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Are some BL Lacs artefacts of gravitational lensing?

Abstract

WE suggested in 1985 that a significant fraction of BL Lacertae objects, a kind of lineless quasar, seen in nearby galaxies are in fact images, gravitationally lensed and substantially amplified by stars in the nearby galaxy, of background objects, optically violent variable (OVV) quasars at redshifts z > 1 (ref. 1). This hypothesis was made on the basis of certain general similarities between BL Lacs and O Ws, but for two recently observed BL Lacs2,3 a strong case can be made that the accompanying elliptical galaxy is a foreground object. In addition, we argue that the distribution of BL Lac redshifts is hard to understand without gravitational lensing, unless we happen to be at a very local maximum of the spatial cosmic distribution of BL Lacs. Our analysis also indicates that the galaxies whose stars are likely to act as microlenses will be found in two peaks, one nearby, with redshift 0.05–0.10, and the other near the distant quasar.

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References

  1. 2. Stickel, M., Fried, J. W. & Kühr, H. Astr. Astrophys. 198, L13–L16 (1988). 3. Stickel, M. in Proc. BL LAC Objects: 10 Years After (eds Maraschi, L, Maccacaro, T. & Hulrich, U.) (Springer, Berlin, in the press). 4. Arp, H. & Sargent, W. L. W. Astrophys. J. 230, 68–78 (1979). 5. Kayser, R. Astr. Astrophys. 206, L8–L10 (1988). 6. Paczynski, B. Astrophys. J. 301, 503–516 (1986). 7. Deguchi, S. & Watson, W. D. Astrophys. J. 335, 67–73 (1988). 8. Blades, J. C., Hunstead, R. W., Murdoch, H. S. & Pettinci, M. in IAU Symp. No. 119 Quasars (eds Swarup, G. & Kapachi, V. K.) 571–572 (Reidel, Dordrecht, 1986). 9. Burbidge, G. & Hewitt, A. Astr. J. 93, 1–5 (1987). 10. Braccesi, A., Zitelli, V., Bonoli, F. & Formiggini, L. Astr. Astrophys. 85, 80–92 (1980). 11. Turner, E. L, Ostriker, J. P. & Gott, J. R. Astrophys. J. 284, 1–22 (1984). 12. Ostriker, J. P. & Vietri, M. Astrophys. J. 267, 488–510 (1983). 13. Vietri, M. & Ostriker, J. P. Astrophys. J. 300, 68–76 (1986). 14. Huchra, J. P. et al. Astr. J. 90, 691–696 (1985). 15. Schneider, D. P. et al. Astr. J. 95, 1619–1628 (1988). 16. Turner, E. L. Astrophys. J. 242, L135–L140 (1980). 17. Narayan, R. Astrophys. J. 339, L53–L56 (1989).

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Ostriker, J., Vietri, M. Are some BL Lacs artefacts of gravitational lensing?. Nature 344, 45–47 (1990). https://doi.org/10.1038/344045a0

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