Modelling star formation in interacting galaxies
- Autor(en)
- Stefan Harfst, Christian Theis, Gerhard Hensler
- Abstrakt
Converting gas to stars by star formation (SF) is one of the key processes for the evolution of galaxies. Due to the complexity of SF no complete theory applicable to models of galactic evolution exists so far. Therefore, the treatment of SF in numerical simulations is usually based on semi-phenomenological schemes like the Schmidt Law SFR/area = cn ž Sgn, with the gas surface density Sg and n ˜ 1.5. The parameter cn combines a time scale and an efficiency (SFE) of the SF process. The time scale can be reasonably estimated by the dynamical time, whereas the SFE cannot be determined well from current SF theories, i.e. the SFE remains a free parameter. Also, a constant SFE cannot account for local feedback processes, by this prohibiting any self-regulation of the SF. Though the standard approach for SF works well for isolated galaxies, it fails to reproduce interacting galaxies (Mihos et al., 1993, ApJ, 418, 82). One solution might be to introduce a new SF mode like the shock-induced SF proposed by Barnes (2004, MNRAS, 350, 798) for the price of introducing new free parameters. We present a different approach for describing SF in galaxy simulations based on a time- and position dependent SF efficiency as proposed by Elmegreen & Efremov (1997, ApJ, 480, 235): the SFE is controlled in a physically consistent manner by the properties of the local interstellar medium (ISM) including stellar feedback. After gauging the SFE to the solar vicinity, there is no free parameter in the SFE. A pre-requisite of this modelling is a multi-phase treatment of the ISM which we included in our new particle code. Apart from SF, we consider stellar feedback by massive stars and planetary nebulae, phase transitions and interactions between gas clouds and ambient diffuse gas, namely condensation, evaporation, drag and energy dissipation. The latter is realised by radiative cooling and inelastic cloud-cloud collisions. As an application of our code we study interacting galaxies. We address the question about the reaction of an externally perturbed ISM which is otherwise in a dynamical equilibrium. Especially, we investigate the strength of the SF response and the local and temporal variations of the SF efficiency. Fig. A 10 shows the star formation rate for an infalling satellite triggering a single burst-like SF event even though the host galaxy has consumed most of its gas. Œ 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
- Organisation(en)
- Institut für Astrophysik
- Externe Organisation(en)
- Christian-Albrechts-Universität zu Kiel
- Journal
- Astronomische Nachrichten
- Band
- 326
- Seiten
- 493
- ISSN
- 0004-6337
- Publikationsdatum
- 2005
- ÖFOS 2012
- 103003 Astronomie
- Link zum Portal
- https://ucris.univie.ac.at/portal/de/publications/modelling-star-formation-in-interacting-galaxies(0e711ab5-913f-4139-b086-b96b4d6c26a3).html