Statistical Detection of the He ii Transverse Proximity Effect: Evidence for Sustained Quasar Activity for &gt;25 Million Years

Schmidt, T.; Worseck, G.; Prochaska, J. Xavier; Crighton, Neil H. M.

doi:10.3847/1538-4357/aa83ac

Cited by 53 publications

(69 citation statements)

References 118 publications

(186 reference statements)

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“…Each source can become active multiple times dur-ing a simulation run. The resulting duty cycle is consistent with many observational studies which, however, set only weak constraints (Jakobsen et al 2003;Martini 2004;Porciani et al 2004;Cantalupo et al 2007;Worseck et al 2007;Kelly et al 2010;Bolton et al 2012;Cantalupo et al 2012;Trainor & Steidel 2013;Borisova et al 2016;Schmidt et al 2017).…”

Section: Ionizing Sourcessupporting

confidence: 87%

The Goldilocks problem of the quasar contribution to reionization

Garaldi

Compostella

Porciani

2018

Monthly Notices of the Royal Astronomical Society

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The detection of an unexpectedly large number of faint candidate quasars (QSO) at z 4 has motivated Madau and Haardt to investigate a reionization scenario in which active galactic nuclei dominate the photon budget at all times. Their analytical study reveals that this picture is in agreement with the evolution of the H I volume fraction in the intergalactic medium (IGM) and the optical depth to Thomson scattering of the cosmic microwave background. We employ a suite of hydrodynamical simulations post-processed with a radiative transfer code to further investigate the properties of such a reionization history. In particular, we generate synthetic absorption-line spectra for H I and He II that we compare with observational data. Although we confirm the analytical results mentioned above, we also find that the evolution of the IGM temperature and of the He II optical depth are at odds with current observational constraints. Nevertheless, the QSO-dominated scenario presents the attractive feature that it naturally generates an inhomogeneous IGM and thus produces an extended tail at high values in the distribution function of the H I effective optical depth, in agreement with recent observations. We find tentative evidence that considering some QSO emission at redshift z 5 could reconcile such observations with numerical simulations that have so far failed to reproduce this feature. Finally, we show that collecting more He II-absorption spectra at z 3 and studying their distinctive characteristics will be key to precisely constraining the QSO contribution to reionization.

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Section: Ionizing Sourcessupporting

confidence: 87%

The Goldilocks problem of the quasar contribution to reionization

Garaldi

Compostella

Porciani

2018

Monthly Notices of the Royal Astronomical Society

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“…Future samples of high-quality z ∼ 6 quasar spectra with precise systemic redshift estimates from current observational programs will soon increase the number of z ∼ 6 proximity zone measurements by a factor of a few. Studying these proximity zones in the context of the non-equilibrium phenomenology developed here will allow for powerful constraints on the lightcurves of accreting supermassive black holes, especially when combined with additional IGM-based probes of quasar activity at lower redshift that are sensitive to much longer timescales (Khrykin et al 2016(Khrykin et al , 2017(Khrykin et al , 2019Schmidt et al 2017Schmidt et al , 2018b. While we have focused on R p in this work, in principle the timescale at which the proximity zone is sensitive to variability differs along the line of sight as t eq ∝ r 2 .…”

Section: Discussionmentioning

confidence: 99%

Time-dependent behaviour of quasar proximity zones at z ∼ 6

Davies

Eilers

2019

Monthly Notices of the Royal Astronomical Society

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Since the discovery of z ∼ 6 quasars two decades ago, studies of their Lyα-transparent proximity zones have largely focused on their utility as a probe of cosmic reionization. But even when in a highly ionized intergalactic medium, these zones provide a rich laboratory for determining the timescales that govern quasar activity and the concomitant growth of their supermassive black holes. In this work, we use a suite of 1D radiative transfer simulations of quasar proximity zones to explore their timedependent behaviour for activity timescales from ∼ 10 3 -10 8 years. The sizes of the simulated proximity zones, as quantified by the distance at which the smoothed Lyα transmission drops below 10% (denoted R p ), are in excellent agreement with observations, with the exception of a handful of particularly small zones that have been attributed to extremely short 10 4 lifetimes. We develop a physically motivated semi-analytic model of proximity zones which captures the bulk of their equilibrium and non-equilibrium behaviour, and use this model to investigate how quasar variability on < ∼ 10 5 year timescales is imprinted on the distribution of observed proximity zone sizes. We show that large variations in the ionizing luminosity of quasars on timescales of < ∼ 10 4 years are disfavored based on the good agreement between the observed distribution of R p and our model prediction based on "lightbulb" (i.e. steady constant emission) light curves.

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“…Galaxies with AGNs that outshine their host galaxies ("quasars") are ubiquitous at  z 1 (e.g., Pâris et al 2017), i.e., during the epoch in which the universe formed most of its stars (Madau & Dickinson 2014). However, quasars are transient phenomena with duty cycles that are difficult to measure (Martini & Schneider 2003;Wang et al 2006;Shen et al 2007;Shankar et al 2010;Schmidt et al 2017). AGNs also acts as a source of feedback, injecting energy both radiatively and mechanically back into their immediate environments.…”

Section: Introductionmentioning

confidence: 99%

Spatially Resolved Patchy Lyα Emission within the Central Kiloparsec of a Strongly Lensed Quasar Host Galaxy at z = 2.8

Bayliss¹,

Sharon²,

Acharyya³

et al. 2017

ApJL

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We report the detection of extended Lyα emission from the host galaxy of SDSSJ2222+2745, a strongly lensed quasar at z=2.8. Spectroscopic follow-up clearly reveals extended Lyα in emission between two images of the central active galactic nucleus (AGN). We reconstruct the lensed quasar host galaxy in the source plane by applying a strong lens model to HST imaging and resolve spatial scales as small as ∼200 pc. In the source plane, we recover the host galaxy morphology to within a few hundred parsecs of the central AGN and map the extended Lyα emission to its physical origin on one side of the host galaxy at radii ∼0.5-2 kpc from the central AGN. There are clear morphological differences between the Lyα and rest-frame ultraviolet stellar continuum emission from the quasar host galaxy. Furthermore, the relative velocity profiles of quasar Lyα, host galaxy Lyα, and metal lines in outflowing gas reveal differences in the absorbing material affecting the AGN and host galaxy. These data indicate the presence of patchy local intervening gas in front of the central quasar and its host galaxy. This interpretation is consistent with the central luminous quasar being obscured across a substantial fraction of its surrounding solid angle, resulting in strong anisotropy in the exposure of the host galaxy to ionizing radiation from the AGN. This work demonstrates the power of strong-lensing-assisted studies to probe spatial scales that are currently inaccessible by other means.

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Statistical Detection of the He ii Transverse Proximity Effect: Evidence for Sustained Quasar Activity for >25 Million Years

Cited by 53 publications

References 118 publications

The Goldilocks problem of the quasar contribution to reionization

The Goldilocks problem of the quasar contribution to reionization

Time-dependent behaviour of quasar proximity zones at z ∼ 6

Spatially Resolved Patchy Lyα Emission within the Central Kiloparsec of a Strongly Lensed Quasar Host Galaxy at z = 2.8

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