Understanding the fanaroff-riley radio galaxy classification

Saripalli, Lakshmi

Please use this identifier to cite or link to this item: http://hdl.handle.net/2289/5562

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DC Field	Value	Language
dc.contributor.author	Saripalli, Lakshmi	-
dc.date.accessioned	2013-04-25T06:05:51Z	-
dc.date.available	2013-04-25T06:05:51Z	-
dc.date.issued	2012-09	-
dc.identifier.citation	Astronomical Journal, 2012, Vol.144, p85	en
dc.identifier.issn	0004-6256	-
dc.identifier.issn	1538-3881(Online)	-
dc.identifier.uri	http://hdl.handle.net/2289/5562	-
dc.description	Restricted Access. An open-access version is available at arXiv.org (one of the alternative locations)	en
dc.description.abstract	A simple, yet profoundly far-reaching classification scheme based on extended radiomorphologies of radio galaxies, the Fanaroff-Riley (FR) classification has been a cornerstone in our understanding of radio galaxies. Over the decades since the recognition that there are two basic types of radio galaxy morphologies, there have been several findings in different wavebands that have reported properties on different scales. Although it is realized that there may be intrinsic as well as external causes, an overarching view of how we may understand the two morphological types is missing. With the radio-power-absolute-magnitude relation (the Owen-Ledlow diagram) as a backdrop, we review and develop an understanding of the two radio galaxy types in light of what is known about them. We have for the first time included the dust properties of the two FR classes together with the relative orientations of dust, host major axis, and the radio axis to present a qualitative framework within which to understand the conditions under which they form. We discuss how the host elliptical and its history can explain the distribution of radio galaxies in the Owen-Ledlow diagram. The mass of the host elliptical galaxy is a crucial player in deciding what type of a radio galaxy it can host in what conditions. Benign conditions, characterized by natural evolutionary processes, most easily give rise to FR-I-type sources in ellipticals of all mass regimes, whereas with FR-IIs we reason that it is hard to form them without mergers. In undisturbed conditions elliptical galaxies appear to acquire stable states where the black hole axis settles along the host minor axis. With the steady conditions and the continuous supply of ambient gas, the FR-Is in principle may be powered for a long time. Aided by mergers and interactions, low-mass ellipticals more easily form FR-II-type sources than more massive hosts. LEG FR-IIs may include dying as well as restarted FR-II radio galaxies.	en
dc.language.iso	en	en
dc.publisher	American Astronomical Society	en
dc.relation.uri	http://adsabs.harvard.edu/abs/2012AJ....144...85S	en
dc.relation.uri	http://dx.doi.org/10.1088/0004-6256/144/3/85	en
dc.rights	2012 American Astronomical Society	en
dc.subject	galaxies	en
dc.subject	elliptical and lenticular	en
dc.subject	jets	en
dc.subject	nuclei	en
dc.subject	radio continuum	en
dc.title	Understanding the fanaroff-riley radio galaxy classification	en
dc.type	Article	en
Appears in Collections:	Research Papers (A&A)

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