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Superluminal sources

Vermeulen, R. C. (1995) Superluminal sources. Proceedings of the National Academy of Sciences of the United States of America, 93 (25). pp. 11385-11389. ISSN 0027-8424. PMCID PMC40406.

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Predictions for the apparent velocity statistics under simple beaming models are presented and compared to the observations. The potential applications for tests of unification models and for cosmology (source counts, measurements of the Hubble constant H0 and the deceleration parameter q_0) are discussed. First results from a large homogeneous survey are presented. The data do not show compelling evidence for the existence of intrinsically different populations of galaxies, BL Lacertae objects, or quasars. Apparent velocities β_(app) in the range 1-5 h^(-1), where h = H_0/100 km.s^(-1).Mpc^(-1) [1 megaparsec (Mpc) = 3.09 x 10^(22) m], occur with roughly equal frequency; higher values, up to β_(app) = 10 h^(-1), are rather more scarce than appeared to be the case from earlier work, which evidently concentrated on sources that are not representative of the general population. The β_(app) distribution suggests that there might be a skewed distribution of Lorentz factors over the sample, with a peak at y_b ≈ 2 h^(-1) and a tail up to at least y_b ≈ 10 h^(-1). There appears to be a clearly rising upper envelope to the β_(app) distribution when plotted as a function of observed 5-GHz luminosity; a combination of source counts and the apparent velocity statistics in a larger sample could provide much insight into the properties of radio jet sources.

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Additional Information:© 1995 National Academy of Sciences. This review builds on earlier work done in collaboration with Marshall Cohen as cited. It includes many new measurements of the cited CJ VLBI survey sources, which will be published separately after further analysis. Wenge Xu, David Henstock, and Greg Taylor reduced most of the first-epoch data sets; Greg was also heavily involved in working on the second epochs and the motion measurements. The CJ survey has benefitted from generous allocations of time by the Global VLBI Network, involving the dedicated efforts of many people at the individual telescopes. The data were all correlated on the California Institute of Technology-Jet Propulsion Laboratory Block II correlator. The pace of the project would not have been so rapid without Martin Shepherd's DIFMAP (43). Tim Pearson is thanked for his stimulating role as the referee. This work has been supported in part by the National Science Foundation under Grants AST 88-14554, AST 91-17100, and AST 94-20018.
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NSFAST 88-14554
NSFAST 91-17100
NSFAST 94-20018
Issue or Number:25
PubMed Central ID:PMC40406
Record Number:CaltechAUTHORS:20150126-154906224
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Official Citation:Vermeulen RC. Superluminal sources. Proceedings of the National Academy of Sciences of the United States of America 1995;92(25):11385-11389.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:54097
Deposited By: Ruth Sustaita
Deposited On:27 Jan 2015 17:42
Last Modified:11 May 2020 23:02

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