| Name: | SAIKHOM PRAVASH SINGH |
| Affiliation: | Indian Institute of Astrophysics, Bengaluru |
| Conference ID: | ASI2025_587 |
| Title: | Dust grain alignment and disruption mechanisms in G34.43+0.24 using thermal dust polarization observations from JCMT/POL-2 |
| Authors: | Saikhom Pravash 1, Archana Soam 1, Pham Ngoc Diep 2,3, Thiem Hoang 4,5, Nguyen Bich Ngoc 2,3, Le Ngoc Tram 6 |
| Authors Affiliation: | 1 Indian Institute of Astrophysics, II Block, Koramangala, 560034, India
2 Department of Astrophysics, Vietnam National Space Center, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, 8Hanoi, Vietnam
3 Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Hanoi, Vietnam
4 Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon 34055, Republic of Korea
5 University of Science and Technology, Korea, 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea
6 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands |
| Mode of Presentation: | Oral |
| Abstract Category: | Stars, Interstellar Medium, and Astrochemistry in Milky Way |
| Abstract: | Polarization of starlight and thermal dust emission due to aligned non-spherical grains helps us to trace magnetic field (B-field) morphology in molecular clouds and to constrain dust grain properties and their alignment mechanisms. Alignment of grains based on RAdiative Torques (RATs) is the most acceptable mechanism that can explain grain alignment from diffused interstellar medium to star-forming regions. In this work, we study the grain alignment and disruption mechanisms in a filamentary infrared dark cloud G34.43+0.24 which harbors multiple cores using polarized thermal dust emission observations from JCMT/POL-2 at 850 µm in three sub-regions as North having MM3 core, Center having MM1, MM2 cores and South having no core. We find decrease in polarization fraction (P) with increasing total intensity, known as polarization hole or depolarization which can be caused by decrease in grain alignment efficiency or magnetic field tangling due to turbulence or both. To disentangle the effect of magnetic field tangling on polarization hole, we estimate polarization angle dispersion function. Our analysis finds depolarizations in North and Center are dominantly due to decrease in net alignment efficiency of grains in denser regions but in South magnetic field tangling is significant to cause depolarization. To test whether RAT Alignment (RAT-A) mechanism can reproduce the observational data, we estimate minimum size of aligned grains using RAT theory. We find RAT-A can explain depolarization in North and Center where B-field tangling effect is less significant, except the MM3 (North), MM1 and MM2 (Center) cores where we find evidence of RAdiative Torque Disruption (RAT-D) that reduces P. We also estimate the effect of enhanced magnetic relaxation on RAT alignment for second time in a filament and find evidence of Magnetically enhanced RAT (M-RAT) alignment mechanism that can explain the observed high P of around 20% in outer parts of the filament. |
