Correlation of the radio continuum, infrared, and CO molecular emissions in NGC 3627

TL;DR

This study investigates the spatial correlation between radio continuum, infrared, and CO emissions in NGC 3627 at 100 pc resolution, revealing consistent correlations without breakdown at small scales and providing new visualization methods.

Contribution

It presents new high-resolution radio and CO observations of NGC 3627 and introduces a three-dimensional visualization of emission correlations, enhancing understanding of electron diffusion and star formation links.

Findings

Radio continuum correlates well with CO and dust emissions at 100 pc scales.

No correlation breakdown observed at scales below electron diffusion length.

Three-dimensional fitting reveals complex electron and star formation processes.

Abstract

We present new radio continuum observations, taken at 1.4 GHz with the Very Large Array, and new observations in the CO line, taken with the Plateau de Bure interferometer, of two regions of the spiral galaxy NGC 3627. Comparing these observations with archival Spitzer and H_{alpha} data we study the correlation of the radio continuum (RC), infrared-8 um and CO emissions at a spatial resolution of 100 pc. We compare the point-by-point variations of the RC, CO, and 8um brightnesses in two distinct regions of 2 kpc \times 2 kpc in size of NGC 3627. We examined scale much lower than the electron diffusion scale, where a break down of the correlations would be expected. However no evidence for such correlation break down has been found. The RC emission follows well the distribution of CO and the widths of several structures, measured along slices across them, are comparable. Furthermore, we found that down to a spatial scale of 100 pc the radio continuum emission is correlated with dust emissions at 4.5, 5.8, and 8 um, that traces different dust temperatures. We present a new perspective with which visualizing and studying the RC-CO-24 um and RC-CO-8 um correlations, by using a three-dimensional representation. We fit the observed data with a three dimensional line, obtaining a rms of 0.25 dex. The observed correlation enhances the complexity of the electrons diffusion, losses and injection mechanisms, and of their connection to star formation processes, described by molecular and dust emissions. We plan to further investigate this connection using spatially resolved spectral index studies at low radio frequencies where the thermal emission component is seemingly negligible.