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How Strong Should an Emission Line Be for BL Lac Classification?

Published online by Cambridge University Press:  12 April 2016

M.J.M. Marchã
M.J.M. Marchã*
Affiliation:
University of Lisbon, Complexo II da Universidade de Lisboa, Av. Prof. Gama Pinto 2, 1699 Lisboa Codex, Portugal

Abstract

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An equivalent-width limit EW < 5 Å has been imposed as a selection criterion for BL Lac objects. However, such sharp cutoff has no physical meaning, and it is likely to be biasing BL Lac samples. This result is suggested by the analysis of a sample of low-luminosity, flat radiospectrum sources selected for the purpose of investigating the limits of BL Lac phenomena. In this work it is proposed that, instead of imposing sharp limits on the quantities observed, we should look for clear breaks occurring in the distributions of the observed properties for each sample.

Type
IX. Surveys and Properties of Active Galaxies and Related Sources
Information
International Astronomical Union Colloquium , Volume 159: Emission Lines in Active Galaxies: New Methods and Techniques , 1997 , pp. 441 - 442
Copyright
Copyright © Astronomical Society of the Pacific 1997

References

Marchã, M.J.M., Browne, I.W.A., Impey, C.D., & Smith, P.S. 1996, MNRAS, 281, 425.Google Scholar
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