IAS/CEA Evolution of Dust in Nearby Galaxies (ICED): the spatially-resolved dust properties of NGC4254

TL;DR

This study analyzes the spatially-resolved dust properties of galaxy NGC4254 using multi-wavelength data and hierarchical Bayesian modeling, revealing how radiation fields influence small grain destruction and dust composition.

Contribution

It introduces a novel application of hierarchical Bayesian fitting with the THEMIS dust model to derive detailed dust parameters in a galaxy.

Findings

Anti-correlation between radiation field and small grain fraction in galaxy center.

Small grains are destroyed by UV radiation in high-radiation regions.

Radial flattening of the anti-correlation linked to metallicity gradient.

Abstract

We present the first preliminary results of the project \textit{ICED}, focusing on the face-on galaxy NGC4254. We use the millimetre maps observed with NIKA2 at IRAM-30m, as part of the IMEGIN Guaranteed Time Large Program, and of a wide collection of ancillary data (multi-wavelength photometry and gas phase spectral lines) that are publicly available. We derive the global and local properties of interstellar dust grains through infrared-to-radio spectral energy distribution fitting, using the hierarchical Bayesian code HerBIE, which includes the grain properties of the state-of-the-art dust model, THEMIS. Our method allows us to get the following dust parameters: dust mass, average interstellar radiation field, and fraction of small grains. Also, it is effective in retrieving the intrinsic correlations between dust parameters and interstellar medium properties. We find an evident anti-correlation between the interstellar radiation field and the fraction of small grains in the centre of NGC4254, meaning that, at strong radiation field intensities, very small amorphous carbon grains are efficiently destroyed by the ultra-violet photons coming from newly formed stars, through photo-desorption and sublimation. We observe a flattening of the anti-correlation at larger radial distances, which may be driven by the steep metallicity gradient measured in NGC4254.