# EXO 2030+375 Restarts in Reverse

## TL;DR

This study investigates the unusual low-flux state and potential transition to centrifugal inhibition in the Be X-ray binary pulsar EXO 2030+375 through multi-instrument observations, revealing changes in accretion behavior and disk properties.

## Contribution

First multi-instrument campaign exploring the low-flux state and possible accretion transition in EXO 2030+375, providing new insights into its variable accretion dynamics.

## Key findings

- Decreased outburst regularity and brightness in 2015.
- Indications of disk changes from Hα line variations.
- Preliminary evidence of altered accretion behavior.

## Abstract

The Be X-ray binary pulsar EXO 2030+375, first detected in 1985, has shown a significant detected X-ray outburst at nearly every periastron passage of its 46-day orbit for the past ~25 years, with one low state accompanied by a torque reversal in the 1990s. In early 2015 the outbursts progressively became fainter and less regular while the monotonic spin-up flattened. At the same time a decrease in the H$\alpha$ line equivalent width was reported, indicating a change in the disk surrounding the mass donor. In order to explore the source behaviour in the poorly explored low-flux state with a possible transition to a state of centrifugal inhibition of accretion we have undertaken an observing campaign with Swift/XRT, NuSTAR and the Nordic Optical Telescope (NOT). This conference contribution reports the preliminary results obtained from our campaign.