Before its time: A remarkably evolved protocluster core at z = 7.88

Open Access

Table 1.

Sample of A2744-PC-z7p9-resident galaxies.

Name	RA	Dec	z_phot	z_spec	M_UV	β	μ
Spectroscopically confirmed galaxies
YD4	3.60384	–30.38224	7.91 ± 0.04	7.8742 ± 0.0001 ^[1]	$- 19 . 71_{- 0.02}^{+ 0.02}$ $Mathematical equation: $ -19.71^{+0.02}_{-0.02} $$	−1.5 ± 0.1	1.95
YD6	3.60398	–30.38227	7.95 ± 0.03	7.880 ± 0.001 ^[2]	$- 18 . 99_{- 0.04}^{+ 0.04}$ $Mathematical equation: $ -18.99^{+0.04}_{-0.04} $$	−1.9 ± 0.2	1.95
YD7-W	3.60327	–30.38224	7.89 ± 0.05	7.8721 ± 0.0001 ^[1]	$- 19 . 08_{- 0.03}^{+ 0.03}$ $Mathematical equation: $ -19.08^{+0.03}_{-0.03} $$	−1.3 ± 0.2	1.96
s1	3.60365	–30.38192	$0 . 06_{- 0.02}^{+ 7.88}$ $Mathematical equation: $ 0.06^{+7.88}_{-0.02} $$	7.8732 ± 0.0001 ^[1]	$- 18 . 00_{- 0.11}^{+ 0.10}$ $Mathematical equation: $ -18.00^{+0.10}_{-0.11} $$	NA	1.94
YD1	3.60383	–30.38189	7.89 ± 0.05	7.8778 ± 0.0001 ^[1]	$- 19 . 04_{- 0.05}^{+ 0.05}$ $Mathematical equation: $ -19.04^{+0.05}_{-0.05} $$	−1.9 ± 0.3	1.94
ZD3	3.60645	–30.38098	7.91 ± 0.04	7.8808 ± 0.0001 ^[3]	$- 19 . 47_{- 0.03}^{+ 0.03}$ $Mathematical equation: $ -19.47^{+0.03}_{-0.03} $$	−2.2 ± 0.1	1.87
ZD6	3.60656	–30.38090	7.91 ± 0.04	7.8797 ± 0.0001 ^[3]	$- 19 . 23_{- 0.03}^{+ 0.03}$ $Mathematical equation: $ -19.23^{+0.03}_{-0.03} $$	−2.1 ± 0.1	1.86
ZD12-W	3.60694	–30.38081	7.91 ± 0.04	7.8759 ± 0.0001 ^[3]	$- 18 . 98_{- 0.06}^{+ 0.05}$ $Mathematical equation: $ -18.98^{+0.05}_{-0.06} $$	−2.1 ± 0.3	1.86
ZD12-E	3.60699	–30.38070	7.91 ± 0.04	7.8782 ± 0.0001 ^[3]	$- 19 . 45_{- 0.03}^{+ 0.03}$ $Mathematical equation: $ -19.45^{+0.03}_{-0.03} $$	−2.5 ± 0.1	1.86
ZD2	3.60452	–30.38044	7.89 ± 0.05	7.8800 ± 0.0001 ^[4]	$- 20 . 36_{- 0.02}^{+ 0.02}$ $Mathematical equation: $ -20.36^{+0.02}_{-0.02} $$	−2.1 ± 0.1	1.89
ZD4	3.60525	–30.38058	7.81 ± 0.08	7.883 ± 0.001 ^[5]	$- 18 . 04_{- 0.10}^{+ 0.09}$ $Mathematical equation: $ -18.04^{+0.09}_{-0.10} $$	−2.1 ± 0.5	1.87
z8-2	3.60134	–30.37920	7.88 ± 0.06	7.8831 ± 0.0001 ^[4]	$- 20 . 04_{- 0.03}^{+ 0.02}$ $Mathematical equation: $ -20.04^{+0.02}_{-0.03} $$	−2.1 ± 0.1	2.03
YD8	3.59608	–30.38582	7.91 ± 0.04	7.8869 ± 0.0001 ^[4]	$- 19 . 25_{- 0.03}^{+ 0.03}$ $Mathematical equation: $ -19.25^{+0.03}_{-0.03} $$	−2.1 ± 0.1	2.76
ALT-41799	3.59512	–30.38112	7.88 ± 0.06	7.883 ± 0.005 ^[6]	$- 19 . 87_{- 0.02}^{+ 0.02}$ $Mathematical equation: $ -19.87^{+0.02}_{-0.02} $$	−1.8 ± 0.1	2.61

Previously identified candidates
ZD1	3.60358	–30.38243	7.9 ± 0.2		$- 17 . 61_{- 0.13}^{+ 0.12}$ $Mathematical equation: $ -17.61^{+0.12}_{-0.13} $$	NA	1.96
YD7-E	3.60339	–30.38224	7.93 ± 0.04		$- 19 . 52_{- 0.02}^{+ 0.02}$ $Mathematical equation: $ -19.52^{+0.02}_{-0.02} $$	−2.1 ± 0.1	1.96

Newly identified candidates and confirmed galaxies
PC1	3.60444	–30.38022	7.88 ± 0.04		$- 17 . 67_{- 0.16}^{+ 0.14}$ $Mathematical equation: $ -17.67^{+0.14}_{-0.16} $$	−2.2 ± 0.4	1.88
PC2-E	3.58790	–30.37630	7.90 ± 0.05	7.8798 ± 0.001 ^[5]	$- 18 . 26_{- 0.05}^{+ 0.05}$ $Mathematical equation: $ -18.26^{+0.05}_{-0.05} $$	−2.5 ± 0.3	2.75
PC2-W	3.58781	–30.37628	7.93 ± 0.03		$- 18 . 98_{- 0.03}^{+ 0.03}$ $Mathematical equation: $ -18.98^{+0.03}_{-0.03} $$	−2.5 ± 0.1	2.75
PC3	3.61349	–30.43473	7.88 ± 0.09		$- 19 . 53_{- 0.02}^{+ 0.02}$ $Mathematical equation: $ -19.53^{+0.02}_{-0.02} $$	−2.4 ± 0.1	1.53
PC4	3.61573	–30.36839	7.89 ± 0.05		$- 18 . 60_{- 0.08}^{+ 0.08}$ $Mathematical equation: $ -18.60^{+0.08}_{-0.08} $$	−2.2 ± 0.3	1.57
PC5	3.58897	–30.37864	7.91 ± 0.04	7.8709 ± 0.001 ^[5]	$- 17 . 63_{- 0.11}^{+ 0.10}$ $Mathematical equation: $ -17.63^{+0.10}_{-0.11} $$	−2.0 ± 0.4	2.72
PC6	3.60012	–30.38350	7.91 ± 0.09		$- 17 . 35_{- 0.21}^{+ 0.17}$ $Mathematical equation: $ -17.35^{+0.17}_{-0.21} $$	−1.6 ± 0.5	2.14

Notes. The following citations are for the spectroscopic redshift: [1] Hashimoto et al. (2023); [2] Venturi et al. (2024); [3] Morishita et al. (2025a); [4] Morishita et al. (2023); [5] this work, based on UNCOVER spectra (see Appendix A); [6] Naidu et al. (2024). The UV slopes of s1 and ZD1 could not be established due to the low signal-to-noise of their SEDs. The magnification factor is taken from the z ∼ 8 magnification map from Furtak et al. (2022), Price et al. (2025).

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