E. D. Paspaliaris | Searcharxiv

arXiv2026

The MaNGA Low-mass disks HUnt for CO (MaLHUCO) Survey

We present James Clerk Maxwell Telescope (JCMT) observations of the $^{12}$CO(J = 2-1) emission of 42 low-mass, star-forming disk galaxies of morphological type Scd or later from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey. The sample, which probes the M33-like stellar-mass regime, is complemented with metallicities, star formation rates, and \hi\ masses used to investigate the star formation process and to test scaling relations involving molecular gas mass in low-mass systems. We detect CO emission in 55% of the sample and derive H$_2$ masses using both a constant Galactic and a metallicity-dependent CO-to-H$_2$ conversion factor. The 12 $μ$m luminosity, which includes polycyclic aromatic hydrocarbon features, exhibits a tight linear correlation with the CO line emission, making it a robust tracer of global molecular gas content. The molecular gas mass - star formation rate relation, i.e. the Kennicutt-Schmidt law, is the most fundamental one and it is found to remain linear down to low stellar masses. We also find that the mean molecular gas depletion time is slightly shorter in low-mass late-type galaxies than in more massive systems, consistent with their higher specific star formation rates. Finally, while the specific molecular gas mass ($M_{\rm H_2}/M_*$) shows no significant dependence on stellar mass and a large intrinsic scatter, the HI-to-stellar mass ratio ($M_{\rm HI}/M_*$) decreases with increasing stellar mass and molecular fraction ($M_{\rm H_2}/M_{\rm gas}$), highlighting the progressive transition from atomic- to molecular-dominated interstellar medium along the galaxy population.

astro-ph.GA↗

arXiv2025

Relating spatially resolved optical attenuation, dust and gas in nearby galaxies

We relate the optical attenuation inferred by the Balmer decrement, $A_{V\mathrm{,BD}}$, and by the SED-fitting, $A_{V\mathrm{,SED}}$, to the dust distribution and gas surface density throughout the disc of galaxies, down to scales smaller than 0.5 kpc. We investigate five nearby star-forming spirals with available FUV to sub-mm observations, along with atomic and molecular gas surface density maps and optical integral-field spectroscopic data. We use the CIGALE SED-fitting code to map the dust mass surface density ($Σ_\mathrm{dust}$) and $A_{V,\mathrm{SED}}$ of different stellar populations. For each pixel, we independently estimate the attenuation from the BD. We find that both $Σ_\mathrm{dust}$ and $A_{V,\mathrm{BD}}$ trace better the molecular and total gas mass surface density, rather than the atomic gas. Since regions sampled in this study have high molecular fractions, atomic gas surface densities, indicative of molecular gas shielding layers, decrease as the mean dust-to-gas ratio increases from galaxy to galaxy. The fitted attenuation towards young stars, $A^\mathrm{young}_{V,\mathrm{SED}}$, is in good agreement with $A_{V,\mathrm{BD}}$ and it can then be used to trace the attenuation in star forming galaxies where integral-field observations are not available. We estimate the ratio of $A_{V,\mathrm{BD}}$ over the total stellar $A_{V,\mathrm{SED}}$ and find it slightly larger than what has been found in previous studies. Finally, we investigate which dust distribution reproduces better the estimated $A_{V,\mathrm{BD}}$ and $A_{V,\mathrm{SED}}$. We find that the attenuation towards old stars is consistent with the expectations for a standard galactic disc, where the stellar and dust distributions are mixed, while $A_{V, \mathrm{BD}}$ and the $A^\mathrm{young}_{V, \mathrm{SED}}$ are between the values expected for a foreground dust screen and a mixed configuration.

astro-ph.GA↗