| Name: | Dr. ATANU KOLEY |
| Affiliation: | Postdoctoral Fellow, University of Concepcion, Chile |
| Conference ID: | ASI2025_462 |
| Title: | ALMA-IMF XIX: C18O (J = 2−1): Measurements of turbulence in 15 massive protoclusters |
| Authors: | Koley et al. 2024 (in preparation, in collaboration with ALMA-IMF large group) |
| Authors Affiliation: | Dr. Atanu Koley
CATA (The Centre of Excellence in Astrophysics and Related Technologies) postdoctoral Fellow
University of Concepcion, Chile |
| Mode of Presentation: | Oral |
| Abstract Category: | Stars, Interstellar Medium, and Astrochemistry in Milky Way |
| Abstract: | ALIMA-IMF is a large program of the Atacama Large Millimeter/submillimeter Array (ALMA) that aims to determine the origin of the core mass function (CMF) of fifteen massive Galactic protoclusters (∼ 1.0 − 25.0 × 10^3 M⊙, estimated from the dust continuum emission) located towards the Galactic plane. In addition, the objective of the program is to obtain a thorough understanding of their entire physical and kinematic properties. Here we study the turbulence in the protoclusters with C18O (2−1) line using sonic Mach number (M_s) analysis and linewidth-size relation. The probability distribution function (PDF) of the sonic Mach number (M_s) for all of these regions exhibits a similar pattern, peaking between ∼ 4 and ∼ 7 and then extending up to ∼ 30. Values of the sonic Mach numbers (M_s) indicate that turbulence within the protoclusters is supersonic in nature. We also compare the non-thermal velocity
dispersions (σ_nth) obtained from the C18O (2−1) line with the non-thermal line widths (σ_nth) of the cores obtained from the DCN (3−2) line and observe that on average, the non-thermal line widths (σnth) of the cores are approximately half compared to the non-thermal line widths (σ_nth) obtained from the C18O (2−1) lines. This suggests that supersonic turbulence dissipates towards the cores, which are on the verge of star formation. In addition, the linewidth-size relation from the C18O (2−1) line is also examined after extracting the structures from the position-position-velocity (PPV) cube analysis. A relatively large number of structures have been obtained in the evolved protoclusters compared to the young and intermediate protoclusters. This suggests a complex dynamic inside the protoclusters, especially when H ii regions may have a significant impact on the surrounding environment. Moreover, the power-law index (p) obtained from the linewidth-size relation is around 0.50, which is steeper than the Kolmogorov law of turbulence and is expected for compressible media. |
