  Dwarf galaxies located in extremely under-dense cosmic voids are excellent
test-beds for disentangling the effects of large-scale environment on galaxy
formation and evolution. We present integral field spectroscopy for low-mass
galaxies ($M_{\star}=10^{7}-10^{9}~M_{\odot}$) located inside (N=21) and
outside (N=9) cosmic voids using the Keck Cosmic Web Imager (KCWI). Using
measurements of stellar line-of-sight rotational velocity $v_{\mathrm{rot}}$
and velocity dispersion $\sigma_{\star}$, we test the tidal stirring
hypothesis, which posits that dwarf spheroidal galaxies are formed through
tidal interactions with more massive host galaxies. We measure low values of
$v_{\mathrm{rot}}/\sigma_{\star}\lesssim2$ for our sample of isolated dwarf
galaxies, and we find no trend between $v_{\mathrm{rot}}/\sigma_{\star}$ and
distance from a massive galaxy $d_{L^{\star}}$ out to $d_{L^{\star}}\sim10$
Mpc. These suggest that dwarf galaxies can become dispersion-supported "puffy"
systems even in the absence of environmental effects like tidal interactions.
We also find indications of an upward trend between
$v_{\mathrm{rot}}/\sigma_{\star}$ and galaxy stellar mass, perhaps implying
that stellar disk formation depends on mass rather than environment. Although
some of our conclusions may be slightly modified by systematic effects, our
main result still holds: that isolated low-mass galaxies may form and remain as
puffy systems rather than the dynamically cold disks predicted by classical
galaxy formation theory.
