TY - JOUR
T1 - Synchrotr on signatures of cosmic ray transport physics in galaxies
AU - Ponnada, Sam B.
AU - Butsky, Iryna S.
AU - Skalidis, Raphael
AU - Hopkins, Philip F.
AU - Panopoulou, Georgia V.
AU - Hummels, Cameron
AU - Kereš, Dušan
AU - Quataert, Eliot
AU - Faucher-Giguére, Claude André
AU - Su, Kung Yi
N1 - Publisher Copyright:
© 2024 The Author(s).
PY - 2024/5/1
Y1 - 2024/5/1
N2 - Cosmic rays (CRs) may drive outflows and alter the phase structure of the circumgalactic medium, with potentially important implications on galaxy formation. Ho we ver, these ef fects ultimately depend on the dominant mode of transport of CRs within and around galaxies, which remains highly uncertain. To explore potential observable constraints on CR transport, we investigate a set of cosmological FIRE -2 CR-magnetohydrodynamic simulations of L*galaxies which evolve CRs with transport models moti v ated by self-confinement (SC) and extrinsic turbulence (ET) paradigms. To first order, the synchrotron properties diverge between SC and ET models due to a CR physics-driven hysteresis. SC models show a higher tendency to undergo 'ejective' feedback events due to a runaway buildup of CR pressure in dense gas due to the behaviour of SC transport scalings at extremal CR energy densities. The corresponding CR wind-driven hysteresis results in brighter , smoother , and more extended synchrotron emission in SC runs relative to ET and constant diffusion runs. The differences in synchrotron arise from different morphology, interstellar medium gas, and B properties, potentially ruling out SC as the dominant mode of CR transport in typical star-forming L*galaxies, and indicating the prospect for non-thermal radio continuum observations to constrain CR transport physics.
AB - Cosmic rays (CRs) may drive outflows and alter the phase structure of the circumgalactic medium, with potentially important implications on galaxy formation. Ho we ver, these ef fects ultimately depend on the dominant mode of transport of CRs within and around galaxies, which remains highly uncertain. To explore potential observable constraints on CR transport, we investigate a set of cosmological FIRE -2 CR-magnetohydrodynamic simulations of L*galaxies which evolve CRs with transport models moti v ated by self-confinement (SC) and extrinsic turbulence (ET) paradigms. To first order, the synchrotron properties diverge between SC and ET models due to a CR physics-driven hysteresis. SC models show a higher tendency to undergo 'ejective' feedback events due to a runaway buildup of CR pressure in dense gas due to the behaviour of SC transport scalings at extremal CR energy densities. The corresponding CR wind-driven hysteresis results in brighter , smoother , and more extended synchrotron emission in SC runs relative to ET and constant diffusion runs. The differences in synchrotron arise from different morphology, interstellar medium gas, and B properties, potentially ruling out SC as the dominant mode of CR transport in typical star-forming L*galaxies, and indicating the prospect for non-thermal radio continuum observations to constrain CR transport physics.
KW - ISM: magnetic fields
KW - cosmic rays
KW - galaxies: formation
KW - methods: numerical
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U2 - 10.1093/mnrasl/slae017
DO - 10.1093/mnrasl/slae017
M3 - Article
AN - SCOPUS:85188287070
SN - 1745-3925
VL - 530
SP - L1-L6
JO - Monthly Notices of the Royal Astronomical Society: Letters
JF - Monthly Notices of the Royal Astronomical Society: Letters
IS - 1
ER -