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Recovering the H ii region size statistics from 21-cm tomography

Kakiichi, Koki; Majumdar, Suman; Mellema, Garrelt; Ciardi, Benedetta; Dixon, Keri L.; Iliev, Ilian T.; Jelić, Vibor; Koopmans, Léon V. E.; Zaroubi, Saleem; Busch, Philipp (2017) Recovering the H ii region size statistics from 21-cm tomography. Monthly Notices of the Royal Astronomical Society, 471 (2). pp. 1936-1954. ISSN 0035-8711

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We introduce a novel technique, called “granulometry", to characterize and recover the mean size and the size distribution of H II regions from 21-cm tomography. The technique is easy to implement, but places the previously not very well defined concept of morphology on a firm mathematical foundation. The size distribution of the cold spots in 21-cm tomography can be used as a direct tracer of the underlying probability distribution of H II region sizes. We explore the capability of the method using large-scale reionization simulations and mock observational data cubes while considering capabilities of SKA1-low and a future extension to SKA2. We show that the technique allows the recovery of the H II region size distribution with a moderate signal-to-noise ratio from wide-field imaging (SNR 3), for which the statistical uncertainty is sample variance dominated. We address the observational requirements on the angular resolution, the field-of-view, and the thermal noise limit for a successful measurement. To achieve a full scientific return from 21-cm tomography and to exploit a synergy with 21- cm power spectra, we suggest an observing strategy using wide-field imaging (several tens of square degrees) by an interferometric mosaicking/multi-beam observation with additional intermediate baselines (∼ 2 − 4 km).

Item Type: Article
Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Uncontrolled Keywords: radiative transfer; methods: data analysis; techniques: image processing; intergalactic medium; dark ages; reionization; first stars; cosmology: theory
Subjects: NATURAL SCIENCES > Physics
NATURAL SCIENCES > Physics > Astronomy and Astrophysics
Divisions: Division of Experimental Physics
Depositing User: Vibor Jelić
Date Deposited: 23 Aug 2017 15:18
DOI: 10.1093/mnras/stx1568

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