Discovery of two Einstein crosses from massive post--blue nugget galaxies at z>1 in KiDS

Abstract

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 $R_{\mathrm{E}}=5.2$ 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, $R_{\mathrm{e}}\sim 0.9$ kpc (at redshift $z_{\mathrm{s}}=1.59$) and $R_{\mathrm{e}}\sim 0.5$ kpc ($z_{\mathrm{s}}=1.10$), 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.

arXiv commentAccepted for publication on APJL

References in corpus (46)

• Star Formation in Galaxies Along the Hubble Sequence
• Accurate photometric redshifts for the CFHT Legacy Survey calibrated using the VIMOS VLT Deep Survey
• Improving the full spectrum fitting method: accurate convolution with Gauss-Hermite functions
• CIGALE: a python Code Investigating GALaxy Emission
• The SAURON project - IV. The mass-to-light ratio, the virial mass estimator and the fundamental plane of elliptical and lenticular galaxies
• A systematic variation of the stellar initial mass function in early-type galaxies
• Compaction and Quenching of High-z Galaxies in Cosmological Simulations: Blue and Red Nuggets
• The Sloan Lens ACS Survey. X. Stellar, Dynamical, and Total Mass Correlations of Massive Early-type Galaxies
• The Sloan Lens ACS Survey. III - The Structure and Formation of Early-type Galaxies and their Evolution since z~1
• Wet Disc Contraction to Galactic Blue Nuggets and Quenching to Red Nuggets
• Gravitationally lensed quasars and supernovae in future wide-field optical imaging surveys
• The initial mass function of early-type galaxies
• The cosmological size and velocity dispersion evolution of massive early-type galaxies
• The Confinement of Star-Forming Galaxies into a Main Sequence through Episodes of Gas Compaction, Depletion, and Replenishment
• Two accurate time-delay distances from strong lensing: Implications for cosmology
• Evidence for Ubiquitous Collimated Galactic-Scale Outflows along the Star-Forming Sequence at z~0.5
• The population of galaxy-galaxy strong lenses in forthcoming optical imaging surveys
• The fourth data release of the Kilo-Degree Survey: ugri imaging and nine-band optical-IR photometry over 1000 square degrees
• Multiple Images of a Highly Magnified Supernova Formed by an Early-Type Cluster Galaxy Lens
• Finding Strong Gravitational Lenses in the Kilo Degree Survey with Convolutional Neural Networks
• Central mass-to-light ratios and dark matter fractions in early-type galaxies
• A massive, dead disk galaxy in the early Universe
• LinKS: Discovering galaxy-scale strong lenses in the Kilo-Degree Survey using Convolutional Neural Networks
• The BOSS Emission-Line Lens Survey. IV. : Smooth Lens Models for the BELLS GALLERY Sample
• The X-Shooter Lens Survey - I. Dark-Matter Domination and a Salpeter-type IMF in a Massive Early-type Galaxy
• Deep Learning Identifies High-z Galaxies in a Central Blue Nugget Phase in a Characteristic Mass Range
• The Size Evolution of Star-forming Galaxies Since z~7 Using ZFOURGE
• New high-quality strong lens candidates with deep learning in the Kilo Degree Survey
• The evolving relation between star-formation rate and stellar mass in the VIDEO Survey since $z=3$
• Central dark matter trends in early-type galaxies from strong lensing, dynamics and stellar populations
• Evolution of galaxy size--stellar mass relation from the Kilo Degree Survey
• Resolving Quiescent Galaxies at $z\gtrsim 2$: I. Search for Gravitationally Lensed Sources and Characterization of their Structure, Stellar Populations, and Line Emission
• Galaxy structure with strong gravitational lensing: decomposing the internal mass distribution of massive elliptical galaxies
• Testing Convolutional Neural Networks for finding strong gravitational lenses in KiDS
• KiDS-SQuaD: The KiDS Strongly lensed Quasar Detection project
• SPIDER - VI. The Central Dark Matter Content of Luminous Early-Type Galaxies: Benchmark Correlations with Mass, Structural Parameters and Environment
• Redshift evolution of the dynamical properties of massive galaxies from SDSS-III/BOSS
• The inner dark matter distribution of the Cosmic Horseshoe (J1148+1930) with gravitational lensing and dynamics
• The Discovery of a Five-Image Lensed Quasar at z = 3.34 using PanSTARRS1 and Gaia
• The last 6 Gyr of dark matter assembly in massive galaxies from the Kilo Degree Survey
• Lensed: a code for the forward reconstruction of lenses and sources from strong lensing observations
• A Strongly-Lensed Massive Ultra-Compact Quiescent Galaxy at z ~ 2.4 in the COSMOS/UltraVISTA Field
• A New Einstein Cross: A Highly Magnified, Intrinsically Faint Lyman-Alpha Emitter at z=2.7
• Bright lenses are easy to find: Spectroscopic confirmation of lensed quasars in the Southern Sky
• VLT/X-Shooter Near-Infrared Spectroscopy and HST Imaging of Gravitationally-Lensed z~2 Compact Quiescent Galaxies
• A new Einstein Cross gravitational lens of a Lyman-break galaxy

Cited by in corpus (7)

• High-quality strong lens candidates in the final Kilo Degree survey footprint
• Euclid Preparation XXXIII. Characterization of convolutional neural networks for the identification of galaxy-galaxy strong lensing events
• LeMoN: Lens Modelling with Neural networks -- I. Automated modelling of strong gravitational lenses with Bayesian Neural Networks
• DESI-253.2534+26.8843: A New Einstein Cross Spectroscopically Confirmed with VLT/MUSE and Modeled with GIGA-Lens
• Galaxy Spectra neural Networks (GaSNets). I. Searching for strong lens candidates in eBOSS spectra using Deep Learning
• Multi-band analysis of strong gravitationally lensed post-blue nugget candidates from the Kilo-Degree Survey
• HerS-3: An Exceptional Einstein Cross Reveals a Massive Dark Matter Halo