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Cinématique Et Dynamique Des Galaxies Spirales Barrées

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Cinématique Et Dynamique Des Galaxies Spirales Barrées Universit´edeMontr´eal et Universit´edeProvence Cin´ematique et dynamique des galaxies spirales barr´ees par Olivier Hernandez Th`ese effectu´ee en cotutelle au D´epartement de Physique Facult´e des arts et des sciences Universit´edeMontr´eal et au Laboratoire d’Astrophysique de Marseille Universit´edeProvence Th`ese pr´esent´ee `alaFacult´edes´etudes sup´erieures de l’Universit´edeMontr´eal en vue de l’obtention du grade de Philosophiæ Doctor (Ph.D.) en Physique et `a l’Universit´e de Provence en vue de l’obtention du grade de Docteur de l’Universit´ede Provence D´ecembre, 2004 c Olivier Hernandez, 2004 Universit´edeMontr´eal Facult´edes´etudes sup´erieures et Laboratoire d’Astrophysique de Marseille Universit´edeProvence Cette th`ese intitul´ee : Cin´ematique et dynamique des galaxies spirales barr´ees pr´esent´ee et soutenue `a l’Universit´edeMontr´eal par : Olivier Hernandez a´et´e´evalu´ee par un jury compos´e des personnes suivantes : Anthony Moffat, Pr´esident-rapporteur et membre du jury (Universit´edeMontr´eal) Claude Carignan, Directeur de recherche (Universit´edeMontr´eal) Philippe Amram, Directeur de recherche (Universit´edeProvence) Jacques Boulesteix, Membre du jury (Universit´edeProvence) Fran¸coise Combes, Examinateur externe (Observatoire de Paris) Paul Arminjon, Repr´esentant du Doyen de la FES Th`ese accept´ee le : 21 f´evrier 2005 R´esum´e La masse totale (lumineuse et non lumineuse) des galaxies est d´eduite de la vitesse circulaire de rotation des galaxies. L’observation spectroscopique de type Fabry-Perot du gaz ionis´e des galaxies spirales permet d’obtenir leur cin´ematique. Dans le cas de champs de vitesses parfaitement axisym´etriques - c’esta ` dire pour des galaxies spirales non barr´ees et non actives - ces champs de vitesses donnent directement acc`es `a la composante circulaire de la vitesse de rotation. Les champs de vitesses des galaxies barr´ees sont plus complexes et ont besoin d’une analyse plus pouss´ee pour en d´eduire leur vitesse circulaire. Or, les galaxies spirales barr´ees constituent plus des deux tiers des galaxies spirales. Une ´etude `a grande ´echelle sur un ´echantillon de spirales barr´ees est donc n´ecessaire pour comprendre les mouvements non circulaires dans les galaxies. Cette th`ese propose les moyens n´ecessaires pour rechercher la composante axisym´etrique des ga- laxies spirales. L’accent a d’abord ´et´e mis sur une instrumentation de haute qualit´e, en d´eveloppant FaNTOmM, la cam´era `a comptage de photons la plus sensible au monde coupl´ee `auninterf´erom`etre de Fabry-Perot. Dans un premier temps, l’analyse des donn´ees d’observation d’un ´echantillon rigoureusement choisi de spi- rales barr´ees - BHαBAR - a permis d’obtenir des champs de vitesses de grande qualit´e.Parlasuite,lam´ethode de Tremaine-Weinberg, surtout utilis´ee jusqu’`a maintenant avec la composante stellaire et qui permet de d´eterminer la fr´equence de rotation de la barre dans une galaxie, a ´et´e utilis´ee sur ces donn´ees Hα et s’est r´ev´el´ee ´egalement efficace avec la composante de gaz ionis´e. Enfin tous les ´el´ements pr´ec´edents ont per- mis d’´etudier, parmi les galaxies de l’´echantillon BHαBAR,des´el´ements cl´es de leur ´evolution - r´esonances des orbites, fr´equences de rotation des barres, ondes stationnaires multiples,... - qui permettront, grˆace aux mod`eles N-corps+SPH d´evelopp´es en parall`ele, de d´eterminer beaucoup plus pr´ecis´ement la masse de galaxies spirales barr´ees. Mots cl´es : Instrumentation astronomique - Cam´era `a comptage de photons - Spectroscopie 3D - Interf´erom´etrie Fabry-Perot - Evolution´ des galaxies spirales barr´ees - Cin´ematique - Dynamique - Mod´elisation N-coprs+SPH. Summary The total mass (luminous and dark) of galaxies is derived from their circular velocities. Spectro- scopic Fabry-Perot observations of the ionized gas component of spiral galaxies allow one to derive their kinematics. In the case of purely axisymmetric velocity fields - as in non-active and unbarred spirals galaxies - the circular velocities can be derived directly. However, the velocity fields of barred galaxies (which consti- tute two thirds of the spirals) exhibit strong non-circular motions and need a careful analysis to retrieve the circular component. This thesis proposes the necessary steps to recover the axisymmetric component of barred spiral galaxies. The first step was to develop the best instrumentation possible for this work. FaNTOmM,whichisthe most sensitive photon counting camera ever developed, was coupled to a Fabry-Perot interferometer. The observations of a sample of barred spiral galaxies - the BHαBAR sample - was assembled in order to obtain the most rigourous velocity fields. Then, the Tremaine-Weinberg method, which can determine the bar pattern speed and is usually used with the observations of stellar component, has been tested on the ionised gas and gave satisfactory results. Finally, all the above techniques have been applied to the BHαBAR sample in order to study the key parameters of the galaxies’ evolution - bar pattern speeds, multiple stationary waves, resonances etc... - which will allow one to use N-body+SPH simulations to model properly the non-circular motions and determine the true total mass of barred spiral galaxies. Keywords : Astronomical instrumentation - Photon counting system - 3D Spectroscopy - Fabry-Perot Interferometer - Evolution of bar spiral galaxies - Kinematics - Dynamics - N-coprs+SPH modelling. Remerciements Mes premiers remerciements vont tout naturellement `a mes deux directeurs de th`ese Claude Cari- gnan et Philippe Amram, qui ont toujours ´et´epr´esents au cours de ce doctorat et m’ont sinc`erement soutenu sur divers plans (universitaire, moral, financiers, ...). Merci beaucoup, j’esp`ere vivement que nous auront encore beaucoup de projets en commun. Je voudrais aussi profiter de cette occasion pour remercier les personnes avec qui j’ai travaill´eet qui ont contribu´e`alaqualit´edecetravail.D’abord,ceuxdeMontr´eal, Olivier II et Laurent, votre aide et savoir pr´ecieux nous ont permis d’aller plus loin et de mieux comprendre la physique des Galaxies. Marie- Maude et Damien, merci pour votre disponibilit´e et vos savoir-faire respectifs. Enfin, merciaS´ ` ebastien pour les longues discussions et les perspectives de carri`ere... Ensuite, je ne voudrais pas oublier le soutien et la collaboration avec l’´equipe de l’Observatoire de Marseille. Jean-Luc et Jacques, c’est un plaisir de travailler avec vous, mˆeme `a 2500 m d’altitude. Michel, Philippe B., Olivier B. et Olivia, je vous remercie aussi pour votre exp´erience utilis´ee `a juste profit dans ce travail. Herv´e, de l’Observatoire de Lyon, je tiens aussi `ate remercier pour m’avoir re¸cu plusieurs fois et partager tes exp´eriences th´eoriques et multiprocesseurs. Enfin, une mention sp´eciale pour Chantal B., de l’Observatoire de Paris, pour ton enthousiasme in´egalable mˆeme `a 4500 m d’altitude ! vi Table des mati`eres R´esum´e iii Summary iv Remerciements v Liste des tableaux x Liste des figures xi Abr´eviations xiv Introduction 1 1 Du photon `a la corotation 3 1.1Instrumentation............................................ 4 1.1.1 Beaucoupdebruitpourrien................................ 4 1.1.2 L’interf´erom`etreFabry-Perotetlecomptagedephotons................. 7 1.1.3 FaNTOmM ............................................ 10 1.2 Champs de vitesses et mod`elesdemasse.............................. 11 1.2.1 Composantesd’unegalaxie................................. 11 1.2.2 Les diff´erentes formes de l’hydrog`ene............................ 12 1.2.3 Leschampsdevitesses.................................... 13 1.2.4 Probl´ematique des champs non axisym´etriques...................... 15 1.3 Les galaxies spirales barr´ees..................................... 15 1.3.1 Approximation des ´epicycles................................ 18 1.3.2 La m´ethodedeTremaine-Weinberg............................. 24 1.4 Dynamique num´eriquedesgalaxies................................. 26 1.4.1 Probl`emes `aN-corps..................................... 26 1.4.2 Codehydrodynamique-SPH................................ 28 1.4.3 Codes coupl´es ´etoiles-gaz.................................. 30 1.4.4 GADGET........................................... 30 1.4.5 Lascienceenmouvement.................................. 31 TABLE DES MATIERES` vii 2 FaNTOmM : Le Fabry-Perot au sommet de son art 33 2.1Introduction.............................................. 35 2.2 Basic considerations about the use of IPCSs with multiplex instruments . 35 2.2.1 PhotoncountingsystemsvsCCDs:thereadoutnoiseproblem............. 35 2.2.2 Using CCDs and IPCS with multiplex instruments : the real-time advantage . 37 2.3GaAssystemoverview........................................ 39 2.3.1 Camerahead......................................... 39 2.3.2 Acquisition.......................................... 39 2.3.3 Cooling............................................ 40 2.3.4 Performances......................................... 40 2.4Observations............................................. 41 2.4.1 Star formation triggering in blue compact galaxies . 42 2.4.2 TheGHASPproject..................................... 42 2.4.3 Velocityfieldsofgalaxiesincompactgroups........................ 42 2.4.4 Early-typegalaxies...................................... 45 2.4.5 Activegalaxies........................................ 45 2.5Futuredevelopmentsandotherapplications............................ 45 3 BHαBAR :un´echantillon de spirales barr´ees 47 3.1Introduction.............................................
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