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Register a new userA strong lensing model of the galaxy cluster PSZ1 G311.65-18.48
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Added by
Giada Venusta Pignataro
Publication date
2021
fields
Physics
and research's language is
English
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We present a strong lensing analysis of the galaxy cluster PSZ1 G311.65-18.48 (z=0.443) using multi-band observations with Hubble Space Telescope, complemented with VLT/MUSE spectroscopic data. The MUSE observations provide redshift estimates for the lensed sources and help reducing the mis-identification of the multiple images. Spectroscopic data are also used to measure the inner velocity dispersions of 15 cluster galaxies and calibrate the scaling relations to model the subhalo cluster component. The model is based on 62 multiple images grouped in 17 families belonging to 4 different sources. The majority of them are multiple images of compact stellar knots belonging to a single star-forming galaxy at z=2.3702. This source is strongly lensed by the cluster to form the Sunburst Arc system. To accurately reproduce all the multiple images, we build a parametric mass model, which includes both cluster-scale and galaxy-scale components. The resulting model has a r.m.s. separation between the model-predicted and the observed positions of the multiple images of only 0.14. We conclude that PSZ1 G311.65-18.48 has a relatively round projected shape and a large Einstein radius (29 for z_s = 2.3702), which could indicate that the cluster is elongated along the line of sight. The Sunburst Arc source is located at the intersection of a complex network of caustics, which explains why parts of the arc are imaged with unprecedented multiplicity (up to 12 times).
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We present a new high-precision parametric strong lensing model of the galaxy cluster MACS J0416.1-2403, at z=0.396, which takes advantage of the MUSE Deep Lensed Field (MDLF), with 17.1h integration in the northeast region of the cluster, and Hubble Frontier Fields data. We spectroscopically identify 182 multiple images from 48 background sources at 0.9<z<6.2, and 171 cluster member galaxies. Several multiple images are associated to individual clumps in multiply lensed resolved sources. By defining a new metric, which is sensitive to the gradients of the deflection field, we show that we can accurately reproduce the positions of these star-forming knots despite their vicinity to the model critical lines. The high signal-to-noise ratio of the MDLF spectra enables the measurement of the internal velocity dispersion of 64 cluster galaxies, down to m(F160W)=22. This allowed us to independently estimate the contribution of the subhalo mass component of the lens model from the measured Faber-Jackson scaling relation. Our best reference model, which represents a significant step forward compared to our previous analyses, was selected from a comparative study of different mass parametrizations. The root-mean-square displacement between the observed and model-predicted image positions is only 0.40, which is 33% smaller than in all previous models. The mass model appears to be particularly well constrained in the MDLF region. We characterize the robustness of the magnification map at varying distances from the model critical lines and the total projected mass profile of the cluster.
We identify a strong lensing galaxy in the cluster IRC 0218 (also known as XMM-LSS J02182$-$05102) that is spectroscopically confirmed to be at $z=1.62$, making it the highest-redshift strong lens galaxy known. The lens is one of the two brightest cluster galaxies and lenses a background source galaxy into an arc and a counterimage. With Hubble Space Telescope (HST) grism and Keck/LRIS spectroscopy, we measure the source redshift to be $z_{rm S}=2.26$. Using HST imaging in ACS/F475W, ACS/F814W, WFC3/F125W, and WFC3/F160W, we model the lens mass distribution with an elliptical power-law profile and account for the effects of the cluster halo and nearby galaxies. The Einstein radius is $theta_{rm E}=0.38^{+0.02}_{-0.01}$ ($3.2_{-0.1}^{+0.2}$ kpc) and the total enclosed mass is M$_{rm tot} (< theta_{rm E})=1.8^{+0.2}_{-0.1}times10^{11}~{rm M}_{odot}$. We estimate that the cluster environment contributes $sim10$% of this total mass. Assuming a Chabrier IMF, the dark matter fraction within $theta_{{rm E}}$ is $f_{rm DM}^{{rm Chab}} = 0.3_{-0.3}^{+0.1}$, while a Salpeter IMF is marginally inconsistent with the enclosed mass ($f_{rm DM}^{{rm Salp}} = -0.3_{-0.5}^{+0.2}$). The total magnification of the source is $mu_{rm tot}=2.1_{-0.3}^{+0.4}$. The source has at least one bright compact region offset from the source center. Emission from Ly$alpha$ and [O III] are likely to probe different regions in the source.
We present a detailed strong lensing (SL) mass reconstruction of the core of the galaxy cluster MACSJ 2129.4-0741 ($rm z_{cl}=0.589$) obtained by combining high-resolution HST photometry from the CLASH survey with new spectroscopic observations from the CLASH-VLT survey. A background bright red passive galaxy at $rm z_{sp}=1.36$, sextuply lensed in the cluster core, has four radial lensed images located over the three central cluster members. Further 19 background lensed galaxies are spectroscopically confirmed by our VLT survey, including 3 additional multiple systems. A total of 31 multiple images are used in the lensing analysis. This allows us to trace with high precision the total mass profile of the cluster in its very inner region ($rm R<100$ kpc). Our final lensing mass model reproduces the multiple images systems identified in the cluster core with high accuracy of $0.4$. This translates to an high precision mass reconstruction of MACS 2129, which is constrained at level of 2%. The cluster has Einstein parameter $Theta_E=(29pm4)$, and a projected total mass of $rm M_{tot}(<Theta_E)=(1.35pm0.03)times 10^{14}M_{odot}$ within such radius. Together with the cluster mass profile, we provide here also the complete spectroscopic dataset for the cluster members and lensed images measured with VLT/VIMOS within the CLASH-VLT survey.
We present a first strong-lensing model for the galaxy cluster RM J121218.5+273255.1 ($z=0.35$; hereafter RMJ1212; also known as Abell 1489). This cluster is amongst the top 0.1% richest clusters in the redMaPPer catalog; it is significantly detected in X-ray and through the Sunyaev-Zeldovich effect in ROSAT and emph{Planck} data, respectively; and its optical luminosity distribution implies a very large lens, following mass-to-light scaling relations. Based on these properties it was chosen for the Webb Medium Deep Fields (WMDF) JWST/GTO program. In preparation for this program, RMJ1212 was recently imaged with GMOS on Gemini North and in seven optical and near-infrared bands with the emph{Hubble Space Telescope}. We use these data to map the inner mass distribution of the cluster, uncovering various sets of multiple images. We also search for high-redshift candidates in the data, as well as for transient sources. We find over a dozen high-redshift ($zgtrsim6$) candidates based on both photometric redshift and the dropout technique. No prominent ($gtrsim5 sigma$) transients were found in the data between the two HST visits. Our lensing analysis reveals a relatively large lens with an effective Einstein radius of $theta_{E}simeq32pm3$ ($z_{s}=2$), in broad agreement with the scaling-relation expectations. RMJ1212 demonstrates that powerful lensing clusters can be selected in a robust and automated way following the light-traces-mass assumption.
I report discovery of a new galaxy-scale gravitational lens system, identified using public data from the MaNGA survey, as part of a systematic search for lensed background line-emitters. The lens is SDSS J170124.01+372258.0, a giant elliptical galaxy with velocity dispersion $sigma=256$ km/s, at a redshift of $z_l=0.122$. After modelling and subtracting the target galaxy light, the integral-field data-cube reveals [OII], [OIII] and H$beta$ emission lines corresponding to a source at $z_s=0.791$, forming an identifiable ring around the galaxy center. The Einstein radius is $R_{Ein} approx 2.3$ arcsec, projecting to ~5 kpc at the distance of the lens. The total projected lensing mass is $(3.6pm0.6) times 10^{11} M_odot$, and the total J-band mass-to-light ratio is $3.0pm0.7$ solar units. Plausible estimates of the likely dark matter content could reconcile this with a Milky-Way-like initial mass function (for which M/L~1.5 is expected), but heavier IMFs are by no means excluded with the present data. An alternative interpretation of the system, with a more complex source plane, is also discussed. The discovery of this system bodes well for future lens searches based on MaNGA and other integral-field spectroscopic surveys.
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