arXiv subjects

Suphakorn Suphapolthaworn

Publications and source records attributed to Suphakorn Suphapolthaworn.

3 recordsLinked to original sources

arXiv2026

High-Resolution [CI] $({^3\mathrm{P}_2}\rightarrow{^3\mathrm{P}_1})$ and CO $(J=7\rightarrow6)$ Observations of Circumnuclear Disks in Nearby Seyfert Galaxies

We present [CI] $({^3\mathrm{P}_2}\mathrm{-}{^3\mathrm{P}_1})$, CO $(J=7\mathrm{-}6)$, and 800-GHz continuum observations of the circumnuclear disks (CNDs) in the Seyfert galaxies NGC 613 and NGC 1808 with the Atacama Large Millimeter/submillimeter Array. The images reveal the distributions of neutral gas and dust in nearby galaxy nuclei at a resolution of $0.2''$ (10 pc) which is unprecedented at these frequencies. Both lines and continuum exhibit peaks at the position of molecular tori. The maximum [CI]$({^3\mathrm{P}_2}\mathrm{-}{^3\mathrm{P}_1})/({^3\mathrm{P}_1}\mathrm{-}{^3\mathrm{P}_0})$ integrated-intensity ratio is $\approx1.1$ $(\mathrm{K~km~s}^{-1}$ scale) in the region of the torus, yielding an excitation temperature of $T_\mathrm{ex}\approx60~\mathrm{K}$ under the approximation of local thermodynamic equilibrium (LTE) and optically thin emission. A non-LTE radiative transfer analysis of the [CI] line ratio in the CND constrains the density and kinetic temperature of molecular gas to $n_\mathrm{H_2}>10^3~\mathrm{cm}^{-3}$ and $T_\mathrm{k}>50~\mathrm{K}$, respectively. To estimate the C/CO abundance ratio and physical conditions, we simultaneously modeled the [CI] and multiple CO lines, and obtained solutions with densities and temperatures of $n_\mathrm{H_2}\sim10^{3\mathrm{-}4}~\mathrm{cm}^{-3}$ and $T_\mathrm{k}\sim80\mathrm{-}250~\mathrm{K}$ in the central 63 pc. The C/CO ratios are $\approx2$ in NGC 613 and $\approx0.6$ in NGC 1808. C/CO tends to increase with $T_\mathrm{k}$ and decrease with $n_\mathrm{H_2}$ in the CND, which is consistent with models of photodissociation regions. Based on the kinematics of gas traced by [CI] $({^3\mathrm{P}_2}\mathrm{-}{^3\mathrm{P}_1})$ and CO $(J=7\mathrm{-}6)$, the mass of the supermassive black hole at the center of NGC 613 is estimated to be $\sim2\times10^7~M_\odot$.

astro-ph.GA↗

arXiv2025

CO Multi-line Imaging of Nearby Galaxies (COMING). XI. Azimuthally averaged star formation rate and stellar mass relation with molecular gas amount

This study investigated the relation between the surface density of star formation rate (SFR) ($Σ_{\mathrm{SFR}}$), stellar mass ($Σ_{M_{\ast}}$), and molecular gas mass ($Σ_{M_\mathrm{mol}}$) on nearly 1 kpc scales averaged over concentric tilted rings using the $^{12}$CO $J=1-0$ mapping data of 92 nearby galaxies obtained in the CO Multi-line Imaging of Nearby Galaxies (COMING) project. We categorized these galaxies into three groups based on the deviation of each global SFR from the star-forming main sequence (MS), $Δ$MS: upper MS (UMS), MS, and lower MS (LMS). UMS galaxies tend to be less massive or barred spiral galaxies, exhibiting molecular gas fraction ($f_{\mathrm{gas}}$) comparable to those of MS galaxies but higher star formation efficiency (SFE). In contrast, the LMS galaxies tend to be massive or active galaxies hosting an active galactic nucleus (AGN). Their $f_{\mathrm{gas}}$ values are lower than those of MS galaxies, and their SFEs are slightly lower or comparable to those of MS galaxies in the inner region. These trends indicate that enhanced SFE contributes to higher $Δ$MS values, whereas reduced $f_{\mathrm{gas}}$ results in lower $Δ$MS values. The less prominent bulge or the presence of a bar structure in UMS galaxies induces disk-wide star formation, consequently increasing the SFE. In LMS galaxies, the molecular gas is exhausted, and their star formation activity is low. Environmental effects, such as tidal gas stripping, may also reduce gas supply from the outer regions. Furthermore, our sample galaxies show that both the specific star formation rate (sSFR) and $f_{\mathrm{gas}}$ decrease in the central region in LMS galaxies but did not change in the same region in UMS galaxies. These results seem to support the inside-out quenching of star formation although the dominant cause of depletion remains uncertain.

astro-ph.GA↗

arXiv2023

Molecular outflow in the reionization-epoch quasar J2054-0005 revealed by OH 119 $μ$m observations

Molecular outflows are expected to play a key role in galaxy evolution at high redshift. To study the impact of outflows on star formation at the epoch of reionization, we performed sensitive ALMA observations of OH 119 $μ$m toward J2054-0005, a luminous quasar at $z=6.04$. The OH line is detected and exhibits a P-Cygni profile that can be fitted with a broad blue-shifted absorption component, providing unambiguous evidence of an outflow, and an emission component at near-systemic velocity. The mean and terminal outflow velocities are estimated to be $v_\mathrm{out}\approx670~\mathrm{km~s}^{-1}$ and $1500~\mathrm{km~s}^{-1}$, respectively, making the molecular outflow in this quasar one of the fastest at the epoch of reionization. The OH line is marginally spatially resolved for the first time in a quasar at $z>6$, revealing that the outflow extends over the central 2 kpc region. The mass outflow rate is comparable to the star formation rate ($\dot{M}_\mathrm{out}/\mathrm{SFR}\sim2$), indicating rapid ($\sim10^7~\mathrm{yr}$) quenching of star formation. The mass outflow rate in a sample star-forming galaxies and quasars at $4<z<6.4$ exhibits a positive correlation with the total infrared luminosity, although the scatter is large. Owing to the high outflow velocity, a large fraction (up to $\sim50\%$) of the outflowing molecular gas may be able to escape from the host galaxy into the intergalactic medium.

astro-ph.GA↗