TY - UNPB

T1 - Lessons from the first multiply imaged supernova II: A parametric strong-lensing model for the galaxy cluster MACS J1149.5+2223

AU - Zitrin, Adi

PY - 2020

Y1 - 2020

N2 - We present a parametric, grid-based lens model for the galaxy cluster
MACS J1149.5+2223, concentrating on the properties of the first multiply
imaged supernova Refsdal. This model complements our updated
light-traces-mass (LTM) strong-lensing model for this cluster, described
in a companion paper, and is generated using the same pipeline but with
a different parametrization. Together these two models probe different
possible solutions in a relatively self-consistent manner and can be
used to examine systematic uncertainties and relevant differences
between the two parameterizations. We obtain reasonably similar
(agreeing to within $\simeq1-3\sigma$, in most cases) time delays and
magnification ratios, with respect to S1, from the two different
methods, although the LTM predictions seem to be systematically
shorter/smaller for some of the images. Most notably, the time delay
[and 95\% CI] between the Einstein cross (in particular, image S1), and
SX, the image that appeared about a year after the original discovery of
the cross, differs substantially between the parametric method (326 [300
-- 359] days) and the LTM method (224 [198 -- 306] days), which seems to
underestimates the true reappearance time. The cause for this systematic
difference is unclear at present. We speculate on its possible origin
and note that a refined measurement of SN Refsdal's properties should
help to more strongly discriminate between the two solutions, and thus
between the two descriptions for the intrinsic shape of the underlying
matter distribution. We also discuss the implications of our results for
the Hubble constant.

AB - We present a parametric, grid-based lens model for the galaxy cluster
MACS J1149.5+2223, concentrating on the properties of the first multiply
imaged supernova Refsdal. This model complements our updated
light-traces-mass (LTM) strong-lensing model for this cluster, described
in a companion paper, and is generated using the same pipeline but with
a different parametrization. Together these two models probe different
possible solutions in a relatively self-consistent manner and can be
used to examine systematic uncertainties and relevant differences
between the two parameterizations. We obtain reasonably similar
(agreeing to within $\simeq1-3\sigma$, in most cases) time delays and
magnification ratios, with respect to S1, from the two different
methods, although the LTM predictions seem to be systematically
shorter/smaller for some of the images. Most notably, the time delay
[and 95\% CI] between the Einstein cross (in particular, image S1), and
SX, the image that appeared about a year after the original discovery of
the cross, differs substantially between the parametric method (326 [300
-- 359] days) and the LTM method (224 [198 -- 306] days), which seems to
underestimates the true reappearance time. The cause for this systematic
difference is unclear at present. We speculate on its possible origin
and note that a refined measurement of SN Refsdal's properties should
help to more strongly discriminate between the two solutions, and thus
between the two descriptions for the intrinsic shape of the underlying
matter distribution. We also discuss the implications of our results for
the Hubble constant.

KW - Astrophysics - Cosmology and Nongalactic Astrophysics

M3 - Preprint

BT - Lessons from the first multiply imaged supernova II: A parametric strong-lensing model for the galaxy cluster MACS J1149.5+2223

ER -