No CrossRef data available.
Published online by Cambridge University Press: 15 February 2018
There is a growing body of evidence that the non-thermal extra-galactic sources in the Universe- -the Radio Galaxies, Seyfert nuclei, QSO's, BL Lacertae objects and the X-ray galaxies- -are all powered ultimately by collapsed objects at the centers of galaxies. Moreover, there is no reason at this stage to doubt that the central energy source is probably the same in all cases. At this point, five years before the Space Telescope is to be launched, the fundamental problem is to identify the nature of the central engine and then to understand in detail the variety of observed phenomena.
To send this article to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Find out more about the Kindle Personal Document Service.
To save this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you used this feature, you will be asked to authorise Cambridge Core to connect with your Dropbox account. Find out more about saving content to Dropbox.
To save this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you used this feature, you will be asked to authorise Cambridge Core to connect with your Google Drive account. Find out more about saving content to Google Drive.