Exploring the millimetre emission in nearby galaxies: Analysis of the edge-on galaxy NGC 891

S Katsioli ,F.-X Désert ,J F Macías-Pérez ,N Ponthieu ,R Adam ,S Berta ,H Roussel ,A Gómez ,G Lagache ,A Maury ,Peter A R Ade ,A P Jones ,Annie Hughes ,H Ajeddig ,M De Petris ,C Krämer ,A Monfardini ,M Smith ,M Muñoz-Echeverría ,A Benoı̂t ,I De Looze ,Angelos Nersesian ,J F Lestrade ,A Ritacco ,V Revéret ,K Schüster ,E M Xilouris ,Andrew Rigby ,Anita Beelen ,M Galametz ,S Lecrercq ,E Artis ,L Perotto ,O Bourrion ,E F C Driessen ,G Ejlali ,A Catalano ,P André ,Philip Mauskopf ,J Goupy ,S Shu ,H Aussel ,F Kéruzoré ,F Ruppin ,G Pisano ,S Doyle ,S C Madden ,F Mayet ,B Ladjelate ,C Tucker ,L Bing ,M Calvo ,F Tabatabei ,C Romero ,A Sievers ,F Galliano ,R Zylka

doi:10.1051/epjconf/202225700023

Abstract

New observations of the edge-on galaxy NGC 891, at 1.15 and 2mm obtained with the IRAM 30-m telescope and the NIKA2 camera, within the framework of the IMEGIN (Interpreting the Millimetre Emission of Galaxies with IRAM and NIKA2) Large Program, are presented in this work. By using multiwavelength maps (from the mid-IR to the cm wavelengths) we perform SED fitting in order to extract the physical properties of the galaxy on both global and local (~kpc) scales. For the interpretation of the observations we make use of a state-of-the-art SED fitting code, HerBIE (HiERarchical Bayesian Inference for dust Emission). The observations indicate a galaxy morphology, at mm wavelengths, similar to that of the cold dust emission traced by submm observations and to that of the molecular gas. The contribution of the radio emission at the NIKA2 bands is very small (negligible at 1.15 mm and ~ 10% at 2 mm) while it dominates the total energy budget at longer wavelengths (beyond 5 mm). On local scales, the distribution of the free-free emission resembles that of the dust thermal emission while the distribution of the synchrotron emission shows a deficiency along the major axis of the disc of the galaxy.

Highlights

Nearby galaxies have provided a great piece of knowledge in the field of galaxy formation and evolution
Modelling the Spectral Energy Distribution (SED) of NGC 891 in the wavelength range from 3.4 μm to 6.3 cm allows us to accurately determine the dust content, taking into account emission from the aromatic features as well as from the continuum emission from small and big grains, and the radio emission composed by the free-free and the synchrotron radiation
From this plot it is evident that the dust thermal emission dominates to up to ∼ 3 mm where the contributions of the free-free and synchrotron emission mechanisms become almost significant to the dust emission

Summary

Introduction

Nearby galaxies have provided a great piece of knowledge in the field of galaxy formation and evolution. The main objective of the project is to explore the emission at millimetre wavelengths originating from nearby galaxies, a complex wavelength regime with contributions from a mix of different emission mechanisms (free-free, synchrotron, and dust thermal emission). This is the first time that nearby galaxies are being observed in the continuum at mm wavelengths at resolutions of 11.1 and 17.6 (∼ 0.5 kpc, and ∼ 0.8 kpc at a distance of 10 Mpc) at 1.15 and 2 mm respectively. At these scales it is possible to disentangle the contribution of the different emission mechanisms in different environments inside the galaxies (disc, halo, HII regions, etc)

Objectives

Results

Conclusion