When galaxies burst: enhanced shot-noise for line-intensity mapping in the JWST era
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| Format: | Preprint |
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2026
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| _version_ | 1866914564677828608 |
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| author | Kovetz, Ely D. Lazare, Hovav Libanore, Sarah Muñoz, Julian B. Vanzan, Eleonora |
| author_facet | Kovetz, Ely D. Lazare, Hovav Libanore, Sarah Muñoz, Julian B. Vanzan, Eleonora |
| contents | Recent JWST observations indicate that star formation at $z\!\sim\!4-6$ is more stochastic than previously assumed, with rms log-SFR scatter $\sim\!0.6$ dex at $M_h\!\sim\!10^{11}M_{\odot}$, growing toward smaller halos and time-correlated on $\sim\!25$ Myr. This is significantly higher than the typical $\sim\!0.3$ dex phenomenological lognormal scatter assumed in standard line-intensity mapping (LIM) forecasts. We propagate the JWST-era burstiness through to the LIM shot-noise power spectrum and show that the result is a simple multiplicative correction: the deterministic shot noise multiplied by a line-dependent boost factor $B_λ$ derived in closed form by convolving the SFR correlation function with the stellar-population-synthesis kernel of each line. At $z\!\sim\!6$, we find $B_{{\rm H}α}\!\simeq\!7$ and $B\!\sim\!2.5$-$3.5$ for longer-window tracers ([CII], CO, UV) - factors of $\sim\!2$-$5$ above the standard prescription, and growing further toward higher redshift. The enhancement transforms the LIM landscape: it improves auto-spectrum detectability and suppresses lower-redshift interloper contamination, but degrades cosmological applications such as BAO that rely on a clean clustering measurement. Crucially, it also opens a new use of LIM as a diagnostic of high-redshift star-formation physics beyond the regime of individually resolved galaxies: redshift tomography of a single line constrains the amplitude and mass dependence of the burstiness, while cross-line shot-noise correlations probe its time coherence. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2605_13967 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | When galaxies burst: enhanced shot-noise for line-intensity mapping in the JWST era Kovetz, Ely D. Lazare, Hovav Libanore, Sarah Muñoz, Julian B. Vanzan, Eleonora Astrophysics of Galaxies Cosmology and Nongalactic Astrophysics Recent JWST observations indicate that star formation at $z\!\sim\!4-6$ is more stochastic than previously assumed, with rms log-SFR scatter $\sim\!0.6$ dex at $M_h\!\sim\!10^{11}M_{\odot}$, growing toward smaller halos and time-correlated on $\sim\!25$ Myr. This is significantly higher than the typical $\sim\!0.3$ dex phenomenological lognormal scatter assumed in standard line-intensity mapping (LIM) forecasts. We propagate the JWST-era burstiness through to the LIM shot-noise power spectrum and show that the result is a simple multiplicative correction: the deterministic shot noise multiplied by a line-dependent boost factor $B_λ$ derived in closed form by convolving the SFR correlation function with the stellar-population-synthesis kernel of each line. At $z\!\sim\!6$, we find $B_{{\rm H}α}\!\simeq\!7$ and $B\!\sim\!2.5$-$3.5$ for longer-window tracers ([CII], CO, UV) - factors of $\sim\!2$-$5$ above the standard prescription, and growing further toward higher redshift. The enhancement transforms the LIM landscape: it improves auto-spectrum detectability and suppresses lower-redshift interloper contamination, but degrades cosmological applications such as BAO that rely on a clean clustering measurement. Crucially, it also opens a new use of LIM as a diagnostic of high-redshift star-formation physics beyond the regime of individually resolved galaxies: redshift tomography of a single line constrains the amplitude and mass dependence of the burstiness, while cross-line shot-noise correlations probe its time coherence. |
| title | When galaxies burst: enhanced shot-noise for line-intensity mapping in the JWST era |
| topic | Astrophysics of Galaxies Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2605.13967 |