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The Lyman-limit photon mean free path at the end of late reionization in the Sherwood–Relics simulations (2024)
Journal Article
Feron, J., Conaboy, L., Bolton, J. S., Chapman, E., Haehnelt, M. G., Keating, L. C., Kulkarni, G., & Puchwein, E. (2024). The Lyman-limit photon mean free path at the end of late reionization in the Sherwood–Relics simulations. Monthly Notices of the Royal Astronomical Society, 532(2), 2401-2417. https://doi.org/10.1093/mnras/stae1636

Recent evidence supporting reionization ending at redshift z ≲ 6 includes the rapid redshift evolution of the mean free path, λmfp , for Lyman-limit photons through the intergalactic medium (IGM) at 5 < z < 6. Here, we investigate λmfp predicted by t... Read More about The Lyman-limit photon mean free path at the end of late reionization in the Sherwood–Relics simulations.

Damping Wing-Like Features in the Stacked Ly𝛼 Forest: Potential Neutral Hydrogen Islands at 𝑧 < 6 (2024)
Journal Article
Zhu, Y., Becker, G. D., Bosman, S. E. I., Cain, C., Keating, L. C., Nasir, F., …Yang, J. (2024). Damping Wing-Like Features in the Stacked Ly𝛼 Forest: Potential Neutral Hydrogen Islands at 𝑧 < 6. Monthly Notices of the Royal Astronomical Society: Letters, 533(1), L49–L56. https://doi.org/10.1093/mnrasl/slae061

Recent quasar absorption line observations suggest that reionization may end as late as z ≈ 5.3. As a means to search for large neutral hydrogen islands at z &amp;lt; 6, we revisit long dark gaps in the Lyβ forest in VLT/X-Shooter and Keck/ESI quasar... Read More about Damping Wing-Like Features in the Stacked Ly𝛼 Forest: Potential Neutral Hydrogen Islands at 𝑧 < 6.

JWST observations of galaxy damping wings during reionization interpreted with cosmological simulations (2024)
Journal Article
Keating, L. C., Bolton, J. S., Cullen, F., Haehnelt, M. G., Puchwein, E., & Kulkarni, G. (2024). JWST observations of galaxy damping wings during reionization interpreted with cosmological simulations. Monthly Notices of the Royal Astronomical Society, 532(2), 1646–1658. https://doi.org/10.1093/mnras/stae1530

Spectra of the highest redshift galaxies taken with JWST are now allowing us to see into the heart of the reionization epoch. Many of these observed galaxies exhibit strong damping wing absorption redward of their Lyman-α emission. These observations... Read More about JWST observations of galaxy damping wings during reionization interpreted with cosmological simulations.

The origin of the characteristic shape and scatter of intergalactic damping wings during reionization (2024)
Journal Article
Keating, L. C., Puchwein, E., Bolton, J. S., Haehnelt, M. G., & Kulkarni, G. (2024). The origin of the characteristic shape and scatter of intergalactic damping wings during reionization. Monthly Notices of the Royal Astronomical Society: Letters, 531(1), L34-L39. https://doi.org/10.1093/mnrasl/slae022

Ly α damping wings in the spectra of bright objects at high redshift are a useful probe of the ionization state of the intergalactic medium during the reionization epoch. It has recently been noted that, despite the inhomogeneous nature of reionizati... Read More about The origin of the characteristic shape and scatter of intergalactic damping wings during reionization.

Particle initialization effects on Lyman- αforest statistics in cosmological SPH simulations (2024)
Journal Article
Khan, N. K., Kulkarni, G., Bolton, J. S., Haehnelt, M. G., Iršič, V., Puchwein, E., & Asthana, S. (2024). Particle initialization effects on Lyman- αforest statistics in cosmological SPH simulations. Monthly Notices of the Royal Astronomical Society, 530(4), 4920-4935. https://doi.org/10.1093/mnras/stae662

Confronting measurements of the Lyman- αforest with cosmological hydrodynamical simulations has produced stringent constraints on models of particle dark matter and the thermal and ionization state of the intergalactic medium. We investigate the robu... Read More about Particle initialization effects on Lyman- αforest statistics in cosmological SPH simulations.

Unveiling dark matter free streaming at the smallest scales with the high redshift Lyman-alpha forest (2024)
Journal Article
Iršič, V., Viel, M., Haehnelt, M. G., Bolton, J. S., Molaro, M., Puchwein, E., …Kulkarni, G. (2024). Unveiling dark matter free streaming at the smallest scales with the high redshift Lyman-alpha forest. Physical Review D, 109(4), Article 043511. https://doi.org/10.1103/physrevd.109.043511

This study introduces novel constraints on the free streaming of thermal relic warm dark matter (WDM) from Lyman-α forest flux power spectra. Our analysis utilizes a high resolution, high redshift sample of quasar spectra observed using the HIRES and... Read More about Unveiling dark matter free streaming at the smallest scales with the high redshift Lyman-alpha forest.

The Sherwood-Relics simulations: overview and impact of patchy reionization and pressure smoothing on the intergalactic medium (2022)
Journal Article
Puchwein, E., Bolton, J. S., Keating, L. C., Molaro, M., Gaikwad, P., Kulkarni, G., …Meiksin, A. (2023). The Sherwood-Relics simulations: overview and impact of patchy reionization and pressure smoothing on the intergalactic medium. Monthly Notices of the Royal Astronomical Society, 519(4), 6162-6183. https://doi.org/10.1093/mnras/stac3761

We present the Sherwood-Relics simulations, a new suite of large cosmological hydrodynamical simulations aimed at modelling the intergalactic medium (IGM) during and after the cosmic reionization of hydrogen. The suite consists of over 200 simulation... Read More about The Sherwood-Relics simulations: overview and impact of patchy reionization and pressure smoothing on the intergalactic medium.

Probing quasar lifetimes with proximate 21-centimetre absorption in the diffuse intergalactic medium at redshifts z ≥ 6 (2022)
Journal Article
Šoltinský, T., Bolton, J. S., Molaro, M., Hatch, N., Haehnelt, M. G., Keating, L. C., …Puchwein, E. (2023). Probing quasar lifetimes with proximate 21-centimetre absorption in the diffuse intergalactic medium at redshifts z ≥ 6. Monthly Notices of the Royal Astronomical Society, 519(2), 3027-3045. https://doi.org/10.1093/mnras/stac3710

Enhanced ionizing radiation in close proximity to redshift z ≳ 6 quasars creates short windows of intergalactic Ly α transmission blueward of the quasar Ly α emission lines. The majority of these Ly α near-zones are consistent with quasars that have... Read More about Probing quasar lifetimes with proximate 21-centimetre absorption in the diffuse intergalactic medium at redshifts z ≥ 6.

Comparison of Low-Redshift Lyman- α Forest Observations to Hydrodynamical Simulations with Dark Photon Dark Matter (2022)
Journal Article
Bolton, J. S., Caputo, A., Liu, H., & Viel, M. (2022). Comparison of Low-Redshift Lyman- α Forest Observations to Hydrodynamical Simulations with Dark Photon Dark Matter. Physical Review Letters, 129(21), Article 211102. https://doi.org/10.1103/physrevlett.129.211102

Recent work has suggested that an additional ≲6.9 eV per baryon of heating in the intergalactic medium is needed to reconcile hydrodynamical simulations with Lyman-α forest absorption line widths at redshift z≃0.1. Resonant conversion of dark photon... Read More about Comparison of Low-Redshift Lyman- α Forest Observations to Hydrodynamical Simulations with Dark Photon Dark Matter.

Limits on non-canonical heating and turbulence in the intergalactic medium from the low redshift Lyman α forest (2022)
Journal Article
Bolton, J. S., Gaikwad, P., Haehnelt, M. G., Kim, T. S., Nasir, F., Puchwein, E., …Wakker, B. P. (2022). Limits on non-canonical heating and turbulence in the intergalactic medium from the low redshift Lyman α forest. Monthly Notices of the Royal Astronomical Society, 513(1), 864-885. https://doi.org/10.1093/mnras/stac862

We examine the column density distribution function (CDDF) and Doppler parameter distribution from hydrodynamical simulations and Cosmic Origins Spectrograph (COS) observations of the Ly α forest at redshift 0 ≤ z ≤ 0.2. Allowing for a factor of two... Read More about Limits on non-canonical heating and turbulence in the intergalactic medium from the low redshift Lyman α forest.

The mean free path of ionizing photons at 5 &lt; z &lt; 6: evidence for rapid evolution near reionization (2021)
Journal Article
Becker, G. D., D’Aloisio, A., Christenson, H. M., Zhu, Y., Worseck, G., & Bolton, J. S. (2021). The mean free path of ionizing photons at 5 < z < 6: evidence for rapid evolution near reionization. Monthly Notices of the Royal Astronomical Society, 508(2), 1853-1869. https://doi.org/10.1093/mnras/stab2696

The mean free path of ionizing photons, λmfp, is a key factor in the photoionization of the intergalactic medium (IGM). At z ≳ 5, however, λmfp may be short enough that measurements towards QSOs are biased by the QSO proximity effect. We present new... Read More about The mean free path of ionizing photons at 5 &lt; z &lt; 6: evidence for rapid evolution near reionization.

Searching for the shadows of giants II: the effect of local ionisation on the Lyman-alpha absorption signatures of protoclusters at redshift z=2.4 (2021)
Journal Article
Miller, J., Bolton, J., & Hatch, N. (2021). Searching for the shadows of giants II: the effect of local ionisation on the Lyman-alpha absorption signatures of protoclusters at redshift z=2.4. Monthly Notices of the Royal Astronomical Society, 506(4), 6001-6013. https://doi.org/10.1093/mnras/stab2083

Local variations in the intergalactic medium (IGM) neutral hydrogen fraction will affect the Ly α absorption signature of protoclusters identified in tomographic surveys. Using the IllustrisTNG simulations, we investigate how the AGN proximity effect... Read More about Searching for the shadows of giants II: the effect of local ionisation on the Lyman-alpha absorption signatures of protoclusters at redshift z=2.4.

The detectability of strong 21-cm forest absorbers from the diffuse intergalactic medium in late reionization models (2021)
Journal Article
Šoltinsky, T., Bolton, J. S., Hatch, N., Haehnelt, M. G., Keating, L. C., Kulkarni, G., …Aubert, D. (2021). The detectability of strong 21-cm forest absorbers from the diffuse intergalactic medium in late reionization models. Monthly Notices of the Royal Astronomical Society, 506(4), 5818-5835. https://doi.org/10.1093/mnras/stab1830

A late end to reionization at redshift z 5.3 is consistent with observed spatial variations in the Ly α forest transmission and the deficit of Ly α emitting galaxies around extended Ly α absorption troughs at z = 5.5. In this model, large islands of... Read More about The detectability of strong 21-cm forest absorbers from the diffuse intergalactic medium in late reionization models.

The detectability of strong 21-cm forest absorbers from the diffuse intergalactic medium in late reionization models (2021)
Journal Article
Šoltinskí, T., Bolton, J. S., Hatch, N., Haehnelt, M. G., Keating, L. C., Kulkarni, G., …Aubert, D. (2021). The detectability of strong 21-cm forest absorbers from the diffuse intergalactic medium in late reionization models. Monthly Notices of the Royal Astronomical Society, 506(4), 5818–5835. https://doi.org/10.1093/mnras/stab1830

A late end to reionization at redshift z ≈ 5.3 is consistent with observed spatial variations in the Ly α forest transmission and the deficit of Ly α emitting galaxies around extended Ly α absorption troughs at z = 5.5. In this model, large islands o... Read More about The detectability of strong 21-cm forest absorbers from the diffuse intergalactic medium in late reionization models.

The evolution of the low-density H i intergalactic medium from z = 3.6 to 0: Data, transmitted flux, and H i column density (2020)
Journal Article
Kim, T.-S., Wakker, B. P., Nasir, F., Carswell, R. F., Savage, B. D., Bolton, J. S., …Rosenwasser, B. E. (2021). The evolution of the low-density H i intergalactic medium from z = 3.6 to 0: Data, transmitted flux, and H i column density. Monthly Notices of the Royal Astronomical Society, 501(4), 5811-5833. https://doi.org/10.1093/mnras/staa3844

We present a new, uniform analysis of the H I transmitted flux (F) and H I column density (⁠NHI⁠) distribution in the low-density IGM as a function of redshift z for 0 < z < 3.6 using 55 HST/COS FUV (Δz = 7.2 at z < 0.5), five HST/STIS+COS NUV (Δz =... Read More about The evolution of the low-density H i intergalactic medium from z = 3.6 to 0: Data, transmitted flux, and H i column density.

Probing the thermal state of the intergalactic medium at z > 5 with the transmission spikes in high-resolution Lyαforest spectra (2020)
Journal Article
Gaikwad, P., Rauch, M., Haehnelt, M. G., Puchwein, E., Bolton, J. S., Keating, L. C., …Rorai, A. (2020). Probing the thermal state of the intergalactic medium at z > 5 with the transmission spikes in high-resolution Lyαforest spectra. Monthly Notices of the Royal Astronomical Society, 494(4), 5091–5109. https://doi.org/10.1093/mnras/staa907

Searching for the shadows of giants: characterizing protoclusters with line of sight Lyman-α absorption (2019)
Journal Article
Miller, J. S. A., Bolton, J. S., & Hatch, N. (2019). Searching for the shadows of giants: characterizing protoclusters with line of sight Lyman-α absorption. Monthly Notices of the Royal Astronomical Society, 489(4), 5381-5397. https://doi.org/10.1093/mnras/stz2504

© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. We use state-of-the-art hydrodyamical simulations from the Sherwood, EAGLE, and Illustris projects to examine the signature of Mz = 0 ≃ 1014 M prot... Read More about Searching for the shadows of giants: characterizing protoclusters with line of sight Lyman-α absorption.

Revealing reionization with the thermal history of the intergalactic medium: new constrainst from the Lyα flux power spectrum (2019)
Journal Article
Boera, E., Becker, G. D., Bolton, J. S., & Nasir, F. (2019). Revealing reionization with the thermal history of the intergalactic medium: new constrainst from the Lyα flux power spectrum. Astrophysical Journal, 872(1), 1-35. https://doi.org/10.3847/1538-4357/aafee4

We present a new investigation of the thermal history of the intergalactic medium (IGM) during and after reionization using the Lyman-α forest flux power spectrum at 4.0 z 5.2. Using a sample of 15 high– resolution spectra, we measure the flux power... Read More about Revealing reionization with the thermal history of the intergalactic medium: new constrainst from the Lyα flux power spectrum.

A new measurement of the intergalactic temperature at z∼2.55 − 2.95 (2017)
Journal Article
Rorai, A., Carswell, R., Haehnelt, M. G., Becker, G. D., Bolton, J. S., & Murphy, M. T. (2017). A new measurement of the intergalactic temperature at z∼2.55 − 2.95. Monthly Notices of the Royal Astronomical Society, 474(3), 2871-2883. https://doi.org/10.1093/mnras/stx2862

We present two measurements of the temperature-density relationship (TDR) of the intergalactic medium (IGM) in the redshift range 2.55 < z < 2.95 using a sample of 13 high-quality quasar spectra and high resolution numerical simulations of the IGM. O... Read More about A new measurement of the intergalactic temperature at z∼2.55 − 2.95.

First constraints on fuzzy dark matter from Lyman-alpha forest data and hydrodynamical simulations (2017)
Journal Article
Irsic, V., Viel, M., Haehnelt, M. G., Bolton, J. S., & Becker, G. D. (2017). First constraints on fuzzy dark matter from Lyman-alpha forest data and hydrodynamical simulations. Physical Review Letters, 119(3), Article 031302. https://doi.org/10.1103/PhysRevLett.119.031302

We present constraints on the masses of extremely light bosons dubbed fuzzy dark matter from Lyman- α forest data. Extremely light bosons with a De Broglie wavelength of ~ 1 kpc have been suggested as dark matter candidates that may resolve some of t... Read More about First constraints on fuzzy dark matter from Lyman-alpha forest data and hydrodynamical simulations.

New constraints on the free-streaming of warm dark matter from intermediate and small scale Lyman-alpha forest data (2017)
Journal Article
Iršič, V., Viel, M., Haehnelt, M. G., Bolton, J. S., Cristiani, S., Becker, G. D., …Worseck, G. (2017). New constraints on the free-streaming of warm dark matter from intermediate and small scale Lyman-alpha forest data. Physical Review D, 96(2), Article 023522. https://doi.org/10.1103/PhysRevD.96.023522

We present new measurements of the free-streaming of warm dark matter (WDM) from Lyman-α flux-power spectra. We use data from the medium resolution, intermediate redshift XQ-100 sample observed with the X-shooter spectrograph (z = 3 – 4.2) and the hi... Read More about New constraints on the free-streaming of warm dark matter from intermediate and small scale Lyman-alpha forest data.

The effect of stellar and AGN feedback on the low-redshift Lyman α forest in the Sherwood simulation suite (2017)
Journal Article
Sijacki, D., Puchwein, E., Haehnelt, M. G., Nasir, F., Bolton, J. S., Viel, M., & Kim, T.-S. (2017). The effect of stellar and AGN feedback on the low-redshift Lyman α forest in the Sherwood simulation suite. Monthly Notices of the Royal Astronomical Society, 471(1), 1056-1069. https://doi.org/10.1093/mnras/stx1648

We study the effect of different feedback prescriptions on the properties of the low redshift (z ≤ 1.6) Ly α forest using a selection of hydrodynamical simulations drawn from the Sherwood simulation suite. The simulations incorporate stellar feedback... Read More about The effect of stellar and AGN feedback on the low-redshift Lyman α forest in the Sherwood simulation suite.

Gas around galaxy haloes - III: hydrogen absorption signatures around galaxies and QSOs in the Sherwood simulation suite (2017)
Journal Article
Meiksin, A., Bolton, J. S., & Puchwein, E. (2017). Gas around galaxy haloes - III: hydrogen absorption signatures around galaxies and QSOs in the Sherwood simulation suite. Monthly Notices of the Royal Astronomical Society, 468(2), 1893-1901. https://doi.org/10.1093/mnras/stx191

Modern theories of galaxy formation predict that galaxies impact on their gaseous surroundings, playing the fundamental role of regulating the amount of gas converted into stars. While star-forming galaxies are believed to provide feedback through ga... Read More about Gas around galaxy haloes - III: hydrogen absorption signatures around galaxies and QSOs in the Sherwood simulation suite.

Diagnosing galactic feedback with line broadening in the low redshift Lyα forest (2017)
Journal Article
Viel, M., Haehnelt, M. G., Bolton, J. S., Kim, T., Puchwein, E., Nasir, F., & Wakker, B. P. (2017). Diagnosing galactic feedback with line broadening in the low redshift Lyα forest. Monthly Notices of the Royal Astronomical Society: Letters, 467(1), L86-L90. https://doi.org/10.1093/mnrasl/slx004

We compare the low-redshift (z 0.1) Lyα forest from hydrodynamical simulations with data from the Cosmic Origins Spectrograph. We find the tension between the observed number of lines with b-parameters in the range of 25–45 km s−1 and the prediction... Read More about Diagnosing galactic feedback with line broadening in the low redshift Lyα forest.

The Lyman α forest power spectrum from the XQ-100 legacy survey (2016)
Journal Article
Irsic, V., Viel, M., Berg, T. A., D'Odorico, V., Haehnelt, M. G., Cristiani, S., …Bolton, J. S. (2016). The Lyman α forest power spectrum from the XQ-100 legacy survey. Monthly Notices of the Royal Astronomical Society, 466(4), 4332-4345. https://doi.org/10.1093/mnras/stw3372

We present the Lyman α flux power spectrum measurements of the XQ-100 sample of quasar spectra obtained in the context of the European Southern Observatory Large Programme ‘Quasars and their absorption lines: a legacy survey of the high redshift univ... Read More about The Lyman α forest power spectrum from the XQ-100 legacy survey.

The Sherwood simulation suite: overview and data comparisons with the Lyman-α forest at redshifts 2≤z≤5 (2016)
Journal Article
Bolton, J. S., Puchwein, E., Sijacki, D., Haehnelt, M. G., Kim, T.-S., Meiksin, A., …Viel, M. (2017). The Sherwood simulation suite: overview and data comparisons with the Lyman-α forest at redshifts 2≤z≤5. Monthly Notices of the Royal Astronomical Society, 464(1), 897-914. https://doi.org/10.1093/mnras/stw2397

We introduce a new set of large-scale, high-resolution hydrodynamical simulations of the intergalactic medium: the Sherwood simulation suite. These are performed in volumes of 103–1603h−3 comoving Mpc3, span almost four orders of magnitude in mass re... Read More about The Sherwood simulation suite: overview and data comparisons with the Lyman-α forest at redshifts 2≤z≤5.

Inferring the IGM thermal history during reionization with the Lyman α forest power spectrum at redshiftz≃ 5 (2016)
Journal Article
Nasir, F., Bolton, J. S., & Becker, G. D. (2016). Inferring the IGM thermal history during reionization with the Lyman α forest power spectrum at redshiftz≃ 5. Monthly Notices of the Royal Astronomical Society, 463(3), 2335-2347. https://doi.org/10.1093/mnras/stw2147

We use cosmological hydrodynamical simulations to assess the feasibility of constraining the thermal history of the intergalactic medium during reionisation with the Lyα forest at z ≃ 5. The integrated thermal history has a measureable impact on the... Read More about Inferring the IGM thermal history during reionization with the Lyman α forest power spectrum at redshiftz≃ 5.

Testing the effect of galactic feedback on the IGM at z∼ 6 with metal-line absorbers (2016)
Journal Article
Keating, L. C., Puchwein, E., Haehnelt, M. G., Bird, S., & Bolton, J. S. (2016). Testing the effect of galactic feedback on the IGM at z∼ 6 with metal-line absorbers. Monthly Notices of the Royal Astronomical Society, 461(1), 606-626. https://doi.org/10.1093/mnras/stw1306

We present models of low- and high-ionization metal-line absorbers (O i, C ii, C iv and Mg ii) during the end of the reionization epoch, at z ∼ 6. Using four cosmological hydrodynamical simulations with different feedback schemes (including the Illus... Read More about Testing the effect of galactic feedback on the IGM at z∼ 6 with metal-line absorbers.

Constraining the temperature–density relation of the intergalactic medium with the Lyman α and β forests (2015)
Journal Article
Boera, E., Murphy, M. T., Becker, G. D., & Bolton, J. S. (2016). Constraining the temperature–density relation of the intergalactic medium with the Lyman α and β forests. Monthly Notices of the Royal Astronomical Society, 456(1), L79-L83. https://doi.org/10.1093/mnrasl/slv172

The post-reionization thermal state of the intergalactic medium is characterized by a power-law relationship between temperature and density, with a slope determined by the parameter γ. We describe a new method to measure γ using the ratio of flux cu... Read More about Constraining the temperature–density relation of the intergalactic medium with the Lyman α and β forests.

Reionisation and High-Redshift Galaxies: The View from Quasar Absorption Lines (2015)
Journal Article
Becker, G. D., Bolton, J. S., & Lidz, A. (2015). Reionisation and High-Redshift Galaxies: The View from Quasar Absorption Lines. Publications of the Astronomical Society of Australia, 32, Article e045. https://doi.org/10.1017/pasa.2015.45

Determining when and how the first galaxies reionised the intergalactic medium promises to shed light on both the nature of the first objects and the cosmic history of baryons. Towards this goal, quasar absorption lines play a unique role by probing... Read More about Reionisation and High-Redshift Galaxies: The View from Quasar Absorption Lines.

Gas around galaxy haloes – II. Hydrogen absorption signatures from the environments of galaxies at redshifts 2 (2015)
Journal Article
Tittley, E. R., Meiksin, A., Bolton, J. S., & Tittley, E. (2015). Gas around galaxy haloes – II. Hydrogen absorption signatures from the environments of galaxies at redshifts 2. Monthly Notices of the Royal Astronomical Society, 453(1), 899-913. https://doi.org/10.1093/mnras/stv1682

We compare predictions of large-scale cosmological hydrodynamical simulations for neutral hydrogen absorption signatures in the vicinity of 1011–1012.5 M⊙ haloes with observational measurements. Two different hydrodynamical techniques and a variety o... Read More about Gas around galaxy haloes – II. Hydrogen absorption signatures from the environments of galaxies at redshifts 2.

Simulating the 21cm forest detectable with LOFAR and SKA in the spectra of high-zGRBs (2015)
Journal Article
Schaye, J., Jelić, V., Bolton, J. S., Ciardi, B., Inoue, S., Abdalla, F. B., …Zaroubi, S. (2015). Simulating the 21cm forest detectable with LOFAR and SKA in the spectra of high-zGRBs. Monthly Notices of the Royal Astronomical Society, 453(1), 101-105. https://doi.org/10.1093/mnras/stv1640

We investigate the feasibility of detecting 21 cm absorption features in the afterglow spectra of high redshift long Gamma Ray Bursts (GRBs). This is done employing simulations of cosmic reionization, together with estimates of the GRB radio afterglo... Read More about Simulating the 21cm forest detectable with LOFAR and SKA in the spectra of high-zGRBs.

Lyman α emitters gone missing: evidence for late reionization? (2015)
Journal Article
Choudhury, T. R., Puchwein, E., Haehnelt, M. G., & Bolton, J. S. (2015). Lyman α emitters gone missing: evidence for late reionization?. Monthly Notices of the Royal Astronomical Society, 452(1), 261-277. https://doi.org/10.1093/mnras/stv1250

We combine high resolution hydrodynamical simulations with an intermediate resolution, dark matter only simulation and an analytical model for the growth of ionized regions to estimate the large scale distribution and redshift evolution of the visibi... Read More about Lyman α emitters gone missing: evidence for late reionization?.

The photoheating of the intergalactic medium in synthesis models of the UV background (2015)
Journal Article
Puchwein, E., Bolton, J. S., Haehnelt, M. G., Madau, P., Becker, G. D., & Haardt, F. (2015). The photoheating of the intergalactic medium in synthesis models of the UV background. Monthly Notices of the Royal Astronomical Society, 450(4), 4081-4097. https://doi.org/10.1093/mnras/stv773

We compare cosmological hydrodynamical simulations combined with the homogeneous metagalactic UV background (UVB) of Haardt & Madau (2012) (HM2012) to observations of the Lyman-alpha forest that are sensitive to the thermal and ionization state of th... Read More about The photoheating of the intergalactic medium in synthesis models of the UV background.

IGM constraints from the SDSS-III/BOSS DR9 Lyα forest transmission probability distribution function (2015)
Journal Article
Lee, K. G., Lee, K.-G., Hennawi, J., Spergel, D. N., Weinberg, D. H., Hogg, D. W., …Yeche, C. (2015). IGM constraints from the SDSS-III/BOSS DR9 Lyα forest transmission probability distribution function. Astrophysical Journal, 799(2), 196. https://doi.org/10.1088/0004-637X/799/2/196

© 2015. The American Astronomical Society. All rights reserved. The Lyα forest transmission probability distribution function (PDF) is an established probe of the intergalactic medium (IGM) astrophysics, especially the temperature-density relationshi... Read More about IGM constraints from the SDSS-III/BOSS DR9 Lyα forest transmission probability distribution function.

Evidence of patchy hydrogen reionization from an extreme Lyα trough below redshift six (2015)
Journal Article
Becker, G. D., Bolton, J. S., Madau, P., Pettini, M., Ryan-Weber, E. V., & Venemans, B. P. (2015). Evidence of patchy hydrogen reionization from an extreme Lyα trough below redshift six. Monthly Notices of the Royal Astronomical Society, 447(4), 3402-3419. https://doi.org/10.1093/mnras/stu2646

© 2015 The Authors. We report the discovery of an extremely long (~110 Mpc h -1 ) and dark (τ eff ≳ 7) Lyα trough extending down to z ≃ 5.5 towards the z em ≃ 6.0 quasar ULAS J0148+0600. We use these new data in combination with Lya forest measureme... Read More about Evidence of patchy hydrogen reionization from an extreme Lyα trough below redshift six.

The impact of temperature fluctuations on the large-scale clustering of the Lyα forest (2015)
Journal Article
Greig, B., Bolton, J. S., & Wyithe, J. S. B. (2015). The impact of temperature fluctuations on the large-scale clustering of the Lyα forest. Monthly Notices of the Royal Astronomical Society, 447(3), 2503-2511. https://doi.org/10.1093/mnras/stu2624

We develop a semi-analytic method for assessing the impact of the large-scale IGM temperature fluctuations expected following He ii reionization on three-dimensional clustering measurements of the Lyα forest. Our methodology builds upon the existing... Read More about The impact of temperature fluctuations on the large-scale clustering of the Lyα forest.

Gas around galaxy haloes: Methodology comparisons using hydrodynamical simulations of the intergalactic medium (2014)
Journal Article
Meiksin, A., Bolton, J. S., & Tittley, E. R. (2014). Gas around galaxy haloes: Methodology comparisons using hydrodynamical simulations of the intergalactic medium. Monthly Notices of the Royal Astronomical Society, 445(3), 2462-2475. https://doi.org/10.1093/mnras/stu1938

© 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. We perform cosmological simulations of the intergalactic medium (IGM) at redshift z ~ 3 using the numerical gravity-hydrodynamics codes GADGET-3 and... Read More about Gas around galaxy haloes: Methodology comparisons using hydrodynamical simulations of the intergalactic medium.

Heating and ionization of the primordial intergalactic medium by high mass x-ray binaries (2014)
Journal Article
Knevitt, G., Wynn, G., Power, C., & Bolton, J. S. (2014). Heating and ionization of the primordial intergalactic medium by high mass x-ray binaries. Monthly Notices of the Royal Astronomical Society, 445(2), https://doi.org/10.1093/mnras/stu1803

We investigate the influence of high-mass X-ray binaries (HMXBs) on their high-redshift environments. Using a one-dimensional radiative transfer code, we predict the ionization and temperature profiles surrounding a coeval stellar population, compose... Read More about Heating and ionization of the primordial intergalactic medium by high mass x-ray binaries.

Suite of hydrodynamical simulations for the Lyman-alpha forest with massive neutrinos (2014)
Journal Article
Rossi, G., Palanque-Delabrouille, N., Borde, A., Viel, M., Yeche, C., Bolton, J. S., …Le Goff, J.-M. (2014). Suite of hydrodynamical simulations for the Lyman-alpha forest with massive neutrinos. Astronomy and Astrophysics, 567, Article A79. https://doi.org/10.1051/0004-6361/201423507

The signature left in quasar spectra by neutral hydrogen in the Universe allows constraining the sum of the neutrino masses with a better sensitivity than laboratory experiments and may shed new light on the neutrino mass hierarchy and the absolute m... Read More about Suite of hydrodynamical simulations for the Lyman-alpha forest with massive neutrinos.

New approach for precise computation of Lyman-alpha forest power spectrum with hydrodynamical simulations (2014)
Journal Article
Borde, A., Palanque-Delabrouille, N., Rossi, G., Viel, M., Bolton, J. S., Yeche, C., …Le Goff, J.-M. (2014). New approach for precise computation of Lyman-alpha forest power spectrum with hydrodynamical simulations. Journal of Cosmology and Astroparticle Physics, 2014(July), Article 005. https://doi.org/10.1088/1475-7516/2014/07/005

Current experiments are providing measurements of the flux power spectrum from the Lyman-α forests observed in quasar spectra with unprecedented accuracy. Their interpretation in terms of cosmological constraints requires specific simulations of at l... Read More about New approach for precise computation of Lyman-alpha forest power spectrum with hydrodynamical simulations.

The thermal history of the intergalactic medium down to redshift z=1.5: a new curvature measurement (2014)
Journal Article
Boera, E., Murphy, M. T., Becker, G. D., & Bolton, J. S. (2014). The thermal history of the intergalactic medium down to redshift z=1.5: a new curvature measurement. Monthly Notices of the Royal Astronomical Society, 441(3), https://doi.org/10.1093/mnras/stu660

According to the photoheating model of the intergalactic medium (IGM), He ii reionization is expected to affect its thermal evolution. Evidence for additional energy injection into the IGM has been found at 3 ≲ z ≲ 4, though the evidence for the subs... Read More about The thermal history of the intergalactic medium down to redshift z=1.5: a new curvature measurement.

A consistent determination of the temperature of the intergalactic medium at redshift z=2.4 (2014)
Journal Article
Bolton, J. S., Becker, G. D., Haehnelt, M. G., & Viel, M. (2014). A consistent determination of the temperature of the intergalactic medium at redshift z=2.4. Monthly Notices of the Royal Astronomical Society, 438, https://doi.org/10.1093/mnras/stt2374

We present new measurements of the thermal state of the intergalactic medium (IGM) at z∼2.4 derived from absorption line profiles in the Lyα forest. We use a large set of high-resolution hydrodynamical simulations to calibrate the relationship betwee... Read More about A consistent determination of the temperature of the intergalactic medium at redshift z=2.4.

The one-dimensional Lyα forest power spectrum from BOSS (2013)
Journal Article
Palanque-Delabrouille, N., Yèche, C., Borde, A., Le Goff, J.-M., Rossi, G., Viel, M., …Weinberg, D. H. (2013). The one-dimensional Lyα forest power spectrum from BOSS. Astronomy and Astrophysics, 559, Article A85. https://doi.org/10.1051/0004-6361/201322130

We have developed two independent methods for measuring the one-dimensional power spectrum of the transmitted flux in the Lyman-α forest. The first method is based on a Fourier transform and the second on a maximum-likelihood estimator. The two metho... Read More about The one-dimensional Lyα forest power spectrum from BOSS.

New measurements of the ionizing ultraviolet background over 2 < z < 5 and implications for hydrogen reionization (2013)
Journal Article
Becker, G. D., & Bolton, J. S. (2013). New measurements of the ionizing ultraviolet background over 2 < z < 5 and implications for hydrogen reionization. Monthly Notices of the Royal Astronomical Society, 436(2), 1023-1039. https://doi.org/10.1093/mnras/stt1610

We present new measurements of the intensity of the ionizing ultraviolet background and the global emissivity of ionizing photons over 2 < z < 5. Our results are based on a suite of updated measurements of physical properties of the high-redshift int... Read More about New measurements of the ionizing ultraviolet background over 2 < z < 5 and implications for hydrogen reionization.

On the rapid demise of Lyman-alpha emitters at z>7 due to the increasing incidence of optically thick absorption systems (2013)
Journal Article
S. Bolton, J., & G. Haehnelt, M. (2013). On the rapid demise of Lyman-alpha emitters at z>7 due to the increasing incidence of optically thick absorption systems. Monthly Notices of the Royal Astronomical Society, 429(2), 1695–1704. https://doi.org/10.1093/mnras/sts455

A variety of independent observational studies have now reported a significant decline in the fraction of Lyman-break galaxies which exhibit Ly-a emission over the redshift interval z=6-7. In combination with the strong damping wing extending redward... Read More about On the rapid demise of Lyman-alpha emitters at z>7 due to the increasing incidence of optically thick absorption systems.

Prospects for detecting the 21 cm forest from the diffuse intergalactic medium with LOFAR (2012)
Journal Article
Ciardi, B., Labropoulos, P., Maselli, A., Thomas, R., Zaroubi, S., Graziani, L., …Yatawatta, S. (2013). Prospects for detecting the 21 cm forest from the diffuse intergalactic medium with LOFAR. Monthly Notices of the Royal Astronomical Society, 428(2), 1755-1765. https://doi.org/10.1093/mnras/sts156

We discuss the feasibility of the detection of the 21 cm forest in the diffuse intergalactic medium (IGM) with the radio telescope LOFAR. The optical depth to the 21 cm line has been derived using simulations of reionization which include detailed ra... Read More about Prospects for detecting the 21 cm forest from the diffuse intergalactic medium with LOFAR.

The intergalactic medium thermal history at redshift z = 1.7–3.2 from the Lyα forest: a comparison of measurements using wavelets and the flux distribution (2012)
Journal Article
Garzilli, A., Bolton, J., -S. Kim, T., Leach, S., & Viel, M. (2012). The intergalactic medium thermal history at redshift z = 1.7–3.2 from the Lyα forest: a comparison of measurements using wavelets and the flux distribution. Monthly Notices of the Royal Astronomical Society, 424(3), 1723-1736. https://doi.org/10.1111/j.1365-2966.2012.21223.x

We investigate the thermal history of the intergalactic medium (IGM) in the redshift interval z = 1.7–3.2 by studying the small-scale fluctuations in the Lyman α forest transmitted flux. We apply a wavelet filtering technique to 18 high-resolution qu... Read More about The intergalactic medium thermal history at redshift z = 1.7–3.2 from the Lyα forest: a comparison of measurements using wavelets and the flux distribution.

The effect of intergalactic helium on hydrogen reionization: implications for the sources of ionizing photons at z>6 (2012)
Journal Article
Ciardi, B., Bolton, J., Maselli, A., & Graziani, L. (2012). The effect of intergalactic helium on hydrogen reionization: implications for the sources of ionizing photons at z>6. Monthly Notices of the Royal Astronomical Society, 423(1), 558-574. https://doi.org/10.1111/j.1365-2966.2012.20902.x

We investigate the effect of primordial helium on hydrogen reionization using a hydrodynamical simulation combined with the cosmological radiative transfer code CRASH. The radiative transfer simulations are performed in a 35.12 h−1 comoving Mpc box u... Read More about The effect of intergalactic helium on hydrogen reionization: implications for the sources of ionizing photons at z>6.

The Lyman α forest flux probability distribution at z>3 (2012)
Journal Article
Calura, F., Tescari, E., D’Odorico, V., Viel, M., Cristiani, S., Kim, T.-S., & Bolton, J. (2012). The Lyman α forest flux probability distribution at z>3. Monthly Notices of the Royal Astronomical Society, 422(4), 3019-3036. https://doi.org/10.1111/j.1365-2966.2012.20811.x

We present a measurement of the Lyman α flux probability distribution function (PDF) obtained from a set of eight high-resolution quasar spectra with emission redshifts in the range 3.3 ≤z≤ 3.8. We carefully study the effect of metal absorption lines... Read More about The Lyman α forest flux probability distribution at z>3.

Improved measurements of the intergalactic medium temperature around quasars: possible evidence for the initial stages of He-II reionisation at z~6 (2012)
Journal Article
S. Bolton, J., D. Becker, G., Raskutti, S., Stuart B. Wyithe, J., G. Haehnelt, M., & L. W. Sargent, W. (2012). Improved measurements of the intergalactic medium temperature around quasars: possible evidence for the initial stages of He-II reionisation at z~6. Monthly Notices of the Royal Astronomical Society, 419(4), 2880–2892. https://doi.org/10.1111/j.1365-2966.2011.19929.x

We present measurements of the intergalactic medium (IGM) temperature within ~5 proper Mpc of seven luminous quasars at z~6. The constraints are obtained from the Doppler widths of Lyman-alpha absorption lines in the quasar near-zones and build upon... Read More about Improved measurements of the intergalactic medium temperature around quasars: possible evidence for the initial stages of He-II reionisation at z~6.

How neutral is the intergalactic medium surrounding the redshift z=7.085 quasar ULAS J1120+0641? (2011)
Journal Article
S. Bolton, J., G. Haehnelt, M., J. Warren, S., C. Hewett, P., J. Mortlock, D., P. Venemans, B., …Simpson, C. (2011). How neutral is the intergalactic medium surrounding the redshift z=7.085 quasar ULAS J1120+0641?. Monthly Notices of the Royal Astronomical Society: Letters, 416(1), L70–L74. https://doi.org/10.1111/j.1745-3933.2011.01100.x

The quasar ULAS J1120+0641 at redshift z=7.085 has a highly ionised near zone which is smaller than those around quasars of similar luminosity at z~6. The spectrum also exhibits evidence for a damping wing extending redward of the systemic Lya redshi... Read More about How neutral is the intergalactic medium surrounding the redshift z=7.085 quasar ULAS J1120+0641?.

The impact of spatial fluctuations in the ultra-violet background on intergalactic carbon and silicon (2011)
Journal Article
S. Bolton, J., & Viel, M. (2011). The impact of spatial fluctuations in the ultra-violet background on intergalactic carbon and silicon. Monthly Notices of the Royal Astronomical Society, 414(1), 241–252. https://doi.org/10.1111/j.1365-2966.2011.18384.x

Spatial inhomogeneities in the spectral shape of the ultra-violet background (UVB) at the tail-end of HeII reionisation are thought to be the primary cause of the large fluctuations observed in the HeII to HI Ly-a forest optical depth ratio, tau_HeII... Read More about The impact of spatial fluctuations in the ultra-violet background on intergalactic carbon and silicon.

Resolving the high redshift Lyman-alpha forest in smoothed particle hydrodynamics simulations (2009)
Journal Article
S. Bolton, J., & D. Becker, G. (2009). Resolving the high redshift Lyman-alpha forest in smoothed particle hydrodynamics simulations. Monthly Notices of the Royal Astronomical Society: Letters, 398(1), L26–L30. https://doi.org/10.1111/j.1745-3933.2009.00700.x

We use a large set of cosmological smoothed particle hydrodynamics (SPH) simulations to examine the effect of mass resolution and box size on synthetic Lya forest spectra at 2 \leq z \leq 5. The mass resolution requirements for the convergence of the... Read More about Resolving the high redshift Lyman-alpha forest in smoothed particle hydrodynamics simulations.

The evolution of the Lyman-alpha forest effective optical depth following HeII reionisation (2009)
Journal Article
S. Bolton, J., Peng Oh, S., & R. Furlanetto, S. (2009). The evolution of the Lyman-alpha forest effective optical depth following HeII reionisation. Monthly Notices of the Royal Astronomical Society, 396(4), 2405–2418. https://doi.org/10.1111/j.1365-2966.2009.14914.x

Three independent observational studies have now detected a narrow (\Delta z ~ 0.5) dip centred at z=3.2 in the otherwise smooth redshift evolution of the Lya forest effective optical depth. This feature has previously been interpreted as an indirect... Read More about The evolution of the Lyman-alpha forest effective optical depth following HeII reionisation.

Photo-heating and the fate of hard photons during the reionisation of HeII by quasars (2009)
Journal Article
S. Bolton, J., Peng Oh, S., & R. Furlanetto, S. (2009). Photo-heating and the fate of hard photons during the reionisation of HeII by quasars. Monthly Notices of the Royal Astronomical Society, 395(2), 736–752. https://doi.org/10.1111/j.1365-2966.2009.14597.x

We use a combination of analytic and numerical arguments to consider the impact of quasar photo-heating during HeII reionisation on the thermal evolution of the intergalactic medium (IGM). We demonstrate that rapid (\Delta z< 0.1-0.2), strong (\Delta... Read More about Photo-heating and the fate of hard photons during the reionisation of HeII by quasars.

Possible evidence for an inverted temperature-density relation in the intergalactic medium from the flux distribution of the Lyman-alpha forest (2008)
Journal Article
S. Bolton, J., Viel, M., -S. Kim, T., G. Haehnelt, M., & F. Carswell, R. (2008). Possible evidence for an inverted temperature-density relation in the intergalactic medium from the flux distribution of the Lyman-alpha forest. Monthly Notices of the Royal Astronomical Society, 386(2), 1131-1144. https://doi.org/10.1111/j.1365-2966.2008.13114.x

An improved measurement of the flux distribution of the Ly-alpha forest in QSO absorption spectra: the effect of continuum fitting, metal contamination and noise properties (2007)
Journal Article
-S. Kim, T., S. Bolton, J., Viel, M., G. Haehnelt, M., & F. Carswell, R. (2007). An improved measurement of the flux distribution of the Ly-alpha forest in QSO absorption spectra: the effect of continuum fitting, metal contamination and noise properties. Monthly Notices of the Royal Astronomical Society, 382(4), 1657–1674. https://doi.org/10.1111/j.1365-2966.2007.12406.x

We have performed an extensive Voigt profile analysis of the neutral hydrogen (HI) and metal absorption present in a sample of 18 high resolution, high signal-to-noise QSO spectra observed with VLT/UVES. We use this analysis to separate the metal con... Read More about An improved measurement of the flux distribution of the Ly-alpha forest in QSO absorption spectra: the effect of continuum fitting, metal contamination and noise properties.

A closer look at using quasar near-zones as a probe of neutral hydrogen in the intergalactic medium (2007)
Journal Article
S. Bolton, J., & G. Haehnelt, M. (2007). A closer look at using quasar near-zones as a probe of neutral hydrogen in the intergalactic medium. Monthly Notices of the Royal Astronomical Society: Letters, 381(1), L35-L39. https://doi.org/10.1111/j.1745-3933.2007.00361.x

We examine a large set of synthetic quasar spectra to realistically assess the potential of using the relative sizes of highly ionized near-zones in the Lya and Lyb forest as a probe of the neutral hydrogen content of the intergalactic medium (IGM) a... Read More about A closer look at using quasar near-zones as a probe of neutral hydrogen in the intergalactic medium.

The observed ionization rate of the intergalactic medium and the ionizing emissivity at z >5: Evidence for a photon starved and extended epoch of reionization (2007)
Journal Article
S. Bolton, J., & G. Haehnelt, M. (2007). The observed ionization rate of the intergalactic medium and the ionizing emissivity at z >5: Evidence for a photon starved and extended epoch of reionization. Monthly Notices of the Royal Astronomical Society, 382(1), 325–341. https://doi.org/10.1111/j.1365-2966.2007.12372.x

We use a large set of hydrodynamical simulations, combined with measurements of the Lyman alpha opacity of the IGM taken from the literature, to obtain robust estimates for the photoionization rate per hydrogen atom at z=5 and 6. We find the photoion... Read More about The observed ionization rate of the intergalactic medium and the ionizing emissivity at z >5: Evidence for a photon starved and extended epoch of reionization.

The nature and evolution of the highly ionized near-zones in the absorption spectra of z~6 quasars (2006)
Journal Article
S. Bolton, J., & G. Haehnelt, M. (2007). The nature and evolution of the highly ionized near-zones in the absorption spectra of z~6 quasars. Monthly Notices of the Royal Astronomical Society, 374(2), 493–514. https://doi.org/10.1111/j.1365-2966.2006.11176.x

We use state-of-the-art hydrodynamical simulations combined with a 1D radiative transfer code to assess the extent to which the highly ionized regions observed close to z~6 quasars, which we refer to as near-zones, can constrain the ionization state... Read More about The nature and evolution of the highly ionized near-zones in the absorption spectra of z~6 quasars.

Spatial fluctuations in the spectral shape of the UV background at 2 (2006)
Journal Article
S. Bolton, J., G. Haehnelt, M., Viel, M., & F. Carswell, R. (2006). Spatial fluctuations in the spectral shape of the UV background at 2. Monthly Notices of the Royal Astronomical Society, 366(4), 1378-1390. https://doi.org/10.1111/j.1365-2966.2006.09927.x

The low density hydrogen and helium in the IGM probed by QSO absorption lines is sensitive to the amplitude and spectral shape of the metagalactic UV background. We use realistic HI and HeII Ly-alpha forest spectra, constructed from state-of-the-art... Read More about Spatial fluctuations in the spectral shape of the UV background at 2.

The Lyman-alpha forest opacity and the metagalactic hydrogen ionization rate at z~2-4 (2005)
Journal Article
S. Bolton, J., G. Haehnelt, M., Viel, M., & Springel, V. (2005). The Lyman-alpha forest opacity and the metagalactic hydrogen ionization rate at z~2-4. Monthly Notices of the Royal Astronomical Society, 357(4), 1178–1188. https://doi.org/10.1111/j.1365-2966.2005.08704.x

Estimates of the metagalactic hydrogen ionization rate from the Lyman-alpha forest opacity in QSO absorption spectra depend on the complex density distribution of neutral hydrogen along the line-of-sight. We use a large suite of high resolution hydro... Read More about The Lyman-alpha forest opacity and the metagalactic hydrogen ionization rate at z~2-4.

Radiative transfer through the intergalactic medium (2004)
Journal Article
Bolton, J., Meiksin, A., & White, M. (2004). Radiative transfer through the intergalactic medium. Monthly Notices of the Royal Astronomical Society, 348(3), L43-L48. https://doi.org/10.1111/j.1365-2966.2004.07567.x

We use a probabilistic method to compute the propagation of an ionization front corresponding to the reionization of the intergalactic medium in a Λ-cold dark matter (ΛCDM) cosmology, including both hydrogen and helium. The effects of radiative trans... Read More about Radiative transfer through the intergalactic medium.