  We present for the first-time the photonuclear cross section of $^{10}$B
calculated within the ab-initio No Core Shell Model framework. Realistic
two-nucleon (NN) chiral forces up to next-to-next-to-next-order (N3LO), which
have been softened by the similarity renormalization group method (SRG) to
$\lambda=2.02$ fm$^{-1}$, were utilized. The electric-dipole response function
is calculated using the Lanczos method. The effects of the continuum were
accounted for by including neutron escape widths derived from R-matrix theory.
The calculated cross section agrees well with experimental data in terms of
structure as well as in absolute peak height, $\sigma_{\rm max}=4.85~{\rm mb}$
at photon energy $\omega=23.61~{\rm MeV}$, and integrated cross section
$85.36\, {\rm MeV \cdotp mb}$. We test the Brink hypothesis by calculating the
electric-dipole response for the first five positive-parity states in $^{10}$B
and verify that dipole excitations built upon the ground- and excited states
have similar characteristics.
