  We present a realistic numerical model of sunspot and active region formation
based on the emergence of flux bundles generated in a solar convective dynamo.
To this end we use the magnetic and velocity fields in a horizontal layer near
the top boundary of the solar convective dynamo simulation to drive realistic
radiative-magnetohydrodynamic simulations of the upper most layers of the
convection zone. The main results are: (1) The emerging flux bundles rise with
the mean speed of convective upflows, and fragment into small-scale magnetic
elements that further rise to the photosphere, where bipolar sunspot pairs are
formed through the coalescence of the small-scale magnetic elements. (2)
Filamentary penumbral structures form when the sunspot is still growing through
ongoing flux emergence. In contrast to the classical Evershed effect, the
inflow seems to prevail over the outflow in a large part of the penumbra. (3) A
well formed sunspot is a mostly monolithic magnetic structures that is anchored
in a persistent deep-seated downdraft lane. The flow field outside the spot
shows a giant vortex ring that comprises of an inflow below 15 Mm depth and an
outflow above 15 Mm depth. (4) The sunspots successfully reproduce the
fundamental properties of the observed solar active regions, including the more
coherent leading spots with a stronger field strength, and the correct tilts of
bipolar sunspot pairs. These asymmetries can be linked to the intrinsic
asymmetries in the magnetic and flow fields adapted from the convective dynamo
simulation.
