Small-scale Intensity Mapping: Extended Ly$\alpha$, H$\alpha$ and
  Continuum emission as a Probe of Halo Star Formation in High-redshift
  Galaxies
  Lyman alpha halos are observed ubiquitously around star-forming galaxies at
high redshift, but their origin is still a matter of debate. We demonstrate
that the emission from faint unresolved satellite sources, $M_{\rm UV} \gtrsim
-17$, clustered around the central galaxies may play a major role in generating
spatially extended Ly$\alpha$, continuum (${\rm UV + VIS}$) and H$\alpha$
halos. We apply the analytic formalism developed in Mas-Ribas & Dijkstra (2016)
to model the halos around Lyman Alpha Emitters (LAEs) at $z=3.1$, for several
different satellite clustering prescriptions. In general, our UV and Ly$\alpha$
surface brightness profiles match the observations well at $20\lesssim r
\lesssim 40$ physical kpc from the centers of LAEs. We discuss how our profiles
depend on various model assumptions and how these can be tested and constrained
with future H$\alpha$ observations by the James Webb Space Telescope (JWST).
Our analysis shows how spatially extended halos constrain (i) the presence of
otherwise undetectable satellite sources, (ii) the integrated, volumetric
production rates of Ly$\alpha$ and LyC photons, and (iii) their
population-averaged escape fractions. These quantities are all directly
relevant for understanding galaxy formation and evolution and, for high enough
redshifts, cosmic reionization.
