We have observed a sample of nine Extended Green Objects (EGOs) at 1.3 and 5cm with the Very Large Array (VLA) with subarcsecond resolution and ~7-14{mu}Jy/beam-sensitivities in order to characterize centimeter continuum emission as it first appears in these massive protoclusters. We find an EGO-associated continu um emission --within 1" of the extended 4.5{mu}m emission-- in every field, which is typically faint (order 10^1^-10^2^{mu}Jy) and compact (unresolved at 0.3"-0.5"). The derived spectral indices of our 36 total detections are consistent with a wide array of physical processes, including both non-thermal (19% of detections) and thermal free-free processes (e.g., ionized jets and compact HII regions, 78% of sample) and warm dust (1 source). We also find an EGO-associated 6.7GHz CH_3_OH and 22GHz H_2_O maser emission in 100% of the sample and a NH_3_(3,3) masers in ~45%; we do not detect any NH_3_(6,6) masers at ~5.6mJy/beam sensitivity. We find statistically-significant correlations between Lradio and Lbol at two physical scales and three frequencies, consistent with thermal emission from ionized jets, but no correlation between L_H2O_ and L_radio_ for our sample. From these data, we conclude that EGOs likely host multiple different centimeter continuum-producing processes simultaneously. Additionally, at our ~1000au resolution, we find that all EGOs except G18.89-0.47 contain 1~2 massive sources based on the presence of CH_3_OH maser groups, which is consistent with our previous work suggesting that these are typical massive protoclusters, in which only one to a few of the young stellar objects are massive.

Cone search capability for table J/ApJ/923/263/table1 (Extended Green Object (EGO) source properties)

Cone search capability for table J/ApJ/923/263/table4 (Properties of centimeter continuum sources)

Cone search capability for table J/ApJ/923/263/table5 (Extended centimeter continuum sources: flux density not recoverable in one or both bands)

Cone search capability for table J/ApJ/923/263/table6 (Summary of maser emission)

Cone search capability for table J/ApJ/923/263/table7 (2D Gaussian fit results)