Earliest galaxy evolution in the CANUCS+Technicolor fields: galaxy properties at $z \sim 10–16$ seen with the full NIRCam medium- and broadband filters

Asada, Yoshihisa (author), Bradač, Maruša (author), Martis, Nicholas S. (author), Felicioni, Giordano (author), Judež, Jon (author)

We present a sample of $z_{\mathrm{phot}}\sim 10–16$ galaxies by exploiting some of the richest JWST NIRCam imaging data, taken in the CANUCS survey in Cycle 1 and the Technicolor (TEC) survey in Cycle 2. The combination of the CANUCS+TEC provides multiepoch, deep NIRCam images in all medium bands (MBs) and broad bands (BBs) onboard NIRCam (22 filters in total), over $\sim 23\ \mathrm{arcmin}^2$ in three independent lines of sight. We select high-z galaxy candidates based on photometric redshifts, and obtain eight candidates at $z \sim 10–16$, including a very robust candidate at $z \sim 15.4$. The ultraviolet (UV) luminosity function (LF) from our sample is consistent with previous JWST studies showing a scatter of $\sim 0.6$ dex across the literature, marking the significance of the field-to-field variance in interpreting galaxy abundance measurements at $z > 10$. We find that the UV LF moderately evolves at $z > 10$, and the LF normalization and the luminosity density decline by a factor of $\sim 7$ from $z \sim 11$ to $z \sim 15$, indicating less steep evolution than z < 11. We highlight the importance of MB filters, not only to minimize the contamination by low-z interlopers but also to maximize the completeness. In particular, faint and less blue galaxies could be missed when the sample is built solely on BB data. The contamination and incompleteness of BB-only selected samples can bias our views of earliest galaxy evolution at $z > 10$, including the UV LF by $\sim 0.6$ dex, the size–magnitude relation by $\sim 0.6$ dex, and the UV slope-magnitude relation by $\Delta\beta_{\mathrm{UV}} \sim −0.3$.

• Language: English
• Keywords: galaxies, galaxy formation, galaxy evolution, luminosity function, high-redshift galaxies
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FMF - Faculty of Mathematics and Physics
• Publication status: Published
• Publication version: Version of Record
• Year: 2026
• Number of pages: 17 str.
• Numbering: Vol. 996, no. 2, art. no. 115
• PID: 20.500.12556/RUL-178335
• UDC: 524.8
• ISSN on article: 1538-4357
• DOI: 10.3847/1538-4357/ae1f8d
• COBISS.SI-ID: 265884931
• Publication date in RUL: 23.01.2026

Record is a part of a journal

• Title: The Astrophysical journal
• Shortened title: Astrophys. j.
• Publisher: University of Chicago Press for the American Astronomical Society
• ISSN: 1538-4357
• COBISS.SI-ID: 515079705

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: galaksije, nastanek galaksij, razvoj galaksij, porazdelitev izsevov, galaksije z velikim rdečim premikom