Quantifying the Relationship Between Galaxy Specific Star Formation Rate And Halo Spin For Star-forming Galaxies

TL;DR

This study tests whether galaxy sSFR correlates with halo spin using ALFALFA HI data and a semi-analytic halo-spin estimator. sSFR is computed from SFR and stellar mass, and halo spin $\lambda_h$ is inferred from HI disk properties and rotation velocity, with careful control for environment and HI profile shape. The authors find a weak but statistically significant positive correlation between sSFR and $\lambda_h$ across mass bins, robust to inclination and environment, and more pronounced in low-mass systems; however, the trend is not reproduced in the TNG50 simulations, highlighting gaps in current baryonic modeling. The results support a scenario where higher-spin halos foster extended, gas-rich disks and sustained star formation, contributing to angular momentum–regulated gas accretion as a driver of star formation efficiency in star-forming galaxies.

Abstract

Utilizing ALFALFA HI data, we investigate the relationship between specific star formation rate (sSFR) and halo spin across various star-forming galaxies. Our analysis reveals weak yet statistically significant positive correlation between sSFR and halo spin, irrespective of the galactic environment. This trend suggests that galaxies with higher spin parameters tend to host dynamically colder, gas-rich disks, sustaining elevated gas surface densities and prolonged star formation. These findings align with theoretical expectations of angular momentum-regulated gas accretion but highlight discrepancies with cosmological simulations, underscoring unresolved challenges in modeling baryonic feedback and star formation efficiency.

Figures (7)

• Figure 1: a). SFR vs. stellar mass for the star-forming (blue) and quiescent (red) galaxies. b). Stellar mass distribution for the star-forming galaxies in this study.
• Figure 2: sSFR versus halo spin parameter for low-mass (left) and high-mass (right) galaxies. The top panels show the full star-forming galaxy sample, while the bottom panels focus on isolated galaxies. The numbers of galaxies are shown in the brackets of the corresponding panels. Median sSFR values with $1\sigma$ error bars for each bin in $\log \lambda_{\rm{h}}$ are represented. Best-fit linear trends are indicated by the corresponding lines. CC and $p$-value for the subsample are also shown in the corresponding panels.
• Figure 3: The correlations between sSFR and halo spin for low-mass (left) and high-mass (right) galaxies at the different inclination cutting thresholds. From the top panels to the bottom panels, we show the results for the isolated star-forming galaxies with the inclination cutting thresholds of $30^{\circ}$, $40^{\circ}$, $60^{\circ}$, $70^{\circ}$, respectively. Analogous to Fig. \ref{['fig1']}, the median sSFR values with $1\sigma$ error bars for each bin in $\log \lambda_{\rm{h}}$ are represented, with the lines indicating the best-fit linear trends. CC and $p$-value for the subsample are also shown in the corresponding panels.
• Figure 4: sSFR versus halo spin parameter calculated with the scale length of stellar disk, for isolated low-mass (a) and high-mass (b) star-forming galaxies.
• Figure 5: sSFR versus halo spin parameter for low-mass (left) and high-mass (right) star-forming galaxies. The upper and lower panels show the correlation for the low and high surface density subsamples, respectively.