On the possibility of magnetic field detection on a microlensed source star

TL;DR

This paper explores the feasibility of detecting stellar magnetic fields during microlensing events by analyzing spectral Zeeman splitting, proposing methods to identify magnetic signals with modern spectrographs.

Contribution

It introduces a novel approach to detect magnetic fields in microlensed stars using Fourier analysis of spectra and Monte Carlo simulations to evaluate detection efficiency.

Findings

Detection feasibility depends on spectral resolution and S/N ratio.

Magnification contrast enhances magnetic field detectability.

Proposes specific observational strategies for future surveys.

Abstract

In a microlensing event, a large magnification occurs at caustic crossing and provides an opportunity to obtain a stronger signal associated with the object. In this paper we study the possibility of magnetic field detection in a microlensing event through the Zeeman effect. We follow the prescription introduced by \citep{Robinson:1980} which analyses the spectrum of a star in a Fourier space to deconvolve other broadening mechanism from the actual Zeeman effect. First we study magnification contrast between source and spot in terms of spot size and then consider two distinct strategies using modern spectrographs and perform a Monte Carlo simulation to find the detection efficiency in magnification-magnetic field plan. The spectral resolution and signal to noise ratio in each strategies, specify suitable places in this plane to detect a magnetic field. Apart from complexity of magnetic field on a star, we consider a simple model and propose a fantastic method to detect magnetic field using spectrum of source stars at caustic crossing.