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Evolution of Galactic Star Formation in Galaxy Clusters and Post-Starburst Galaxies

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Evolution of Galactic Star Formation in Galaxy Clusters and Post-Starburst Galaxies Evolution of galactic star formation in galaxy clusters and post-starburst galaxies Marcel Lotz M¨unchen2020 Evolution of galactic star formation in galaxy clusters and post-starburst galaxies Marcel Lotz Dissertation an der Fakult¨atf¨urPhysik der Ludwig{Maximilians{Universit¨at M¨unchen vorgelegt von Marcel Lotz aus Frankfurt am Main M¨unchen, den 16. November 2020 Erstgutachter: Prof. Dr. Andreas Burkert Zweitgutachter: Prof. Dr. Til Birnstiel Tag der m¨undlichen Pr¨ufung:8. Januar 2021 Contents Zusammenfassung viii 1 Introduction 1 1.1 A brief history of astronomy . .1 1.2 Cosmology . .5 1.2.1 The Cosmological Principle and our expanding Universe . .6 1.2.2 Dark matter, dark energy and the ΛCDM cosmological model . .9 1.2.3 Chronology of the Universe . 13 1.3 Galaxy properties . 16 1.3.1 Morphology . 17 1.3.2 Colour . 20 1.4 Galaxy evolution . 22 1.4.1 Galaxy formation . 22 1.4.2 Star formation and feedback . 24 1.4.3 Mergers . 25 1.4.4 Galaxy clusters and environmental quenching . 26 1.4.5 Post-starburst galaxies . 29 2 State-of-the-art simulations 33 2.1 Brief introduction to numerical simulations . 33 2.1.1 Treatment of the gravitational force . 34 2.1.2 Varying hydrodynamic approaches . 35 2.2 Magneticum Pathfinder simulations . 39 2.2.1 Smoothed particle hydrodynamics . 39 2.2.2 Details of the Magneticum Pathfinder simulations . 40 3 Gone after one orbit: How cluster environments quench galaxies 45 3.1 Data sample . 46 3.1.1 Observational comparison with CLASH . 46 3.2 Velocity-anisotropy Profiles . 47 3.2.1 CLASH comparison . 47 3.2.2 Quenching fractions . 50 3.2.3 Mass and temporal evolution . 52 vi CONTENTS 3.3 Phase Space . 54 3.3.1 Line-of-sight phase space . 54 3.3.2 Mass and temporal evolution . 57 3.3.3 Stellar mass comparison . 61 3.4 Satellite galaxy quenching prior to infall . 63 3.4.1 Tracking in-falling star-forming satellite galaxies . 63 3.4.2 Tracking survivors . 68 3.4.3 Impact of infall environment . 71 3.5 Summary & discussion . 74 3.6 Conclusions . 76 4 Rise and fall of post-starburst galaxies 79 4.1 Sample selection . 81 4.2 Environment, distribution, and evolution of post-starburst galaxies . 82 4.2.1 Quenched and PSB fractions . 82 4.2.2 Stellar mass functions of satellite galaxies . 84 4.2.3 Galaxy distribution within halos . 87 4.2.4 A closer look: Evolution of massive post-starburst galaxies . 88 4.2.5 Main sequence tracks . 89 4.3 The role of mergers . 92 4.3.1 Case study: Gas evolution . 93 4.3.2 Merger statistics . 95 4.3.3 Cold gas fractions . 97 4.4 Shutdown of star formation . 100 4.4.1 Active galactic nucleus and supernova feedback . 100 4.4.2 Black hole growth statistics . 105 4.5 Post-starburst galaxies in galaxy clusters . 110 4.5.1 Galaxy cluster stellar mass function comparison . 110 4.5.2 Line-of-sight velocity: Observational comparison . 112 4.5.3 Radial velocity as function of cluster mass and redshift . 114 4.5.4 Cluster merger statistics . 117 4.5.5 Active galactic nuclei and supernovae . 118 4.6 Discussion . 121 4.6.1 Environment and redshift evolution . 121 4.6.2 The impact of mergers . 121 4.6.3 Shutting down star formation . 123 4.6.4 Post-starburst galaxies in galaxy clusters . 124 4.6.5 Numerical considerations . 127 4.7 Conclusions . 127 5 Summary and conclusion 133 A Gone after one orbit: How cluster environments quench galaxies 137 Table of Contents vii Bibliography 141 List of Figures 184 List of Tables 185 Danksagung 187 viii Zusammenfassung Zusammenfassung W¨ahrenddie meisten Galaxien sich allm¨ahlich entwickeln, gibt es Galaxien, welche eine wesentlich rasantere Entwicklung durchlaufen, zum Beispiel sternbildende Galaxien, die in Galaxienhaufen hineinfallen oder Post-Sternausbruch Galaxien (PSG). Diese sich rasant entwickelnden Galaxien kennzeichnen sich durch erhebliche Anderungen¨ der Sternentste- hungsrate auf kurzen Zeitskalen und erm¨oglichen entscheidende Einblicke in die Prozesse, welche die Galaxienentwicklung vorantreiben. Zum Entschl¨usseln dieser Prozesse wird die interne Galaxienentwicklung, die Bahndynamik in Galaxienhaufen und das Wachstum Schwazer L¨ocher ¨uber zahlreiche Giga-jahre untersucht. Zu diesem Zwecke, nutzten wir die modernen hydrodynamischen Magneticum Pathfinder Simulationen. Diese erm¨oglichen die Betrachtung und Auswertung der Galaxienentwicklung in verschiedenen Umgebungen innerhalb kosmologischer Volumina. Im ersten Teil dieser Dissertation analysieren wir die Prozesse und Bedingungen, welche zur Unterdr¨uckung der Sternbildung von Galaxien in Galaxienhaufen f¨uhren.Der Vergle- ich der Bahndynamiken zwischen sternbildenden Galaxien und Galaxien, die keine Sterne bilden, also 'erloschene' Galaxien, zeigt, dass erstere wesentlich h¨aufiger radiale Umlaufbah- nen innerhalb von Galaxienhaufen haben. Dieser Unterschied zwischen sternbildenden und erloschenen Galaxien zeigt sich auch bei der Betrachtung des Phasenraums: Erstere sind dabei in die Galaxienhaufen hineinzufallen und liegen mehrheitlich außerhalb des Virialra- dius des Galaxienhaufens, w¨ahrend Zweitere ¨uberwiegend innerhalb des Virialradius liegen. Die Analyse einzelner Galaxien zeigt, dass die ¨uberw¨altigendeMehrheit an sternbildenden Galaxien w¨ahrendder ersten Umlaufbahn, innerhalb von 1 Ga nach Durchquerung des Virialradius des Galaxienhaufens, gel¨oscht werden. Die verbleibenden Galaxien (< 5%), welche eine Sternentstehung l¨angeraufrechterhalten k¨onnen,haben entweder tangentiale Umlaufbahnen oder eine sehr hohe stellare Masse. Aus alledem wird ersichtlich, dass der erhebliche Staudruck, welcher beim Hineinfallen in einen Galaxienhaufen aufkommt, dass f¨urdie Sternentstehung notwendige galaktische Gas ausst¨oßtund dadurch die Sternbildung der Galaxie erlischt. Der zweite Teil widmet sich der Untersuchung der Ursache des Sternausbruches, und dem nachfolgenden abrupten Abfall der Sternentstehung, der in PSG beobachtet wird. Wir zeigen, dass PSG, ¨ahnlich zu sternbildenden Galaxien, sich durch eine Vielzahl von Galaxienverschmelzungen auszeichnen. Innerhalb der letzten 2:5 Ga erlebten 89% der z ∼ 0 PSG mindestens eine Galaxienverschmelzungen und 65% durchliefen sogar mindestens eine Verschmelzung zwischen Galaxien ¨ahnlicher Masse. Bemerkenswerterweise haben 23% der x Zusammenfassung PSG sogar eine Verj¨ungung erlebt, also waren vor ihrem Sternausbruch erloschen. Durch die Galaxienverschmelzungen, welche unter anderem neues Gas einbringen, wird die Ster- nentstehung kurzfristig angeregt. Im Anschluss w¨aschst das zentrale Schwarze Loch inner- halb der PSG rasant und die Energie, die der aktive Galaxienkern in der Umgebung de- poniert, senkt die Sternentstehung abrupt. Diese Senkung ist besonders effektiv, weil PSG statistisch weniger kaltes Gas haben. Beim Vergleich mit Beobachtungen gibt es sowohl Ubereinstimmungen¨ mit der stellaren Massenfunktion als auch mit der Verteilung von PSG im Phasenraum innerhalb von Galaxienhaufen. Die Untersuchung von PSG in Galaxien- haufen zeigt, ¨ahnlich zu den Ergebnissen aus dem ersten Teil, dass PSG ¨uberwiegend zum ersten Mal in Galaxienhaufen hineinfallen. Zusammenfassend, w¨ahrendPSG in Galaxien- haufen durch den Staudruck gel¨oscht werden, ist der aktive Galaxienkern außerhalb von Galaxienhaufen maßgeblich f¨urdie Stilllegung der Sternentstehung verantwortlich. Abstract While most galaxies evolve gradually, a subset of galaxies, such as star-forming galaxies falling into galaxy cluster or post-starburst galaxies (PSBs), evolve far more quickly. These transition galaxies are characterised by a short timescale decrease of star formation and offer key insights into how and by what mechanisms galaxies evolve. To resolve the ex- tensive range of relevant physical processes involved in galaxy evolution, we analyse the state-of-the-art cosmological hydrodynamical simulation suite Magneticum Pathfinder. We track the orbits, merger history, galactic properties, and black holes of transition galaxies and control samples in different environments over several ∼ Gyr. The first part of this thesis investigates the processes whereby, and the conditions under which, star-forming satellite galaxies are quenched in galaxy cluster. We find a strong dichotomy in both the line-of-sight and radial phase space between star-forming and quiescent galaxies: While the former are generally found beyond the cluster virial radius and are dominated by radial orbits, the latter populate the inner cluster region. More importantly, most star-forming satellite galaxies are quenched during their first passage through the galaxy cluster. In particular, the tracking of individual orbits shows that the star formation of almost all satellite galaxies drops to zero within 1 Gyr after cluster infall. The subset (< 5%) of satellite galaxies that remain star-forming the longest after infall have either tangential orbits or high stellar mass. All this indicates that star-forming satellite galaxies are quenched by ram-pressure stripping. In the second part, we explore the reasons for the starburst phase and the subsequent rapid shutdown observed in PSBs. We find that z ∼ 0 PSBs, similar to star-forming control galaxies, show a high abundance of mergers within the last 2:5 Gyr: 89% of PSBs have ex- perienced at least one merger, and 65% have had at least one major merger event. Notably, 23% of PSBs underwent rejuvenation during their starburst. While mergers generally in- crease the gas supply, leading to star formation, PSB progenitors have statistically less cold gas compared to star-forming galaxies. Following the mergers, strong active galactic nucleus (AGN) feedback is registered,
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