A Merger Origin for [SANS]X[/SANS] Structures in S0 Galaxies

Mihos, J. Christopher; Walker, Ian R.; Hernquist, Lars; Oliveira, C. Mendes de; Bolte, Michael

doi:10.1086/309576

Cited by 91 publications

(102 citation statements)

References 33 publications

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“…Similar flarings and radial increase of disk scale heights were observed in VV 490 that has a close companion (Reshetnikov & Combes 1996. Such a radial increase of disk scale heights is a general property of tidally perturbed disks (Schwarzkopf & Dettmar 2001) which can be explained by the tidal heating by companions or merged satellites (Töth & Ostriker 1992;Mihos et al 1995).…”

Section: Summary and Discussionsupporting

confidence: 68%

The Warped Disk of Integral-Sign Galaxy PGC 20348

Ann

2007

Journal of The Korean Astronomical Society

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We examine the morphology and luminosity distribution of a strongly warped spiral galaxy PGC 20348 by conducting a detailed BV I CCD surface photometry using BOAO 1.8m telescope. The radial surface brightness shows a break at warp radius (r w ) with a shallow gradient in the inner disk and a steeper gradient in the outer disk. The luminosity of east side of the disk is ∼ 0.5 mag fainter than the west side at r > r w . The reason for the asymmetric luminosity distribution is thought to be the asymmetric flarings that result in the formation of a large diffuse region at the edge of the east disk and a smaller diffuse region at the west disk. The vertical luminosity profiles show a thick disk component whose scale heights increase with increasing galactocentric distances. The warp of PGC 20348 seems to be made by the tidal interactions with the two massive companion galaxies since the flarings and radial increase of disk scale heights are thought to be general properties of tidally perturbed disks. According to the colors of the two clumps inside the diffuse region at the edge of the east disk, they seem to be sites of active star formation triggered by tidal forces from the companion galaxies.

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Section: Summary and Discussionsupporting

confidence: 68%

The Warped Disk of Integral-Sign Galaxy PGC 20348

Ann

2007

Journal of The Korean Astronomical Society

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“…We also note that there is limited evidence from our sample for so-called hybrid bar/bulge formation scenarios (Mihos et al 1995), whereby a bar is first excited by an interaction (e.g., Noguchi 1987;Gerin, Combes, & Athanassoula 1990) and then buckles. Indeed, NGC 128, NGC 6771, and ESO 597-G036 all have strong peanut-shaped bulges (strong bars) and presumably interacting close-by companions.…”

Section: Secular Evolutionmentioning

confidence: 81%

Stellar Kinematics of Boxy Bulges: Large-Scale Bars and Inner Disks

2004

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Long-slit stellar kinematic observations were obtained along the major axis of 30 edge-on spiral galaxies, 24 with a boxy or peanut-shaped (B/PS) bulge and six with other bulge types for comparison. Such B/ PS bulges are identified in at least 45% of highly inclined systems, and a growing body of theoretical and observational work suggests that they are the edge-on projection of thickened bars. Profiles of the mean stellar velocity V, the velocity dispersion , as well as the asymmetric (h 3 ) and symmetric (h 4 ) deviations from a pure Gaussian are presented for all objects. Comparing these profiles with stellar kinematic bar diagnostics developed from N-body simulations, we find bar signatures in 24 of our sample galaxies (80%). Galaxies with a B/ PS bulge typically show a double-humped rotation curve with an intermediate dip or plateau. They also frequently show a rather flat central velocity dispersion profile accompanied by a secondary peak or plateau, and numerous galaxies have a local central minimum (k40%). The h 3 profiles display up to three slope reversals. Most importantly, h 3 is normally correlated with V over the presumed bar length, contrary to expectations from axisymmetric disks. These characteristic bar signatures strengthen the case for a close relationship between B/ PS bulges and bars and leave little room for other explanations of the bulges' shape. We also find that h 3 is anticorrelated with V in the very center of most galaxies (k60%), indicating that these objects additionally harbor cold and dense decoupled (quasi-) axisymmetric central stellar disks, which may be related to the central light peaks. These central disks coincide with previously identified star-forming ionized-gas disks (nuclear spirals) in gas-rich systems, and we argue that they formed out of gas accumulated by the bar at its center through inflow. As suggested by N-body models, the asymmetry of the velocity profile (h 3 ) appears to be a reliable tracer of asymmetries in disks, allowing us to discriminate between axisymmetric and barred disks seen in projection. B/ PS bulges (and thus a large fraction of all bulges) appear to be made up mostly of disk material, which has acquired a large vertical extent through bar-driven vertical instabilities. Their formation is thus probably dominated by secular evolution processes rather than merging.

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“…During their evolution, stellar bars can indeed go through one (or multiple) buckling phase (s), which are the consequences of Appendix A is available in electronic form at http://www.aanda.org vertical instabilities, and depending on the bar viewing angle, the resulting thick structure can appear boxy, if observed mainly along the bar major axis, or peanut-shaped, if observed mainly along the bar minor axis. It is also possible that a combination of these mechanisms, satellite accretion and bar instability, may be responsible for some of the observed bulge morphologies (Mihos et al 1995).…”

Section: Introductionmentioning

confidence: 99%

Mapping a stellar disk into a boxy bulge: The outside-in part of the Milky Way bulge formation

Matteo¹,

Haywood²,

Gómez³

et al. 2014

A&A

120

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By means of idealized, dissipationless N-body simulations that follow the formation and subsequent buckling of a stellar bar, we study the characteristics of boxy/peanut-shaped bulges and compare them with the properties of the stellar populations in the Milky Way (MW) bulge. The main results of our modeling, valid for the general family of boxy/peanut shaped bulges, are the following: (i) Because of the spatial redistribution in the disk initiated at the epoch of bar formation, stars from the innermost regions to the outer Lindblad resonance (OLR) of the stellar bar are mapped into a boxy bulge.(ii) The contribution of stars to the local bulge density depends on their birth radius: stars born in the innermost disk tend to dominate the innermost regions of the boxy bulge, while stars originating closer to the OLR are preferably found in the outer regions of the boxy/peanut structure. (iii) Stellar birth radii are imprinted in the bulge kinematics: the larger the birth radii of stars ending up in the bulge, the greater their rotational support and the higher their line-of-sight velocity dispersions (but note that this last trend depends on the bar viewing angle). (iv) The higher the classical bulge-over-disk ratio, the larger its fractional contribution of stars at large vertical distance from the galaxy midplane. Comparing these results with the properties of the stellar populations of the MW bulge recently revealed by the ARGOS survey, we conclude that (I) the two most metal-rich populations of the MW bulge, labeled A and B in the ARGOS survey, originate in the disk, with the population of A having formed on average closer to the Galaxy center than the population of component B; (II) a massive (B/D ∼ 0.25) classical spheroid can be excluded for the MW, thus confirming previous findings that the MW bulge is composed of populations that mostly have a disk origin. On the basis of their chemical and kinematic characteristics, the results of our modeling suggest that the populations A, B, and C, as defined by the ARGOS survey, can be associated, respectively, with the inner thin disk, to the young thick and to the old thick disk, following the nomenclature that we recently suggested for stars in the solar neighborhood.

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A Merger Origin for [SANS]X[/SANS] Structures in S0 Galaxies

Cited by 91 publications

References 33 publications

The Warped Disk of Integral-Sign Galaxy PGC 20348

The Warped Disk of Integral-Sign Galaxy PGC 20348

Stellar Kinematics of Boxy Bulges: Large-Scale Bars and Inner Disks

Mapping a stellar disk into a boxy bulge: The outside-in part of the Milky Way bulge formation

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