分类： 天文学 >> 天文学 提交时间： 2023-02-19
Kristan Boyett
Michele Trenti
Nicha Leethochawalit
Antonello Calabró
Benjamin Metha
Guido Roberts-Borsani
Nicoló Dalmasso
Lilan Yang
Paola Santini
Tommaso Treu
Tucker Jones
Alaina Henry
Charlotte A. Mason
Takahiro Morishita
Themiya Nanayakkara
Namrata Roy
Xin Wang
Adriano Fontana
Emiliano Merlin
Marco Castellano
摘要： JWST observations confirm the existence of galaxies as early as 300Myr and at a higher number density than expected based on galaxy formation models and HST observations. Yet, sources confirmed spectroscopically in the first 500Myr have estimated stellar masses $8$, we identify evidence of absorption lines (Si, C and Fe), with low confidence individual detections but SNR$>6$ when stacked. The absorption features suggest that Ly$\alpha$ is damped by the interstellar and circumgalactic medium. Our observations provide evidence of rapid efficient build-up of mass and metals in the immediate aftermath of the Big Bang through mergers, demonstrating that massive galaxies with several billion stars exist earlier than expected.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Guido Roberts-Borsani
Takahiro Morishita
Tommaso Treu
Gabriel Brammer
Victoria Strait
Xin Wang
Marusa Bradac
Ana Acebron
Pietro Bergamini
Kristan Boyett
Antonello Calabró
Marco Castellano
Adriano Fontana
Karl Glazebrook
Claudio Grillo
Alaina Henry
Tucker Jones
Matthew Malkan
Danilo Marchesini
Sara Mascia
摘要： We present the first search for $z\geqslant7$, continuum-confirmed sources with NIRISS/WFS spectroscopy over the Abell 2744 Frontier Fields cluster, as part of the GLASS-JWST ERS survey. With $\sim15$ hrs of pre-imaging and multi-angle grism exposures in the F115W, F150W, and F200W filters, we describe the general data handling (i.e., reduction, cleaning, modeling, and extraction processes) and analysis for the GLASS-JWST survey. We showcase the power of JWST to peer deep into reionization, when most intergalactic hydrogen is neutral, by confirming two galaxies at $z=8.04\pm0.15$ and $z=7.90\pm0.13$ by means of their Lyman breaks. Fainter continuum spectra are observed in both the F150W and F200W bands, indicative of blue ($-1.69$ and $-1.33$) UV slopes and moderately-bright absolute magnitudes ($-20.37$ and $-19.68$ mag). We do not detect strong Ly$\alpha$ in either galaxy, but do observe tentative ($\sim2.7-3.8\sigma$) HeII$\lambda$1640 A, OIII]$\lambda\lambda$1661,1666 A, and NIII]$\lambda\lambda$1747,1749 A line emission in one, suggestive of low metallicity, star-forming systems with possible non-thermal contributions. These novel observations provide a first look at the extraordinary potential of JWST/NIRISS for confirming representative samples of bright $z\geqslant7$ sources in the absence of strong emission lines, and gain unprecedented insight into their contributions towards cosmic reionization.
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