Figure1. rms distance (rpar) of the satellites projected on to their best-fittingplane plotted against the rms height (rper) of the satellites from the plane for the ‘far’ sample.

  In 2014, researchers from Purple Mountain Observatory, Nanjing University and Max Planck institute for Astronomy employed a high-resolution Eulerian code using the positive preserving WENO scheme to determine the stability of cold flows under Kelvin-  Helmholtz instability, Rayleigh-Taylor instability, thermal evaporation and the impact of satellites. In the model, the hot halo gas is initially set to be isothermal and in hydrostatic equilibrium under the gravitational petential of the Milky Way size dark matter halo at redshift z=2. The results of simulations show that a cold stream penetrating a hot 

gaseous halo is stable against thermal convection and Kelven-Helmholtz and Rayleigh-Taylor instabilities. In other hand, under the disturbing action of a satellite (with a mass ratio of 1:33) merging with the central halo, the accretioin rate of cold gas at half of the virial radius experiences a dramatic drop for 0.5 Gyr. In this period the supply of cold gas into the central region decreases by more than 70%. However, the interaction probility between isotropically distributed stream and satellites is only 1% and the cold flow towards the halo center is able to re-establish itself in less than 0.3 Gyr. Therefore, this work confirm the cold stream are very stable against a large variety of internal and external pertubations. 

  This research highly supports the two modes accretion in galaxy formation theory and published on Monthly Notice of the Royal Astronomical Society Letter. The first author is Liang Wang, co-authors are Weishan Zhu, Longlong Feng, Andrea Maccio, Jiang Chang and Xi Kang. 

  The link of this paper is:  http://mnrasl.oxfordjournals.org/content/439/1/L85