The HI mass function of star-forming galaxies at \(\mathbf{z \sim 0.35}\)

• Published in: arXiv.org
• Main Authors: Bera, Apurba, Kanekar, Nissim, Chengalur, Jayaram N, Bagla, Jasjeet S
• Format: Paper
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 31.10.2022
• Subjects: Astronomical models; Atomic properties; Blue stars; Deposition; Galactic evolution; Galaxy distribution; Local group (astronomy); Luminosity; Massive stars; Radio astronomy; Radio telescopes; Scaling; Scattering; Space telescopes; Star & galaxy formation; Star formation; Stars & galaxies; Universe
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2210.17018

The neutral atomic hydrogen (HI) mass function (HIMF) describes the distribution of the HI content of galaxies at any epoch; its evolution provides an important probe of models of galaxy formation and evolution. Here, we report Giant Metrewave Radio Telescope HI 21cm spectroscopy of blue star-forming galaxies at \(z\approx0.20-0.42\) in the Extended Groth Strip, which has allowed us to determine the scaling relation between the average HI mass (\(\rm{M_{HI}}\)) and the absolute B-band magnitude (\(\rm{M_B}\)) of such galaxies at \(z \approx 0.35\), by stacking the HI 21cm emission signals of galaxy subsamples in different \(\rm{M_B}\) ranges. We combine this \(\rm{M_{HI}-M_B}\) scaling relation (with a scatter assumed to be equal to that in the local Universe) with the known B-band luminosity function of star-forming galaxies at these redshifts to determine the HIMF at \(z\approx0.35\). We show that the use of the correct scatter in the \(\rm{M_{HI}-M_B}\) scaling relation is critical for an accurate estimate of the HIMF. We find that the HIMF has evolved significantly from \(z\approx0.35\) to \(z\approx0\), i.e. over the last four Gyr, especially at the high-mass end. High-mass galaxies, with \(\rm{M_{HI}\gtrsim10^{10}\ M_\odot}\), are a factor of \(\approx3.4\) less prevalent at \(z\approx0.35\) than at \(z \approx 0\). Conversely, there are more low-mass galaxies, with \(\rm{M_{HI} \approx10^9\ {M}_\odot}\), at \(z\approx0.35\) than in the local Universe. While our results may be affected by cosmic variance, we find that massive star-forming galaxies have acquired a significant amount of HI through merger events or accretion from the circumgalactic medium over the past four Gyr.