Simulating the impact of HI fluctuations on matched filter search for ionized bubbles in redshifted 21 cm maps

Abstract

Extending the formalism of Datta, Bharadwaj & Choudhury (2007) for detecting ionized bubbles in redshifted 21 cm maps using a matched-filtering technique, we use different simulations to analyze the impact of HI fluctuations outside the bubble on the detectability of the bubble. In the first three kinds of simulations there is a spherical bubble of comoving radius R_b, the one that we are trying to detect, located at the center, and the neutral hydrogen (HI) outside the bubble traces the underlying dark matter distribution. We consider three different possible scenarios of reionization, i.e., (i) there is a single bubble (SB) in the field of view (FoV) and the hydrogen neutral fraction is constant outside this bubble (ii) patchy reionization with many small ionized bubbles in the FoV (PR1) and (iii) many spherical ionized bubbles of the same radius $R_b$ (PR2). The fourth kind of simulation uses more realistic maps based on semi-numeric modelling (SM) of ionized regions. We find that for both the SB and PR1 scenarios the fluctuating IGM restricts bubble detection to size R_b<= 6 Mpc and R_b<= 12 Mpc for the GMRT and the MWA respectively, however large be the integration time. These results are well explained by analytical predictions. Large uncertainty due to the HI fluctuations restricts bubble detection in the PR2 scenario for neutral fraction x_HI<0.6. The matched-filter technique works well even when the targeted ionized bubble is non-spherical due to surrounding bubbles and inhomogeneous recombination (SM). We find that determining the size and positions of the bubbles is not limited by the HI fluctuations in the SB and PR1 scenario but limited by the instrument's angular resolution instead, and this can be done more precisely for larger bubble (abridged).

arXiv comment14 pages, 15 Postscript figures, Revised to incorporate ionization maps produced by the semi-numeric approach. Accepted for publication in MNRAS

References in corpus (40)

• Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
• Three Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Polarization Analysis
• Constraining the Evolution of the Ionizing Background and the Epoch of Reionization with z ~ 6 Quasars II: A Sample of 19 Quasars
• Evidence for Reionization at z ~ 6: Detection of a Gunn-Peterson Trough in a z=6.28 Quasar
• Observational constraints on Cosmic Reionization
• Evolution of the Ionizing Background and the Epoch of Reionization from the Spectra of z~6 Quasars
• Strong size evolution of the most massive galaxies since z~2
• Efficient Simulations of Early Structure Formation and Reionization
• 21 Centimeter Fluctuations from Cosmic Gas at High Redshifts
• 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
• Simulations and Analytic Calculations of Bubble Growth During Hydrogen Reionization
• Multifrequency analysis of 21 cm fluctuations from the Era of Reionization
• Toward Epoch of Reionization Measurements with Wide-Field Radio Observations
• Fossil HII Regions: Self-Limiting Star Formation at High Redshift
• The CMBR fluctuations from HI perturbations prior to reionization
• Radio Foregrounds for the 21cm Tomography of the Neutral Intergalactic Medium at High Redshifts
• Inside-out or Outside-in: The topology of reionization in the photon-starved regime suggested by Lyman-alpha forest data
• On using visibility correlations to probe the HI distribution from the dark ages to the present epoch I: Formalism and the expected signal
• Evidence for a Cosmological Stromgren Surface and for Significant Neutral Hydrogen Surrounding the Quasar SDSS J1030+0524
• Foregrounds for 21cm Observations of Neutral Gas at High Redshift
• Characteristic Scales During Reionization
• Foregrounds for redshifted 21 cm studies of reionization: GMRT 153 MHz observations
• A Size of ~10 Mpc for the Ionized Bubbles at the End of Cosmic Reionization
• The multi-frequency angular power spectrum of the epoch of reionization 21 cm signal
• The Impact of a Percolating IGM on Redshifted 21 cm Observations of Quasar HII Regions
• On the Size of HII Regions around High Redshift Quasars
• HI Signal from Reionization Epoch
• Field Deployment of Prototype Antenna Tiles for the Mileura Widefield Array--Low Frequency Demonstrator
• Prospects for Redshifted 21-cm observations of quasar HII regions
• On the minimum mass of reionization sources
• Redshifted 21cm Signatures Around the Highest Redshift Quasars
• Detecting ionized bubbles in redshifted 21 cm maps
• Quasar H II Regions During Cosmic Reionization
• Free-Free Emission at Low Radio Frequencies
• The apparent shape of the "Strömgren sphere'' around the highest-redshift QSOs with Gunn-Peterson troughs
• What will anisotropies in the clustering pattern in redshifted 21 cm maps tell us?
• Redshifted 21 cm Emission From the Pre-Reionization Era II. HII Regions Around Individual Quasars
• Fossil Ionized Bubbles Around Dead Quasars During Reionization
• Physics of Cosmic Reionization
• Redshifted 21cm Observations of High Redshift Quasar Proximity Zones

Cited by in corpus (19)

• Reionization and Cosmology with 21 cm Fluctuations
• Reionization and the Cosmic Dawn with the Square Kilometre Array
• Science with the Murchison Widefield Array
• Imaging the redshifted 21-cm pattern around the first sources during the cosmic dawn using the SKA
• Recovering the HII region size statistics from 21-cm tomography
• Prospects of observing a quasar HII region during the Epoch of Reionization with redshifted 21cm
• Prospects for detecting the 21cm forest from the diffuse intergalactic medium with LOFAR
• Constraining Quasar and IGM Properties Through Bubble Detection in Redshifted 21-cm Maps
• Studying Cosmic Dawn using redshifted HI 21-cm signal: A brief review
• The impact of anisotropy from finite light travel time on detecting ionized bubbles in redshifted 21-cm maps
• Stars and Reionization: The Cross-Correlation of the 21cm Line and the Near Infrared Background
• Identifying Ionized Regions in Noisy Redshifted 21 cm Data Sets
• Probing early universe through redshifted 21-cm signal: Modelling and observational challenges
• Bubble mapping with the Square Kilometer Array -- I. Detecting galaxies with Euclid, JWST, WFIRST and ELT within ionized bubbles in the intergalactic medium at z>6
• The optimal redshift for detecting ionized bubbles in HI 21-cm maps
• Growth and anisotropy of ionization fronts near high redshift quasars in the MassiveBlack simulation
• Probing individual sources during reionization and cosmic dawn using SKA HI 21-cm observations
• Stacking Redshifted 21cm Images of HII Regions Around High Redshift Galaxies as a Probe of Early Reionization
• Probing Cosmological Reionization through Radio-interferometric Observations of Neutral Hydrogen