Free-form lens model and mass estimation of the high redshift galaxy cluster ACT-CL J0102-4915, “El Gordo”. (arXiv:1905.00025v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Diego_J/0/1/0/all/0/1">J.M. Diego</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Molnar_S/0/1/0/all/0/1">S. Molnar</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cerny_C/0/1/0/all/0/1">C. Cerny</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Broadhurst_T/0/1/0/all/0/1">T. Broadhurst</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Windhorst_W/0/1/0/all/0/1">W. Windhorst</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zitrin_A/0/1/0/all/0/1">A. Zitrin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bouwens_R/0/1/0/all/0/1">R. Bouwens</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Coe_D/0/1/0/all/0/1">D. Coe</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Conselice_C/0/1/0/all/0/1">C. Conselice</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sharon_K/0/1/0/all/0/1">K. Sharon</a>
We examine the massive colliding cluster El Gordo, one of the most massive
clusters at high redshift and with previous mass estimates close to (or even
exceeding) the maximum mass allowed by standard cosmological models. We use a
free-form lensing reconstruction method that avoids making assumptions about
the mass distribution. We use data from the RELICS program and identify new
multiply lensed system candidates. The new set of constraints provides a more
precise mass estimate of this colliding cluster. By fitting a projected NFW
mass distribution to the strong-lensing regime, we infer a total mass for the
cluster of $M_{200c}=(1.35 pm 0.15)times10^{15}$M$_{odot}$, that is lower
than earlier estimates and eases the claimed tension with LCDM models. We also
find in our lens map a mass overdensity corresponding to the large cometary
tail of hot gas, reinforcing its interpretation as a large tidal feature
predicted by our hydrodynamical simulations. Finally, we discuss the observed
relation between the plasma and the mass map, finding that the peak in the
projected mass map may be associated with a large concentration of colder gas,
exhibiting possible star formation. El Gordo is one of the first clusters that
will be observed with JWST, which is expected to unveil new high redshift
lensed galaxies around this interesting cluster, thus allowing us to improve on
its mass estimation.
We examine the massive colliding cluster El Gordo, one of the most massive
clusters at high redshift and with previous mass estimates close to (or even
exceeding) the maximum mass allowed by standard cosmological models. We use a
free-form lensing reconstruction method that avoids making assumptions about
the mass distribution. We use data from the RELICS program and identify new
multiply lensed system candidates. The new set of constraints provides a more
precise mass estimate of this colliding cluster. By fitting a projected NFW
mass distribution to the strong-lensing regime, we infer a total mass for the
cluster of $M_{200c}=(1.35 pm 0.15)times10^{15}$M$_{odot}$, that is lower
than earlier estimates and eases the claimed tension with LCDM models. We also
find in our lens map a mass overdensity corresponding to the large cometary
tail of hot gas, reinforcing its interpretation as a large tidal feature
predicted by our hydrodynamical simulations. Finally, we discuss the observed
relation between the plasma and the mass map, finding that the peak in the
projected mass map may be associated with a large concentration of colder gas,
exhibiting possible star formation. El Gordo is one of the first clusters that
will be observed with JWST, which is expected to unveil new high redshift
lensed galaxies around this interesting cluster, thus allowing us to improve on
its mass estimation.
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