New constraints on Lyman-α opacity with a sample of 62 quasars at z &gt; 5.7

Bosman, Sarah E. I.; Fan, Xiaohui; Jiang, Linhua; Reed, S. L.; Matsuoka, Yoshiki; Becker, George D.; Haehnelt, Martin G.

doi:10.1093/mnras/sty1344

Cited by 195 publications

(221 citation statements)

References 68 publications

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“…We use the same ESI spectrum of J1148 as in Paper I, originally observed by Eilers et al (2017). The quasars already presented in Bosman et al (2018 were reduced using a custom pipeline based on the standard ESORex XShooter recipes as detailed therein. The remaining quasars (J0305, J1526, J2032, J2100, J2329) were reduced with the open-source reduction package PypeIt 2 (Prochaska et al 2019).…”

Section: Quasar Spectroscopic Observationsmentioning

confidence: 99%

“…The signal is still dominated by the small number of objects and sightlines as the large uncertainties show. The errors are estimated by bootstrapping the sample of detected galaxies, and thus they might be even underestimated given the small sample of sightlines and the large cosmic variance seen between Lyman-α forest at that redshift (Bosman et al 2018). The issue is potentially more acute for LBGs as the selection is not complete down to a given luminosity as 1) only a fraction of drop-out candidates could be observed per field due to the instrument and time constraints 2) only a fraction of LBGs have a bright Lyman- α line (e.g.…”

Section: The Cross-correlation Of the Igm Transmission With Field Galmentioning

confidence: 99%

“…The 2PCCF however is shown to be rather unaffected by the addition of noise as the spikes we consider are at high enough SNR and transmission. Indeed, because the distribution of transmission pixels is log-normal (Bosman et al 2018), there will be more pixels with intrinsic transmission below any given threshold (T > 0.02) than above. As the observational error is drawn from a normal distribution, there will be more pixels observed to have a higher transmission than the given threshold but with lower intrinsic transmission than the reverse, increasing the number of spurious spike detections.…”

Section: Impact Of Noise On the Detection Of Transmission Spikes And mentioning

confidence: 99%

“…A large set of observational probes such as the Lyman-α forest opacity (e.g. Becker et al 2001;Fan et al 2002Fan et al , 2006Bosman et al 2018;Eilers et al 2018), the decline of the fraction of Lyman-α Emitters (e.g. Stark et al 2010Stark et al , 2011Ono et al 2012;Schenker et al 2012;De Barros et al 2017;Pentericci et al 2018;Mason et al 2018a), the number of "dark pixels" in the Lyman-α forests at z ∼ 6 (Mesinger 2010;McGreer et al 2015) and the damping wing of quasars (e.g.…”

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confidence: 99%

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The role of galaxies and AGN in reionizing the IGM – III. IGM–galaxy cross-correlations at z ∼ 6 from eight quasar fields with DEIMOS and MUSE

Meyer

Kakiichi

Bosman

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We present improved results of the measurement of the correlation between galaxies and the intergalactic medium (IGM) transmission at the end of reionisation. We have gathered a sample of 13 spectroscopically confirmed Lyman-break galaxies (LBGs) and 21 Lyman-α emitters (LAEs) at angular separations 20 θ 10 (∼ 0.1 − 4 pMpc at z ∼ 6) from the sightlines to 8 background z 6 quasars. We report for the first time the detection of an excess of Lyman-α transmission spikes at ∼ 10 − 60 cMpc from LAEs (3.6σ) and LBGs (3.1σ). We interpret the data with an improved model of the galaxy-Lyman-α transmission and two-point cross-correlations which includes the enhanced photoionisation due to clustered faint sources, enhanced gas densities around the central bright objects and spatial variations of the mean free path. The observed LAE(LBG)-Lyman-α transmission spike two-point cross-correlation function (2PCCF) constrains the luminosity-averaged escape fraction of all galaxies contributing to reionisation to f esc M UV <−12 = 0.10 +0.17 −0.05 (0.18 +0.52 −0.06 ). We investigate if the 2PCCF measurement can determine whether bright or faint galaxies are the dominant contributors to reionisation. Our results show that a contribution from faint galaxies (M UV > −20 (2σ)) is necessary to reproduce the observed 2PCCF and that reionisation might be driven by different sub-populations around LBGs and LAEs at z ∼ 6.

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Section: Quasar Spectroscopic Observationsmentioning

confidence: 99%

Section: The Cross-correlation Of the Igm Transmission With Field Galmentioning

confidence: 99%

Section: Impact Of Noise On the Detection Of Transmission Spikes And mentioning

confidence: 99%

mentioning

confidence: 99%

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The role of galaxies and AGN in reionizing the IGM – III. IGM–galaxy cross-correlations at z ∼ 6 from eight quasar fields with DEIMOS and MUSE

Meyer

Kakiichi

Bosman

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…Reionization is expected to be patchy (e.g. Iliev et al 2006;Pentericci et al 2014;Becker et al 2015;Bosman et al 2018;Kulkarni et al 2019) and therefore we should model a more sophisticated reionization topology than a homogeneous IGM to measure the amount of damping. The highly homogeneous model used in this work (Miralda-Escudé 1998) is clearly in contradiction with this theory.…”

Section: Discussionmentioning

confidence: 99%

Reionization history constraints from neural network based predictions of high-redshift quasar continua

Ďurovčíková

Katz

Davies

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Observations of the early Universe suggest that reionization was complete by z ∼ 6, however, the exact history of this process is still unknown. One method for measuring the evolution of the neutral fraction throughout this epoch is via observing the Lyα damping wings of high-redshift quasars. In order to constrain the neutral fraction from quasar observations, one needs an accurate model of the quasar spectrum around Lyα, after the spectrum has been processed by its host galaxy but before it is altered by absorption and damping in the intervening IGM. In this paper, we present a novel machine learning approach, using artificial neural networks, to reconstruct quasar continua around Lyα. Our QSANNdRA algorithm improves the error in this reconstruction compared to the state-of-the-art PCA-based model in the literature by 14.2% on average, and provides an improvement of 6.1% on average when compared to an extension thereof. In comparison with the extended PCA model, QSANNdRA further achieves an improvement of 22.1% and 16.8% when evaluated on low-redshift quasars most similar to the two high-redshift quasars under consideration, ULAS J1120+0641 at z = 7.0851 and ULAS J1342+0928 at z = 7.5413, respectively. Using our more accurate reconstructions of these two z > 7 quasars, we estimate the neutral fraction of the IGM using a homogeneous reionization model and findx HI = 0.25 +0.05 −0.05 at z = 7.0851 andx HI = 0.60 +0.11 −0.11 at z = 7.5413. Our results are consistent with the literature and favour a rapid end to reionization.

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Dark photon dark matter in the presence of inhomogeneous structure

Witte

Rosauro-Alcaraz

McDermott

et al. 2020

J. High Energ. Phys.

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Dark photon dark matter will resonantly convert into visible photons when the dark photon mass is equal to the plasma frequency of the ambient medium. In cosmological contexts, this transition leads to an extremely efficient, albeit short-lived, heating of the surrounding gas. Existing work in this field has been predominantly focused on understanding the implications of these resonant transitions in the limit that the plasma frequency of the Universe can be treated as being perfectly homogeneous, i.e. neglecting inhomogeneities in the electron number density. In this work we focus on the implications of heating from dark photon dark matter in the presence of inhomogeneous structure (which is particularly relevant for dark photons with masses in the range 10 −15 eV m A 10 −12 eV), emphasizing both the importance of inhomogeneous energy injection, as well as the sensitivity of cosmological observations to the inhomogeneities themselves. More specifically, we derive modified constraints on dark photon dark matter from the Ly-α forest, and show that the presence of inhomogeneities allows one to extend constraints to masses outside of the range that would be obtainable in the homogeneous limit, while only slightly relaxing their strength. We then project sensitivity for near-future cosmological surveys that are hoping to measure the 21cm transition in neutral hydrogen prior to reionization, and demonstrate that these experiments will be extremely useful in improving sensitivity to masses near ∼ 10 −14 eV, potentially by several orders of magnitude. Finally, we discuss implications for reionization, early star formation, and late-time y-type spectral distortions, and show Open Access, c The Authors. Article funded by SCOAP 3 .

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New constraints on Lyman-α opacity with a sample of 62 quasars at z > 5.7

Cited by 195 publications

References 68 publications

The role of galaxies and AGN in reionizing the IGM – III. IGM–galaxy cross-correlations at z ∼ 6 from eight quasar fields with DEIMOS and MUSE

The role of galaxies and AGN in reionizing the IGM – III. IGM–galaxy cross-correlations at z ∼ 6 from eight quasar fields with DEIMOS and MUSE

Reionization history constraints from neural network based predictions of high-redshift quasar continua

Dark photon dark matter in the presence of inhomogeneous structure

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