| Summary: | We present the first measurement of the H I mass function (HIMF) using data from MeerKAT, based on 276 direct detections from the MeerKAT International GigaHertz Tiered Extragalactic Exploration (MIGHTEE) Survey Early Science data covering a period of approximately a billion years (0 ≤ z
≤ 0.084). This is the first HIMF measured using interferometric data over non-group or cluster field, i.e. a deep blank field. We constrain the parameters of the Schechter function that describes the HIMF with two different methods: 1/Vmax
and modified maximum likelihood (MML). We find a low-mass slope α=−1.29+0.37−0.26
, ‘knee’ mass log10(M∗/M⊙)=10.07+0.24−0.24
and normalization log10(ϕ∗/Mpc−3)=−2.34+0.32−0.36
(H0 = 67.4 km s−1 Mpc−1) for 1/Vmax
, and α=−1.44+0.13−0.10
, ‘knee’ mass log10(M∗/M⊙)=10.22+0.10−0.13
and normalization log10(ϕ∗/Mpc−3)=−2.52+0.19−0.14
for MML. When using 1/Vmax
we find both the low-mass slope and ‘knee’ mass to be consistent within 1σ with previous studies based on single-dish surveys. The cosmological mass density of H I is found to be slightly larger than previously reported: ΩHI=5.46+0.94−0.99×10−4h−167.4
from 1/Vmax
and ΩHI=6.31+0.31−0.31×10−4h−167.4
from MML but consistent within the uncertainties. We find no evidence for evolution of the HIMF over the last billion years.
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