Vaisala, Miikka 韋米卡

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Exploring protostellar disk formation via misaligned rotation axes and magnetic field, and their observable features. The streamlines on the column density maps show the direction of flows along the picture frame. The black lines over Stokes Q and U parameters depict the direction of magnetic field estimated from the polarization angles. We predict that we witness magnetically directed spiraling behavior by polarization observations (Väisälä et al. 2019).

Observational signatures of early disk formation by MHD models

The panel of two figures illustrate the synthetic gas column density and linear polarization component q along the line of sight, inclined 15 degrees from the midplane, for a very early disk forming from collapsing magnetic flow with the Perspective code developed by the CHARMS project. The early disk in the model shows a spiral-like shape, presumably created by the magnetic field aligned along the rotational plane of the original cloud, that is streaming into the central source. (Perspective code; CHARMS Project; Väisälä, Shang et al., 2018, in preparation)

An early disk in formation from collapsing magnetic flows

A sample picture based on the radiative transfer code Perspective exploring a very early stage disk formed within the MHD model of Li et al. (2014). The picture shows gas column density and linear polarization component q along the line of sight, inclined 15 degrees from the midplane. The early disk in the model shows a spiral-like shape, presumably created by the magnetic field aligned along the rotational plane of the original cloud. (Väisälä, Shang et al., a work in progress)

Polarization Calculation and Visualization from MHD Simulation Data

Vaisala, Miikka Project Scientist
	Office: ASMAB 1405 TEL: +886-2-2366-5466 FAX: +886-2-2367-7849 Email: mvaisalaasiaa.sinica.edu.tw

Education and Positions

Postdoctoral Fellow, Academia Sinica, Institute of Astronomy and Astrophysics (2018~present)
Doctor of Philosophy (Astronomy), University of Helsinki (2010~2017)
Bachelor/Master of Science (Astronomy), University of Helsinki (2004~2010)

Research Interests

I am interested in the magnetic turbulence of interstellar medium in all scales, from the supernova driving of galactic dynamo to the relatively small scales of star formation. I also wish to find way to connect theoretical models with observational signatures, and therefore I consider radiative transfer modeling to be an integral part of my work. In addition, I have general interest in the computational methods of astrophysics, particularly using GPUs.

Journal Papers affiliated with ASIAA

Väisälä MS; Shang H; Galli D; Lizano S; Krasnopolsky R, "Exploring the Formation of Resistive Pseudodisks with the GPU Code Astaroth" , ApJ: 959(1), id.32 (21pp), Dec, 2023 [SCI] ( ADS | Fulltext )
Pekkilä, Johannes; Väisälä, Miikka S.; Käpylä, Maarit J. search by orcid; Rheinhardt, Matthias; Lappi, Oskar, "Scalable communication for high-order stencil computations using CUDA-aware MPI" , Parallel Computing: 111, id.102904, July, 2022 [SCI] ( ADS | Fulltext )
Wang W; Väisälä MS; Shang H; Krasnopolsky R; Li Z-Y; Lam KH; Yuan F, "Magnetic Spirals in Accretion Flows Originated from Misaligned Magnetic Fields" , ApJ: 928(1), id.85 (23pp), March, 2022 [SCI] ( ADS | Fulltext )
Mannfors E; Juvela M; Bronfman L; Eden DJ; He J; Kim G; Kim K-T; Kirppu H; Liu T; Montillaud J; Parsons H; Sanhueza P; Shang H; Soam A; Tatematsu K; Traficante A; Väisälä MS; Lee CW, "Characterization of dense Planck clumps observed with Herschel and SCUBA-2" , A&A: 654, id.A123 (54pp), Oct, 2021 [SCI] ( ADS | Fulltext )
Väisälä MS; Pekkilä J; Käpylä MJ; Rheinhardt M; Shang H; Krasnopolsky R, "Interaction of Large- and Small-scale Dynamos in Isotropic Turbulent Flows from GPU-accelerated Simulations" , ApJ: 907(2), id.83 (18pp.), Feb, 2021 [SCI] ( ADS | Fulltext )
Vaisala M; Shang H; Krasnopolsky R; Liu S-Y; et al., "Time Evolution of 3D Disk Formation with Misaligned Magnetic Field and Rotation Axes" , ApJ: 873(2), id. 114 (22 pp.), Mar, 2019 [SCI] ( ADS | Fulltext )