Emission-line properties of 3CR radio galaxies III: origins and implications of the velocity fields

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dc.contributor.author Baum, Stefi en_US
dc.contributor.author McCarthy, Patrick en_US
dc.date.accessioned 2006-05-08T22:54:46Z en_US
dc.date.available 2006-05-08T22:54:46Z en_US
dc.date.issued 2000-06 en_US
dc.identifier.citation Astrophys.J. 119 (2000) 2634-2644 en_US
dc.identifier.issn 1538-4365 en_US
dc.identifier.uri http://hdl.handle.net/1850/1763 en_US
dc.description Also archived in: arXiv: astro-ph/0002329 v1 16 Feb 2000 en_US
dc.description.abstract We present the results of an analysis of the large scale velocity fields of the ionized gas associated with powerful radio galaxies. Long-slit spectra of 52 objects provide a sample of resolved velocities that span a wide range of redshifts, radio and emission-line luminosities. Line widths reaching 1000 km s−1 and resolved velocity fields with amplitudes of up 1500 km s−1 are found on scales from 10 to 100 kpc in the environments of radio galaxies at redshifts larger than 0.5. The global velocities and FWHM are of comparable amplitudes in the FRII sources, while the FRI sources have FWHM values that are larger than their resolved velocity fields. We find evidence for systematically larger line widths and velocity field amplitudes at z > 0.6. Several of the largest amplitude systems contain two galaxies with small projected separations. All of the > 1000 km s−1 systems occur in objects at z > 0.6 and all have comparable radio and [OII] sizes. There is a weak correlation of off-nuclear line widths and velocity field with the ratio of the radio and emission-line sizes, but it is of low statistical significance and there is a very large dispersion. The change in properties at redshifts above z ~ 0.6 could reflect a difference in environments of the host galaxies, with the hosts inhabiting higher density regions with increasing redshift (e.g., Hill & Lilly 1991). The mass of ionized gas and the apparent enclosed dynamical mass are correllated and both increase steeply with redshift and/or radio power. The origin of the velocities remains uncertain. The data do not require jet-gas interactions to explain the kinematics and superficially are slightly more consistent with gravitational origins for the bulk of the kinematics. If the line width reflects the underlying gravitational potential, the observed FWHM traces the velocity dispersion of the host galaxy or its surrounding group or cluster. The highest velocities seen then point to interesting environments for intermediate and high redshift radio galaxies. Turbulent interactions with the expanding radio source as the origin of the kinematics are certainly not ruled out. In the jet interaction scenario, the maximum velocities seen in the nebula can be used to constrain the density of the pre-shock gas to be roughly ne > 0.6 cm−3 (Refer to PDF file for exact formulas). en_US
dc.description.sponsorship We thank the staffs of the Kitt Peak and Cerro Tololo sites of the National Optical Astronomy Observatories as well as those of the Lick and Palomar Observatories. At the time these observations were being carried out, the Carnegie Institution had access to the Hale 5 m telescope under a cooperative agreement with the California Institute of Technology. en_US
dc.format.extent 224097 bytes en_US
dc.format.mimetype application/pdf en_US
dc.language.iso en_US en_US
dc.publisher Astrophysical Journal en_US
dc.relation.ispartofseries vol. 119 en_US
dc.relation.ispartofseries no. 6 en_US
dc.subject Galaxies - kinematics and dynamics en_US
dc.subject Radio emission lines en_US
dc.title Emission-line properties of 3CR radio galaxies III: origins and implications of the velocity fields en_US
dc.type Article en_US

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