Subaru medium-resolution spectra of a QSO at z=6.62: Three reionization tests

Abstract

Investigating the Gunn-Peterson trough of high redshift quasars (QSOs) is a powerful way to reveal the cosmic reionization. As one of such attempts, we perform a series of analyses to examine the absorption lines observed with one of the highest redshift QSOs, PSO J006.1240+39.2219, which we previously discovered at z = 6.62. Using the Subaru telescope, we obtained medium-resolution spectrum with a total exposure time of 7.5 hours. We calculate the Ly$\alpha$ transmission in different redshift bins to determine the near zone radius and the optical depth at 5.6$<$z$<$6.5. We find a sudden change in the Ly$\alpha$ transmission at 5.75$<$z$<$5.86, which is consistent with the result from the literature. The near zone radius of the QSO is 5.79$\pm$0.09 $p$Mpc, within the scatter of the near zone radii of other QSOs measured in previous studies. We also analyze the dark gap distribution to probe the neutral hydrogen fractions beyond the saturation limit of the Gunn-Peterson trough. We extend the measurement of the dark gaps to 5.7$<$z$<$6.3. We find that the gap widths increase with increasing redshifts, suggesting more neutral Universe at higher redshifts. However, these measurements strongly depend on the continuum modeling. As a continuum model-free attempt, we also perform the dark-pixel counting analysis, to find the upper limit of $⟨x_{\mathrm{HI}}⟩\sim$0.6 (0.8) at $z<$5.8 ($z>$5.8). All three analyses based on this QSO show increasingly neutral hydrogen towards higher redshifts, adding precious measurements up to z$\sim$6.5.

arXiv comment11 pages, 10 figures, 5 tables, Accepted for Publication in ApJ

References in corpus (29)

• Constraining the Evolution of the Ionizing Background and the Epoch of Reionization with z ~ 6 Quasars II: A Sample of 19 Quasars
• In the Beginning: The First Sources of Light and the Reionization of the Universe
• An 800-million-solar-mass black hole in a significantly neutral Universe at redshift 7.5
• Evidence for Reionization at z ~ 6: Detection of a Gunn-Peterson Trough in a z=6.28 Quasar
• Observational constraints on Cosmic Reionization
• Evolution of the Ionizing Background and the Epoch of Reionization from the Spectra of z~6 Quasars
• Model-independent evidence in favor of an end to reionization by z~6
• Evidence of patchy hydrogen reionization from an extreme Ly$\alpha$ trough below redshift six
• The Reionization of the Universe by the First Stars and Quasars
• Physical properties of 15 quasars at $z\gtrsim 6.5$
• Four quasars above redshift 6 discovered by the Canada-France High-z Quasar Survey
• How neutral is the intergalactic medium surrounding the redshift z=7.085 quasar ULAS J1120+0641?
• New constraints on Lyman-α opacity with a sample of 62 quasars at z > 5.7
• The Evolution of the Intergalactic Medium Transmission to Redshift Six
• Long troughs in the Lyman-$\alpha$ forest below redshift 6 due to islands of neutral hydrogen
• The identification of z-dropouts in Pan-STARRS1: three quasars at 6.5<z<6.7
• The Opacity of the Intergalactic Medium Measured Along Quasar Sightlines at $z\sim 6$
• Ionization near-zones associated with quasars at z ~ 6
• Approaching Reionization: The Evolution of the Lyman Alpha Forest from Redshifts Four to Six
• The first (nearly) model-independent constraint on the neutral hydrogen fraction at z~5--6
• Glimpsing through the high redshift neutral hydrogen fog
• Constraining the reionization history with QSO absorption spectra
• Observations of the Lyman series forest towards the redshift 7.1 quasar ULAS J1120+0641
• Cosmic Reionization On Computers. Properties of the Post-reionization IGM
• A Statistical Analysis of Intergalactic Medium Transmission Approaching Reionization
• Rapid Black Hole Growth at the Dawn of the Universe: A Super-Eddington Quasar at z=6.6
• A Quasar Discovered at redshift 6.6 from Pan-STARRS1
• A Gunn-Peterson test with a QSO at z=6.4
• The Space Density of Galaxy Peaks and the Linear Matter Power Spectrum

Cited by in corpus (6)

• The THESAN project: properties of the intergalactic medium and its connection to Reionization-era galaxies
• UNCOVERing the contribution of black holes to reionization in the JWST era
• SPICE: the connection between cosmic reionisation and stellar feedback in the first galaxies
• Revealing the cosmic reionisation history with fast radio bursts in the era of Square Kilometre Array
• The Distribution and Evolution of Quasar Proximity Zone Sizes
• Early Results from GLASS-JWST XXIII: The transmission of Lyman-alpha from UV-faint z ~ 3-6 galaxies