# Ly$\alpha$ Halos Around $z\sim6$ Quasars

## TL;DR

This study uses deep MUSE observations to detect and analyze Ly$ extalpha$ halos around five quasars at $z
oughly6$, revealing diverse, asymmetric halos with significant luminosities and extents, and no clear link to quasar properties.

## Contribution

First detection of Ly$ extalpha$ halos around quasars at $z
oughly6$ using PSF subtraction, expanding understanding of circum-galactic medium in early universe.

## Key findings

- Four Ly$ extalpha$ halos are detected with diverse morphologies.
- Halos show no significant velocity offset from quasars.
- Luminosities and sizes exceed previous measurements at similar redshifts.

## Abstract

We present deep MUSE observations of five quasars within the first Gyr of the Universe ($z\gtrsim6$), four of which display extended Ly$\alpha$ halos. After PSF-subtraction, we reveal halos surrounding two quasars for the first time, as well as confirming the presence of two more halos for which tentative detections exist in long-slit spectroscopic observations and narrow-band imaging. The four Ly$\alpha$ halos presented here are diverse in morphology and size, they each display spatial asymmetry, and none are centred on the position of the quasar. Spectra of the diffuse halos demonstrate that none are dramatically offset in velocity from the systemic redshift of the quasars ($\Delta$ v $< 200$ kms$^{-1}$), however each halo shows a broad Ly$\alpha$ line, with a velocity width of order $\sim1000$ kms$^{-1}$. Total Ly$\alpha$ luminosities range between $\sim$ $2 \times 10^{43}$ erg s$^{-1}$ and $\sim$ $2 \times 10^{44}$ erg s$^{-1}$, reaching maximum radial extents of $13 - 30$ pkpc from the quasar positions. We find larger sizes and higher Ly$\alpha$ luminosities than previous literature results at this redshift, but find no correlation between the quasar properties and the Ly$\alpha$ halo, suggesting that the detected emission is most closely related to the physical properties of the circum-galactic medium