Discovery of two Einstein crosses from massive post–blue nugget galaxies at z>1 in KiDS. (arXiv:2011.09150v2 [astro-ph.GA] UPDATED)

Discovery of two Einstein crosses from massive post–blue nugget galaxies at z>1 in KiDS. (arXiv:2011.09150v2 [astro-ph.GA] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Napolitano_N/0/1/0/all/0/1">N.R. Napolitano</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Li_R/0/1/0/all/0/1">R. Li</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Spiniello_C/0/1/0/all/0/1">C. Spiniello</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tortora_C/0/1/0/all/0/1">C. Tortora</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sergeyev_A/0/1/0/all/0/1">A. Sergeyev</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+DAgo_G/0/1/0/all/0/1">G. D'Ago</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Guo_X/0/1/0/all/0/1">X. Guo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Xie_L/0/1/0/all/0/1">L. Xie</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Radovich_M/0/1/0/all/0/1">M. Radovich</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Roy_N/0/1/0/all/0/1">N. Roy</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Koopmans_L/0/1/0/all/0/1">L. V. E. Koopmans</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kuijken_K/0/1/0/all/0/1">K. Kuijken</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bilicki_M/0/1/0/all/0/1">M. Bilicki</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Erben_T/0/1/0/all/0/1">T. Erben</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Getman_F/0/1/0/all/0/1">F. Getman</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Heymans_C/0/1/0/all/0/1">C. Heymans</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hildebrandt_H/0/1/0/all/0/1">H. Hildebrandt</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Moya_C/0/1/0/all/0/1">C. Moya</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shan_H/0/1/0/all/0/1">H.Y. Shan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vernardos_G/0/1/0/all/0/1">G. Vernardos</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wright_A/0/1/0/all/0/1">A.H. Wright</a>

We report the discovery of two Einstein Crosses (ECs) in the footprint of the
Kilo-Degree Survey (KiDS): KIDS J232940-340922 and KIDS J122456+005048. Using
integral field spectroscopy from MUSE@VLT, we confirm their gravitational-lens
nature. In both cases, the four spectra of the source clearly show a prominence
of absorption features, hence revealing an evolved stellar population with
little star formation. The lensing model of the two systems, assuming a
singular isothermal ellipsoid (SIE) with external shear, shows that: 1) the two
crosses, located at redshift $z=0.38$ and 0.24, have Einstein radius $R_{rm
E}=5.2$ kpc and 5.4 kpc, respectively; 2) their projected dark matter fractions
inside the half effective radius are 0.60 and 0.56 (Chabrier IMF); 3) the
sources are ultra-compact galaxies, $R_{rm e}sim0.9$ kpc (at redshift $z_{rm
s}=1.59$) and $R_{rm e}sim0.5$ kpc ($z_{rm s}=1.10$), respectively. These
results are unaffected by the underlying mass density assumption. Due to size,
blue color and absorption-dominated spectra, corroborated by low specific
star-formation rates derived from optical-NIR spectral energy distribution
fitting, we argue that the two lensed sources in these ECs are blue nuggets
migrating toward their quenching phase.

http://arxiv.org/icons/sfx.gif