Kavli Affiliate: Feng Yuan
| First 5 Authors: , , , ,
| Summary:
We investigate the synchrotron emission signatures of shocks driven by active
galactic nucleus (AGN) wind in elliptical galaxies based on our two-dimensional
axisymmetric hydrodynamic MACER numerical simulations. Using these simulation
data, we calculate the synchrotron radiation produced by nonthermal electrons
accelerated at shocks, adopting reasonable assumptions for the magnetic field
and relativistic electron distribution (derived from diffusive shock
acceleration theory), and predict the resulting observational signatures. In
our fiducial model, shocks driven by AGN winds produce synchrotron emission
with luminosities of approximately $10^29,mathrmerg,s^-1,Hz^-1$ in
the radio band (0.5-5 GHz), with spectral indices of $alpha approx -0.4$ to
$-0.6$ during the strongest shock phases, gradually steepening to about $-0.8$
to $-1.4$ as the electron population ages. Spatially, the emission is initially
concentrated in regions of strong shocks, later expanding into more extended,
diffuse structures. We also apply our model to the dwarf elliptical galaxy
Messier 32 (M32), and find remarkable consistency between our simulated
emission and the observed nuclear radio source, suggesting that this radio
component likely originates from hot-wind-driven shocks. Our results indicate
that AGN winds not only influence galaxy gas dynamics through mechanical energy
input but also yield direct observational evidence via nonthermal radiation.
With the advent of next-generation radio facilities such as the FAST Core
Array, SKA, and ngVLA, these emission signatures serve as important probes for
detecting and characterizing AGN feedback.
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