Influence of baryonic physics in galaxy simulations:

Radial stellar migration in galactic discs has received much attention in studies of galactic dynamics and chemical evolution, but remains a dynamical phenomenon that needs to be fully quantified. In this work, using a Tree-SPH simulation of an Sb-type disc galaxy, we quantify the effects of blurring (epicyclic excursions) and churning (change of guiding radius). We quantify migration (either blurring or churning) both in terms of flux (the number of migrators passing at a given radius), and by estimating the population of migrators at a given radius at the end of the simulation compared to non-migrators, but also by giving the distance over which the migration is effective at all radii. We confirm that the corotation of the bar is the main source of migrators by churning in a bardominated galaxy, its intensity being directly linked to the episode of a strong bar, in the first 1-3 Gyr of the simulation. We show that within the outer Lindblad resonance (OLR), migration is strongly dominated by churning, while blurring gains progressively more importance towards the outer disc and at later times. Most importantly, we show that the OLR limits the exchange of angular momentum, separating the disc in two distinct parts with minimal or null exchange, except in the transition zone, which is delimited by the position of the OLR at the epoch of the formation of the bar, and at the final epoch. We discuss the consequences of these findings for our understanding of the structure of the Milky Way disc. Because the Sun is situated slightly outside the OLR, we suggest that the solar vicinity may have experienced very limited churning from the inner disc.

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“…We used one of the simulations presented in Halle & Combes (2013). We briefly summarize the main characteristics of the simulations.…”

Section: Numerical Simulationmentioning

confidence: 99%

Quantifying stellar radial migration in anN-body simulation: blurring, churning, and the outer regions of galaxy discs

Halle

Matteo

Haywood

et al. 2015

A&A

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101

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“…Since the initial disk does not extend further, it is natural to investigate what is the response and redistribution of stars to bar formation and evolution that are initially at even larger radii than in our original simulations. In this Appendix, we have analyzed two additional simulations which are part of the sample of simulations described in Hallé & Combes (2013). These simulations include gas physics, implementing a cooling prescription which allows the gas to cool low temperatures and the formation of a molecular hydrogen component, together with star formation and several different stellar feedback efficiencies (see Hallé & Combes 2013, for details).…”

Section: Appendix A: Exploring Different Galaxy Modelsmentioning

confidence: 99%

“…In this Appendix, we have analyzed two additional simulations which are part of the sample of simulations described in Hallé & Combes (2013). These simulations include gas physics, implementing a cooling prescription which allows the gas to cool low temperatures and the formation of a molecular hydrogen component, together with star formation and several different stellar feedback efficiencies (see Hallé & Combes 2013, for details). For the purpose of the comparison to the models presented in this paper, we have chosen two simulations from this suite without molecular hydrogen and alternatively, with and without including stellar feedback.…”

Section: Appendix A: Exploring Different Galaxy Modelsmentioning

confidence: 99%

“…We have chosen these two simulations because they develop stellar bars with different characteristics, thus allowing us to investigate the impact of those characteristics, and specifically, the impact of the location of the associated resonances, on the overall disk evolution. We summarize the main features of the simulated galaxies for these two simulations from Hallé & Combes (2013): they consist of a gSb-like galaxy, composed of a stellar disk whose mass is M d = 4.5 × 10 10 M , and whose scale length is a d = 5 kpc; a classical bulge whose mass is 0.25 M d and characteristic radius a b = 1 kpc; and a gaseous disk whose mass is 0.2 M d , and whose scale length is 11.8 kpc. The gaseous and stellar disk components follow a Miyamoto-Nagai density profile while the stellar bulge and dark halo components have Plummer density profiles (see Hallé & Combes 2013, for a complete description of the models).…”

Section: Appendix A: Exploring Different Galaxy Modelsmentioning

confidence: 99%

“…We summarize the main features of the simulated galaxies for these two simulations from Hallé & Combes (2013): they consist of a gSb-like galaxy, composed of a stellar disk whose mass is M d = 4.5 × 10 10 M , and whose scale length is a d = 5 kpc; a classical bulge whose mass is 0.25 M d and characteristic radius a b = 1 kpc; and a gaseous disk whose mass is 0.2 M d , and whose scale length is 11.8 kpc. The gaseous and stellar disk components follow a Miyamoto-Nagai density profile while the stellar bulge and dark halo components have Plummer density profiles (see Hallé & Combes 2013, for a complete description of the models). In particular, in these models the initial stellar disk extends to 36 kpc from the galaxy center, thus allowing us to trace the evolution of stars up to distances of ∼8 disk scale lengths.…”

Section: Appendix A: Exploring Different Galaxy Modelsmentioning

confidence: 99%

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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

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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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Role of galactic bars in the formation of spiral arms: a study through orbital and escape dynamics—I

Mondal

Chattopadhyay

2021

Celest Mech Dyn Astr

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Influence of baryonic physics in galaxy simulations:

Cited by 16 publications

References 65 publications

Quantifying stellar radial migration in anN-body simulation: blurring, churning, and the outer regions of galaxy discs

Quantifying stellar radial migration in anN-body simulation: blurring, churning, and the outer regions of galaxy discs

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

Role of galactic bars in the formation of spiral arms: a study through orbital and escape dynamics—I

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