STAGE Accretion of multiphase gas onto galaxy halos

Date de mise à jour de l’offre

Centre National de la Recherche Scientifique - Institut d'Astrophysique de Paris :

Unité mixte de recherche CNRS & Sorbonne Université (UMR 7095)

Description de la mission

Galactic halo gas traces both the inflowing fuel for star formation and feedback from galactic disks. Knowing how inflows, outflows, and star formation regulate the baryonic content of galaxies is essential to understand their formation and evolution. To regulate the gas content within galaxies, models of galaxy evolution generally focus on how gas cools to form stars within galactic disks, and how gas is expelled by feedback from supernovae and Active Galactic Nuclei.
In this M2 project, we propose to focus on how gas is accreted from the intergalactic medium onto halos. We have recently built a phenomenological model of a collimated stream of warm gas that flows into a halo from an overdense filament of the cosmic web. The streaming gas is shocked at the virial radius and the shock is sustained by the hot phase. The post-shock gas expands because it has a higher pressure than ambient halo gas and fragments as it cools. This model allowed us to determine the halos parameter space (mass, redshift) in which the halo gas can become multiphase when the gas cooling and dynamical times are of the same order of magnitude, and predict the mass fraction and volume filling factor of the cold gas.
The goal of this internship is to include this physically-motivated phenomenology into the semi-analytical model G.A.S (Cousin et al. 2019), test the impact of multiphase accretion on the properties of simulated galaxies, and compare with observations of mass and luminosity functions. The immediate objectives and methodology are the following:
1) calculate the mass fractions of accreted cold gas for the different parameters space of halos, implement those into the G.A.S code (F90), and test how does multiphase accretion impact galaxy growth. For instance, the student will compare the galaxy mass and luminosity functions to the previous published version of the model.
2) build a new physical model of turbulent dissipation within cold halo gas into the G.A.S code. The code already allows us to follow the cascade of turbulent energy from the disk scale height to the star formation scale (assumed to be 0.1 pc), and to compute the velocity dispersion in galactic disks. Now we would like to add the contribution of turbulent dissipation from gas accretion at the halo scale, and test the impact on the star formation efficiency and some important line emission (e.g. [CII]) of galaxies.

Profil recherché

Nature du travail demandé :
Simulations numériques
Modélisation

Pré-requis :
M2 in astrophysics or physics. Highly-motivated student with good programming skills in Fortran90 and Python is required.

Niveau de qualification requis

Bac + 4/5 et +
  • Employeur
    Centre National de la Recherche Scientifique - Institut d'Astrophysique de Paris
  • Secteur d’activité de la structure
    Enseignement - Formation - Recherche
  • Effectif de la structure
    De 51 à 250 salariés
  • Site internet de la structure
    http://www.iap.fr
  • Type de stage ou contrat
    Stage pour lycéens et étudiants en formation initiale
  • Date prévisionnelle de démarrage
  • Durée du stage ou contrat
    Plus de 2 mois et jusqu'à 4 mois
  • Le stage est-il rémunéré ?
    Oui
  • Niveau de qualification requis

    Bac + 4/5 et +
  • Lieu du stage
    98 bis Boulevard Arago
    Institut d'Astrophysique de Paris
    75014 PARIS 14E ARRONDISSEMENT
  • Accès et transports
    Denfert-Rochereau