  The recent 230 GHz observations from the Event Horizon Telescope
collaboration can image the innermost structure of the M87 galaxy showing the
shadow of the black hole, a photon ring, and a ring-like structure that agrees
with thermal synchrotron emission from the accretion disc. However, at lower
frequencies, M87 is characterized by a large-scale jet with clear signatures of
nonthermal emission. It is necessary to explore the impacts of nonthermal
emission on black hole shadow images and extended jets, especially at lower
frequencies. In this study, we aim to compare models with different electron
heating prescriptions and investigate how these prescriptions and nonthermal
electron distributions may affect black hole shadow images and the broadband
spectrum energy distribution (SED) function. We performed general relativistic
radiative transfer (GRRT) calculations in various two-temperature general
relativistic magnetohydrodynamic (GRMHD) models utilizing different black hole
spins and different electron heating prescriptions coupled with different
electron distribution functions (eDFs). Through a comparison with GRRT images
and SEDs, we found that when considering a variable kappa eDF, the
parameterized prescription of the R-beta model with Rh = 1 is similar to the
model with electron heating in the morphology of images, and the SEDs at a
high-frequency. This is consistent with previous studies using the thermal eDF.
However, the nuance between them could be differentiated through the diffuse
extended structure seen in GRRT images, especially at a lower frequency, and
the behavior of SEDs at low frequency. The emission from the nearside jet
region is enhanced in the reconnection heating case and it will increase the
contribution from the regions with stronger magnetization is included or if the
magnetic energy contribution to kappa eDF mainly in the magnetized regions is
considered.
