Dense Molecular gas and Dusty Torus in NGC 4303

TL;DR

This study analyzes molecular gas and dust in NGC 4303's center, revealing dense gas contributions, estimating torus properties, and confirming a Type 2 AGN with a marginal AGN contribution to the galaxy's infrared emission.

Contribution

First detailed molecular gas analysis combined with spectral energy distribution fitting to characterize the dusty torus and AGN in NGC 4303.

Findings

Dense gas contributes significantly to total molecular mass.

Estimated torus luminosity and inclination suggest a Type 2 AGN.

AGN contributes about 20% to the infrared luminosity.

Abstract

Spectrum analysis at 3 mm of the central region ($r\sim$800 pc) of NGC\,4303 showed molecular gas lines of both dense gas tracers (HCN, HNC, HCO$^+$, and C$_2$H) and diffuse gases ($^{13}$CO and C$^{18}$O). Molecular gas derived parameters: $H_2$ mass $M_{H_2}$=(1.75$\pm$0.32)$\times10^{8}$ M$_{\odot}$; radial velocity, V$_{dense}=$178$\pm$60 km\,s$^{-1}$, and V$_{CO}=$151$\pm$29 km\,s$^{-1}$; HCN luminosity $L_{HCN}$=(7.38$\pm$1.40)$\times10^{6}\,\,K\,\,km\,\,s^{-1}\,pc^{2}$; dense gas mass $M_{dense}$=(4.7$\pm$0.3) $\times 10^{7}$ M$_{\odot}$, and dense gas tracers abundances indicating that dense gas contributes significantly to the total molecular gas mass. To explore the AGN nature and central dusty torus of the galaxy, CIGALE was used to fit the integrated spectral energy distribution from submillimeter to UV frequencies. Large torus properties are estimated: luminosity $L_{TORUS}$\,=\,(7.1$\pm$2.8) $\times 10^{43}$ erg s$^{-1}$ and line of sight inclination of 67$\pm$16$^\circ$, which is consistent with a Type 2 AGN; total infrared luminosity $L_{IR}$=(3.51$\,\pm$\,0.30)$\times 10^{44}$ erg s$^{-1}$; star formation rate $SFR$=6.0$\pm$0.3 M$_{\odot}$\,yr$^{-1}$; and found that the AGN contribution is marginal at $\sim$20\%.