Two populations of the solar magnetic field

• Published in: Monthly notices of the Royal Astronomical Society 2017-12, Vol.472 (3), p.2575-2582
• Main Authors: Obridko, V. N., Livshits, I. M., Sokoloff, D. D.
• Format: Article
• Language: English
• Subjects: Magnetic fields; Magnetism; Populations; Solar magnetic field; Sunspots; Tracers
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stx2015

Abstract Dynamo theory suggests that there are two types of solar dynamo, namely the conventional mean-field dynamo, which produces large- and small-scale magnetic fields involved in the activity cycle, and also the small-scale dynamo, which produces a cycle independent small-scale magnetic field. The relative contribution of the two mechanisms to solar magnetism remains a matter of scientific debate, which includes the opinion that the contribution of the small-scale dynamo is negligible. Here, we consider several tracers of magnetic activity that separate cycle-dependent contributions to the background solar magnetic field from those that are independent of the cycle. We call background fields the magnetic fields outside active regions and give further development of this concept. The main message of our paper is that background fields include two relative separate populations. The background fields with a strength up to 100 Mx cm−2 are very poorly correlated with the sunspot numbers and vary little with the phase of the cycle. In contrast, stronger magnetic fields demonstrate pronounced cyclic behaviour. We discuss how this result can be included in the above-mentioned concepts of solar dynamo studies.