Issue |
A&A
Volume 454, Number 3, August II 2006
|
|
---|---|---|
Page(s) | 695 - 706 | |
Section | Astrophysical processes | |
DOI | https://doi.org/10.1051/0004-6361:20054652 | |
Published online | 17 July 2006 |
How accurate are the time delay estimates in gravitational lensing?
1
School of Computer Science, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK e-mail: J.C.Cuevas@cs.bham.ac.uk;P.Tino@cs.bham.ac.uk
2
Engineering Faculty, Autonomous University of San Luis Potosí, México
3
School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK e-mail: somak@star.sr.bham.ac.uk
Received:
6
December
2005
Accepted:
25
April
2006
We present a novel approach to estimate the time delay
between light curves of multiple images in a gravitationally lensed
system, based on Kernel methods in the context of machine learning.
We perform various experiments with artificially
generated irregularly-sampled data sets to study the effect of the
various levels of noise and the presence of gaps of various size in
the monitoring data. We compare the performance of our method with
various other popular methods of estimating the time delay and
conclude, from experiments with artificial data, that our method is
least vulnerable to missing data and irregular sampling, within
reasonable bounds of Gaussian noise. Thereafter, we use our method to
determine the time delays between the two images of quasar Q0957+561
from radio monitoring data at 4 cm and 6 cm, and conclude that if only
the observations at epochs common to both wavelengths are used, the
time delay gives consistent estimates, which can be combined to yield
days. The full 6 cm dataset, which covers a longer
monitoring period, yields a value which is 10% larger, but this can
be attributed to differences in sampling and missing data.
Key words: methods: statistical / methods: data analysis / gravitational lensing / quasars: individual: Q0957+561A,B
© ESO, 2006
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.