The dark matter problem cannot be solved by 10^6 – 10^12 solar mass black holes

Augusto P., Wilkinson P. N.,  Browne I. W. A. & Henstock D. R.

Nuffield Radio Astronomy Laboratories, University of Manchester, Jodrell Bank, Macclesfield, Cheshire SK11 9DL

We are finalising the first systematic search for gravitational multiple images separated by 50–200 milliarcseconds (mas) corresponding to a mass range ~10^8.5–10^10 solar masses. In a parent sample of 1586 radio sources selected from two VLA surveys, only 67 were found to have structure which could be ascribed to high magnification lensing on this scale. These were all observed with MERLIN, reducing the number that could be multiple imaged to 16. The best 7 of the remaining candidates have been observed with the VLBA, but none were confirmed as lenses. It is unlikely that any of the remaining 9 objects is multiply imaged. If this is confirmed a limit ΩL < 0.05 can then be placed on 10^9 – 10^10 solar mass black holes (BH). This range can be extended to 10^6 – 10^12 solar masses by combining our work with that of others, implying that BH in this range do not contribute importantly to the total mass of the Universe.

Class:	Proceeding
Links:	ADS
Reference:	Augusto, P.,Wilkinson, P.N., Browne, I.W.A. & Henstock, D.R., 1996; Nuclear Physics B (Proc. Supp.); 51B, p. 118-122; ed. Cline, D.B.; Elsevier Science (ISSN 0920-5632).
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