MIGHTEE-H <scp>i</scp>: the first MeerKAT H <scp>i</scp> mass function from an untargeted interferometric survey
Anastasia A Ponomareva, M. J. Jarvis, Hengxing Pan, Natasha Maddox, Michael G. Jones, B. S. Frank, Sambatriniaina H A Rajohnson, Wanga Mulaudzi, M. Meyer, Elizabeth A. K. Adams, M. Baes, Kelley M. Hess, Sushma Kurapati, I. Prandoni, Francesco Sinigaglia, Kristine Spekkens, Madalina N. Tudorache, Ian Heywood, J. D. Collier, Srikrishna Sekhar
Abstract
ABSTRACT 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: $1/V_{\rm max}$ and modified maximum likelihood (MML). We find a low-mass slope $\alpha =-1.29^{+0.37}_{-0.26}$ , ‘knee’ mass $\log _{10}(M_{*}/{\rm {\rm M}_{\odot }}) = 10.07^{+0.24}_{-0.24}$ and normalization $\log _{10}(\phi _{*}/\rm Mpc^{-3})=-2.34^{+0.32}_{-0.36}$ (H0 = 67.4 km s−1 Mpc−1) for $1/V_{\rm max}$ , and $\alpha =-1.44^{+0.13}_{-0.10}$ , ‘knee’ mass $\log _{10}(M_{*}/{\rm {\rm M}_{\odot }}) = 10.22^{+0.10}_{-0.13}$ and normalization $\log _{10}(\phi _{*}/\rm Mpc^{-3})=-2.52^{+0.19}_{-0.14}$ for MML. When using $1/V_{\rm max}$ 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: $\Omega _{\rm H\,{\small I}}=5.46^{+0.94}_{-0.99} \times 10^{-4}\,h^{-1}_{67.4}$ from $1/V_{\rm max}$ and $\Omega _{\rm H\,{\small I}}=6.31^{+0.31}_{-0.31} \times 10^{-4}\,h^{-1}_{67.4}$ from MML but consistent within the uncertainties. We find no evidence for evolution of the HIMF over the last billion years.