TY  - JOUR
A1  - Petruk, Oleh
A1  - Kuzyo, T.
A1  - Orlando, S.
A1  - Pohl, Martin
A1  - Miceli, M.
A1  - Bocchino, F.
A1  - Beshley, V.
A1  - Brose, Robert
T1  - Post-adiabatic supernova remnants in an interstellar magnetic field
BT  - oblique shocks and non-uniform environment
JF  - Monthly notices of the Royal Astronomical Society
N2  - We present very-high-resolution 1D MHD simulations of the late-stage supernova remnants (SNRs). In the post-adiabatic stage, the magnetic field has an important and significant dynamical effect on the shock dynamics, the flow structure, and hence the acceleration and emission of cosmic rays. We find that the tangential component of the magnetic field provides pressure support that to a fair degree prevents the collapse of the radiative shell and thus limits the total compression ratio of the partially or fully radiative forward shock. A consequence is that the spectra of cosmic rays would not be as hard as in hydrodynamic simulations. We also investigated the effect on the flow profiles of the magnetic-field inclination and a large-scale gradient in the gas density and/or the magnetic field. A positive density gradient shortens the evolutionary stages, whereas a shock obliquity lowers the shock compression. The compression of the tangential component of the magnetic field leads to its dominance in the downstream region of post-adiabatic shocks for a wide range of orientation of the upstream field, which may explain why one preferentially observes tangential radio polarization in old SNRs. As most cosmic rays are produced at late stages of SNR evolution, the post-adiabatic phase and the influence of the magnetic field during it are most important for modeling the cosmic-ray acceleration at old SNRs and the gamma-ray emission from late-stage SNRs interacting with clouds.
KW  - shock waves
KW  - ISM: magnetic fields
KW  - ISM: supernova remnants
Y1  - 2018
U6  - https://doi.org/10.1093/mnras/sty1750
SN  - 0035-8711
SN  - 1365-2966
VL  - 479
IS  - 3
SP  - 4253
EP  - 4270
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Zhang, Heshou
A1  - Yan, Huirong
T1  - Polarization of submillimetre lines from interstellar medium
JF  - Monthly notices of the Royal Astronomical Society
N2  - Magnetic fields play important roles in many astrophysical processes. However, there is no universal diagnostic for the magnetic fields in the interstellar medium (ISM) and each magnetic tracer has its limitation. Any new detection method is thus valuable. Theoretical studies have shown that submillimetre fine-structure lines are polarized due to atomic alignment by ultraviolet photon-excitation, which opens up a new avenue to probe interstellar magnetic fields. We will, for the first time, perform synthetic observations on the simulated three-dimensional ISM to demonstrate the measurability of the polarization of submillimetre atomic lines. The maximum polarization for different absorption and emission lines expected from various sources, including star-forming regions are provided. Our results demonstrate that the polarization of submillimetre atomic lines is a powerful magnetic tracer and add great value to the observational studies of the submilimetre astronomy.
KW  - polarization
KW  - turbulence
KW  - H II regions
KW  - ISM: magnetic fields
KW  - photodissociation region (PDR)
KW  - submillimetre: ISM
Y1  - 2017
U6  - https://doi.org/10.1093/mnras/stx3164
SN  - 0035-8711
SN  - 1365-2966
VL  - 475
IS  - 2
SP  - 2415
EP  - 2420
PB  - Oxford University Press
CY  - Oxford
ER  -