Article (Scientific journals)
Can microlensing explain the long-term optical variability of quasars?
Zackrisson, E.; Bergvall, N.; Marquart, T. et al.
2003In Astronomy and Astrophysics, 408 (1), p. 17-25
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Keywords :
dark matter; gravitational lensing; quasars: general; cosmology: miscellaneous
Abstract :
[en] Although controversial, the scenario of microlensing as the dominant mechanism for the long-term optical variability of quasars does provide a natural explanation for both the statistical symmetry, achromaticity and lack of cosmological time dilation in quasar light curves. Here, we investigate to what extent dark matter populations of compact objects allowed in the currently favored Omega[SUB]M[/SUB]=0.3, Omega[SUB]Lambda[/SUB] =0.7 cosmology really can explain the quantitative statistical features of the observed variability. We find that microlensing reasonably well reproduces the average structure function of quasars, but fails to explain both the high fraction of objects with amplitudes higher than 0.35 mag and the mean amplitudes observed at redshifts below one. Even though microlensing may still contribute to the long-term optical variability at some level, another significant mechanism must also be involved. This severely complicates the task of using light-curve statistics from quasars which are not multiply imaged to isolate properties of any cosmologically significant population of compact objects which may in fact be present.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Zackrisson, E.;  Department of Astronomy and Space Physics, Box 515, 75120 Uppsala, Sweden
Bergvall, N.;  Department of Astronomy and Space Physics, Box 515, 75120 Uppsala, Sweden
Marquart, T.;  Department of Astronomy and Space Physics, Box 515, 75120 Uppsala, Sweden
Helbig, Phillip  ;  Multivax C&R, Friedrich-Ebert-Str. 83, 61118 Bad Vilbel, Germany
Language :
English
Title :
Can microlensing explain the long-term optical variability of quasars?
Publication date :
01 September 2003
Journal title :
Astronomy and Astrophysics
ISSN :
0004-6361
eISSN :
1432-0746
Publisher :
EDP Sciences, Les Ulis, France
Volume :
408
Issue :
1
Pages :
17-25
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
since 07 February 2020

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