%0 Generic %1 arata2017clump %A Arata, Shohei %A Yajima, Hidenobu %A Nagamine, Kentaro %D 2017 %K clouds cold instabilities %T Gas clump formation via thermal instability in high-redshift dwarf galaxy mergers %U http://arxiv.org/abs/1710.11503 %X Star formation in high-redshift dwarf galaxies is a key to understand early galaxy evolution in the early Universe. Using the three-dimensional hydrodynamics code GIZMO, we study the formation mechanism of cold, high-density gas clouds in interacting dwarf galaxies with halo masses of $\sim 3 10^7~M_ødot$, which are likely to be the formation sites of early star clusters. Our simulations can resolve both the structure of interstellar medium on small scales of $0.1$ pc and the galactic disk simultaneously. We find that the cold gas clouds form in the post-shock region via thermal instability due to metal-line cooling, when the cooling time is shorter than the galactic dynamical time. The mass function of cold clouds shows almost a power-law initially with an upper limit of thermally unstable scale. We find that some clouds merge into more massive ones with $\gtrsim 10^4~M_ødot$ within $2~Myr$. Only the massive cold clouds with $10^3~M_ødot$ can keep collapsing due to gravitational instability, resulting in the formation of star clusters. In addition, we investigate the dependence of cloud mass function on metallicity and $\rm H_2$ abundance, and show that the cases with low metallicities ($łesssim 10^-2~Z_ødot$) or high $H_2$ abundance ($10^-3$) cannot form massive cold clouds with $10^3~M_ødot$.

@misc{arata2017clump, abstract = {Star formation in high-redshift dwarf galaxies is a key to understand early galaxy evolution in the early Universe. Using the three-dimensional hydrodynamics code GIZMO, we study the formation mechanism of cold, high-density gas clouds in interacting dwarf galaxies with halo masses of $\sim 3 \times 10^{7}~M_{\odot}$, which are likely to be the formation sites of early star clusters. Our simulations can resolve both the structure of interstellar medium on small scales of $\lesssim 0.1$ pc and the galactic disk simultaneously. We find that the cold gas clouds form in the post-shock region via thermal instability due to metal-line cooling, when the cooling time is shorter than the galactic dynamical time. The mass function of cold clouds shows almost a power-law initially with an upper limit of thermally unstable scale. We find that some clouds merge into more massive ones with $\gtrsim 10^{4}~M_{\odot}$ within $\sim 2~{\rm Myr}$. Only the massive cold clouds with $\gtrsim 10^{3}~M_{\odot}$ can keep collapsing due to gravitational instability, resulting in the formation of star clusters. In addition, we investigate the dependence of cloud mass function on metallicity and ${\rm H_{2}}$ abundance, and show that the cases with low metallicities ($\lesssim 10^{-2}~Z_{\odot}$) or high ${\rm H_{2}}$ abundance ($\gtrsim 10^{-3}$) cannot form massive cold clouds with $\gtrsim 10^{3}~M_{\odot}$.}, added-at = {2017-11-01T10:31:52.000+0100}, author = {Arata, Shohei and Yajima, Hidenobu and Nagamine, Kentaro}, biburl = {https://www.bibsonomy.org/bibtex/2de08e0f4d59185a6fbc102c4dfcafb32/miki}, description = {[1710.11503] Gas clump formation via thermal instability in high-redshift dwarf galaxy mergers}, interhash = {a3ef0210ee0c92b8765bb98abfef5c77}, intrahash = {de08e0f4d59185a6fbc102c4dfcafb32}, keywords = {clouds cold instabilities}, note = {cite arxiv:1710.11503Comment: 11 pages, 11 figures}, timestamp = {2017-11-01T10:31:52.000+0100}, title = {Gas clump formation via thermal instability in high-redshift dwarf galaxy mergers}, url = {http://arxiv.org/abs/1710.11503}, year = 2017 }