153 research outputs found
RELICS: Strong Lensing Analysis of MACS J0417.5–1154 and Predictions for Observing the Magnified High-redshift Universe with JWST
Strong gravitational lensing by clusters of galaxies probes the mass distribution at the core of each cluster and magnifies the universe behind it. MACS J0417.5−1154 at z = 0.443 is one of the most massive clusters known based on weak lensing, X-ray, and Sunyaev–Zel'dovich analyses. Here we compute a strong lens model of MACS J0417 based on Hubble Space Telescope imaging observations collected, in part, by the Reionization Lensing Cluster Survey (RELICS), and recently reported spectroscopic redshifts from the MUSE instrument on the Very Large Telescope (VLT). We measure an Einstein radius of θ_{E} ≃ 36" at z = 9 and a mass projected within 200 kpc of M_(200 kpc) = 1.78_(0.03)^(0.01) x 10^(14) M_⊙. Using this model, we measure a ratio between the mass attributed to cluster-member galaxy halos and the main cluster halo of order 1:100. We assess the probability to detect magnified high-redshift galaxies in the field of this cluster, both for comparison with RELICS HST results and as a prediction for the James Webb Space Telescope (JWST) Guaranteed Time Observations upcoming for this cluster. Our lensing analysis indicates that this cluster has similar lensing strength to other clusters in the RELICS program. Our lensing analysis predicts a detection of at least a few z ~ 6–8 galaxies behind this cluster, at odds with a recent analysis that yielded no such candidates in this field. Reliable strong lensing models are crucial for accurately predicting the intrinsic properties of lensed galaxies. As part of the RELICS program, our strong lensing model produced with the Lenstool parametric method is publicly available through the Mikulski Archive for Space Telescopes
Evaluating price-based demand response in practice – with application to the EcoGrid EU Experiment
Gravitational lensing effects of supermassive black holes in cluster environments
This study explores the gravitational lensing effects of supermassive black
holes (SMBHs) in galaxy clusters. While the presence of central SMBHs in
galaxies is firmly established, recent work from high-resolution simulations
predict the existence of an additional population of wandering SMBHs. Though
the masses of these SMBHs are a minor perturbation on the larger scale and
individual galaxy scale dark matter components in the cluster, they can impact
statistical lensing properties and individual lensed image configurations.
Probing for these potentially observable signatures, we find that SMBHs imprint
detectable signatures in rare, higher-order strong lensing image configurations
although they do not manifest any statistically significant detectable evidence
in either the magnification distribution or the integrated shear profile.
Investigating specific lensed image geometries, we report that a massive, near
point-like, potential of an SMBH causes the following detectable effects: (i)
image splitting leading to the generation of extra images; (ii) positional and
magnification asymmetries in multiply imaged systems; and (iii) the apparent
disappearance of a lensed counter-image. Of these, image splitting inside the
cluster tangential critical curve, is the most prevalent notable observational
signature. We demonstrate these possibilities in two cases of observed giant
arcs in and , wherein specific image
configurations seen can be reproduced with SMBHs. Future observations with
high-resolution instrumentation (e.g. MAVIS-Very Large Telescope,
MICADO-Extremely Large Telescope, and the upgraded ngVLA, along with data from
the \textit{Euclid} \& \textit{Nancy Grace Roman} Space Telescopes and the
Rubin LSST Observatory are likely to allow us to probe these unique yet rare
SMBHs lensing signatures.Comment: 12 pages, 12 figures, submitted to MNRAS. For associated online
animation, see
https://sites.google.com/view/guillaume-mahler-astronomer/paper-animatio
RELICS: Strong Lensing Analysis of MACS J0417.5–1154 and Predictions for Observing the Magnified High-redshift Universe with JWST
Strong gravitational lensing by clusters of galaxies probes the mass distribution at the core of each cluster and magnifies the universe behind it. MACS J0417.5−1154 at z = 0.443 is one of the most massive clusters known based on weak lensing, X-ray, and Sunyaev–Zel'dovich analyses. Here we compute a strong lens model of MACS J0417 based on Hubble Space Telescope imaging observations collected, in part, by the Reionization Lensing Cluster Survey (RELICS), and recently reported spectroscopic redshifts from the MUSE instrument on the Very Large Telescope (VLT). We measure an Einstein radius of θ_{E} ≃ 36" at z = 9 and a mass projected within 200 kpc of M_(200 kpc) = 1.78_(0.03)^(0.01) x 10^(14) M_⊙. Using this model, we measure a ratio between the mass attributed to cluster-member galaxy halos and the main cluster halo of order 1:100. We assess the probability to detect magnified high-redshift galaxies in the field of this cluster, both for comparison with RELICS HST results and as a prediction for the James Webb Space Telescope (JWST) Guaranteed Time Observations upcoming for this cluster. Our lensing analysis indicates that this cluster has similar lensing strength to other clusters in the RELICS program. Our lensing analysis predicts a detection of at least a few z ~ 6–8 galaxies behind this cluster, at odds with a recent analysis that yielded no such candidates in this field. Reliable strong lensing models are crucial for accurately predicting the intrinsic properties of lensed galaxies. As part of the RELICS program, our strong lensing model produced with the Lenstool parametric method is publicly available through the Mikulski Archive for Space Telescopes
Gravitational lensing reveals ionizing ultraviolet photons escaping from a distant galaxy
During the epoch of reionisation, neutral gas in the early Universe was
ionized by hard ultraviolet radiation emitted by young stars in the first
galaxies. To do so, ionizing ultraviolet photons must escape from the host
galaxy. We present Hubble Space Telescope observations of the gravitationally
lensed galaxy PSZ1-ARC G311.6602-18.4624, revealing bright, multiply-imaged
ionizing photon escape from a compact star-forming region through a narrow
channel in an optically thick gas. The gravitational lensing magnification
shows how ionizing photons escape this galaxy, contributing to the
re-ionization of the Universe. The multiple sight lines to the source probe
absorption by intergalactic neutral hydrogen on scales of no more than a few
hundred, perhaps even less than ten, parsec.Comment: 17 pages, 9 figures. Published in Scienc
Star formation at the smallest scales: a JWST study of the clump populations in SMACS0723
We present the clump populations detected in 18 lensed galaxies at redshifts 1--8.5 within the lensing cluster field SMACS0723. The recent JWST Early Release Observations of this poorly known region of the sky have revealed numerous point-like sources within and surrounding their host galaxies, undetected in the shallower Hubble Space Telescope images. We use JWST multi-and photometry and the lensing model of this galaxy cluster to estimate the intrinsic sizes and magnitudes of the stellar clumps. We derive optical restframe effective radii from <10 to hundreds pc and masses ranging from ∼105 to 109 M ⊙, overlapping with massive star clusters in the local universe. Clump ages range from 1 Myr to 1 Gyr. We compare the crossing time to the age of the clumps and determine that between 45 and 60 per cent of the detected clumps are consistent with being gravitationally bound. On average, the dearth of Gyr old clumps suggests that the dissolution time scales are shorter than 1 Gyr. We see a significant increase in the luminosity (mass) surface density of the clumps with redshift. Clumps in reionization era galaxies have stellar densities higher than star clusters in the local universe. We zoom in into single galaxies at redshift <6 and find for two galaxies, the Sparkler and the Firework, that their star clusters/clumps show distinctive colour distributions and location surrounding their host galaxy that are compatible with being accredited or formed during merger events. The ages of some of the compact clusters are between 1 and 4 Gyr, e.g. globular cluster precursors formed around 9--12 Gyr ago. Our study, conducted on a small sample of galaxies, shows the potential of JWST observations for understanding the conditions under which star clusters form in rapidly evolving galaxies
Strong Lens Models for 37 Clusters of Galaxies from the SDSS Giant Arcs Survey
We present strong gravitational lensing models for 37 galaxy clusters from
the SDSS Giant Arcs Survey. We combine data from multi-band Hubble Space
Telescope WFC3imaging, with ground-based imaging and spectroscopy from
Magellan, Gemini, APO, and MMT, in order to detect and spectroscopically
confirm new multiply-lensed background sources behind the clusters. We report
spectroscopic or photometric redshifts of sources in these fields, including
cluster galaxies and background sources. Based on all available lensing
evidence, we construct and present strong lensing mass models for these galaxy
clusters.Comment: 53 pages; submitted to ApJ
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