Article
Astronomy & Astrophysics
Elimboto Yohana, Yin-Zhe Ma, Di Li, Xuelei Chen, Wei-Ming Dai
Summary: The study presents a foreground components model and removal method, including various foregrounds and thermal/l/f noises to reduce the standard deviation between the reconstructed 21-cm IM map and the input pure 21-cm signal to 0.034 mK. The PCA method is shown to accurately recover the H I power spectra for FAST.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Francesco Sinigaglia, Ed Elson, Giulia Rodighiero, Mattia Vaccari
Summary: We assess the accuracy of common operations in 21-cm spectral line stacking experiments and present the results. We generate mock interferometric data to mimic real MeerKAT observations and evaluate the effects of weighting schemes, distance-based corrections, and spectroscopic redshift uncertainties. Additionally, we propose a novel technique to enhance the signal-to-noise ratio by exploiting the geometric symmetries of galaxy cubelets.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Bradley Greig, Andrei Mesinger, Leon V. E. Koopmans, Benedetta Ciardi, Garrelt Mellema, Saleem Zaroubi, Sambit K. Giri, Raghunath Ghara, Abhik Ghosh, Ilian T. Iliev, Florent G. Mertens, Rajesh Mondal, Andre R. Offringa, Vishambhar N. Pandey
Summary: By utilizing the latest upper limits on the 21-cm power spectrum at z around 9.1 from LOFAR, the study explores regions of parameter space inconsistent with the data and connects them with existing observational constraints. Models exceeding the 21-cm signal limits are ruled out by other probes, demonstrating the potential of forward modeling tools like 21CMMC in constraining the astrophysics of galaxies at high redshifts.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Hannah E. Ross, Sambit K. Giri, Garrelt Mellema, Keri L. Dixon, Raghunath Ghara, Ilian T. Iliev
Summary: The study indicates that redshift-space distortions have a significant impact on the 21-cm signal from the Cosmic Dawn, increasing the detectability of the signal while also decreasing non-Gaussianity of fluctuations from inhomogeneous X-ray heating. Mock observations suggest that imaging the Cosmic Dawn may be possible through telescope observations, with redshift-space distortions dramatically boosting fluctuations from the inhomogeneous Ly alpha background.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Kanan K. Datta, Raghunath Ghara, Ariful Hoque, Suman Majumdar
Summary: In this study, it was found that large optical depth has a significant impact on signal statistics during cosmic dawn, with the linearized equation often underestimating the spin temperature and the probability distribution function of T-b becoming more Gaussian without approximations. The variance, skewness, and kurtosis are overpredicted at simulation resolution, while the spherically averaged HI power spectrum is overestimated at all scales for both standard and excess-cooling scenarios.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Benedetta Spina, Cristiano Porciani, Carlo Schimd
Summary: This study investigates the possibility of constraining the HI-halo mass relation from intensity maps of the redshifted 21-cm line. Results from mock maps generated using Minkowski functionals show that measuring the HIHMR is achievable effectively in a single frequency channel. Combining results from different frequency channels can provide exquisite constraints on the evolution of the HIHMR, especially in the central frequency range of the data cube.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Raghunath Ghara, Sambit K. Giri, Benedetta Ciardi, Garrelt Mellema, Saleem Zaroubi
Summary: The MWA team obtained new upper limits on the power spectrum of the 21-cm signal at 6.5-8.7 redshifts and used Bayesian inference to constrain the ionization and thermal state of the IGM, revealing no constraints on IGM state above 7.8 redshift in the absence of an additional radio background. The results suggest that models with an IGM fraction of ionized regions below 0.6 and average gas temperature less than or equal to 10(3) h(-1) are disfavored, along with an exclusion of an additional radio background of at least 0.008% of the CMB at 1.42 GHz within the same credible interval limits.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Barun Maity, Tirthankar Roy Choudhury
Summary: One of the most promising ways to study the reionization history of the universe is through the power spectrum of neutral hydrogen 21 cm emission fluctuations. In this study, we use a seminumerical code called SCRIPT to model reionization and investigate its ability to constrain the parameters. Our findings show that the model is accurate and insensitive to the resolution of the simulation, and we also develop a simple template model that can reliably recover the global reionization history.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Harman Deep Kaur, Yuxiang Qin, Andrei Mesinger, Andrea Pallottini, Tassos Fragos, Antara Basu-Zych
Summary: Investigating the impact of metallicity on the X-ray luminosity to star formation rate ratio during Cosmic Dawn allows for indirect study of the properties of HMXBs in early galaxies. Mock observations suggest that constant luminosity to star formation rate models can accurately capture the evolution of the intergalactic medium only during the Epoch of Heating.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Selim C. Hotinli, Thomas Binnie, Julian B. Munoz, Bikash R. Dinda, Marc Kamionkowski
Summary: This study evaluates the detection significance of compensated isocurvature perturbations (CIPs) from observations of the 21-cm hydrogen line during the cosmic dawn era, finding that ongoing and upcoming experiments will provide constraints on uncorrelated CIPs.
Article
Astronomy & Astrophysics
Bradley Greig, Yuan-Sen Ting, Alexander A. Kaurov
Summary: Detecting the 21-cm hyperfine transition from neutral hydrogen in the intergalactic medium is crucial for understanding the astrophysical processes driving the Epoch of Reionization (EoR). The 21-cm signal is non-Gaussian, and the Wavelet Scattering Transform (WST) can extract this information directly from 2D images. This work introduces a novel method to isolate non-Gaussian information and applies it to quantify the strength of non-Gaussian information in individual mock 21-cm images.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Bradley Greig, Yuan-Sen Ting, Alexander A. Kaurov
Summary: This study introduces a new technique called the Wavelet Scattering Transform (WST) for analyzing non-Gaussian information. By compressing 2D spatial information into a set of coefficients, the WST provides a better interpretation of the non-Gaussian information in the cosmic 21-cm signal. Experimental results show that the WST applied to 2D images outperforms the 3D spherically averaged 21-cm power spectrum (PS), and higher cadences between the 21-cm images can further improve the constraining power.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Melis O. Irfan, Philip Bull
Summary: The high dynamic range between contaminating foreground emission and 21 cm brightness temperature field is a problematic characteristic. Kernel PCA method shows effectiveness in separating foregrounds and the 21 cm signal in simulated data.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Yuxiang Qin, Andrei Mesinger, Bradley Greig, Jaehong Park
Summary: By simulating 21-cm power spectra, the study suggests that the first generation of galaxies may form in minihaloes through H-2 cooling, possessing unique properties and contributing significantly to the Cosmic Dawn. Comparing Bayesian evidences, the model including molecular-cooling galaxies (MCGs) is preferred, indicating the potential to infer their properties from upcoming observations.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Bradley Greig, Cathryn M. Trott, Nichole Barry, Simon J. Mutch, Bart Pindor, Rachel L. Webster, J. Stuart B. Wyithe
Summary: By utilizing the latest multiredshift upper limits on the 21-cm signal from the Murchison Widefield Array, disfavoured astrophysical models have been explored, with the majority found to be inconsistent with existing observational constraints. Interestingly, some models inconsistent with the MWA seem to align with other constraints, excluding X-ray emissivity, indicating the unique information provided by the current MWA limits. The study also presents the first limits on the soft-band X-ray emissivity from galaxies at high redshifts, as well as disfavoured limits on the IGM spin temperature.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)