分类： 天文学 >> 天文学 提交时间： 2023-02-19
Marco Castellano
Adriano Fontana
Tommaso Treu
Emiliano Merlin
Paola Santini
Pietro Bergamini
Claudio Grillo
Piero Rosati
Ana Acebron
Nicha Leethochawalit
Diego Paris
Andrea Bonchi
Davide Belfiori
Antonello Calabrò
Matteo Correnti
Mario Nonino
Gianluca Polenta
Michele Trenti
Kristan Boyett
G. Brammer
摘要： We report the detection of a high density of redshift $z\approx 10$ galaxies behind the foreground cluster Abell 2744, selected from imaging data obtained recently with NIRCam onboard JWST by three programs -- GLASS-JWST, UNCOVER, and DDT-2756. To ensure robust estimates of the lensing magnification $\mu$, we use an improved version of our model that exploits the first epoch of NIRCam images and newly obtained MUSE spectra, and avoids regions with $\mu>5$ where the uncertainty may be higher. We detect seven bright $z\approx 10$ galaxies with demagnified rest-frame $-22 \lesssim M_{\rm UV}\lesssim -19$ mag, over an area of $\sim37$ sq. arcmin. Taking into account photometric incompleteness and the effects of lensing on luminosity and cosmological volume, we find that the density of $z\approx 10$ galaxies in the field is about $10\times$ ($3\times$) larger than the average at $M_{UV}\approx -21 (-20)$ mag reported so far. The density is even higher when considering only the GLASS-JWST data, which are the depeest and the least affected by magnification and incompleteness. The GLASS-JWST field contains 5 out of 7 galaxies, distributed along an apparent filamentary structure of 2 Mpc in projected length, and includes a close pair of candidates with $M_{\rm UV}< -20$ mag having a projected separation of only 16 kpc. These findings suggest the presence of a $z\approx 10$ overdensity in the field. In addition to providing excellent targets for efficient spectroscopic follow-up observations, our study confirms the high density of bright galaxies observed in early JWST observations, but calls for multiple surveys along independent lines of sight to achieve an unbiased estimate of their average density and a first estimate of their clustering.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Emiliano Merlin
Andrea Bonchi
Diego Paris
Davide Belfiori
Adriano Fontana
Marco Castellano
Mario Nonino
Gianluca Polenta
Paola Santini
Lilan Yang
Karl Glazebrook
Tommaso Treu
Guido Roberts-Borsani
Michele Trenti
Simon Birrer
Gabriel Brammer
Claudio Grillo
Antonello Calabrò
Danilo Marchesini
Charlotte Mason
摘要： We present the reduced images and multi-wavelength catalog of the first JWST NIRCam extra-galactic observations from the GLASS Early Release Science Program, obtained as coordinated parallels of the NIRISS observations of the Abell 2744 cluster. Images in seven bands (F090W, F115W, F150W, F200W, F277W, F356W, F444W) have been reduced using an augmented version of the official JWST pipeline; we discuss the procedures adopted to remove or mitigate defects in the raw images. We obtain a multi--band catalog by means of forced aperture photometry on PSF-matched images at the position of F444W-detected sources. The catalog is intended to enable early scientific investigations, and it is optimized for faint galaxies; it contains 6368 sources, with limiting magnitude 29.7 at 5$\sigma$ in F444W. We release both images and catalog in order to allow the community to familiarize with the JWST NIRCam data and evaluate their merit and limitations given the current level of knowledge of the instrument.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Marco Castellano
Adriano Fontana
Tommaso Treu
Paola Santini
Emiliano Merlin
Nicha Leethochawalit
Michele Trenti
Uros Mestric
Eros Vanzella
Andrea Bonchi
Davide Belfiori
Mario Nonino
Diego Paris
Gianluca Polenta
Guido Roberts-Borsani
Kristan Boyett
Marusa Bradac
Antonello Calabro
Karl Glazebrook
Claudio Grillo
摘要： We present the results of a first search for galaxy candidates at z$\sim$9--15 on deep seven-bands NIRCam imaging acquired as part of the GLASS-JWST Early Release Science Program on a flanking field of the Frontier Fields cluster A2744. Candidates are selected via two different renditions of the Lyman-break technique, isolating objects at z$\sim$9-11, and z$\sim$9-15, respectively, supplemented by photometric redshifts obtained with two independent codes. We find five color-selected candidates at z$>$9, plus one additional candidate with photometric redshift z$_{phot}\geq$9. In particular, we identify two bright candidates at $M_{UV}\simeq -21$ that are unambiguously placed at $z\simeq 10.6$ and $z\simeq 12.2$, respectively. The total number of galaxies discovered at $z>9$ is in line with the predictions of a non-evolving LF. The two bright ones at $z>10$ are unexpected given the survey volume, although cosmic variance and small number statistics limits general conclusions. This first search demonstrates the unique power of JWST to discover galaxies at the high redshift frontier. The candidates are ideal targets for spectroscopic follow-up in Cycle$-2$.
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