Constraints on Cosmological and Galaxy Parameters from Strong Gravitational Lensing Systems. (arXiv:2002.06354v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Kumar_D/0/1/0/all/0/1">Darshan Kumar</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jain_D/0/1/0/all/0/1">Deepak Jain</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mahajan_S/0/1/0/all/0/1">Shobhit Mahajan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mukherjee_A/0/1/0/all/0/1">Amitabha Mukherjee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rani_N/0/1/0/all/0/1">Nisha Rani</a>
Strong gravitational lensing along with the distance sum rule method can
constrain both cosmological parameters as well as density profiles of galaxies
without assuming any fiducial cosmological model. To constrain galaxy
parameters and cosmic curvature, we use a newly compiled database of $161$
galactic scale strong lensing systems for distance ratio data. For the
luminosity distance in the distance sum rule method, we use databases of
supernovae type-Ia (Pantheon) and Gamma Ray Bursts (GRBs). We use a general
lens model, namely the Extended Power-Law lens model. We consider three
different parametrisations of mass density power-law index $(gamma)$ to study
the dependence of $gamma$ on redshift. We find that parametrisations of
$gamma$ have a negligible impact on the best fit value of cosmic curvature
parameter.
Furthermore, measurement of time delay can provide a promising cosmographic
probe via the “time delay distance” that includes the ratio of distances
between the observer, lens and the source. We use the distance sum rule method
with $12$ datapoints of time-delay distance data to put constraints on the
Cosmic Distance Duality Relation (CDDR) and the cosmic curvature parameter. For
this we consider three different parametrisations of distance duality parameter
$(eta)$. Our results indicate that a flat universe can be accommodated within
$95%$ confidence level for all the parametrisations of $eta$. Further, we
find that within 95% confidence level, there is no violation of CDDR if $eta$
is assumed to be redshift dependent but CDDR is violated if $eta$ is
considered redshift independent. Hence, we need a larger sample of strong
gravitational lensing systems in order to improve the constraints on the cosmic
curvature and distance duality parameter.
Strong gravitational lensing along with the distance sum rule method can
constrain both cosmological parameters as well as density profiles of galaxies
without assuming any fiducial cosmological model. To constrain galaxy
parameters and cosmic curvature, we use a newly compiled database of $161$
galactic scale strong lensing systems for distance ratio data. For the
luminosity distance in the distance sum rule method, we use databases of
supernovae type-Ia (Pantheon) and Gamma Ray Bursts (GRBs). We use a general
lens model, namely the Extended Power-Law lens model. We consider three
different parametrisations of mass density power-law index $(gamma)$ to study
the dependence of $gamma$ on redshift. We find that parametrisations of
$gamma$ have a negligible impact on the best fit value of cosmic curvature
parameter.
Furthermore, measurement of time delay can provide a promising cosmographic
probe via the “time delay distance” that includes the ratio of distances
between the observer, lens and the source. We use the distance sum rule method
with $12$ datapoints of time-delay distance data to put constraints on the
Cosmic Distance Duality Relation (CDDR) and the cosmic curvature parameter. For
this we consider three different parametrisations of distance duality parameter
$(eta)$. Our results indicate that a flat universe can be accommodated within
$95%$ confidence level for all the parametrisations of $eta$. Further, we
find that within 95% confidence level, there is no violation of CDDR if $eta$
is assumed to be redshift dependent but CDDR is violated if $eta$ is
considered redshift independent. Hence, we need a larger sample of strong
gravitational lensing systems in order to improve the constraints on the cosmic
curvature and distance duality parameter.
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