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October 2015
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Debora Sijacki (Cambridge, UK) --- A new look at galaxy - black hole co-evolution

Friday 2 October 2015 11:00-12:00 - Amphi

Abstract: In this talk I will discuss which feedback mechanisms are needed to reproduce realistic stellar masses and galaxy morphologies in the present day Universe and argue that the black hole feedback is necessary for the quenching of massive galaxies. I will then demonstrate how black hole - host galaxy scaling relations depend on galaxy morphology and colour, highlighting the implications for the co-evolutionary picture between galaxies and their central black holes. In the second part of the talk I will present a novel method that permits to resolve gas flows around black holes all the way from large cosmological scales to the Bondi radii of black holes themselves. I will demonstrate that with this new numerical technique it is possible to estimate much more accurately gas properties in the vicinity of black holes than has been feasible before in galaxy and cosmological simulations, allowing to track reliably gas angular momentum transport from Mpc to pc scales. Finally, I will also discuss if AGN-driven outflows are more likely to be energy- or momentum-driven and what implications this has for the redshift evolution of black hole - host galaxy scaling relations.

Stephanie Walch (Cologne, Germany) --- The violent ISM in Milky Way-like disk galaxies

Friday 9 October 2015 11:00-12:00 - Amphi

Abstract: Molecular clouds are cold, dense, and turbulent filamentary structures that condense out of the multi-phase interstellar medium. They are also the sites of star formation. The minority of new-born stars is massive, but these stars are particularly important for the fate of their parental molecular clouds as their feedback drives turbulence and regulates star formation.
I will present results from the SILCC project (SImulating the Life Cycle of molecular Clouds), in which we study the formation and dispersal of molecular clouds within the multi-phase ISM using high-performance, three-dimensional simulations of representative pieces of disk galaxies. Apart from stellar feedback, self-gravity, an external stellar potential, and magnetic fields, we employ an accurate description of gas heating and cooling as well as a small chemical network including molecule formation and (self-)shielding from the interstellar radiation field. We study the impact of the supernova rate and the positioning of the supernova explosions with respect to the molecular gas in a well defined set of simulations. This allows us to draw conclusions on structure of the multi-phase ISM, the amount of molecular gas formed, and the onset of galactic outflows. Furthermore, we show how important stellar wind feedback is for regulating star formation in these disks.

Melville Ulmer (Northwestern, USA) --- The Athena Mission: The Scientific Treasure Trove Brought about by Reaching the Golden Quadrant

Friday 16 October 2015 11:00-12:00 - Amphi

Abstract: The Athena mission will be the most ambitious ESA lead X-ray telescope ever launched in terms of collecting area focused onto a high resolution (baseline goal 2 eV at 6 keV) imaging detector. The detector is called the “Integral Field Unit” or IFU. The mission promises to revolutionize our knowledge of the “Hot Universe,” and the IFU coupled with the collecting area will be able to measure directly redshifts, infer plasma temperatures from line ratios, and bulk motion turbulences and more. Thus the mission will enable unique studies of the Hot Universe. A few examples detection and redshifts the first luminous black holes (AGNs) , track the chemical evolution of the Universe, tell us about the evolution on the intracluster medium, and the physics flaring objects from far (gamma ray burst after glow) to near (galactic) flare stars that could affect the habitability of rocky planets in the otherwise habitable zone. We will show how the complementary instrument the Wide Field Imager will play a key role in finding static (in time) targets of special interest as well as transient but rare phenomena that will de discovered when the WFI monitors hundreds to thousands of targets at once.

Soutenance de thèse --- Giovanni Bruno

Wednesday 21 October 2015 14:00-15:00 - Amphi

Dear all,

it is with the feeling of being disrespectful for what has happened just two days ago that I send to all of you the invitation to my PhD defense. I apologize to those who will feel this indelicate.

The discussion will hold on October 21 at 2pm, in the auditorium. The title is "Characterization of transiting exoplanets: analyzing the impact of the host star on the planet parameters". The presentation will be in English, and you will find the abstract below.

The defense will be followed by the traditional buffet to which all of you are invited.

Best regards,

Giovanni Bruno

Bonjour à tous,

c’est avec la sensation d’être irrespectueux pour ce qui s’est passé il y a juste deux jours que j’envoie à vous tous l’invitation à ma soutenance de thèse. Je m’excuse avec ceux qui sentiront ça comme indélicat.

La discussion aura lieu le 21 Octobre à 14h, dans le Grand Amphi. Le titre est "Caractérisation d’exoplanètes en transit : analyse de l’impact de l’étoile hôte sur les paramètres de la planète". La présentation sera en anglais, et vous trouverez le résumé ici dessous.

La soutenance sera suivie par le traditionnel buffet auquel vous êtes tous invités.

Bien cordialement,

Giovanni Bruno


To test theories of planetary system formation and evolution, a statistical picture of the planet properties needs to be drawn. Hence, it is crucial to detect as many planets as possible, and to look for as much diverse planets as possible. Assessing properties of planets different in nature requires not only the precise measure of the planetary and orbital parameters, but also of those of the parent star.
The work of this PhD is focused on problematics related to the transiting planets. First, I will describe the detailed analyses I have carried out on the parent star of transiting planets, observed from the ground with various spectrographs. Then, I will discuss the problems that stellar variability introduces in exoplanet detection and characterization. I will present a method, developed during this PhD, to clean the observational data from the stellar variability signal and increase the precision on the planet’s parameters.


Pour tester les théories de formation et évolution des systèmes planétaires, il faut disposer de larges statistiques des propriétés des planètes. Pour ça, il est fondamental de détecter autant de planètes que possible, et de chercher des planètes autant diversifiées que possible. Pour déterminer les propriétés de planètes de nature différente, il est nécessaire de mesurer précisément pas seulement les paramètres planétaires et orbitaux, mais aussi ceux de l’étoile hôte.
Le travail de cette thèse est centré sur des problématiques liées aux planètes qui transitent devant leur étoile hôte. Je vais d’abord décrire les analyses détaillées que j’ai amené sur les étoiles hôtes de planètes transitants, observées au sol avec plusieurs spectrographes. Après, je vais discuter les problèmes que l’activité stellaire introduit dans la détection et caractérisation des exoplanètes. Je vais présenter une méthode, développée pendant cette thèse, pour nettoyer les données observationnelles du signal de la variabilité de l’étoile, et augmenter la précision sur les paramètres de la planète.

No Seminar --- School Holidays

Friday 23 October 2015 11:00-12:00 - Amphi

No Seminar --- School Holidays

No Seminar --- School Holidays

Friday 30 October 2015 11:00-12:00 - Amphi

No Seminar --- School Holidays

Soutenance de thèse --- Francesca Fragkoudi

Friday 30 October 2015 14:00-15:00 - Amphi

Dear all,

I’m happy to invite you to my PhD thesis defence, on Friday 30th of October at 2pm, in the Amphitheatre.
The title of the thesis is, "Modelling peanuts in barred galaxies: Gas flows and constraints on the dark matter content” and you can find the abstract below. The presentation will be given in English.

After the defence, I will be happy to share some cypriot delicacies with everyone at the traditional buffet!

Best regards,

Francesca

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Bonjour à toutes/tous,

J’ai le grand plaisir de vous inviter à la soutenance de ma thèse, le Vendredi 30 Octobre a 14h, dans l’amphithéâtre.
Le titre est, “Modélisation des bulbes cacahuètes dans les galaxies barrées: écoulement du gaz et contraintes sur le contenu de la matière noire” et la présentation sera en anglais.

Après la soutenance je serai ravie de partager des gourmandises chypriotes avec tout le monde au traditionnel pot de thèse.

Bien cordialement,

Francesca

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Abstract:

By exploring the dynamics of galaxies we obtain a wealth of information regarding their various mass components, their formation and evolution. In this thesis I make extensive use of dynamical models obtained directly from images of observed galaxies. I therefore start by improving these models by including the geometry of boxy/peanut (B/P) bulges, and quantifying their effects on the models. B/P bulges have a significant effect on the potential, forces, orbital structure and bar strength of the models, and as such should be included in order to make them as accurate as possible. I then employ dynamical models with and without B/P bulges to determine their effect on gas inflow to the central regions. I show that in the presence of B/P bulges the bar strength is reduced, as is the amount of gas inflow, leading to smaller mass concentrations in the centres of galaxies. Furthermore, I employ dynamical models to carry out a detailed study of the nearby galaxy NGC 1291. I use the non-axisymmetric nature of the bar, which induces shocks in the gas - thus creating dust lanes along the leading edges of the bar - to put constraints on the mass-to-light ratio of the disc. The results argue strongly that NGC 1291 has a maximal disc, i.e. that in the central regions, baryonic matter dominates over the dark matter. Furthermore I place limits on the pattern speed of the bar, showing that the bar rotates fast. I thus demonstrate that the dynamical method used can provide constraints on the dark matter distribution of observed galaxies, and therefore also on current models of galaxy formation and evolution.

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