1112.4337 (Fa-bo Feng)
Fa-bo Feng
The lensing effect of a cosmic string is studied, and some new methods are
proposed to detect the cosmic string. The technique for using jets as extended
gravitational lensing probes was firstly explored by Kronberg. We use the
"alignment-breaking parameter" $ \eta_G $ as a sensitive indicator of
gravitational distortion by a wiggly cosmic string. Then, we applied the
non-constant deflection angle to jets, and $ \eta_G $ of a specific jet is just
related to the projected slope of the jet. At least three jets in the sample of
Square Kilometer Array (SKA) would have significant signals ($ \eta_G >10^\circ
$) if the wiggly infinite cosmic string existed. The distortion of elliptical
object is also studied and used to do a statistical research on directions of
axes and ellipticities of galaxies. In the direction of the string, we find
that galaxies appear to be rounder for an observer and the distribution of
apparent ellipticity changes correspondingly. Ellipticity distribution of
current SDSS spiral sample has the signal-to-noise ratio up to 8.48 which is
large enough for astronomical observations. The future survey, such as Large
Synoptic Survey Telescope (LSST) and Dark Energy Survey (DES), would weaken the
requirement of special geometry in the data processing. As a result, all kinds
of distributions, including ellipticity axis distribution, would serve as
probes to detect wiggly strings in the near future. In brief, if a wiggly
cosmic string existed, these signals would be convenient to be observed with
the future weak lensing survey or other surveys in deep space. If there was no
lensing signal in these distributions, it would give the upper limit of the
abundance of infinite strings.
View original:
http://arxiv.org/abs/1112.4337
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