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Composite bulges :
Composite bulges : the coexistence of classical bulges and discy pseudo-bulges in S0 and spiral galaxies
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Erwin, Peter (författare)
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Saglia, Roberto P. (författare)
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Fabricius, Maximilian (författare)
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Thomas, Jens (författare)
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- Nowak, Nina (författare)
- Stockholms universitet,Institutionen för astronomi,Oskar Klein-centrum för kosmopartikelfysik (OKC)
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Rusli, Stephanie (författare)
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Bender, Ralf (författare)
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Vega Beltran, Juan Carlos (författare)
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Beckman, John E. (författare)
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(creator_code:org_t)
- 2014-12-09
- 2015
- Engelska.
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 446:4, s. 4039-4077
- Relaterad länk:
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https://academic.oup...
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- We present an analysis of nine S0-Sb galaxies which have (photometric) bulges consisting of two distinct components. The outer component is a flattened, kinematically cool, disc-like structure: a 'discy pseudo-bulge'. Embedded inside is a rounder, kinematically hot spheroidal structure: a 'classical bulge'. This indicates that pseudo-bulges and classical bulges are not mutually exclusive phenomena: some galaxies have both. The discy pseudo-bulges almost always consist of an exponential disc (scalelengths = 125-870 pc, mean size similar to 440 pc) with one or more disc-related subcomponents: nuclear rings, nuclear bars, and/or spiral arms. They constitute 11-59 per cent of the galaxy stellar mass (mean PB/T = 0.33), with stellar masses similar to 7 x 10(9)-9 x 10(10) M-circle dot. The classical-bulge components have Sersic indices of 0.9-2.2, effective radii of 25-430 pc and stellar masses of 5 x 10(8)-3 x 10(10) M-circle dot; they are usually <10 per cent of the galaxy's stellar mass (mean B/T = 0.06). The classical bulges do show rotation, but are clearly kinematically hotter than the discy pseudo-bulges. Dynamical modelling of three systems indicates that velocity dispersions are isotropic in the classical bulges and equatorially biased in the discy pseudo-bulges. In the mass-radius and mass-stellar mass density planes, classical-bulge components follow sequences defined by ellipticals and (larger) classical bulges. Discy pseudo-bulges also fall on this sequence; they are more compact than large-scale discs of similar mass. Although some classical bulges are quite compact, they are as a class clearly distinct from nuclear star clusters in both size and mass; in at least two galaxies they coexist with nuclear clusters. Since almost all the galaxies in this study are barred, they probably also host boxy/peanut-shaped bulges (vertically thickened inner parts of bars). NGC 3368 shows isophotal evidence for such a zone just outside its discy pseudo-bulge, making it a clear case of a galaxy with all three types of 'bulge'.
Ämnesord
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
Nyckelord
- galaxies: bulges
- galaxies: elliptical and lenticular
- cD
- galaxies: evolution
- galaxies: kinematics and dynamics
- galaxies: spiral
- galaxies: structure
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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