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Title: Implications of z ~ 6 Quasar Proximity Zones for the Epoch of Reionization and Quasar Lifetimes

Journal Article · · The Astrophysical Journal (Online)
ORCiD logo [1];  [2]; ORCiD logo [2]; ORCiD logo [3];  [4];  [1]
  1. Max Planck Inst. for Astronomy, Heidelberg (Germany); Heidelberg Univ. (Germany)
  2. Max Planck Inst. for Astronomy, Heidelberg (Germany); Univ. of California, Santa Barbara, CA (United States)
  3. Univ. of California, Santa Cruz, CA (United States)
  4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
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In this paper, we study quasar proximity zones in the redshift range $$5.77\leqslant z\leqslant 6.54$$ by homogeneously analyzing 34 medium-resolution spectra, encompassing both archival and newly obtained data, and exploiting recently updated systemic redshift and magnitude measurements. Whereas previous studies found strong evolution of proximity zone sizes with redshift and argued that this provides evidence for a rapidly evolving intergalactic medium (IGM) neutral fraction during reionization, we measure a much shallower trend $$\propto {(1+z)}^{-1.44}$$. We compare our measured proximity zone sizes to predictions from hydrodynamical simulations post-processed with one-dimensional radiative transfer and find good agreement between observations and theory, irrespective of the ionization state of the ambient IGM. This insensitivity to IGM ionization state has been previously noted, and results from the fact that the definition of proximity zone size as the first drop of the smoothed quasar spectrum below the 10% flux transmission level probes locations where the ionizing radiation from the quasar is an order of magnitude larger than the expected ultraviolet ionizing background that sets the neutral fraction of the IGM. Our analysis also uncovered three objects with exceptionally small proximity zones (two have $${R}_{p}\lt 1$$ proper Mpc), which constitute outliers from the observed distribution and are challenging to explain with our radiative transfer simulations. Finally, we consider various explanations for their origin, such as strong absorption line systems associated with the quasar or patchy reionization, but find that the most compelling scenario is that these quasars have been shining for ≲105 years.

Research Organization:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)
Sponsoring Organization:
USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR); USDOE Office of Science (SC), High Energy Physics (HEP)
Grant/Contract Number:
AC02-05CH11231
OSTI ID:
1379826
Alternate ID(s):
OSTI ID: 1563931
Journal Information:
The Astrophysical Journal (Online), Vol. 840, Issue 1; ISSN 1538-4357
Publisher:
Institute of Physics (IOP)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 97 works
Citation information provided by
Web of Science

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Cited By (44)

New constraints on Lyman-α opacity using 92 quasar lines of sight journal October 2017
An 800-million-solar-mass black hole in a significantly neutral Universe at a redshift of 7.5 journal December 2017
Discovery of intergalactic bridges connecting two faint z ∼ 3 quasars journal October 2019
Supermassive black holes in the early universe journal April 2019
The role of galaxies and AGN in reionizing the IGM – I. Keck spectroscopy of 5 < z < 7 galaxies in the QSO field J1148+5251 journal May 2018
How proper are Bayesian models in the astronomical literature? journal August 2018
The role of galaxies and AGNs in reionizing the IGM – II. Metal-tracing the faint sources of reionization at 5 ≲ z ≲ 6 journal November 2018
Three new VHS–DES quasars at 6.7 < z < 6.9 and emission line properties at z > 6.5 journal May 2019
Evidence for short ∼ 1 Myr lifetimes from the He   ii proximity zones of z  ∼ 4 quasars journal January 2019
New constraints on quasar evolution: broad-line velocity shifts over 1.5 ≲ z ≲ 7.5 journal June 2019
Nuisance hardened data compression for fast likelihood-free inference journal July 2019
Constraints on reionization from the z = 7.5 QSO ULASJ1342+0928 journal January 2019
Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs). VIII. A less biased view of the early co-evolution of black holes and host galaxies journal September 2019
The Faint End of the z = 5 Quasar Luminosity Function from the CFHTLS journal February 2018
Revealing the Warm and Hot Halo Baryons via Thomson Scattering of Quasar Light journal July 2018
An ALMA [C ii] Survey of 27 Quasars at z > 5.94 journal February 2018
A New Method to Measure the Post-reionization Ionizing Background from the Joint Distribution of Ly α and Ly β Forest Transmission journal March 2018
Modeling the He ii Transverse Proximity Effect: Constraints on Quasar Lifetime and Obscuration journal July 2018
The Opacity of the Intergalactic Medium Measured along Quasar Sightlines at z ∼ 6 journal August 2018
Quantitative Constraints on the Reionization History from the IGM Damping Wing Signature in Two Quasars at z > 7 journal September 2018
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First Spectroscopic Study of a Young Quasar journal October 2018
No Evidence for Millimeter Continuum Source Overdensities in the Environments of z ≳ 6 Quasars journal November 2018
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The Evolution of the He ii-ionizing Background at Redshifts 2.3 < z < 3.8 Inferred from a Statistical Sample of 24 HST /COS He ii Ly α Absorption Spectra journal April 2019
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Modeling the HeII Transverse Proximity Effect: Constraints on Quasar Lifetime and Obscuration text January 2017
The Faint End of the z=5 Quasar Luminosity Function from the CFHTLS text January 2017
Revealing the Warm and Hot Halo Baryons via Thomson Scattering of Quasar Light text January 2018
The Opacity of the Intergalactic Medium Measured Along Quasar Sightlines at $z\sim 6$ text January 2018
No Evidence for Millimeter Continuum Source Overdensities in the Environments of $z\gtrsim6$ Quasars text January 2018
Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs). V. Quasar Luminosity Function and Contribution to Cosmic Reionization at z = 6 text January 2018
Nuisance hardened data compression for fast likelihood-free inference text January 2019
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Figures / Tables (19)

TABLE 1(p. 3)table TABLE 1
TABLE 2(p. 5)table TABLE 2
Fig. 1.(p. 7)figure Fig. 1.
Fig. 2.(p. 8)figure Fig. 2.
Fig. 3.(p. 10)figure Fig. 3.
Fig. 4.(p. 11)figure Fig. 4.
Fig. 5.(p. 11)figure Fig. 5.
Fig. 6.(p. 12)figure Fig. 6.
Fig. 7.(p. 13)figure Fig. 7.
Fig. 8.(p. 14)figure Fig. 8.
Fig. 9.(p. 16)figure Fig. 9.
Fig. 10.(p. 17)figure Fig. 10.
Fig. 11.(p. 19)figure Fig. 11.
Fig. 12.(p. 20)figure Fig. 12.
Fig. 13.(p. 20)figure Fig. 13.
Fig. 14.(p. 21)figure Fig. 14.
Fig. 15.(p. 24)figure Fig. 15.
TABLE 3(p. 25)table TABLE 3
Fig. 16.(p. 26)figure Fig. 16.

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Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
dark ages
reionization
first stars
intergalactic medium
data analysis methods
quasar absorption lines