Probing the magnetic field of the nearby galaxy pair Arp 269

TL;DR

This study uses multiwavelength radio observations to uncover extended magnetic structures and star formation activity in the galaxy pair Arp 269, revealing new features and insights into their interaction history.

Contribution

It provides the first detailed radio continuum mapping of Arp 269, revealing a previously unknown extension and analyzing the origin and age of the electron populations involved.

Findings

Discovered a new extension of radio emission differing from neutral gas tail.

Magnetic fields exceed 20 μG, indicating vigorous star formation.

Estimated electron age in intergalactic bridge is 3.7–16.9 Myr.

Abstract

We present a multiwavelength radio study of the nearby galaxy pair Arp 269 (NGC 4490/85). High sensitivity to extended structures gained by using the merged interferometric and single- dish maps allowed us to reveal a previously undiscovered extension of the radio continuum emission. Its direction is significantly different from that of the neutral gas tail, suggesting that different physical processes might be involved in their creation. The population of radio- emitting electrons is generally young, signifying an ongoing, vigorous star formation -- this claim is supported by strong magnetic fields (over 20 {\mu}G), similar to the ones found in much larger spiral galaxies. From the study of the spectral energy distribution, we conclude that the electron population in the intergalactic bridge between member galaxies originates from the disc areas, and therefore its age (approximately 3.7--16.9 Myr, depending on the model used) reflects the time-scale of the interaction. We have also discovered an angularly near compact steep source -- which is a member of a different galaxy pair -- at a redshift of approximately 0.125.