  Electron temperature anisotropies and electron beams are nonthermal features
of the observed nonequilibrium electron velocity distributions in the solar
wind. In collision-poor plasmas these nonequilibrium distributions are expected
to be regulated by kinetic instabilities through wave-particle interactions.
This study considers electron instabilities driven by the interplay of core
electron temperature anisotropies and the electron beam, and firstly gives a
comprehensive analysis of instabilities in arbitrary directions to the
background magnetic field. It clarifies the dominant parameter regime (e.g.,
parallel core electron plasma beta $\beta_{\mathrm{ec\parallel}}$, core
electron temperature anisotropy $A_{\mathrm{ec}}\equiv
T_{\mathrm{ec\perp}}/T_{\mathrm{ec\parallel}}$, and electron beam velocity
$V_{\mathrm{eb}}$) for each kind of electron instability (e.g., the electron
beam-driven electron acoustic/magnetoacoustic instability, the electron
beam-driven whistler instability, the electromagnetic electron cyclotron
instability, the electron mirror instability, the electron firehose
instability, and the ordinary-mode instability). It finds that the electron
beam can destabilize electron acoustic/magnetoacoustic waves in the
low-$\beta_{\mathrm{ec\parallel}}$ regime, and whistler waves in the medium-
and large-$\beta_{\mathrm{ec\parallel}}$ regime. It also finds that a new
oblique fast-magnetosonic/whistler instability is driven by the electron beam
with $V_{\mathrm{eb}}\gtrsim7V_{\mathrm{A}}$ in a regime where
$\beta_{\mathrm{ec\parallel}}\sim0.1-2$ and $A_{\mathrm{ec}}<1$. Moreover, this
study presents electromagnetic responses of each kind of electron instability.
These results provide a comprehensive overview for electron instability
constraints on core electron temperature anisotropies and electron beams in the
solar wind.
