High-mass star formation in Orion triggered by cloud-cloud collision II, Two merging molecular clouds in NGC2024

We analyzed the NANTEN2 13CO (J=2-1 and 1-0) datasets in NGC 2024. We found that the cloud consists of two velocity components, whereas the cloud shows mostly single-peaked CO profiles. The two components are physically connected to the HII region as evidenced by their close correlation with the dark lanes and the emission nebulosity. The two components show complementary distribution with a displacement of 0.4 pc. Such complementary distribution is typical to colliding clouds discovered in regions of high-mass star formation. We hypothesize that cloud-cloud collision between the two components triggered the formation of the late O stars and early B stars localized within 0.3 pc of the cloud peak. The collision timescale is estimated to be ~ 10^5 yrs from a ratio of the displacement and the relative velocity 3-4 km s-1 corrected for probable projection. The high column density of the colliding cloud 1023 cm-2 is similar to those in the other massive star clusters in RCW 38, Westerlund 2, NGC 3603, and M42, which are likely formed under trigger by cloud-cloud collision. The present results provide an additional piece of evidence favorable to high-mass star formation by a major cloud-cloud collision in Orion.Comment: 24 pages, 10 figures, submitted for publication in PASJ (cloud-cloud collision special issue

First Application of Lattice QCD to Pezy-SC Processor

AbstractPezy-SC processor is a novel new architecture developed by Pezy Computing K. K. that has achieved large computational power with low electric power consumption. It works as an accelerator device similarly to GPGPUs. A programming environment that resembles OpenCL is provided. Using a hybrid parallel system “Suiren” installed at KEK, we port and tune a simulation code of lattice QCD, which is computational elementary particle physics based on Monte Carlo method. We offload an iterative solver of a linear equation for a fermion matrix, which is in general the most time consuming part of the lattice QCD simulations. On single and multiple Pezy-SC devices, the sustained performance is measured for the matrix multiplications and a BiCGStab solver. We examine how the data layout affects the performance. The results demonstrate that the Pezy-SC processors provide a feasible environment to perform numerical lattice QCD simulations