On the ages of bright galaxies $\sim 500$ Myr after the Big Bang: insights into star formation activity at $z\gtrsim 15$ with JWST

Abstract

With JWST, new opportunities to study the evolution of galaxies in the early Universe are emerging. Spitzer constraints on rest-optical properties of $z\gtrsim 7$ galaxies demonstrated the power of using galaxy stellar masses and star formation histories (SFHs) to indirectly infer the cosmic star formation history. However, only the brightest individual $z\gtrsim 8$ objects could be detected with Spitzer, making it difficult to robustly constrain activity at $z\gtrsim 10$. Here, we leverage the greatly improved rest-optical sensitivity of JWST at $z\gtrsim 8$ to constrain the ages of seven UV-bright ($M_{UV}\lesssim -19.5$) galaxies selected to lie at $z\sim 8.5-11$, then investigate implications for $z\gtrsim 15$ star formation. We infer the properties of individual objects with two spectral energy distribution modelling codes, then infer a distribution of ages for bright $z\sim 8.5-11$ galaxies. We find a median age of $\sim 20$ Myr, younger than that inferred at $z\sim 7$ with a similar analysis, consistent with an evolution towards larger specific star formation rates at early times. The age distribution suggests that only $\sim 3$ percent of bright $z\sim 8.5-11$ galaxies would be similarly luminous at $z\gtrsim 15$, implying that the number density of bright galaxies declines by at least an order of magnitude between $z\sim 8.5-11$ and $z\sim 15$. This evolution is challenging to reconcile with some early JWST results suggesting the abundance of bright galaxies does not significantly decrease towards very early times, but we suggest this tension may be eased if young stellar populations form on top of older stellar components, or if bright $z\sim 15$ galaxies are observed during a burst of star formation.

16 pages, 10 figures, 1 appendix, accepted to MNRAS

References in corpus (31)

• Array Programming with NumPy
• The propagation of uncertainties in stellar population synthesis modeling I: The relevance of uncertain aspects of stellar evolution and the IMF to the derived physical properties of galaxies
• UV Luminosity Functions at redshifts z~4 to z~10: 10000 Galaxies from HST Legacy Fields
• Stellar Population Inference with Prospector
• The All-wavelength Extended Groth Strip International Survey (AEGIS) Data Sets
• New Determinations of the UV Luminosity Functions from z~9 to z~2 show a remarkable consistency with halo growth and a constant star formation efficiency
• Early results from GLASS-JWST. III: Galaxy candidates at z$\sim$9-15
• Modelling the nebular emission from primeval to present-day star-forming galaxies
• The Relation Between SFR and Stellar Mass for Galaxies at 3.5 $\le z\le$ 6.5 in CANDELS
• The mass evolution of the first galaxies: stellar mass functions and star formation rates at $4<z<7$ in the CANDELS GOODS-South field
• The galaxy stellar mass function at 3.5<z<7.5 in the CANDELS/UDS, GOODS-South, and HUDF fields
• Galaxy Formation and Reionization: Key Unknowns and Expected Breakthroughs by the James Webb Space Telescope
• A lack of evolution in the very bright-end of the galaxy luminosity function from z = 8-10
• On the Stellar Populations of Galaxies at z=9-11: The Growth of Metals and Stellar Mass at Early Times
• The Star Formation Main Sequence in the Hubble Space Telescope Frontier Fields
• Galaxy Stellar Mass Functions from z~10 to z~6 using the Deepest Spitzer/IRAC Data: No Significant Evolution in the Stellar-to-Halo Mass Ratio of Galaxies in the First Gyr of Cosmic Time
• The [OIII]$+$H$\beta$ Equivalent Width Distribution at z$\simeq$7: Implications for the Contribution of Galaxies to Reionization
• A New Census of the 0.2< z <3.0 Universe, Part II: The Star-Forming Sequence
• A New Census of the 0.2 < z < 3.0 Universe, Part I: The Stellar Mass Function
• A Census of the Bright z=8.5-11 Universe with the Hubble and Spitzer Space Telescopes in the CANDELS Fields
• A Search for H-Dropout Lyman Break Galaxies at z~12-16
• The ALPINE-ALMA [CII] Survey: Obscured Star Formation Rate Density and Main Sequence of star-forming galaxies at z>4
• The NIRVANDELS Survey: a robust detection of $\alpha$-enhancement in star-forming galaxies at $z\simeq 3.4$
• Evidence for GN-z11 as a luminous galaxy at redshift 10.957
• Probing Cosmic Dawn : Ages and Star Formation Histories of Candidate $z\ge$9 Galaxies
• Near-Infrared Spectroscopy of Galaxies During Reionization: Measuring CIII] in a Galaxy at $\mathbf{z}=7.5$
• Interpreting the Spitzer/IRAC Colours of 7<z<9 Galaxies: Distinguishing Between Line Emission and Starlight Using ALMA
• An alternate approach to measure specific star formation rates at 2<z<7
• The [OIII]$\lambda 5007$ equivalent width distribution at z $\sim 2$: The redshift evolution of the extreme emission line galaxies
• Blue Rest-Frame UV-Optical Colors in z~8 Galaxies from GREATS: Very Young Stellar Populations at ~650 Myr of Cosmic Time
• The high-redshift Universe with Spitzer

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• Detection of the 2175Å UV Bump at z>7: Evidence for Rapid Dust Evolution in a Merging Reionisation-Era Galaxy
• An empirical consistent redshift bias: A possible direct reproducible observation of Zwicky's TL theory
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• Can an Anti-de Sitter Vacuum in the Dark Energy Sector Explain JWST High-Redshift Galaxy and Reionization Observations?
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