An improved Magellan weak lensing analysis of the galaxy cluster Abell 2744 (2402.08364v1)

Abstract: We present a new weak lensing analysis of the Hubble Frontier Fields galaxy cluster Abell 2744 ($z$ = 0.308) using new Magellan/MegaCam multi-band $gri$ imaging data. We carry out our study by applying brand-new PSF and shape measurement softwares that allow for the use of multi-band data simultaneously, which we first test on Subaru/Suprime-Cam $BR_cz'$ imaging data of the same cluster. The projected total mass of this system within $2.35 \, \mathrm{Mpc}$ from the south-west BCG is $(2.56 \pm 0.26) \times 10^{15} \, \mathrm{M}_\odot$, which makes Abell 2744 one of the most massive clusters known. This value is consistent, within the errors, with previous weak lensing and dynamical studies. Our analysis reveals the presence of three high-density substructures, thus supporting the picture of a complex merging scenario. This result is also confirmed by a comparison with a recent strong lensing study based on high-resolution JWST imaging. Moreover, our reconstructed total mass profile nicely agrees with an extrapolation of the strong lensing best-fit model up to several Mpc from the BCG centre.

• The paper presents an advanced weak lensing methodology that accurately estimates Abell 2744’s mass at (2.56 ± 0.26)×10^15 M_⊙ within 2.35 Mpc.
• It reveals three high-density substructures within the cluster, indicating a complex merger scenario supported by strong lensing comparisons.
• The analysis demonstrates the effectiveness of multi-band imaging and innovative PSF correction techniques in mapping galaxy cluster dynamics.

An Improved Magellan Weak Lensing Analysis of the Galaxy Cluster Abell 2744

The paper "An improved Magellan weak lensing analysis of the galaxy cluster Abell 2744" presents an advanced weak lensing (WL) paper using data from the Magellan/MegaCam concerning the massive galaxy cluster Abell 2744. This research aims to enhance our understanding of the mass distribution within Abell 2744 by leveraging new multi-band $gri$ imaging data and applying novel methodologies for point spread function (PSF) and shape measurement. These methods utilize multi-band data integration to refine mass distribution estimates, overcoming some of the limitations seen in previous analyses.

Methodology and Data Handling

The authors applied innovative software for PSF and shape measurements developed specifically for this paper to analyze Subaru/Suprime-Cam $BR_cz'$ imaging data and confirm their approach's accuracy. Subsequently, they employed these tools on Magellan/MegaCam's deeper and broader field imaging data, encompassing approximately $31' \times 33'$. The use of multi-band data allows for a robust measurement of galaxy shapes by reducing systematic errors often associated with single-band data.

In their WL analysis, the authors calculated the shear field $\gamma$ induced by the lensing cluster's gravitational potential through shape measurements of background galaxies. The methodology relies on sophisticated parameter-fitting and statistical analysis techniques, ensuring the resulting mass distribution is both robust and model-free.

Key Findings

1. Mass Estimation: For Abell 2744, the estimated total mass within $2.35$ Mpc from the brightest cluster galaxy (BCG) is $(2.56 \pm 0.26) \times 10^{15} \mathrm{M}_\odot$. This value aligns with previous WL and dynamical estimates, confirming Abell 2744's status as one of the most massive known galaxy clusters.
2. Substructure Analysis: The WL analysis reveals three significant high-density substructures within the cluster, indicating a complex merger scenario. This finding is corroborated by comparisons with strong lensing studies using high-resolution JWST imaging, suggesting that the cluster is dynamically active and not in equilibrium.
3. Consistency with Strong Lensing Models: The WL mass profile agrees with extrapolations from strong lensing models out to several megaparsecs. This consistency affirms the reliability of the WL methodology in mapping mass distribution on varying scales.
4. Luminosity Comparison: The observed surface mass density distribution exhibits a good correspondence with the reconstructed luminosity maps, reinforcing the accuracy of the mass measurement techniques.

Implications and Future Directions

This paper presents a detailed exploration into integrating multi-band WL data with new computational tools to effectively map galaxy cluster masses. By demonstrating that advanced PSF correction and multi-band shape measurement techniques can yield precise mass reconstructions, this paper sets a new standard for future WL studies, particularly for those involving JWST and ground-based large-aperture telescopes.

The implications of this work stretch beyond Abell 2744. It contributes to our broader understanding of the process of structure formation in the Universe, offering insights into the distribution and behavior of dark matter within galaxy clusters.

Looking forward, the integration of AI-driven classification techniques, such as convolutional neural networks, could further refine source selection and classification processes, enhancing the purity and completeness of input samples for WL analyses. Additionally, this research highlights the potential of developing photometric redshift catalogs from extensive multi-band data to improve the precision of lensing studies.

In conclusion, this paper provides a meticulous WL analysis of Abell 2744, augmenting our comprehension of galaxy cluster dynamics and mass distribution with improved methodological rigor. It reinforces the significance of multi-band imaging and advanced data processing techniques in unraveling the cosmic mass structures that underpin our Universe.