Formation and evolution of galactic disks with a multiphase numerical model

نویسنده

  • B. Semelin
چکیده

The formation and evolution of galactic disks are complex phenomena, where gas and star dynamics are coupled through star formation and the related feedback. The physical processes are so numerous and intricate that numerical models focus, in general, on one or a few of them only. We propose here a numerical model with particular attention to the multiphase nature of the interstellar medium; we consider a warm gas phase (≥ 10K), treated as a continuous fluid by an SPH algorithm, and a cold gas phase (down to 10K), fragmented in clouds, treated by a low-dissipation sticky particles component. The two gas phases do not have the same dynamics, nor the same spatial distribution. In addition to gravity, they are coupled through mass exchanges due to heating/cooling processes, and supernovae feedback. Stars form out of the cold phase, and re-inject mass to the warm phase through SN explosions and stellar winds. The baryons are embedded in a live cold dark matter component. Baryonic disks, initially composed of pure gas, encounter violent instabilities, and a rapid phase of star formation, that slows down exponentially. Stars form in big clumps, that accumulate in the center to build a bulge. Exponential metallicity gradients are obtained. External infall of gas should be included to maintain a star formation rate in the disk comparable to what is observed in present disk galaxies.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

The Challenge of Modelling Galactic Disks

Detailed models of galactic disk formation and evolution require knowledge about the initial conditions under which disk galaxies form, the boundary conditions that affect their secular evolution and the micro-physical processes that drive the multi-phase interstellar medium and regulate the star formation history. Unfortunately, up to now, most of these ingredients are still poorly understood....

متن کامل

Early Evolution of Disk Galaxies : Formation of Bulges in Clumpy Young Galactic Disks

A new idea is proposed for the origin of bulges in spiral galaxies. Numerical simulations for the protogalactic collapse suggest strongly that galactic bulges have been assembled from massive clumps formed in the galactic disks in their early evolutionary phase. These clumps result from the gravitational instability of the gas-rich disks of young galaxies. Those massive clumps, individual masse...

متن کامل

Simulating the formation of disk galaxies: The impact of Jets from Active Galactic Nuclei

Recent semi-analytic models have highlighted the role of AGN jets in regulating the formation of galaxies. In this paper, we present a new implementation of feedback due to active galactic nuclei (AGN) in cosmological hydrodynamic simulations of galaxy formation in which AGN feedback is assumed to heat the halo gas through the production of jets. Combining a theoretical model of mass accretion ...

متن کامل

Building Galactic Disks in Triaxial Dark Matter Halos

We review our recent work on the formation and evolution of disks within triaxial dark matter (DM) halos by means of numerical simulations, including star formation and feedback from stellar evolution. The growing disks are strongly influenced by shapes of DM halos and modify them in turn. Disk parameters are in a broad agreement with those in the local universe. Gas-rich stellar bars grow in t...

متن کامل

A Semi-analytic Model of Halo Dynamics

Abstract. We have developed a new semi-analytic model for the formation and evolution of structure on galaxy, group and cluster scales. The model combines merger trees with a detailed, spatially resolved description of the dynamical evolution of halo substructure. It reproduces the results of numerical simulations of mergers and halo formation at a fraction of the computational expense. We use ...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2002