Abstract
The thermodynamic properties of the hot plasma in galaxy clusters retain information on the processes leading to the formation and evolution of the gas in their deep, dark matter potential ...wells. These processes are dictated not only by gravity but also by gas physics, e.g., active galactic nucleus feedback and turbulence. In this work, we study the thermodynamic properties, e.g., density, temperature, pressure, and entropy, of the most massive and the most distant (seven clusters at
z
> 1.2) clusters selected by the South Pole Telescope and compare them with those of the nearby clusters (13 clusters at
z
< 0.1) to constrain their evolution as a function of time and radius. We find that thermodynamic properties in the outskirts of high-redshift clusters are remarkably similar to the low-redshift clusters, and their evolution follows the prediction of the self-similar model. Their intrinsic scatter is larger, indicating that the physical properties that lead to the formation and virialization of cluster outskirts show evolving variance. On the other hand, thermodynamic properties in the cluster cores deviate significantly from self-similarity, indicating that the processes that regulate the core are already in place in these very high redshift clusters. This result is supported by the unevolving physical scatter of all thermodynamic quantities in cluster cores.
Abstract
We present a strong-lensing analysis of the cluster PSZ1 G311.65−18.48, based on Hubble Space Telescope imaging, archival VLT/MUSE spectroscopy, and Chandra X-ray data. This cool-core ...cluster (
z
= 0.443) lenses the brightest lensed galaxy known, dubbed the “Sunburst Arc” (
z
= 2.3703), a Lyman continuum (LyC) emitting galaxy multiply imaged 12 times. We identify in this field 14 additional strongly lensed galaxies to constrain a strong-lens model and report secure spectroscopic redshifts of four of them. We measure a projected cluster core mass of
M
(<250 kpc) =
2.93
−
0.02
+
0.01
×
10
14
M
⊙
. The two least magnified but complete images of the Sunburst Arc’s source galaxy are magnified by ∼13×, while the LyC clump is magnified by ∼4–80×. We present time delay predictions and conclusive evidence that a discrepant clump in the Sunburst Arc, previously claimed to be a transient, is not variable, thus strengthening the hypothesis that it results from an exceptionally high magnification. A source plane reconstruction and analysis of the Sunburst Arc finds its physical size to be 1 × 2 kpc and that it is resolved in three distinct directions in the source plane, 0°, 40°, and 75° (east of north). We place an upper limit of
r
≲ 50 pc on the source plane size of unresolved clumps and
r
≲ 32 pc for the LyC clump. Finally, we report that the Sunburst Arc is likely in a system of two or more galaxies separated by ≲6 kpc in projection. Their interaction may drive star formation and could play a role in the mechanism responsible for the leaking LyC radiation.
Abstract
We present strong gravitational lensing models for 37 galaxy clusters from the Sloan Digital Sky Survey Giant Arcs Survey. We combine data from multi-band
Hubble Space Telescope
Wide Field ...Camera 3 (WFC3) imaging, with ground-based imaging and spectroscopy from
Magellan
, Gemini, Apache Point Observatory, and the Multiple Mirror Telescope, in order to detect and spectroscopically confirm new multiply imaged 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. The clusters span a redshift range of 0.176 <
z
< 0.66 with a median redshift of
z
= 0.45, and sample a wide range of dynamical masses, 1.5 <
M
200
< 35 × 10
14
, as estimated from their velocity dispersions. As these clusters were selected as lenses primarily owing to a fortuitous alignment with background galaxies that results in giant arcs, they exhibit a wide range in Einstein radii, 1.″3 <
θ
E
< 23.″1 for a source at
z
= 2, with a median
θ
E
= 10.″8. The reduced
HST
images and lens model outputs are made available to the scientific community as high-level data products with this publication.
We are entering an age of large surveys where hundreds of Strong Lensing (SL) galaxy clusters will be detected, allowing for complete statistical analyses of these sources. Galaxy clusters are prime ...candidates as cosmic laboratories to learn about the evolution of structure in the Universe, constrain cosmological parameters, and explore the properties of baryonic matter, dark matter, and dark energy. The concentration mass relation of galaxy clusters across cosmic time describes the evolution of matter distribution and test predictions from the $Lambda$ Cold Dark Matter ($Lambda$CDM) paradigm using state-of-the-art simulations. My dissertation describes the combination of the mass at the core from SL and a mass estimate from the outskirts (well established in all wavelengths) of galaxy clusters to constrain the mass distribution and compute the concentration. For this work, we utilize the Outer Rim cosmological simulations to characterize efficient methods to measure the mass at the cores of galaxy clusters and compute the prediction of the concentration-mass relation for strong lensing galaxy clusters. Two efficient methods to measure the core mass from the strong lensing evidence are the mass enclosed by the Einstein radius and the use of Single-Halo Lens Models (SHM). The mass enclosed by the Einstein radius assumes the projected mass distribution to be spherically symmetric. We establish and apply an empirical correction resulting with a measured scatter of $10.9%$ and a bias of $-0.3%$ between the mass enclosed by the Einstein radius and the ``true'' mass from the simulation. The SHM use Lenstool to compute a lens model with a single large scale dark matter halo. SHM benefit from a visual inspection to identify and exclude models which fail to reproduce the lensing configuration. For the SHM that pass the visual inspection, we measure a scatter of $3.3%$ and bias of $0.3%$ between the mass estimate and the ``true'' mass from the simulation. We establish recommendations for applying these two efficient methods to large samples of SL galaxy clusters. Last, we apply these methods to a sample of $67$ SL galaxy clusters from the Sloan Giant Arc Survey (SGAS), Cluster Lensing And Supernova with Hubble (CLASH), Hubble Frontier Fields (HFF), and Reionization Lensing Cluster Survey (RELICS) and compare the mass estimate results to those from the publicly available detailed lens models (DLM). Compared to the DLM, the mass enclosed by the Einstein radius has a scatter of $18.1%$ with $-7.1%$ bias, while the mass from the SHM has a scatter of $9.0%$ with $1.0%$ bias. We conclude, if other uncertainty errors dominate the desired analysis, these two methods become powerful tools particularly when applied to large samples. For the concentration mass relation work presented in this thesis, we use a sample of $51$ strong lensing South Pole Telescope galaxy clusters observed through a Large Hubble Space Telescope Snapshot program. This unique sample of strong lensing galaxy clusters spans a broad redshift and mass range. We constrain the concentration mass relation using the simulations and observations to within $9.3%$ and $5.7%$, respectively, find significant evidence at the level of $4.5$--sigma for an exponential relation between the mass and the concentration, and cannot make any conclusion to the evolution of the concentration with respect to redshift with this sample. Last, we compare the prediction from the simulation to the observed data and find no tensions with $Lambda$CDM.
We present strong gravitational lensing models for 37 galaxy clusters from the Sloan Digital Sky Survey Giant Arcs Survey. We combine data from multi-band Hubble Space Telescope Wide Field Camera 3 ...(WFC3) imaging, with ground-based imaging and spectroscopy from Magellan, Gemini, Apache Point Observatory, and the Multiple Mirror Telescope, in order to detect and spectroscopically confirm new multiply imaged 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. The clusters span a redshift range of 0.176 < z < 0.66 with a median redshift of z = 0.45, and sample a wide range of dynamical masses, 1.5 < M200 < 35 × 1014 , as estimated from their velocity dispersions. As these clusters were selected as lenses primarily owing to a fortuitous alignment with background galaxies that results in giant arcs, they exhibit a wide range in Einstein radii, 1 3 < θE < 23 1 for a source at z = 2, with a median θE = 10 8. The reduced HST images and lens model outputs are made available to the scientific community as high-level data products with this publication.
We present a strong lensing analysis of the cluster PSZ1 G311.65-18.48, based on Hubble Space Telescope imaging, archival VLT/MUSE spectroscopy, and Chandra X-ray data. This cool-core cluster ...(z=0.443) lenses the brightest lensed galaxy known, dubbed the "Sunburst Arc" (z=2.3703), a Lyman continuum (LyC) emitting galaxy multiply-imaged 12 times. We identify in this field 14 additional strongly-lensed galaxies to constrain a strong lens model, and report secure spectroscopic redshifts of four. We measure a projected cluster core mass of M(<250 kpc)=2.93+0.01/-0.02x10^14M_sun. The two least-magnified but complete images of the Sunburst Arc's source galaxy are magnified by ~13x, while the LyC clump is magnified by ~4-80x. We present time delay predictions and conclusive evidence that a discrepant clump in the Sunburst Arc, previously claimed to be a transient, is not variable, thus strengthening the hypothesis that it results from an exceptionally high magnification. A source plane reconstruction and analysis of the Sunburst Arc finds its physical size to be 1x2 kpc, and that it is resolved in three distinct directions in the source plane, 0, 40, and 75 degrees (east of North). We place an upper limit of r <~ 50 pc on the source plane size of unresolved clumps, and r<~ 32 pc for the LyC clump. Finally, we report that the Sunburst Arc is likely in a system of two or more galaxies separated by <~6 kpc in projection. Their interaction may drive star formation and could play a role in the mechanism responsible for the leaking LyC radiation.
In the context of the BUFFALO (Beyond Ultra-deep Frontier Fields And Legacy Observations) survey, we present a new analysis of the merging galaxy cluster MACS\,J0416.1-2403 (\(z = 0.397\)) and its ...parallel field using the data collected by the Hubble Frontier Fields (HFF) campaign. In this work, we measure the surface mass density from a weak-lensing analysis, and characterise the overall matter distribution in both the cluster and parallel fields. The surface mass distribution derived for the parallel field shows clumpy overdensities connected by filament-like structures elongated in the direction of the cluster core. We also characterise the X-ray emission of the cluster, and compare it with the lensing mass distribution. We identify five substructures at the \(>5\sigma\) level over the two fields, four of them being in the cluster one. Furthermore, three of them are located close to the edges of the field of view, and border issues can significantly hamper the determination of their physical parameters. Finally, we compare our results with the predicted subhalo distribution of one of the Hydrangea/C-EAGLE simulated cluster. Significant differences are obtained suggesting the simulated cluster is at a more advanced evolutionary state than MACS\,J0416.1-2403. Our results anticipate the upcoming BUFFALO observations that will link the two HFF fields, extending further the \emph{HST} coverage, and thus allowing a better characterisation of the reported substructures.
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