An Epoch of Reionization simulation pipeline based on BEARS

Krause, Fabian; Thomas, Rajat Mani; Zaroubi, Saleem; Abdalla, F. B.

doi:10.1016/j.newast.2018.03.004

Cited by 6 publications

(3 citation statements)

References 42 publications

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“…These are the same cosmological 𝑁-body simulation previously used in . The code is an independent implementation of the previously developed algorithm (Thomas & Zaroubi 2008;Thomas et al 2009;Thomas & Zaroubi 2011;Krause et al 2018). It is based on a one-dimensional radiative transfer scheme which approximates the transfer of photons (UV, X-rays and Ly𝛼) by assuming that the effect from individual sources is isotropic.…”

Section: Modelling the 21-cm Signal Usingmentioning

confidence: 99%

“…The GRIZZLY algorithm is based on a one-dimensional radiative transfer scheme and is an independent implementation of the BEARS algorithm described by Thomas & Zaroubi (2008); Thomas et al (2009); Thomas & Zaroubi (2011) and Krause et al (2018). It approximates the transfer of photons by assuming that the effect from individual sources is isotropic and can therefore be precalculated as radial profiles around each source.…”

Section: Modelling the 21-cm Signal Using Grizzlymentioning

confidence: 99%

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Constraining the intergalactic medium at z ≈ 9.1 using LOFAR Epoch of Reionization observations

Ghara

Giri

Mellema

et al. 2020

Monthly Notices of the Royal Astronomical Society

108

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We derive constraints on the thermal and ionization states of the intergalactic medium (IGM) at redshift ≈ 9.1 using new upper limits on the 21-cm power spectrum measured by the LO-FAR radio-telescope and a prior on the ionized fraction at that redshift estimated from recent cosmic microwave background (CMB) observations. We have used results from the reionization simulation code GRIZZLY and a Bayesian inference framework to constrain the parameters which describe the physical state of the IGM. We find that, if the gas heating remains negligible, an IGM with ionized fraction 0.13 and a distribution of the ionized regions with a characteristic size 8 h −1 comoving megaparsec (Mpc) and a full width at the half maximum (FWHM) 16 h −1 Mpc is ruled out. For an IGM with a uniform spin temperature T S 3 K, no constraints on the ionized component can be computed. If the large-scale fluctuations of the signal are driven by spin temperature fluctuations, an IGM with a volume fraction 0.34 of heated regions with a temperature larger than CMB, average gas temperature 7-160 K and a distribution of the heated regions with characteristic size 3.5-70 h −1 Mpc and FWHM of 110 h −1 Mpc is ruled out. These constraints are within the 95 per cent credible intervals. With more stringent future upper limits from LOFAR at multiple redshifts, the constraints will become tighter and will exclude an increasingly large region of the parameter space.

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Section: Modelling the 21-cm Signal Usingmentioning

confidence: 99%

Section: Modelling the 21-cm Signal Using Grizzlymentioning

confidence: 99%

Constraining the intergalactic medium at z ≈ 9.1 using LOFAR Epoch of Reionization observations

Ghara

Giri

Mellema

et al. 2020

Monthly Notices of the Royal Astronomical Society

108

View full text Add to dashboard Cite

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“…The code is based on a one-dimensional radiative transfer scheme and is an independent implementation of the previously developed algorithm (Thomas et al 2009;Krause et al 2018). Apart from the density fields and halo catalog at the redshifts of our interest, it also needs a source model to simulate HI differential temperature maps in the simulation box.…”

Section: Simulation Of 21-cm Signal Mapsmentioning

confidence: 99%

Large HI optical depth and Redshifted 21-cm signal from cosmic dawn

Datta,

Ghara,

Hoque

et al. 2021

Preprint

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The HI 21-cm optical depth ( ) can be considerably large as the kinetic and spin temperature of the inter-galactic medium(IGM) is expected to be very low during cosmic dawn. It will be particularly higher at regions with HI over-density. We revisit the validity of the widely used linearized equation for estimating the HI 21-cm differential brightness temperature ( ) which assumes << 1 and approximates [1 − exp(− )] as . We consider two scenarios, one without any additional cooling mechanism or radio background ( referred as standard scenario) and the other (referred as excess-cooling scenario) assumes the EDGES like absorption profile and an excess cooling mechanism. We find that given a measured global absorption signal, consistent with the standard(excess-cooling) scenario, the linearized equation overestimates the spin temperature by ∼ 5%(10%). Further, using numerical simulations, we study impact that the large optical depth has on various signal statistics. We observe that the variance, skewness and kurtosis, calculated at simulation resolution (∼ 0.5ℎ −1 Mpc), are over-predicted up to ∼ 30%, 30% and 15% respectively for the standard and up to ∼ 90%, 50% and 50% respectively for the excess-cooling scenario. Moreover, we find that the probability distribution function of is squeezed and becomes more Gaussian in shape if no approximation is made. The spherically averaged HI power spectrum is over predicted by up to ∼ 25% and 80% at all scales for the standard and excess-cooling scenarios respectively.

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The LORELI database: 21 cm signal inference with 3D radiative hydrodynamics simulations

Meriot,

Semelin

2024

A&A

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The Square Kilometer array is expected to measure the 21cm signal from the Epoch of Reionization (EoR) in the coming decade, and its pathfinders may provide a statistical detection even earlier. The currently reported upper limits provide tentative constraints on the astrophysical parameters of the models of the EoR. In order to interpret such data with 3D radiative hydrodynamics simulations using Bayesian inference, we present the latest developments of the Licorice code. Relying on an implementation of the halo conditional mass function to account for unresolved star formation, this code now allows accurate simulations of the EoR at $256^3$ resolution. We use this version of Licorice to produce the first iteration of LoReLi a public dataset now containing hundreds of 21cm signals computed from radiative hydrodynamics simulations. We train a neural network on LoReLi to provide a fast emulator of the Licorice power spectra LorEMU which has $ 5<!PCT!>$ rms error relative to the simulated signals. LorEMU is used in a Markov Chain Monte Carlo framework to perform Bayesian inference, first on a mock observation composed of a simulated signal and thermal noise corresponding to 100h observations with the SKA. We then apply our inference pipeline to the latest measurements from the HERA interferometer. We report constraints on the X-ray emissivity, and confirm that cold reionization scenarios are unlikely to accurately represent our Universe.

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An Epoch of Reionization simulation pipeline based on BEARS

Cited by 6 publications

References 42 publications

Constraining the intergalactic medium at z ≈ 9.1 using LOFAR Epoch of Reionization observations

Constraining the intergalactic medium at z ≈ 9.1 using LOFAR Epoch of Reionization observations

Large HI optical depth and Redshifted 21-cm signal from cosmic dawn

The LORELI database: 21 cm signal inference with 3D radiative hydrodynamics simulations

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