Discovery of a very large structure at z = 3.78
- Department of Physics, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907 (United States)
- National Optical Astronomy Observatory, Tucson, AZ 85726 (United States)
- Department of Physics and Astronomy, University of California, Riverside, 900 University Avenue, Riverside, CA 92521 (United States)
- Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)
- Department of Astronomy, University of Florida, Gainesville, FL 32611 (United States)
We report the discovery of a large-scale structure containing multiple protoclusters at z = 3.78 in the Boötes field. The spectroscopic discovery of five galaxies at z = 3.783 ± 0.002 lying within 1 Mpc of one another led us to undertake a deep narrow- and broadband imaging survey of the surrounding field. Within a comoving volume of 72 × 72 × 25 Mpc{sup 3}, we have identified 65 Lyα emitter (LAE) candidates at z = 3.795 ± 0.015, and four additional galaxies at z {sub spec} = 3.730, 3.753, 3.780, 3.835. The galaxy distribution within the field is highly non-uniform, exhibiting three large (≈3-5 ×) overdensities separated by 8-14 Mpc (physical) and possibly connected by filamentary structures traced by LAEs. The observed number of LAEs in the entire field is nearly twice the average expected in field environments based on estimates of the Lyα luminosity function at these redshifts. We estimate that by z = 0 the largest overdensity will grow into a cluster of mass ≈10{sup 15} M {sub ☉}; the two smaller overdensities will grow into clusters of mass (2-6) × 10{sup 14} M {sub ☉}. The highest concentration of galaxies is located at the southern end of the image, suggesting that the current imaging may not map the true extent of the large-scale structure. Finding three large protocluster candidates within a single 0.3 deg{sup 2} field is highly unusual; expectations from theory suggest that such alignments should occur less than 2% of the time. Searching for and characterizing such structures and accurately measuring their volume space density can therefore place constraints on the theory of structure formation. Such regions can also serve as laboratories for the study of galaxy formation in dense environments.
- OSTI ID:
- 22370141
- Journal Information:
- Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 796; ISSN ASJOAB; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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