2022ApJ...940L..53V


Query : 2022ApJ...940L..53V

2022ApJ...940L..53V - Astrophys. J., 940, L53 (2022/December-1)

Early Results from GLASS-JWST. VII. Evidence for Lensed, Gravitationally Bound Protoglobular Clusters at z = 4 in the Hubble Frontier Field A2744.

VANZELLA E., CASTELLANO M., BERGAMINI P., TREU T., MERCURIO A., SCARLATA C., ROSATI P., GRILLO C., ACEBRON A., CAMINHA G.B., NONINO M., NANAYAKKARA T., ROBERTS-BORSANI G., BRADAC M., WANG X., BRAMMER G., STRAIT V., VULCANI B., MESTRIC U., MENEGHETTI M., CALURA F., HENRY A., ZANELLA A., TRENTI M., BOYETT K., MORISHITA T., CALABRO A., GLAZEBROOK K., MARCHESINI D., BIRRER S., YANG L. and JONES T.

Abstract (from CDS):

We investigate the blue and optical rest-frame sizes (λ ≃ 2300-4000 Å) of three compact star-forming regions in a galaxy at z = 4 strongly lensed (×30, ×45, and ×100) by the Hubble Frontier Field galaxy cluster A2744 using GLASS-ERS James Webb Space Telescope (JWST)/NIRISS imaging at 1.15 μm, 1.50 μm, and 2.0 μm with a point-spread function ≲0.″1. In particular, the Balmer break is probed in detail for all multiply imaged sources of the system. With ages of a few tens of Myr, stellar masses in the range (0.7-4.0) ×106M and optical/ultraviolet effective radii spanning the interval 3 < Reff < 20 pc, such objects are currently the highest-redshift (spectroscopically confirmed) gravitationally bound young massive star clusters (YMCs), with stellar mass surface densities resembling those of local globular clusters. Optical (4000 Å, JWST-based) and ultraviolet (1600 Å, Hubble Space Telescope-based) sizes are fully compatible. The contribution to the ultraviolet underlying continuum emission (1600 Å) is ∼30%, which decreases by a factor of 2 in the optical for two of the YMCs (∼4000 Å rest-frame), reflecting the young ages (<30 Myr) inferred from the spectral energy distribution fitting and supported by the presence of high-ionization lines secured with the Very Large Telescope/MUSE. Such bursty forming regions enhance the specific star formation rate of the galaxy, which is ≃10 Gyr–1. This galaxy would be among the extreme analogs observed in the local universe having a high star formation rate surface density and a high occurrence of massive stellar clusters in formation.

Abstract Copyright: © 2022. The Author(s). Published by the American Astronomical Society.

Journal keyword(s): High-redshift galaxies - Young star clusters

Status at CDS : Examining the need for a new acronym.

Simbad objects: 3

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Number of rows : 3
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 ACO 2744 ClG 00 14 20.03 -30 23 17.8           ~ 785 0
2 ESO 350-38 Sy2 00 36 52.489 -33 33 17.23   14.31 14.41 13.49   ~ 373 0
3 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 11042 1

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