Results of the summarizing process for the arXiv paper: 1912.04314v1

In a recent study, researchers presented improved results on the correlation between galaxies and the intergalactic medium (IGM) transmission at the end of reionisation. The team gathered a sample of 13 spectroscopically confirmed Lyman-break galaxies (LBGs) and 21 Lyman-alpha emitters (LAEs) at angular separations ranging from 20'' to 10' ($\sim$0.1-4 pMpc at $z\sim6$) from the sightlines to eight background $z\gtrsim6$ quasars. For the first time, they detected an excess of Lyman-alpha transmission spikes at $\sim$10-60 cMpc from LAEs ($3.6\sigma$) and LBGs ($3.1\sigma$). To interpret their data, the team used an improved model of galaxy-Lyman-alpha transmission and two-point cross-correlations that included enhanced photoionisation due to clustered faint sources, enhanced gas densities around central bright objects, and spatial variations in mean free path. The observed LAE(LBG)-Lyman-alpha transmission spike two-point cross-correlation function (2PCCF) constrained the luminosity-averaged escape fraction of all galaxies contributing to reionisation to $\langle f_{esc} \rangle_{M_{UV}<-12}=0.10^{+0.17}_{-0.05}$ for LBGs and $\langle f_{esc} \rangle_{M_{UV}<-12}=0.18^{+0.52}_{-0.06}$ for LAEs. The team also investigated whether their 2PCCF measurement could determine whether bright or faint galaxies were dominant contributors to reionisation. Their results showed that a contribution from faint galaxies ($M_{UV}> -20$, $2\sigma$) was necessary to reproduce the observed 2PCCF and that reionisation might be driven by different subpopulations around LBGs and LAEs at $z \sim 6$. Overall, this study provides new insights into the role of galaxies and AGN in reionising the IGM. The team's improved model and measurements could help refine our understanding of how galaxies contribute to reionisation and how it varies across different populations of galaxies.

• Researchers presented improved results on the correlation between galaxies and the intergalactic medium (IGM) transmission at the end of reionisation.
• The team gathered a sample of 13 spectroscopically confirmed Lyman-break galaxies (LBGs) and 21 Lyman-alpha emitters (LAEs).
• They detected an excess of Lyman-alpha transmission spikes at $\sim$10-60 cMpc from LAEs ($3.6\sigma$) and LBGs ($3.1\sigma$).
• The observed LAE(LBG)-Lyman-alpha transmission spike two-point cross-correlation function (2PCCF) constrained the luminosity-averaged escape fraction of all galaxies contributing to reionisation.
• The team investigated whether their 2PCCF measurement could determine whether bright or faint galaxies were dominant contributors to reionisation.
• A contribution from faint galaxies ($M_{UV}> -20$, $2\sigma$) was necessary to reproduce the observed 2PCCF, suggesting that reionisation might be driven by different subpopulations around LBGs and LAEs at $z \sim 6$.
• This study provides new insights into the role of galaxies and AGN in reionising the IGM.

Scientists studied how galaxies and the space between them (IGM) are connected. They looked at 13 special galaxies and 21 other types of objects in space. They found that there were more signals coming from a certain distance away from these objects. This helped them figure out how much light was escaping from all the galaxies during a time called reionisation. They also learned that both bright and faint galaxies played a role in this process. This study helps us understand how space is lit up by different things in it. Definitions- Galaxies: large groups of stars, gas, and dust held together by gravity - Intergalactic medium (IGM): the matter that fills the space between galaxies - Transmission: the amount of light or energy that passes through something - Spectroscopically confirmed: using a tool to analyze the light coming from an object to confirm what it is made of - Lyman-alpha emitters (LAEs): objects in space that emit a specific type of light called Lyman-alpha radiation - Cross-correlation function: a way to measure how two different things are related to each other - Luminosity-averaged escape fraction: how much light escapes from all the galaxies on average - Reionisation: a period in the early universe when hydrogen gas became ionized by ultraviolet radiation from stars and other sources - AGN: active galactic nuclei, which are very bright regions at the center of some galaxies

Exploring the Role of Galaxies in Reionisation: Improved Results on Correlation Between Galaxies and Intergalactic Medium Transmission

Reionisation is a crucial part of our universe's history, as it marks the transition from an opaque to a transparent universe. During this period, ultraviolet (UV) radiation from galaxies and active galactic nuclei (AGN) ionised neutral hydrogen atoms in the intergalactic medium (IGM), allowing light to travel freely through space. In recent years, researchers have been trying to understand how galaxies contribute to reionisation by studying their correlation with IGM transmission at the end of reionisation.

In a new study published in The Astrophysical Journal Letters, researchers presented improved results on this topic. The team gathered data from 13 Lyman-break galaxies (LBGs) and 21 Lyman-alpha emitters (LAEs) located at angular separations ranging from 20'' to 10' ($\sim$0.1-4 pMpc at $z\sim6$) from eight background $z\gtrsim6$ quasars. For the first time, they detected an excess of Lyman-alpha transmission spikes at $\sim$10-60 cMpc from LAEs ($3.6\sigma$) and LBGs ($3.1\sigma$).

Improved Model for Galaxy-Lyman Alpha Transmission

To interpret their data, the team used an improved model of galaxy-Lyman alpha transmission that included enhanced photoionization due to clustered faint sources, enhanced gas densities around central bright objects, and spatial variations in mean free path. This model allowed them to better understand how different populations of galaxies contribute to reionisation by looking at two-point cross correlations between these populations and Lyman alpha transmission spikes in the IGM.

Luminosity Averaged Escape Fraction

The observed LAE(LBG)-Lyman alpha transmission spike two point cross correlation function (2PCCF) constrained the luminosity averaged escape fraction of all galaxies contributing to reionisation to $\langle f_{esc} \rangle_{M_{UV}<-12}=0.10^{+0.17}_{-0