  The magnetization of solar and extrasolar gas giants is critically dependent
on electronic and mass transport coefficients of their convective fluid
interiors. We analyze recent laboratory experimental results on metallic
hydrogen to derive a new conductivity profile for the Jovian-like planets. We
combine this revised conductivity with a polytropic-based thermodynamic
equation of state to study the dynamo action in 100 extrasolar giant planets
varying from synchronous hot jupiters to fast rotators, with masses ranging
from 0.3MJ to 15MJ. We find conducting cores larger than previous estimates,
but consistent with the results from Juno, suggesting that the dynamos in the
more massive planets might be shallow-seated. Our results reveal that most
extrasolar giants are expected to possess dipole surface magnetic fields in the
range of 0.1-10 Gauss. Assuming radio emission processes similar to our solar
giants, most characterized planets should emit radiation with a maximum
cyclotron frequency between few and 30 MHz, lower than previous estimates. Our
work places new bounds on the observational detectability of extrasolar
magnetic fields.
