Event Horizon Telescope ( EHT ) observations at 230 GHz are combined with Very Long Baseline Interferometry ( VLBI ) observations at 86 GHz and high resolution Hubble Space Telescope optical observations in order to constrain the broadband spectrum of the emission from the base of the jet in M87 .
The recent VLBI observations of Hada et al provide much stricter limits on the 86 GHz luminosity and component acceleration in the jet base than was available to previous modelers .
They reveal an almost hollow jet on sub-mas scales .
Thus , tubular models of the jet base emanating from the innermost accretion disk are considered within the region responsible for the EHT correlated flux .
There is substantial synchrotron self absorbed opacity at 86 GHz .
A parametric analysis indicates that the jet dimensions and power depend strongly on the 86 GHz flux density and the black hole spin , but weakly on other parameters such as jet speed , 230 GHz flux density and optical flux .
The entire power budget of the M87 jet , \lesssim 10 ^ { 44 } ergs / sec , can be accommodated by the tubular jet .
No invisible , powerful spine is required .
Even though this analysis never employs the resolution of the EHT , the spectral shape implies a dimension transverse to the jet direction of 12-21 \muas ( \sim 24-27 \muas ) for 0.99 > a / M > 0.95 ( a / M \sim 0.7 ) , where M is the mass and a is the angular momentum per unit mass of the central black hole .