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Title: Modeling the He II Transverse Proximity Effect: Constraints on Quasar Lifetime and Obscuration

Journal Article · · The Astrophysical Journal (Online)
 [1]; ORCiD logo [2]; ORCiD logo [3]; ORCiD logo [4];  [5]; ORCiD logo [6]
  1. Univ. of California, Santa Barbara, CA (United States). Dept. of Physics; Max-Planck-Inst. für Astronomie, Heidelberg (Germany); Univ. of Heidelberg (IMPRS-HD), Heidelberg (Germany). International Max Planck Research School for Astronomy and Cosmic Physics
  2. Univ. of California, Santa Barbara, CA (United States). Dept. of Physics; Max-Planck-Inst. für Astronomie, Heidelberg (Germany)
  3. Max-Planck-Inst. für Astronomie, Heidelberg (Germany); Univ. Potsdam, Golm (Germany). Inst. für Physik und Astronomie
  4. Univ. of California, Santa Barbara, CA (United States). Dept. of Physics
  5. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  6. Univ. of Edinburgh, Scotland (United Kingdom). The Royal Observatory, Inst. for Astronomy
+ Show Author Affiliations

The He II transverse proximity effect - enhanced He II Lyα transmission in a background sightline caused by the ionizing radiation of a foreground quasar - offers a unique opportunity to probe the emission properties of quasars, in particular the emission geometry (obscuration, beaming) and the quasar lifetime. Building on the foreground quasar survey published in Schmidt et al., we present a detailed model of the He II transverse proximity effect, specifically designed to include light travel time effects, finite quasar ages, and quasar obscuration. Here, we post-process outputs from a cosmological hydrodynamical simulation with a fluctuating He ii ultraviolet background model, with the added effect of the radiation from a single bright foreground quasar. We vary the age tage and obscured sky fractions Ωobsc of the foreground quasar, and explore the resulting effect on the He ii transverse proximity effect signal. Fluctuations in intergalactic medium density and the ultraviolet background, as well as the unknown orientation of the foreground quasar, result in a large variance of the He II Lyα transmission along the background sightline. We develop a fully Bayesian statistical formalism to compare far-ultraviolet He ii Lyα transmission spectra of the background quasars to our models, and extract joint constraints on tage and Ωobsc for the six Schmidt et al. foreground quasars with the highest implied He II photoionization rates. Our analysis suggests a bimodal distribution of quasar emission properties, whereby one foreground quasar, associated with a strong He II transmission spike, is relatively old (22 Myr) and unobscured (Ωobsc < 35%), whereas three others are either younger than 10 Myr or highly obscured (Ωobsc > 70%).

Research Organization:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Grant/Contract Number:
AC02-05CH11231
OSTI ID:
1493259
Journal Information:
The Astrophysical Journal (Online), Journal Name: The Astrophysical Journal (Online) Journal Issue: 2 Vol. 861; ISSN 1538-4357
Publisher:
Institute of Physics (IOP)Copyright Statement
Country of Publication:
United States
Language:
English

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He II Proximity Effect and the Lifetime of Quasars text January 2015
Self-Consistent Modeling of Reionization in Cosmological Hydrodynamical Simulations text January 2016
On the Contribution of Active Galactic Nuclei to the High-Redshift Metagalactic Ionizing Background text January 2016
Galaxy gas as obscurer: II. Separating the galaxy-scale and nuclear obscurers of Active Galactic Nuclei text January 2016
The Thermal Proximity Effect: A New Probe of He II Reionization History and the Quasar Lifetime text January 2016
Dusty winds in active galactic nuclei: reconciling observations with models text January 2017
A self-consistent 3D model of fluctuations in the helium-ionizing background text January 2017
A Uniform Analysis of the Ly-alpha forest at z = 0 - 5: II. Measuring the mean intensity of the extragalactic ionizing background using the proximity effect text January 2000
The proximity effect in a close group of QSOs text January 2001
Caught in the act: a helium-reionizing quasar near the line of sight to Q0302-003 text January 2002
The 2dF QSO Redshift Survey - XIV. Structure and evolution from the two-point correlation function text January 2004
Quasars Probing Quasars I: Optically Thick Absorbers Near Luminous Quasars text January 2006
An Observational Determination of the Bolometric Quasar Luminosity Function text January 2006
Quasars Probing Quasars II: The Anisotropic Clustering of Optically Thick Absorbers around Quasars text January 2006
Atomic Data for Astrophysics. II. New Analytic Fits for Photoionization Cross Sections of Atoms and Ions text January 1996
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Cited By (8)

Discovery of intergalactic bridges connecting two faint z ∼ 3 quasars journal October 2019
Evidence for short ∼ 1 Myr lifetimes from the He   ii proximity zones of z  ∼ 4 quasars journal January 2019
Quantitative Constraints on the Reionization History from the IGM Damping Wing Signature in Two Quasars at z > 7 journal September 2018
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
Mapping Quasar Light Echoes in 3D with Ly α Forest Tomography journal September 2019
Observational Nonstationarity of AGN Variability: The Only Way to Go Is Down! journal January 2020
Discovery of intergalactic bridges connecting two faint $z\sim3$ quasars text January 2019
Observational nonstationarity of AGN variability: The only way to go is down! text January 2020

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