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Mergers and starbursts at large redshifts - The case of 3C 368

Djorgovski, S. and Spinrad, H. and Pedelty, J. and Rudnick, L. and Stockton, A. (1987) Mergers and starbursts at large redshifts - The case of 3C 368. Astronomical Journal, 93 (6). pp. 1307-1317. ISSN 0004-6256. doi:10.1086/114413.

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We report the results of a multiwavelength study of the high-redshift radio galaxy 3C 368, which is observed at a lookback time of about two-thirds of the present galaxian age. This galaxy has optical and spectroscopic properties that are perhaps typical for the powerful 3CR galaxies at large redshifts (z > 1 ), though it is probably more luminous than the most, both in continuum and [O II]. Its resolved, multicomponent morphology of the starlight continuum and the [O II] λ 3727 emission-line gas, and the properties of the ionized-gas velocity field, are suggestive of a strong and highly dissipative merger. There is a good positional and morphological coincidence between the line emission and the optical continuum. The proposed merger is probably enhancing the star formation over the whole galaxy (as evidenced by the large luminosity and the blue colors of the optical continuum), and may be the primary source of the fuel for, or even the trigger of, the strong radio emission from the system. The morphological and spectroscopic similarities with other 3CR galaxies at z > 1 suggest that spectacular merging was a common process in such systems at early epochs. The mergers may be identified with the process of transformation of (large?) E galaxies into cD’s, and the epoch of such “secondary” formation of gE/cD galaxies may be signalled by the appearance of powerful radio sources at z ~ 1-2. The galaxy evolution models with a continuing star formation, suggested by the colors and magnitudes of high-redshift 3CR galaxies, may be understood in terms of a declining sequence of starbursts, stimulated by gas-rich mergers. There are also some indications of an ongoing interaction between the radio lobes and the ambient gas: both radio lobes show a prominent Faraday rotation and depolarization, probably caused by the intervening plasma along the line of sight. There is also a reasonable positional coincidence between the southern radio lobe and the emission-line gas. However, the evidence for an interaction between the radio plasma and the gas in the host galaxy is neither clear nor unambiguous.

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Djorgovski, S.0000-0002-0603-3087
Additional Information:© 1987 American Astronomical Society. Provided by the NASA Astrophysics Data System. Received 24 December 1986; revised 20 February 1987. Based in part on the observations done at Lick Observatory, University of California. We wish to thank the crews of several observatories, who helped in obtaining the data used here: Kitt Peak, CFHT, VLA, and Lick. S. D. was supported in part by Harvard University. H. S. was supported by the NSF grant AST85-13416. L. R. and J. P. were supported by NSF grants AST83-15949 and AST84-05930. A. S. was supported by NSF grant AST83-17457. S. D. and H. S. would like to thank the Canadian CFHT time-allocation committee for the observing time during which some of the data presented here were obtained.
Funding AgencyGrant Number
Harvard UniversityUNSPECIFIED
NSFAST 85-13416
NSFAST 83-15949
NSFAST 84-05930
NSFAST 83-17457
Issue or Number:6
Record Number:CaltechAUTHORS:20190731-160805378
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:97568
Deposited By: Tony Diaz
Deposited On:01 Aug 2019 15:10
Last Modified:16 Nov 2021 17:32

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