Bar-driven Evolution and 2d Spectroscopy of Bulges
نویسندگان
چکیده
A multi-faceted approach is described to constrain the importance of bar-driven evolution in disk galaxies, with a special emphasis on bulge formation. N-body simulations of bars are compared to the stellar kinematics and near-infrared morphology of 30 edge-on spirals, most with a boxy bulge. The N-body simulations allow to construct stellar kinematic bar diagnostics for edge-on systems and to quantify the expected vertical structure of bars. Long-slit spectra of the sample galaxies show characteristic double-hump rotation curves, dispersion profiles with secondary peaks and/or flat maxima, and correlated h3 and V profiles, indicating that most of them indeed harbor edge-on bars. The stellar kinematics also suggests the presence of cold, quasi-axisymmetric central stellar disks. The ionized-gas distribution and kinematics further suggests that those disks formed through bar-driven gaseous inflow and subsequent star formation, which are absent in our simulations. Minimally affected by dust and dominated by Population II stars, K-band imaging of the same galaxies spectacularly highlights radial variations of the bars’ scaleheights, as expected from vertical disk instabilities. The light profiles also vary radially in shape but never approach a classic deVaucouleurs law. Filtering of the images further isolates the specific orbit families at the origin of the boxy structure, which can be directly related to periodic orbit calculations in generic 3D barred potentials. Bars are thus shown to contribute substantially to the formation of both large-scale triaxial bulges and embedded central disks. Relevant results from the SAURON survey of the stellar/ionized-gas kinematics and stellar populations of spheroids are also briefly described. Specific examples supporting the above view are used to illustrate the potential of coupling stellar kinematics and linestrengths (age and metallicity), here specifically to unravel the dynamical evolution and related chemical enrichment history of bars and bulges.
منابع مشابه
Formation and dynamical evolution of galaxies and of their components
From this vast subject, I will pick out and review three specific topics, namely the formation and evolution of bars, the formation of bulges, and the evolution during multiple major mergers. Bars form naturally in galactic discs. Their evolution is driven by the exchange of angular momentum within the galaxy. This is emitted mainly by near-resonant material in the inner disc (bar), and is abso...
متن کاملStar Formation Properties in Barred Galaxies(SFB). III. Statistical Study of Bar-driven Secular Evolution using a sample of nearby barred spirals
Stellar bars are important internal drivers of secular evolution in disk galaxies. Using a sample of nearby spiral galaxies with weak and strong bars, we explore the relationships between the star formation feature and stellar bars in galaxies. We find that galaxies with weak bars tend to be coincide with low concentrical star formation activity, while those with strong bars show a large scatte...
متن کاملBulges or Bars from Secular Evolution?
We use high resolution collisionless N -body simulations to study the secular evolution of disk galaxies and in particular the final properties of disks that suffer a bar and perhaps a bar-buckling instability. Although we find that bars are not destroyed by the buckling instability, when we decompose the radial density profiles of the secularly-evolved disks into inner Sérsic and outer exponen...
متن کاملar X iv : a st ro - p h / 05 08 61 6 v 1 2 9 A ug 2 00 5 THREE - DIMENSIONAL BAR STRUCTURE AND DISC / BULGE SECULAR EVOLUTION
Kn-band imaging of a sample of 30 edge-on spiral galaxies with a boxy or peanut-shaped (B/PS) bulge is discussed. Galaxies with a B/PS bulge tend to have a more complex morphology than galaxies with other bulge types, unsharp-masked images revealing structures that trace the major orbit families of three-dimensional bars. Their surface brightness profiles are also more complex, typically contai...
متن کاملBar-driven Fueling of Galactic Nuclei: a 2d View
I briefly discuss evidences for bar-driven gas fueling in the central regions of galaxies, focusing on scales down to about 10 pc. I thus mention the building of inner disks, and the link with resonances, as well as the corresponding kinematic signatures such as σ-drops and counter-rotating nuclear disks as probed via integral-field spectroscopy.
متن کامل