high-mass (≳ 10 10 M ⊙), high-Σ ⋆ (≳ 10 9 M ⊙ kpc −2) bulges. Furthermore, we find that the bulge-to-disk age and metallicity contrast, as well as the bulge-to-disk mass ratio, show a positive trend with ℳ ⋆,T, raising from, respectively, ~ 0 Gyr, ~ 0 dex and 0.25 to ~ 3 Gyr, ~ 0.3 dex and 0.67 across the mass range covered by our sample. Along this continuum of physical and evolutionary properties, our sample spans a range of ~ 4 mag in ⟨ δμ 9G⟩: high-⟨ δμ 9G⟩ bulges are the oldest, densest and most massive ones (〈 t ⋆〉 ℳ ~ 11.7 Gyr, Σ ⋆ > 10 9 M ⊙ kpc −2, ℳ ⋆ ≥ 10 10 M ⊙), whereas the opposite is the case for low-⟨ δμ 9G⟩ bulges (〈 t ⋆〉 ℳ ~ 7 Gyr) that generally reside in low-mass LTGs. The essential insight from this study is that LTG bulges form over 3 dex in ℳ ⋆ and more than 1 dex in Σ ⋆ a tight continuous sequence of increasing ⟨ δμ 9G⟩ with increasing ℳ ⋆, Σ ⋆, 〈 t ⋆〉 ℳ and 〈 Z ⋆〉 ℳ. We argue that ⟨ δμ 9G⟩ offers a handy semi-empirical tracer of the physical and evolutionary properties of LTG bulges and a promising means for their characterization.
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In particular, the analysis here revolves around ⟨ δμ 9G⟩, a new distance- and formally extinction-independent measure of the contribution by stellar populations of age ≥ 9 Gyr to the mean r-band surface brightness of the bulge.
#CID EPISODE 1298 CODE#
In this study, we have combined three techniques – surface photometry, spectral modeling of integral field spectroscopy data and suppression of stellar populations younger than an adjustable age cutoff with the code R EMOVEY OUNG (ℛ?) – toward a systematic analysis of the physical and evolutionary properties (e.g., ℳ ⋆, Σ ⋆ and mass-weighted stellar age 〈 t ⋆〉 ℳ and metallicity 〈 Z ⋆〉 ℳ, respectively) of a representative sample of 135 nearby (≤ 130 Mpc) LTGs from the CALIFA survey that cover a range between 10 8.9 M ⊙ and 10 11.5 M ⊙ in total stellar mass ℳ ⋆,T. Other questions motivating this study center on evolutionary relations between LTG bulges and their hosting disks, and the occurrence of accretion-powered nuclear activity as a function of bulge stellar mass ℳ ⋆ and stellar surface density Σ ⋆. Our main goal is to explore whether bulges in present-day LTGs segregate into two evolutionary distinct classes, as expected from the standard scenario. These two bulge formation routes obviously yield antipodal predictions on the bulge age and bulge-to-disk age contrast, both expected to be high (low) in CBs (PBs).Īims.
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The standard scenario distinguishes between classical bulges and pseudo-bulges (CBs and PBs, respectively), the first thought to form monolithically prior to disks and the second gradually out of disks. Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP,ĭepartamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto,Į-mail: A key subject in extragalactic astronomy concerns the chronology and driving mechanisms of bulge formation in late-type galaxies (LTGs). Iris Breda 1 ,2 and Polychronis Papaderos 1 Astronomical objects: linking to databases.Including author names using non-Roman alphabets.Suggested resources for more tips on language editing in the sciences Punctuation and style concerns regarding equations, figures, tables, and footnotes