Skip to main content Accessibility help
×
Hostname: page-component-cd9895bd7-jkksz Total loading time: 0 Render date: 2024-12-23T03:00:30.798Z Has data issue: false hasContentIssue false

4 - Quasars and AGN

Published online by Cambridge University Press:  04 May 2023

Kenneth I. Kellermann
Affiliation:
National Radio Astronomy Observatory, Charlottesville, Virginia
Ellen N. Bouton
Affiliation:
National Radio Astronomy Observatory, Charlottesville, Virginia
Get access

Summary

Some celestial objects, later recognized as quasars, were catalogued back in 1887, and their extragalactic nature was discussed as early as 1960. However, the large measured redshift of 3C 48 was rejected, largely because it implied an unrealistically high radio and optical luminosity. Instead it was assumed to be a relatively nearby, less luminous galactic radio star. Following the 1962 observations of lunar occultations of the strong radio source 3C 273 at the Parkes radio telescope and the subsequent identification with an apparent stellar object, Martin Schmidt recognized that 3C 273 had an unmistakable redshift of 0.16. Due to an error in the calculation of the radio position, the occultation position actually played no direct role in the identification of 3C 273, although it was the existence of a claimed accurate occultation position that motivated Schmidt’s 200 inch telescope investigation and his determination of the redshift. Later radio and optical measurements quickly led to the identification of other quasars with increasingly large redshifts, although the nature of the quasar redshifts remained controversial for decades.

Type
Chapter
Information
Publisher: Cambridge University Press
Print publication year: 2023

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Save book to Kindle

To save this book to your Kindle, first ensure [email protected] 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 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.

  • Quasars and AGN
  • Kenneth I. Kellermann, National Radio Astronomy Observatory, Charlottesville, Virginia, Ellen N. Bouton, National Radio Astronomy Observatory, Charlottesville, Virginia
  • Book: Star Noise: Discovering the Radio Universe
  • Online publication: 04 May 2023
  • Chapter DOI: https://doi.org/10.1017/9781009023443.007
Available formats
×

Save book to Dropbox

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.

  • Quasars and AGN
  • Kenneth I. Kellermann, National Radio Astronomy Observatory, Charlottesville, Virginia, Ellen N. Bouton, National Radio Astronomy Observatory, Charlottesville, Virginia
  • Book: Star Noise: Discovering the Radio Universe
  • Online publication: 04 May 2023
  • Chapter DOI: https://doi.org/10.1017/9781009023443.007
Available formats
×

Save book to Google Drive

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

  • Quasars and AGN
  • Kenneth I. Kellermann, National Radio Astronomy Observatory, Charlottesville, Virginia, Ellen N. Bouton, National Radio Astronomy Observatory, Charlottesville, Virginia
  • Book: Star Noise: Discovering the Radio Universe
  • Online publication: 04 May 2023
  • Chapter DOI: https://doi.org/10.1017/9781009023443.007
Available formats
×