Early Results from GLASS-JWST. VII. Evidence for Lensed, Gravitationally Bound Protoglobular Clusters at z = 4 in the Hubble Frontier Field A2744
Articolo
Data di Pubblicazione:
2022
Citazione:
Early Results from GLASS-JWST. VII. Evidence for Lensed, Gravitationally Bound Protoglobular Clusters at z = 4 in the Hubble Frontier Field A2744 / E. Vanzella, M. Castellano, P. Bergamini, T. Treu, A. Mercurio, C. Scarlata, P. Rosati, C. Grillo, A. Acebron Munoz, G.B.C.M. Nonino, T. Nanayakkara, G. Roberts-Borsani, M. Bradac, X. Wang, G. Brammer, V.S.B. Vulcani, U. Meštrić, M. Meneghetti, F. Calura, A. Henry, A. Zanella, M. Trenti, K. Boyett, T. Morishita, A. Calabrò, K. Glazebrook, D. Marchesini, S. Birrer, L. Yang, T. Jones. - In: THE ASTROPHYSICAL JOURNAL LETTERS. - ISSN 2041-8205. - 940:2(2022 Dec 01), pp. L53.1-L53.8. [10.3847/2041-8213/ac8c2d]
Abstract:
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 ≲0farcs1. 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) ×106 M⊙ 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.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
high-redshift galaxies; strong gravitational lensing; star clusters;
Elenco autori:
E. Vanzella, M. Castellano, P. Bergamini, T. Treu, A. Mercurio, C. Scarlata, P. Rosati, C. Grillo, A. Acebron Munoz, G.B.C.M. Nonino, T. Nanayakkara, G. Roberts-Borsani, M. Bradac, X. Wang, G. Brammer, V.S.B. Vulcani, U. Meštrić, M. Meneghetti, F. Calura, A. Henry, A. Zanella, M. Trenti, K. Boyett, T. Morishita, A. Calabrò, K. Glazebrook, D. Marchesini, S. Birrer, L. Yang, T. Jones
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