Measuring the properties of reionised bubbles with resolved Lyman alpha spectra

Abstract

Identifying and characterising reionised bubbles enables us to track both their size distribution, which depends on the primary ionising sources, and the relationship between reionisation and galaxy evolution. We demonstrate that spectrally resolved $z\gtrsim 6$ Lyman-alpha (Ly$\alpha$) emission can constrain properties of reionised regions. Specifically, the distant from a source to a neutral region sets the minimum observable Ly$\alpha$ velocity offset from systemic. Detection of flux on the blue side of the Ly$\alpha$ resonance implies the source resides in a large, sufficiently ionised region that photons can escape without significant resonant absorption, and thus constrains both the sizes of and the residual neutral fractions within ionised bubbles. We estimate the extent of the region around galaxies which is optically thin to blue Ly$\alpha$ photons, analogous to quasar proximity zones, as a function of the source's ionising photon output and surrounding gas density. This optically thin region is typically $\lesssim 0.3$ pMpc in radius (allowing transmission of flux $\gtrsim -250$ km s${}^{-1}$), $\lesssim 20$% of the distance to the neutral region. In a proof-of-concept, we demonstrate the $z\approx 6.6$ galaxy COLA1 -- with a blue Ly$\alpha$ peak -- likely resides in an ionised region $>0.7$ pMpc, with residual neutral fraction $<10^{-5.5}$. To ionise its own proximity zone we infer COLA1 has a high ionising photon escape fraction ($f_{\mathrm{esc}}>0.50$), relatively steep UV slope ($\beta <-1.79$), and low line-of-sight gas density ($\sim 0.5\times$ the cosmic mean), suggesting it is a rare, underdense line-of-sight.

Accepted for publication in MNRAS, 11 pages

References in corpus (24)

• The NumPy array: a structure for efficient numerical computation
• Bayes in the sky: Bayesian inference and model selection in cosmology
• Strong Nebular Line Ratios in the Spectra of z~2-3 Star-forming Galaxies: First Results from KBSS-MOSFIRE
• The morphology of HII regions during reionization
• Using Lyman-alpha to detect galaxies that leak Lyman continuum
• Lyman Alpha Emitting Galaxies as a Probe of Reionization
• Line Emitting Galaxies Beyond a Redshift of 7: An Improved Method for Estimating the Evolving Neutrality of the Intergalactic Medium
• The first ultraviolet quasar stacked spectrum at z=2.4 from WFC3
• Inferences on the Timeline of Reionization at z~8 From the KMOS Lens-Amplified Spectroscopic Survey
• Can the intergalactic medium cause a rapid drop in Lyman alpha emission at z>6?
• Constraining the neutral fraction of hydrogen in the IGM at redshift 7.5
• The Ly-alpha Properties of Faint Galaxies at z2-3 with Systemic Redshifts and Velocity Dispersions from Keck-MOSFIRE
• The nature and evolution of the highly ionized near-zones in the absorption spectra of z~6 quasars
• HST-COS Observations of AGN. II. Extended Survey of Ultraviolet Composite Spectra from 159 Active Galactic Nuclei
• The MUSE Hubble Ultra Deep Field Survey VI: The Faint-End of the Lya Luminosity Function at 2.91 < z < 6.64 and Implications for Reionisation
• UV Radiative Feedback During the Advanced Stages of Reionization
• Spectroscopic properties of luminous Lyman-α emitters at $z\approx 6-7$ and comparison to the Lyman-break population
• The Impact of Scatter in the Galaxy UV Luminosity to Halo Mass Relation on Ly$\alpha$ Visibility During the Epoch of Reionization
• Three Lyman-alpha emitting galaxies within a quasar proximity zone at z=5.8
• The contribution from stars stripped in binaries to cosmic reionization of hydrogen and helium
• Adding Context to JWST Surveys with Current and Future 21cm Radio Observations
• Connecting Faint End Slopes of the Lyman-$\alpha$ emitter and Lyman-break Galaxy Luminosity Functions
• Lyman-alpha transmission properties of the intergalactic medium in the CoDaII simulation
• The Science Case for Multi-Object Spectroscopy on the European ELT

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