arXiv subjects

Erica L. Fogerty

Publications and source records attributed to Erica L. Fogerty.

3 recordsLinked to original sources

arXiv2019

Dust destruction by the reverse shock in the clumpy supernova remnant Cassiopeia A based on hydrodynamic simulations

Observations of the ejecta of core-collapse supernovae have shown that dust grains form in over-dense gas clumps in the expanding ejecta. The clumps are later subject to the passage of the reverse shock and a significant amount of the newly formed dust material can be destroyed due to the high temperatures and high velocities in the post-shock gas. To determine dust survival rates, we have performed a set of hydrodynamic simulations using the grid-based code AstroBEAR in order to model a shock wave interacting with a clump of gas and dust. Afterwards, dust motions and dust destruction rates are computed using our newly developed external, post-processing code Paperboats, which includes gas and plasma drag, grain charging, kinematic and thermal sputtering as well as grain-grain collisions. We have determined dust survival rates for the oxygen-rich supernova remnant Cassiopeia A as a function of initial grain sizes, dust materials and clump gas densities.

astro-ph.GA↗

arXiv2019

Dust survival rates in clumps passing through the Cas A reverse shock I: results for a range of clump densities

The reverse shock in the ejecta of core-collapse supernovae is potentially able to destroy newly formed dust material. In order to determine dust survival rates, we have performed a set of hydrodynamic simulations using the grid-based code AstroBEAR in order to model a shock wave interacting with clumpy supernova ejecta. Dust motions and destruction rates were computed using our newly developed external, post-processing code Paperboats, which includes gas drag, grain charging, sputtering and grain-grain collisions. We have determined dust destruction rates for the oxygen-rich supernova remnant Cassiopeia A as a function of initial grain sizes and clump gas density. We found that up to 30 % of the carbon dust mass is able to survive the passage of the reverse shock if the initial grain size distribution is narrow with radii around ~10 - 50 nm for high gas densities, or with radii around ~0.5 - 1.5 $μ$m for low and medium gas densities. Silicate grains with initial radii around 10 - 30 nm show survival rates of up to 40 % for medium and high density contrasts, while silicate material with micron sized distributions is mostly destroyed. For both materials, the surviving dust mass is rearranged into a new size distribution that can be approximated by two components: a power-law distribution of small grains and a log-normal distribution of grains having the same size range as the initial distribution. Our results show that grain-grain collisions and sputtering are synergistic and that grain-grain collisions can play a crucial role in determining the surviving dust budget in supernova remnants.

astro-ph.SR↗

arXiv2017

Reorienting MHD Colliding Flows: A Shock Physics Mechanism for Generating Filaments Normal to Magnetic Fields

We present numerical simulations of reorienting oblique shocks that form in the collision layer between magnetized colliding flows. Reorientation aligns parsec-scale post-shock filaments normal to the background magnetic field. We find that reorientation begins with pressure gradients between the collision region and the ambient medium. This drives a lateral expansion of post-shock gas, which reorients the growing filament from the outside-in (i.e. from the flow-ambient boundary, toward the colliding flows axis). The final structures of our simulations resemble polarization observations of filaments in Taurus and Serpens South, as well as the integral-shaped filament in Orion A. Given the ubiquity of colliding flows in the interstellar medium, shock reorientation may be relevant to the formation of filaments normal to magnetic fields.

astro-ph.GA↗