vlbi proper motions observed

GPS/CSO radio sources are the progenitors of the large scale radio sources

GPS/CSO are small radio sources in the nuclei of galaxies. They are thought to grow into large radio sources which extend beyond their host galaxies into the intergalactic medium.  There is some evidence that at least some of these sources are not going to become large radio sources. 

the gps cso sources must have sufficient velocity

We assume that if the GPS CSO radio sources are expanding fast enough that they will reach a size of at least 10 kpc in less than one million years, then they can be considered to be the progenitors of the large scale sources.

the gps cso sources must live long enough

We assume that if the gps cso sources have life times which are at least one million years, and they are expanding rapidly enough they will become large scale radio sources

vlbi proper motions are consistent with expansion

vlbi proper motions show expansion at velocities of about 0.1 c

too many gps cso sources

There seem to be too many gps cso sources relative to the extrapolation of the relation between size and number seen at larger sizes. This sugests that not all of them can evolve to become large sources, perhaps because they are trapped on small scales by dense environments or perhaps their lifetimes are short. Or perhaps they are intrinsically weak interlopers which are brightened to the observed radio fluxes by confinement.

gps cso found in star forming environments

work by tadhunter and collaborators shows that gps sources are found associated with star forming regions much more frequently than large scale radio sources.  this would be consistent with sources in star forming regions being boosted in radio flux density because they are confined by the dense star forming gas.

GPS CSO live long enough to become large sources

We assume that the GPS and CSO sources have lifetimes of at least 1 million years.

Expansion velocities are sufficient

We assume that expansion velocities of the GPS/CSO sources are sufficient for them to reach at least 10 kpc sizes in less than one million years.

confinement/interaction increases radio power

We assume that confinement and interaction of radio sources with dense interstellar clouds will increase the radio power.

confinement/interaction increases radio power

We assume that confinement and interaction of a radio source with dense interstellar clouds will increase its radio power

Arguments in Favor

Arguments in Favor

vlbi propermotions are consistent with expansion

Arguments against