MUSE Analysis of Gas around Galaxies (MAGG) -- VII. Emission line galaxies near strong blended Ly$α$ absorption systems at $z\gtrsim3$

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Main Authors: Galbiati, Marta, Tornotti, Davide, Fumagalli, Michele, Fossati, Matteo, Pieri, Matthew
Format: Preprint
Published: 2025
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author Galbiati, Marta
Tornotti, Davide
Fumagalli, Michele
Fossati, Matteo
Pieri, Matthew
author_facet Galbiati, Marta
Tornotti, Davide
Fumagalli, Michele
Fossati, Matteo
Pieri, Matthew
contents We investigate the connection between strong, blended Ly$α$ absorption systems (SBLAs) and $\approx1000$ Ly$α$ emitting galaxies (LAEs) at $z\gtrsim3$ in 28 quasar fields from the MUSE Analysis of Gas around Galaxies (MAGG) survey. Selecting SBLAs as spectral regions with transmitted flux $-0.05<F<0.25$ over $\approx138\text{ km s}^{-1}$ bins, we find a strong correlation with LAEs within a projected distance of $R\le300\rm\,kpc$ and line-of-sight velocity separation of $|Δv|\le300 \text{ km s}^{-1}$. The association rate increases significantly with decreasing flux, a trend that persists also at smaller separations ($R<100$ kpc). A two-dimensional cross-correlation analysis confirms significant clustering of LAEs around SBLAs, while no such clustering is seen for spectral regions with $F>0.25$. The correlation appears to also depend on the width of the spectral window used to identify SBLAs, with a larger window yielding a stronger signal. Our analysis confirms that SBLAs serve as probes of the CGM at the interface between the Ly$α$ forest and the optically-thick Lyman limit systems. The significant dependence of the LAE-SBLA cross-correlation on the spectral binning used to select these absorbers motivates future tests of the current SBLA framework as a tracer of halos.
format Preprint
id arxiv_https___arxiv_org_abs_2512_16422
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle MUSE Analysis of Gas around Galaxies (MAGG) -- VII. Emission line galaxies near strong blended Ly$α$ absorption systems at $z\gtrsim3$
Galbiati, Marta
Tornotti, Davide
Fumagalli, Michele
Fossati, Matteo
Pieri, Matthew
Astrophysics of Galaxies
We investigate the connection between strong, blended Ly$α$ absorption systems (SBLAs) and $\approx1000$ Ly$α$ emitting galaxies (LAEs) at $z\gtrsim3$ in 28 quasar fields from the MUSE Analysis of Gas around Galaxies (MAGG) survey. Selecting SBLAs as spectral regions with transmitted flux $-0.05<F<0.25$ over $\approx138\text{ km s}^{-1}$ bins, we find a strong correlation with LAEs within a projected distance of $R\le300\rm\,kpc$ and line-of-sight velocity separation of $|Δv|\le300 \text{ km s}^{-1}$. The association rate increases significantly with decreasing flux, a trend that persists also at smaller separations ($R<100$ kpc). A two-dimensional cross-correlation analysis confirms significant clustering of LAEs around SBLAs, while no such clustering is seen for spectral regions with $F>0.25$. The correlation appears to also depend on the width of the spectral window used to identify SBLAs, with a larger window yielding a stronger signal. Our analysis confirms that SBLAs serve as probes of the CGM at the interface between the Ly$α$ forest and the optically-thick Lyman limit systems. The significant dependence of the LAE-SBLA cross-correlation on the spectral binning used to select these absorbers motivates future tests of the current SBLA framework as a tracer of halos.
title MUSE Analysis of Gas around Galaxies (MAGG) -- VII. Emission line galaxies near strong blended Ly$α$ absorption systems at $z\gtrsim3$
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2512.16422