Constraining Millimeter Dust Emission in Nearby Galaxies with NIKA2: the case of NGC2146 and NGC2976

TL;DR

This paper presents millimeter continuum observations of two nearby galaxies, NGC2146 and NGC2976, using NIKA2, providing detailed dust property maps and revealing correlations between dust temperature, emissivity, and star formation activity.

Contribution

First millimeter continuum mapping of NGC2146 and NGC2976 with NIKA2, offering spatially resolved dust property analysis and insights into star formation effects.

Findings

Dust temperature correlates with star formation rate in both galaxies.

Star formation activity influences dust temperature more in NGC2976.

An anti-correlation exists between dust emissivity index and temperature.

Abstract

This study presents the first millimeter continuum mapping observations of two nearby galaxies, the starburst spiral galaxy NGC2146 and the dwarf galaxy NGC2976, at 1.15 mm and 2 mm using the NIKA2 camera on the IRAM 30m telescope, as part of the Guaranteed Time Large Project IMEGIN. These observations provide robust resolved information about the physical properties of dust in nearby galaxies by constraining their FIR-radio SED in the millimeter domain. After subtracting the contribution from the CO line emission, the SEDs are modeled spatially using a Bayesian approach. Maps of dust mass surface density, temperature, emissivity index, and thermal radio component of the galaxies are presented, allowing for a study of the relations between the dust properties and star formation activity (using observations at 24$\mu$m as a tracer). We report that dust temperature is correlated with star formation rate in both galaxies. The effect of star formation activity on dust temperature is stronger in NGC2976, an indication of the thinner interstellar medium of dwarf galaxies. Moreover, an anti-correlation trend is reported between the dust emissivity index and temperature in both galaxies.