Chao Liu, Zhao-ming Gan, Fu-guo Xie
We perform two dimensional (2D) hydrodynamic (HD) numerical simulations to study the positive active galaxy nuclei (AGN) feedback which triggers, rather than suppresses, star formation. Recently, it is shown by Nayakshin et al. (2012) and Ishibashi et al. (2012) that star formation occurs when the cold interstellar medium (ISM) is squeezed by the impact of mass outflow or radiation pressure, respectively. Mass outflow is ubiquitous in this astrophysical context, and radiation pressure is also important if the AGN is luminous. For the first time on this subject, we take both mass outflow feedback and radiative feedback into our model. Consequently, the ISM is shocked into shells by the AGN feedback, and then these shells fragment into clumps and filaments very soon because of the Rayleigh-Taylor and thermal instabilities. We have two major findings in this paper: (1) the star formation rate (SFR) can indeed be very large in the clumps and filaments. However, the resultant star formation rate density (SFRD) is somehow too large compared to previous works, which is mainly due to that we ignore that most of the formed stars would be disrupted when they pass away from the galaxy center; (2) although radiation pressure feedback has limited effect, when mass outflow feedback is also included, they reinforce each other. Specifically, in the gas-poor case, mass outflow is always the dominant feedback contributor.
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http://arxiv.org/abs/1303.6745
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