The influence of angular momentum and environment on the H i gas of late-type galaxies

Abstract

We use high-resolution H i data from the Westerbork H i Survey of Spiral and Irregular Galaxies (WHISP) to study the H i and angular momentum properties of a sample of 114 late-type galaxies. We explore the specific baryonic angular momentum–baryonic mass (jb–Mb) relation, and find that an unbroken power law of the form $j_\mathrm{ b} \propto M_\mathrm{ b}^{0.55 \pm 0.02}$ fits the data well, with an intrinsic scatter of ∼0.13 ± 0.01 dex. We revisit the relation between the atomic gas fraction, fatm, and the integrated atomic stability parameter q (the fatm–q relation), originally introduced by Obreschkow et al., and probe this parameter space by populating it with galaxies from different environments, in order to study the influence of the environment on their jb, fatm, and q values. We find evidence that galaxies with close neighbours show a larger intrinsic scatter about the fatm–q relation compared to galaxies without close neighbours. We also find enhanced star formation rate among the deviating galaxies with close neighbours. In addition, we use the bulge-to-total (B/T) ratio as a morphology proxy, and find a general trend of decreasing B/T values with increasing disc stability and H i fraction in the fatm–q plane, indicating a fundamental link between mass, specific angular momentum, gas fraction, and morphology of galaxies.

The baryonic specific angular momentum of disc galaxies

“…The fact that the slope of the relation is 0.5−0.6 is remarkable as this value is very close to the slope of the relation of dark matter haloes, j h ∝ M 2/3 h (e.g. Fall 1983;Romanowsky & Fall 2012;Obreschkow & Glazebrook 2014;P18 and references therein) While these studies have built a relatively coherent picture of the stellar component, the gas ( j gas − M gas ) and baryonic ( j bar − M bar ) relations remain somewhat less well explored, although studies performed in recent years have started to delve into this (Obreschkow & Glazebrook 2014;Butler et al 2017;Chowdhury & Chengalur 2017;Elson 2017;Kurapati et al 2018;Lutz et al 2018;Murugeshan et al 2020). In fact, different authors have reported different results regarding the nature of the j bar − M bar relation, such as whether or not the slope of the correlations in the j bar − M bar and j * − M * planes are the same, if dwarf galaxies follow a different sequence than higher-mass spirals, or whether or not the relations have a break at a characteristic mass.…”

“…For instance, our mass coverage at M bar < 10 9 M is a bit more complete (11 galaxies in their work vs 23 in our convergent sample), and, very importantly, we applied a converge criterion to all our sample in order to select only the most accurate j profiles. In addition to this, while both studies use near infrared luminosities to trace M * (mostly 3.6µm in our case, and 2.2µm for Murugeshan et al 2020), we use a Υ that has been found to reduce the scatter in scaling relations that depend on M * such as the baryonic Tully-Fisher relation (see Lelli et al 2016b), while the calibration used by Murugeshan et al (2020) may have a larger scatter, up to one order of magnitude in M * at given infrared luminosity (Wen et al 2013). Finally, we determine V * instead of assuming co-rotation of gas and stars, although this does not play an important role when determining the global j bar − M bar relation (cf.…”

“…Murugeshan et al (2020) mention that it is likely that their slope is slightly biased towards flatter values given their lack of galaxies with M bar < 10 9 M . For our sample, which extends towards lower masses, the slope is marginally steeper, in agreement with the reasoning of Murugeshan et al (2020).…”

“…Some authors have also discussed the relation of f gas with j bar via the stability parameter q = j bar σ/GM bar , with σ the H i velocity dispersion and G the gravitational constant (see Obreschkow et al 2016;Lutz et al 2018;Stevens et al 2018;Murugeshan et al 2020). According to them (see also Romeo 1) and the gas fraction as colour-coded third parameters.…”

A tight angular-momentum plane for disc galaxies

“…To incorporate f gas , we rewrote the above expression (using 4 We note that assuming a non-constant σ gas is not enough to alleviate the mentioned discrepancies. To match our relations, σ gas ∝ M ∼0.25 bar is required; however, it is observed that σ gas ∝ M 0.07 bar (e.g., Murugeshan et al 2020). Assuming a constantσ gas , as in Romeo (2020), this relation predicts j gas ∝ M bar at fixed f gas and j gas ∝ f gas at fixed M bar .…”