JWST's PEARLS: Prime Extragalactic Areas for Reionization and Lensing Science: Project Overview and First Results (2209.04119v3)

Abstract: We give an overview and describe the rationale, methods, and first results from NIRCam images of the JWST "Prime Extragalactic Areas for Reionization and Lensing Science" ("PEARLS") project. PEARLS uses up to eight NIRCam filters to survey several prime extragalactic survey areas: two fields at the North Ecliptic Pole (NEP); seven gravitationally lensing clusters; two high redshift proto-clusters; and the iconic backlit VV 191 galaxy system to map its dust attenuation. PEARLS also includes NIRISS spectra for one of the NEP fields and NIRSpec spectra of two high-redshift quasars. The main goal of PEARLS is to study the epoch of galaxy assembly, AGN growth, and First Light. Five fields, the JWST NEP Time-Domain Field (TDF), IRAC Dark Field (IDF), and three lensing clusters, will be observed in up to four epochs over a year. The cadence and sensitivity of the imaging data are ideally suited to find faint variable objects such as weak AGN, high-redshift supernovae, and cluster caustic transits. Both NEP fields have sightlines through our Galaxy, providing significant numbers of very faint brown dwarfs whose proper motions can be studied. Observations from the first spoke in the NEP TDF are public. This paper presents our first PEARLS observations, their NIRCam data reduction and analysis, our first object catalogs, the 0.9-4.5 $\mu$m galaxy counts and Integrated Galaxy Light. We assess the JWST sky brightness in 13 NIRCam filters, yielding our first constraints to diffuse light at 0.9-4.5 {\mu}m. PEARLS is designed to be of lasting benefit to the community.

• The paper's main contribution is showcasing the JWST PEARLS survey, delivering convergent 0.9–4.5 µm galaxy counts and integrated galaxy light measurements.
• It employs a strategic methodology using eight NIRCam filters and complementary spectroscopic instruments to study galaxy assembly, AGN growth, and cosmic reionization.
• Initial results validate JWST’s stable L2 platform and refined star-galaxy separation, enhancing sensitivity for detecting faint, early universe phenomena.

Overview of the JWST PEARLS Project: Insights and Preliminary Findings

The paper "JWST's PEARLS: Prime Extragalactic Areas for Reionization and Lensing Science: Project Overview and First Results" introduces an extensive astronomical survey using the James Webb Space Telescope (JWST) to explore prime locations for studying cosmic reionization and gravitational lensing. This research, part of the PEARLS project, leverages JWST's advanced Near-Infrared Camera (NIRCam) capabilities to explore the assembly of galaxies, the growth of active galactic nuclei (AGN), and the epoch of First Light. The following essay provides a detailed synopsis of the project, its methodologies, initial findings, and implications for future astronomical research.

Project Structure and Methodology

PEARLS (Prime Extragalactic Areas for Reionization and Lensing Science) employs JWST's state-of-the-art NIRCam to survey several carefully selected extragalactic regions. The project targets eight NIRCam filters to capture high-resolution images across a variety of astronomical environments, including two fields at the North Ecliptic Pole (NEP), seven gravitationally lensing clusters, two high-redshift proto-clusters, and the backlit VV 191 galaxy to assess dust attenuation. Complementary spectra are obtained using NIRISS and NIRSpec instruments for specific NEP fields and high-redshift quasars.

The primary goal is to investigate the delicate period of galaxy formation, AGN activity, and the First Light of the cosmos. To achieve these objectives, PEARLS incorporates a strategic scheduling of observations, including revisiting certain fields multiple times to capture faint or transient phenomena such as weak AGN, high-redshift supernovae, and cosmic cluster caustic transits. This comprehensive approach allows for both static and dynamic analyses, enriching our understanding of these fundamental cosmic processes.

Initial Results and Findings

The first observations from PEARLS have yielded significant data, offering a glimpse into previously unobservable cosmic phenomena. Key outcomes include:

• Galaxy Counts and Integrated Galaxy Light (IGL): The paper presents the 0.9–4.5 µm galaxy counts, alongside assessments of integrated galaxy light (IGL) across 13 NIRCam filters. Notably, the counts demonstrate convergence, aligning closely with predictive models. This robust dataset serves as a basis for future exploration of the diffuse extragalactic background light.
• Telescope Stability and Sensitivity: JWST's location at the Sun-Earth L2 Lagrange point offers a stable observing platform, minimizing interference and maximizing observation sensitivity. This stability has resulted in high-quality NIRCam data, enhancing faint object detection capabilities and allowing for a refined paper of cosmic reionization and lensing.
• Role of Stellar PSF and Star-Galaxy Classification: The precision of JWST's point spread function (PSF) aids in effective star-galaxy separation critical for accurate galaxy counts. The research highlights the improvement in sensitivity at longer wavelengths, enabling more precise characterization of faint objects.

Implications and Future Directions

The results from PEARLS illustrate JWST's substantial potential for advancing our understanding of the early universe. The findings suggest several avenues for future investigation:

• Refinement of Cosmic Models: The data improves constraints on models of galaxy formation and evolution, particularly during the reionization epoch. The rich dataset can enhance simulations and theoretical frameworks exploring galaxy assembly and AGN feedback mechanisms.
• Potential for Discovering New Phenomena: With its unprecedented sensitivity and spatial resolution, JWST may identify high-redshift phenomena previously unobservable, offering fresh insights into the structure and behavior of the young universe.
• Long-Term Surveillance and Follow-up Studies: The strategic planning of repeated observations over time domains opens the door for identifying variability in cosmic phenomena, enabling in-depth analyses of dynamic changes and transient events in the cosmos.

Conclusion

The PEARLS project represents a significant step forward in leveraging JWST's capabilities for extragalactic astronomy. Through its comprehensive approach to studying reionization, gravitational lensing, and galaxy formation, PEARLS provides a rich dataset that stands to refine our theoretical understanding and catalyze new discoveries regarding the universe's formative epochs. As the project progresses, these findings will undoubtedly guide future research directions, further illuminating the intricate tapestry of the cosmos.