Early Results from GLASS-JWST. XIV. A Spectroscopically Confirmed Protocluster 650 Million Years after the Big Bang

Takahiro Morishita*, Guido Roberts-Borsani, Tommaso Treu, Gabriel Brammer, Charlotte A. Mason, Michele Trenti, Benedetta Vulcani, Xin Wang, Ana Acebron, Yannick Bahe, Pietro Bergamini, Kristan Boyett, Marusa Bradac, Antonello Calabro, Marco Castellano, Wenlei Chen, Gabriella De Lucia, Alexei V. Filippenko, Adriano Fontana, Karl GlazebrookClaudio Grillo, Alaina Henry, Tucker Jones, Patrick L. Kelly, Anton M. Koekemoer, Nicha Leethochawalit, Ting-Yi Lu, Danilo Marchesini, Sara Mascia, Amata Mercurio, Emiliano Merlin, Benjamin Metha, Themiya Nanayakkara, Mario Nonino, Diego Paris, Laura Pentericci, Piero Rosati, Paola Santini, Victoria Strait, Eros Vanzella, Rogier A. Windhorst, Lizhi Xie

*Corresponding author for this work

Research output: Contribution to journalLetterResearchpeer-review

65 Citations (Scopus)
10 Downloads (Pure)

Abstract

We present the spectroscopic confirmation of a protocluster at z = 7.88 behind the galaxy cluster Abell 2744 (hereafter A2744-z7p9OD). Using JWST NIRSpec, we find seven galaxies within a projected radius of 60 kpc. Although the galaxies reside in an overdensity around greater than or similar to 20x greater than a random volume, they do not show strong Ly alpha emission. We place 2 sigma upper limits on the rest-frame equivalent width alpha emission, we constrain the volume-averaged neutral fraction of hydrogen in the intergalactic medium to be x (HI) > 0.45 (68% C i). Using an empirical M (UV)-M (halo) relation for individual galaxies, we estimate that the total halo mass of the system is greater than or similar to 4 x 10(11) M (circle dot). Likewise, the line-of-sight velocity dispersion is estimated to be 1100 +/- 200 km s(-1). Using an empirical relation, we estimate the present-day halo mass of A2744-z7p9OD to be similar to 2 x 10(15) M (circle dot), comparable to the Coma cluster. A2744-z7p9OD is the highest redshift spectroscopically confirmed protocluster to date, demonstrating the power of JWST to investigate the connection between dark-matter halo assembly and galaxy formation at very early times with medium-deep observations at

Original languageEnglish
Article number24
JournalAstrophysical Journal Letters
Volume947
Issue number2
Number of pages11
ISSN2041-8205
DOIs
Publication statusPublished - 1 Apr 2023

Keywords

  • SIMILAR-TO 8
  • IONIZED BUBBLE
  • GALAXY PROTOCLUSTERS
  • COSMIC REIONIZATION
  • PHYSICAL-PROPERTIES
  • NEUTRAL FRACTION
  • ALPHA EMISSION
  • SURVEY DESIGN
  • I.
  • EVOLUTION

Cite this