Evolution of galactic discs: multiple patterns, radial migration, and disc outskirts
Identifieur interne : 000C89 ( PascalFrancis/Corpus ); précédent : 000C88; suivant : 000C90Evolution of galactic discs: multiple patterns, radial migration, and disc outskirts
Auteurs : I. Minchev ; B. Famaey ; A. C. Quillen ; P. Di Matteo ; F. Combes ; M. Vlajic ; P. Erwin ; J. Bland-HawthornSource :
- Astronomy and astrophysics : (Berlin. Print) [ 0004-6361 ] ; 2012.
Descripteurs français
- Pascal (Inist)
- Evolution galactique, Disque galactique, Gradient radial, Métallicité, Brillance surface, Résonance Lindblad, Formation stellaire, Transfert moment cinétique, Couple, Multiplicité, Orbite, Moment cinétique, Fonction structure, Modèle, Couplage non linéaire, Onde densité, Accrétion, Dispersion vitesse, Population stellaire, Vitesse radiale, Voie lactée, Galaxies disques, Evolution galaxies, Cinématique, Dynamique.
English descriptors
- KwdEn :
- Accretion, Angular momentum, Angular momentum transfer, Density waves, Disk galaxies, Dynamics, Galactic disks, Galactic evolution, Galaxy evolution, Kinematics, Lindblad resonance, Metallicity, Milky Way, Models, Multiplicity, Non linear coupling, Orbits, Radial gradient, Radial velocity, Star formation, Stellar population, Structure functions, Surface brightness, Torque, Velocity dispersion.
Abstract
We investigate the evolution of galactic discs in N-body tree-SPH simulations. We find that discs, initially truncated at three scale-lengths, can triple their radial extent, solely driven by secular evolution. At the same time, the initial radial metallicity gradients are flattened and even reversed in the outer discs. Both Type I (single exponential) and Type II (down-turning) observed disc surface-brightness profiles can be explained by our findings. We show that profiles with breaks beyond the bar's outer Lindblad resonance, at present only explained as the effect of star-formation threshold, can occur even if no star formation is considered. We explain these results with the strong angular momentum outward transfer, resulting from torques and radial migration associated with multiple patterns, such as central bars and spiral waves of different multiplicity. We find that even for stars ending up on cold orbits, the changes in angular momentum exhibit complex structure as a function of radius, unlike the expected effect of transient spirals alone. We show that the bars in all of our simulations are the most effective drivers of radial migration through their corotation resonance, throughout the 3 Gyr of evolution studied. Focussing on one of our models, we find evidence for non-linear coupling among m = 1, 2, 3 and 4 density waves, where m is the pattern multiplicity. In this way the waves involved conspire to carry the energy and angular momentum extracted by the first mode from the inner parts of the disc much farther out than a single mode could. We suggest that the naturally occurring larger resonance widths at galactic radii beyond four scale-lengths may have profound consequences on the formation and location of breaks in disc density profiles, provided spirals are present at such large distances. We also consider the effect of gas inflow and show that when in-plane smooth gas accretion of ∼5 M◦./yr is included, the outer discs become more unstable, leading to a strong increase in the stellar velocity dispersion. This, in turn, causes the formation of a Type III (up-turning) profile in the old stellar population. We propose that observations of Type III surface brightness profiles, combined with an up-turn in the stellar velocity dispersions beyond the disc break, could be a signature of ongoing gas-accretion. The results of this study suggest that disc outskirts comprised of stars migrated from the inner disc would have relatively large radial velocity dispersions (>30 km s-1 at 6 scale-lengths for Milky Way-size systems), and significant thickness when seen edge-on.
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Pour connaître la documentation sur le format Inist Standard.
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Format Inist (serveur)
| NO : | PASCAL 13-0059596 INIST |
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| ET : | Evolution of galactic discs: multiple patterns, radial migration, and disc outskirts |
| AU : | MINCHEV (I.); FAMAEY (B.); QUILLEN (A. C.); DI MATTEO (P.); COMBES (F.); VLAJIC (M.); ERWIN (P.); BLAND-HAWTHORN (J.) |
| AF : | Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16/14482 Potsdam/Allemagne (1 aut., 6 aut.); Universite de Strasbourg, CNRS, Observatoire Astronomique, 11 rue de l'Université/67000 Strasbourg/France (2 aut.); AIfA, University of Bonn/Allemagne (2 aut.); Department of Physics and Astronomy, University of Rochester/Rochester, NY 14627/Etats-Unis (3 aut.); Observatoire de Paris-Meudon, GEPI, CNRS UMR 8111, 5 PI. Jules Janssen/92195 Meudon/France (4 aut.); Observatoire de Paris, LERMA, CNRS, 61 avenue de L'Observatoire/75014 Paris/France (5 aut.); Max-Planck-Institut fiir extraterrestrische Physik, Giessenbachstrasse/85748 Garching/Allemagne (7 aut.); Universitäts-Sternwarte München, Scheinerstrasse 1/81679 München/Allemagne (7 aut.); Anglo-Australian Observatory, PO Box 296/Epping, NSW 2121/Australie (8 aut.) |
| DT : | Publication en série; Niveau analytique |
| SO : | Astronomy and astrophysics : (Berlin. Print); ISSN 0004-6361; Coden AAEJAF; France; Da. 2012; Vol. 548; No. p. 2; A126.1-A126.24; Bibl. 3/4 p. |
| LA : | Anglais |
| EA : | We investigate the evolution of galactic discs in N-body tree-SPH simulations. We find that discs, initially truncated at three scale-lengths, can triple their radial extent, solely driven by secular evolution. At the same time, the initial radial metallicity gradients are flattened and even reversed in the outer discs. Both Type I (single exponential) and Type II (down-turning) observed disc surface-brightness profiles can be explained by our findings. We show that profiles with breaks beyond the bar's outer Lindblad resonance, at present only explained as the effect of star-formation threshold, can occur even if no star formation is considered. We explain these results with the strong angular momentum outward transfer, resulting from torques and radial migration associated with multiple patterns, such as central bars and spiral waves of different multiplicity. We find that even for stars ending up on cold orbits, the changes in angular momentum exhibit complex structure as a function of radius, unlike the expected effect of transient spirals alone. We show that the bars in all of our simulations are the most effective drivers of radial migration through their corotation resonance, throughout the 3 Gyr of evolution studied. Focussing on one of our models, we find evidence for non-linear coupling among m = 1, 2, 3 and 4 density waves, where m is the pattern multiplicity. In this way the waves involved conspire to carry the energy and angular momentum extracted by the first mode from the inner parts of the disc much farther out than a single mode could. We suggest that the naturally occurring larger resonance widths at galactic radii beyond four scale-lengths may have profound consequences on the formation and location of breaks in disc density profiles, provided spirals are present at such large distances. We also consider the effect of gas inflow and show that when in-plane smooth gas accretion of ∼5 M◦./yr is included, the outer discs become more unstable, leading to a strong increase in the stellar velocity dispersion. This, in turn, causes the formation of a Type III (up-turning) profile in the old stellar population. We propose that observations of Type III surface brightness profiles, combined with an up-turn in the stellar velocity dispersions beyond the disc break, could be a signature of ongoing gas-accretion. The results of this study suggest that disc outskirts comprised of stars migrated from the inner disc would have relatively large radial velocity dispersions (>30 km s-1 at 6 scale-lengths for Milky Way-size systems), and significant thickness when seen edge-on. |
| CC : | 001E03 |
| FD : | Evolution galactique; Disque galactique; Gradient radial; Métallicité; Brillance surface; Résonance Lindblad; Formation stellaire; Transfert moment cinétique; Couple; Multiplicité; Orbite; Moment cinétique; Fonction structure; Modèle; Couplage non linéaire; Onde densité; Accrétion; Dispersion vitesse; Population stellaire; Vitesse radiale; Voie lactée; Galaxies disques; Evolution galaxies; Cinématique; Dynamique |
| ED : | Galactic evolution; Galactic disks; Radial gradient; Metallicity; Surface brightness; Lindblad resonance; Star formation; Angular momentum transfer; Torque; Multiplicity; Orbits; Angular momentum; Structure functions; Models; Non linear coupling; Density waves; Accretion; Velocity dispersion; Stellar population; Radial velocity; Milky Way; Disk galaxies; Galaxy evolution; Kinematics; Dynamics |
| SD : | Gradiente radial; Metalicidad; Brillantez superficie; Resonancia Lindblad; Modelo; Acoplamiento no lineal; Dispersión velocidad; Población estelar; Evolución galaxias |
| LO : | INIST-14176.354000506265150530 |
| ID : | 13-0059596 |
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Pascal:13-0059596Le document en format XML
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Minchev</name><affiliation><inist:fA14 i1="01"><s1>Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16</s1><s2>14482 Potsdam</s2><s3>DEU</s3><sZ>1 aut.</sZ><sZ>6 aut.</sZ></inist:fA14></affiliation></author><author><name sortKey="Famaey, B" sort="Famaey, B" uniqKey="Famaey B" first="B." last="Famaey">B. Famaey</name><affiliation><inist:fA14 i1="02"><s1>Universite de Strasbourg, CNRS, Observatoire Astronomique, 11 rue de l'Université</s1><s2>67000 Strasbourg</s2><s3>FRA</s3><sZ>2 aut.</sZ></inist:fA14></affiliation><affiliation><inist:fA14 i1="03"><s1>AIfA, University of Bonn</s1><s3>DEU</s3><sZ>2 aut.</sZ></inist:fA14></affiliation></author><author><name sortKey="Quillen, A C" sort="Quillen, A C" uniqKey="Quillen A" first="A. C." last="Quillen">A. C. Quillen</name><affiliation><inist:fA14 i1="04"><s1>Department of Physics and Astronomy, University of Rochester</s1><s2>Rochester, NY 14627</s2><s3>USA</s3><sZ>3 aut.</sZ></inist:fA14></affiliation></author><author><name sortKey="Di Matteo, P" sort="Di Matteo, P" uniqKey="Di Matteo P" first="P." last="Di Matteo">P. Di Matteo</name><affiliation><inist:fA14 i1="05"><s1>Observatoire de Paris-Meudon, GEPI, CNRS UMR 8111, 5 PI. Jules Janssen</s1><s2>92195 Meudon</s2><s3>FRA</s3><sZ>4 aut.</sZ></inist:fA14></affiliation></author><author><name sortKey="Combes, F" sort="Combes, F" uniqKey="Combes F" first="F." last="Combes">F. Combes</name><affiliation><inist:fA14 i1="06"><s1>Observatoire de Paris, LERMA, CNRS, 61 avenue de L'Observatoire</s1><s2>75014 Paris</s2><s3>FRA</s3><sZ>5 aut.</sZ></inist:fA14></affiliation></author><author><name sortKey="Vlajic, M" sort="Vlajic, M" uniqKey="Vlajic M" first="M." last="Vlajic">M. 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Bland-Hawthorn</name><affiliation><inist:fA14 i1="09"><s1>Anglo-Australian Observatory, PO Box 296</s1><s2>Epping, NSW 2121</s2><s3>AUS</s3><sZ>8 aut.</sZ></inist:fA14></affiliation></author></analytic><series><title level="j" type="main">Astronomy and astrophysics : (Berlin. Print)</title><title level="j" type="abbreviated">Astron. astrophys. : (Berl., Print)</title><idno type="ISSN">0004-6361</idno><imprint><date when="2012">2012</date></imprint></series></biblStruct></sourceDesc><seriesStmt><title level="j" type="main">Astronomy and astrophysics : (Berlin. Print)</title><title level="j" type="abbreviated">Astron. astrophys. : (Berl., Print)</title><idno type="ISSN">0004-6361</idno></seriesStmt></fileDesc><profileDesc><textClass><keywords scheme="KwdEn" xml:lang="en"><term>Accretion</term><term>Angular momentum</term><term>Angular momentum transfer</term><term>Density waves</term><term>Disk galaxies</term><term>Dynamics</term><term>Galactic disks</term><term>Galactic evolution</term><term>Galaxy evolution</term><term>Kinematics</term><term>Lindblad resonance</term><term>Metallicity</term><term>Milky Way</term><term>Models</term><term>Multiplicity</term><term>Non linear coupling</term><term>Orbits</term><term>Radial gradient</term><term>Radial velocity</term><term>Star formation</term><term>Stellar population</term><term>Structure functions</term><term>Surface brightness</term><term>Torque</term><term>Velocity dispersion</term></keywords><keywords scheme="Pascal" xml:lang="fr"><term>Evolution galactique</term><term>Disque galactique</term><term>Gradient radial</term><term>Métallicité</term><term>Brillance surface</term><term>Résonance Lindblad</term><term>Formation stellaire</term><term>Transfert moment cinétique</term><term>Couple</term><term>Multiplicité</term><term>Orbite</term><term>Moment cinétique</term><term>Fonction structure</term><term>Modèle</term><term>Couplage non linéaire</term><term>Onde densité</term><term>Accrétion</term><term>Dispersion vitesse</term><term>Population stellaire</term><term>Vitesse radiale</term><term>Voie lactée</term><term>Galaxies disques</term><term>Evolution galaxies</term><term>Cinématique</term><term>Dynamique</term></keywords></textClass></profileDesc></teiHeader><front><div type="abstract" xml:lang="en">We investigate the evolution of galactic discs in N-body tree-SPH simulations. We find that discs, initially truncated at three scale-lengths, can triple their radial extent, solely driven by secular evolution. At the same time, the initial radial metallicity gradients are flattened and even reversed in the outer discs. Both Type I (single exponential) and Type II (down-turning) observed disc surface-brightness profiles can be explained by our findings. We show that profiles with breaks beyond the bar's outer Lindblad resonance, at present only explained as the effect of star-formation threshold, can occur even if no star formation is considered. We explain these results with the strong angular momentum outward transfer, resulting from torques and radial migration associated with multiple patterns, such as central bars and spiral waves of different multiplicity. We find that even for stars ending up on cold orbits, the changes in angular momentum exhibit complex structure as a function of radius, unlike the expected effect of transient spirals alone. We show that the bars in all of our simulations are the most effective drivers of radial migration through their corotation resonance, throughout the 3 Gyr of evolution studied. Focussing on one of our models, we find evidence for non-linear coupling among m = 1, 2, 3 and 4 density waves, where m is the pattern multiplicity. In this way the waves involved conspire to carry the energy and angular momentum extracted by the first mode from the inner parts of the disc much farther out than a single mode could. We suggest that the naturally occurring larger resonance widths at galactic radii beyond four scale-lengths may have profound consequences on the formation and location of breaks in disc density profiles, provided spirals are present at such large distances. We also consider the effect of gas inflow and show that when in-plane smooth gas accretion of ∼5 M<sub>◦.</sub>/yr is included, the outer discs become more unstable, leading to a strong increase in the stellar velocity dispersion. This, in turn, causes the formation of a Type III (up-turning) profile in the old stellar population. We propose that observations of Type III surface brightness profiles, combined with an up-turn in the stellar velocity dispersions beyond the disc break, could be a signature of ongoing gas-accretion. The results of this study suggest that disc outskirts comprised of stars migrated from the inner disc would have relatively large radial velocity dispersions (>30 km s<sup>-1</sup> at 6 scale-lengths for Milky Way-size systems), and significant thickness when seen edge-on.</div></front></TEI><inist><standard h6="B"><pA><fA01 i1="01" i2="1"><s0>0004-6361</s0></fA01><fA02 i1="01"><s0>AAEJAF</s0></fA02><fA03 i2="1"><s0>Astron. astrophys. : (Berl., Print)</s0></fA03><fA05><s2>548</s2></fA05><fA06><s3>p. 2</s3></fA06><fA08 i1="01" i2="1" l="ENG"><s1>Evolution of galactic discs: multiple patterns, radial migration, and disc outskirts</s1></fA08><fA11 i1="01" i2="1"><s1>MINCHEV (I.)</s1></fA11><fA11 i1="02" i2="1"><s1>FAMAEY (B.)</s1></fA11><fA11 i1="03" i2="1"><s1>QUILLEN (A. C.)</s1></fA11><fA11 i1="04" i2="1"><s1>DI MATTEO (P.)</s1></fA11><fA11 i1="05" i2="1"><s1>COMBES (F.)</s1></fA11><fA11 i1="06" i2="1"><s1>VLAJIC (M.)</s1></fA11><fA11 i1="07" i2="1"><s1>ERWIN (P.)</s1></fA11><fA11 i1="08" i2="1"><s1>BLAND-HAWTHORN (J.)</s1></fA11><fA14 i1="01"><s1>Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16</s1><s2>14482 Potsdam</s2><s3>DEU</s3><sZ>1 aut.</sZ><sZ>6 aut.</sZ></fA14><fA14 i1="02"><s1>Universite de Strasbourg, CNRS, Observatoire Astronomique, 11 rue de l'Université</s1><s2>67000 Strasbourg</s2><s3>FRA</s3><sZ>2 aut.</sZ></fA14><fA14 i1="03"><s1>AIfA, University of Bonn</s1><s3>DEU</s3><sZ>2 aut.</sZ></fA14><fA14 i1="04"><s1>Department of Physics and Astronomy, University of Rochester</s1><s2>Rochester, NY 14627</s2><s3>USA</s3><sZ>3 aut.</sZ></fA14><fA14 i1="05"><s1>Observatoire de Paris-Meudon, GEPI, CNRS UMR 8111, 5 PI. Jules Janssen</s1><s2>92195 Meudon</s2><s3>FRA</s3><sZ>4 aut.</sZ></fA14><fA14 i1="06"><s1>Observatoire de Paris, LERMA, CNRS, 61 avenue de L'Observatoire</s1><s2>75014 Paris</s2><s3>FRA</s3><sZ>5 aut.</sZ></fA14><fA14 i1="07"><s1>Max-Planck-Institut fiir extraterrestrische Physik, Giessenbachstrasse</s1><s2>85748 Garching</s2><s3>DEU</s3><sZ>7 aut.</sZ></fA14><fA14 i1="08"><s1>Universitäts-Sternwarte München, Scheinerstrasse 1</s1><s2>81679 München</s2><s3>DEU</s3><sZ>7 aut.</sZ></fA14><fA14 i1="09"><s1>Anglo-Australian Observatory, PO Box 296</s1><s2>Epping, NSW 2121</s2><s3>AUS</s3><sZ>8 aut.</sZ></fA14><fA20><s2>A126.1-A126.24</s2></fA20><fA21><s1>2012</s1></fA21><fA23 i1="01"><s0>ENG</s0></fA23><fA43 i1="01"><s1>INIST</s1><s2>14176</s2><s5>354000506265150530</s5></fA43><fA44><s0>0000</s0><s1>© 2013 INIST-CNRS. All rights reserved.</s1></fA44><fA45><s0>3/4 p.</s0></fA45><fA47 i1="01" i2="1"><s0>13-0059596</s0></fA47><fA60><s1>P</s1></fA60><fA61><s0>A</s0></fA61><fA64 i1="01" i2="1"><s0>Astronomy and astrophysics : (Berlin. Print)</s0></fA64><fA66 i1="01"><s0>FRA</s0></fA66><fC01 i1="01" l="ENG"><s0>We investigate the evolution of galactic discs in N-body tree-SPH simulations. We find that discs, initially truncated at three scale-lengths, can triple their radial extent, solely driven by secular evolution. At the same time, the initial radial metallicity gradients are flattened and even reversed in the outer discs. Both Type I (single exponential) and Type II (down-turning) observed disc surface-brightness profiles can be explained by our findings. We show that profiles with breaks beyond the bar's outer Lindblad resonance, at present only explained as the effect of star-formation threshold, can occur even if no star formation is considered. We explain these results with the strong angular momentum outward transfer, resulting from torques and radial migration associated with multiple patterns, such as central bars and spiral waves of different multiplicity. We find that even for stars ending up on cold orbits, the changes in angular momentum exhibit complex structure as a function of radius, unlike the expected effect of transient spirals alone. We show that the bars in all of our simulations are the most effective drivers of radial migration through their corotation resonance, throughout the 3 Gyr of evolution studied. Focussing on one of our models, we find evidence for non-linear coupling among m = 1, 2, 3 and 4 density waves, where m is the pattern multiplicity. In this way the waves involved conspire to carry the energy and angular momentum extracted by the first mode from the inner parts of the disc much farther out than a single mode could. We suggest that the naturally occurring larger resonance widths at galactic radii beyond four scale-lengths may have profound consequences on the formation and location of breaks in disc density profiles, provided spirals are present at such large distances. We also consider the effect of gas inflow and show that when in-plane smooth gas accretion of ∼5 M<sub>◦.</sub>/yr is included, the outer discs become more unstable, leading to a strong increase in the stellar velocity dispersion. This, in turn, causes the formation of a Type III (up-turning) profile in the old stellar population. We propose that observations of Type III surface brightness profiles, combined with an up-turn in the stellar velocity dispersions beyond the disc break, could be a signature of ongoing gas-accretion. The results of this study suggest that disc outskirts comprised of stars migrated from the inner disc would have relatively large radial velocity dispersions (>30 km s<sup>-1</sup> at 6 scale-lengths for Milky Way-size systems), and significant thickness when seen edge-on.</s0></fC01><fC02 i1="01" i2="3"><s0>001E03</s0></fC02><fC03 i1="01" i2="3" l="FRE"><s0>Evolution galactique</s0><s5>26</s5></fC03><fC03 i1="01" i2="3" l="ENG"><s0>Galactic evolution</s0><s5>26</s5></fC03><fC03 i1="02" i2="3" l="FRE"><s0>Disque galactique</s0><s5>27</s5></fC03><fC03 i1="02" i2="3" l="ENG"><s0>Galactic disks</s0><s5>27</s5></fC03><fC03 i1="03" i2="X" l="FRE"><s0>Gradient radial</s0><s5>28</s5></fC03><fC03 i1="03" i2="X" l="ENG"><s0>Radial gradient</s0><s5>28</s5></fC03><fC03 i1="03" i2="X" l="SPA"><s0>Gradiente radial</s0><s5>28</s5></fC03><fC03 i1="04" i2="X" l="FRE"><s0>Métallicité</s0><s5>29</s5></fC03><fC03 i1="04" i2="X" l="ENG"><s0>Metallicity</s0><s5>29</s5></fC03><fC03 i1="04" i2="X" l="SPA"><s0>Metalicidad</s0><s5>29</s5></fC03><fC03 i1="05" i2="X" l="FRE"><s0>Brillance surface</s0><s5>30</s5></fC03><fC03 i1="05" i2="X" l="ENG"><s0>Surface brightness</s0><s5>30</s5></fC03><fC03 i1="05" i2="X" l="SPA"><s0>Brillantez superficie</s0><s5>30</s5></fC03><fC03 i1="06" i2="X" l="FRE"><s0>Résonance Lindblad</s0><s5>31</s5></fC03><fC03 i1="06" i2="X" l="ENG"><s0>Lindblad resonance</s0><s5>31</s5></fC03><fC03 i1="06" i2="X" l="SPA"><s0>Resonancia Lindblad</s0><s5>31</s5></fC03><fC03 i1="07" i2="3" l="FRE"><s0>Formation stellaire</s0><s5>32</s5></fC03><fC03 i1="07" i2="3" l="ENG"><s0>Star formation</s0><s5>32</s5></fC03><fC03 i1="08" i2="3" l="FRE"><s0>Transfert moment cinétique</s0><s5>33</s5></fC03><fC03 i1="08" i2="3" l="ENG"><s0>Angular momentum transfer</s0><s5>33</s5></fC03><fC03 i1="09" i2="3" l="FRE"><s0>Couple</s0><s5>34</s5></fC03><fC03 i1="09" i2="3" l="ENG"><s0>Torque</s0><s5>34</s5></fC03><fC03 i1="10" i2="3" l="FRE"><s0>Multiplicité</s0><s5>35</s5></fC03><fC03 i1="10" i2="3" l="ENG"><s0>Multiplicity</s0><s5>35</s5></fC03><fC03 i1="11" i2="3" l="FRE"><s0>Orbite</s0><s5>36</s5></fC03><fC03 i1="11" i2="3" l="ENG"><s0>Orbits</s0><s5>36</s5></fC03><fC03 i1="12" i2="3" l="FRE"><s0>Moment cinétique</s0><s5>37</s5></fC03><fC03 i1="12" i2="3" l="ENG"><s0>Angular momentum</s0><s5>37</s5></fC03><fC03 i1="13" i2="3" l="FRE"><s0>Fonction structure</s0><s5>38</s5></fC03><fC03 i1="13" i2="3" l="ENG"><s0>Structure functions</s0><s5>38</s5></fC03><fC03 i1="14" i2="X" l="FRE"><s0>Modèle</s0><s5>39</s5></fC03><fC03 i1="14" i2="X" l="ENG"><s0>Models</s0><s5>39</s5></fC03><fC03 i1="14" i2="X" l="SPA"><s0>Modelo</s0><s5>39</s5></fC03><fC03 i1="15" i2="X" l="FRE"><s0>Couplage non linéaire</s0><s5>40</s5></fC03><fC03 i1="15" i2="X" l="ENG"><s0>Non linear coupling</s0><s5>40</s5></fC03><fC03 i1="15" i2="X" l="SPA"><s0>Acoplamiento no lineal</s0><s5>40</s5></fC03><fC03 i1="16" i2="3" l="FRE"><s0>Onde densité</s0><s5>41</s5></fC03><fC03 i1="16" i2="3" l="ENG"><s0>Density waves</s0><s5>41</s5></fC03><fC03 i1="17" i2="3" l="FRE"><s0>Accrétion</s0><s5>42</s5></fC03><fC03 i1="17" i2="3" l="ENG"><s0>Accretion</s0><s5>42</s5></fC03><fC03 i1="18" i2="X" l="FRE"><s0>Dispersion vitesse</s0><s5>43</s5></fC03><fC03 i1="18" i2="X" l="ENG"><s0>Velocity dispersion</s0><s5>43</s5></fC03><fC03 i1="18" i2="X" l="SPA"><s0>Dispersión velocidad</s0><s5>43</s5></fC03><fC03 i1="19" i2="X" l="FRE"><s0>Population stellaire</s0><s5>44</s5></fC03><fC03 i1="19" i2="X" l="ENG"><s0>Stellar population</s0><s5>44</s5></fC03><fC03 i1="19" i2="X" l="SPA"><s0>Población estelar</s0><s5>44</s5></fC03><fC03 i1="20" i2="3" l="FRE"><s0>Vitesse radiale</s0><s5>45</s5></fC03><fC03 i1="20" i2="3" l="ENG"><s0>Radial velocity</s0><s5>45</s5></fC03><fC03 i1="21" i2="3" l="FRE"><s0>Voie lactée</s0><s5>46</s5></fC03><fC03 i1="21" i2="3" l="ENG"><s0>Milky Way</s0><s5>46</s5></fC03><fC03 i1="22" i2="3" l="FRE"><s0>Galaxies disques</s0><s5>47</s5></fC03><fC03 i1="22" i2="3" l="ENG"><s0>Disk galaxies</s0><s5>47</s5></fC03><fC03 i1="23" i2="X" l="FRE"><s0>Evolution galaxies</s0><s5>48</s5></fC03><fC03 i1="23" i2="X" l="ENG"><s0>Galaxy evolution</s0><s5>48</s5></fC03><fC03 i1="23" i2="X" l="SPA"><s0>Evolución galaxias</s0><s5>48</s5></fC03><fC03 i1="24" i2="3" l="FRE"><s0>Cinématique</s0><s5>49</s5></fC03><fC03 i1="24" i2="3" l="ENG"><s0>Kinematics</s0><s5>49</s5></fC03><fC03 i1="25" i2="3" l="FRE"><s0>Dynamique</s0><s5>50</s5></fC03><fC03 i1="25" i2="3" l="ENG"><s0>Dynamics</s0><s5>50</s5></fC03><fN21><s1>035</s1></fN21><fN44 i1="01"><s1>OTO</s1></fN44><fN82><s1>OTO</s1></fN82></pA></standard><server><NO>PASCAL 13-0059596 INIST</NO><ET>Evolution of galactic discs: multiple patterns, radial migration, and disc outskirts</ET><AU>MINCHEV (I.); FAMAEY (B.); QUILLEN (A. C.); DI MATTEO (P.); COMBES (F.); VLAJIC (M.); ERWIN (P.); BLAND-HAWTHORN (J.)</AU><AF>Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16/14482 Potsdam/Allemagne (1 aut., 6 aut.); Universite de Strasbourg, CNRS, Observatoire Astronomique, 11 rue de l'Université/67000 Strasbourg/France (2 aut.); AIfA, University of Bonn/Allemagne (2 aut.); Department of Physics and Astronomy, University of Rochester/Rochester, NY 14627/Etats-Unis (3 aut.); Observatoire de Paris-Meudon, GEPI, CNRS UMR 8111, 5 PI. Jules Janssen/92195 Meudon/France (4 aut.); Observatoire de Paris, LERMA, CNRS, 61 avenue de L'Observatoire/75014 Paris/France (5 aut.); Max-Planck-Institut fiir extraterrestrische Physik, Giessenbachstrasse/85748 Garching/Allemagne (7 aut.); Universitäts-Sternwarte München, Scheinerstrasse 1/81679 München/Allemagne (7 aut.); Anglo-Australian Observatory, PO Box 296/Epping, NSW 2121/Australie (8 aut.)</AF><DT>Publication en série; Niveau analytique</DT><SO>Astronomy and astrophysics : (Berlin. Print); ISSN 0004-6361; Coden AAEJAF; France; Da. 2012; Vol. 548; No. p. 2; A126.1-A126.24; Bibl. 3/4 p.</SO><LA>Anglais</LA><EA>We investigate the evolution of galactic discs in N-body tree-SPH simulations. We find that discs, initially truncated at three scale-lengths, can triple their radial extent, solely driven by secular evolution. At the same time, the initial radial metallicity gradients are flattened and even reversed in the outer discs. Both Type I (single exponential) and Type II (down-turning) observed disc surface-brightness profiles can be explained by our findings. We show that profiles with breaks beyond the bar's outer Lindblad resonance, at present only explained as the effect of star-formation threshold, can occur even if no star formation is considered. We explain these results with the strong angular momentum outward transfer, resulting from torques and radial migration associated with multiple patterns, such as central bars and spiral waves of different multiplicity. We find that even for stars ending up on cold orbits, the changes in angular momentum exhibit complex structure as a function of radius, unlike the expected effect of transient spirals alone. We show that the bars in all of our simulations are the most effective drivers of radial migration through their corotation resonance, throughout the 3 Gyr of evolution studied. Focussing on one of our models, we find evidence for non-linear coupling among m = 1, 2, 3 and 4 density waves, where m is the pattern multiplicity. In this way the waves involved conspire to carry the energy and angular momentum extracted by the first mode from the inner parts of the disc much farther out than a single mode could. We suggest that the naturally occurring larger resonance widths at galactic radii beyond four scale-lengths may have profound consequences on the formation and location of breaks in disc density profiles, provided spirals are present at such large distances. We also consider the effect of gas inflow and show that when in-plane smooth gas accretion of ∼5 M<sub>◦.</sub>/yr is included, the outer discs become more unstable, leading to a strong increase in the stellar velocity dispersion. This, in turn, causes the formation of a Type III (up-turning) profile in the old stellar population. We propose that observations of Type III surface brightness profiles, combined with an up-turn in the stellar velocity dispersions beyond the disc break, could be a signature of ongoing gas-accretion. The results of this study suggest that disc outskirts comprised of stars migrated from the inner disc would have relatively large radial velocity dispersions (>30 km s<sup>-1</sup> at 6 scale-lengths for Milky Way-size systems), and significant thickness when seen edge-on.</EA><CC>001E03</CC><FD>Evolution galactique; Disque galactique; Gradient radial; Métallicité; Brillance surface; Résonance Lindblad; Formation stellaire; Transfert moment cinétique; Couple; Multiplicité; Orbite; Moment cinétique; Fonction structure; Modèle; Couplage non linéaire; Onde densité; Accrétion; Dispersion vitesse; Population stellaire; Vitesse radiale; Voie lactée; Galaxies disques; Evolution galaxies; Cinématique; Dynamique</FD><ED>Galactic evolution; Galactic disks; Radial gradient; Metallicity; Surface brightness; Lindblad resonance; Star formation; Angular momentum transfer; Torque; Multiplicity; Orbits; Angular momentum; Structure functions; Models; Non linear coupling; Density waves; Accretion; Velocity dispersion; Stellar population; Radial velocity; Milky Way; Disk galaxies; Galaxy evolution; Kinematics; Dynamics</ED><SD>Gradiente radial; Metalicidad; Brillantez superficie; Resonancia Lindblad; Modelo; Acoplamiento no lineal; Dispersión velocidad; Población estelar; Evolución galaxias</SD><LO>INIST-14176.354000506265150530</LO><ID>13-0059596</ID></server></inist></record>Pour manipuler ce document sous Unix (Dilib)
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