Synthetic Modeling of Polarized Dust Emission in Intermediate-mass Young Stellar Objects. II. Effects of Radiative Torque Disruption on Dust Grains in Protostellar Jets/Outflows

Abstract One possible explanation for the presence of very large grains (VLGs) larger than 10 μ m in the inner envelope of intermediate-mass Class 0/I young stellar objects is their migration from the protostellar disk via outflows. To assess whether RATD hinders this grain transport, we conducted numerical modeling of RATD alongside grain dynamics, using gas velocity and density profiles from an MHD simulation of an intermediate Class 0 protostar. Our results show that, when the central luminosity L center is ≥5 L ⊙ , porous grains larger than 1 μ m with tensile strengths <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>S</mml:mi> <mml:mi>max</mml:mi> </mml:msub> <mml:mo>∼</mml:mo> <mml:mn>1</mml:mn> <mml:msup> <mml:mn>0</mml:mn> <mml:mn>3</mml:mn> </mml:msup> <mml:mo>-</mml:mo> <mml:mn>1</mml:mn> <mml:msup> <mml:mn>0</mml:mn> <mml:mn>4</mml:mn> </mml:msup> <mml:mspace width="0.25em"/> <mml:mi>erg</mml:mi> <mml:mspace width="0.25em"/> <mml:msup> <mml:mi>cm</mml:mi> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>3</mml:mn> </mml:mrow> </mml:msup> </mml:math> are efficiently destroyed by RATD at the outflow within ∼1 yr. This limits the outward migration of VLGs/submillimeter grains and leads submicron grains to dominate a few hundred astronomical unit inside the outflow cavity until L center drops below &lt;5 L ⊙ . In contrast, L center &gt; 20 L ⊙ is required for RATD significantly affecting aggregate/composite grains with higher <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>S</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">max</mml:mi> </mml:mrow> </mml:msub> <mml:mspace width="0.25em"/> <mml:mo>≥</mml:mo> <mml:mspace width="0.25em"/> <mml:mn>1</mml:mn> <mml:msup> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>5</mml:mn> </mml:mrow> </mml:msup> <mml:mspace width="0.25em"/> <mml:mi mathvariant="normal">erg</mml:mi> <mml:mspace width="0.25em"/> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">cm</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>3</mml:mn> </mml:mrow> </mml:msup> </mml:math> . We further incorporated RATD into POLARIS under the assumption that grains remain stationary. POLARIS accurately models the disruption for porous grains, but overestimates results for aggregate/composite grains at L center = 100 L ⊙ . At such high luminosities, the destruction of VLGs with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>S</mml:mi> <mml:mi>max</mml:mi> </mml:msub> <mml:mo>∼</mml:mo> <mml:mn>1</mml:mn> <mml:msup> <mml:mn>0</mml:mn> <mml:mn>3</mml:mn> </mml:msup> <mml:mo>-</mml:mo> <mml:mn>1</mml:mn> <mml:msup> <mml:mn>0</mml:mn> <mml:mn>4</mml:mn> </mml:msup> <mml:mspace width="0.25em"/> <mml:mi>erg</mml:mi> <mml:mspace width="0.25em"/> <mml:msup> <mml:mi>cm</mml:mi> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>3</mml:mn> </mml:mrow> </mml:msup> </mml:math> within the outflow cavity wall and inner envelope (after ∼20 yr) can reduce the observed polarization degree along the cavity wall by a factor of 2. However, RATD is not the dominant factor shaping dust polarization; magnetic inclusions, such as iron, play a more significant role.