Doubling the Number of Blue Large-Amplitude Pulsators: Final Results of Searches for BLAPs in the OGLE Inner Galactic Bulge Fields

TL;DR

This study significantly increases the known population of Blue Large-Amplitude Pulsators (BLAPs) by discovering 88 new ones in the OGLE data, doubling the total count and providing extensive observational data for future research.

Contribution

It presents the first large-scale systematic search for BLAPs in the OGLE data, discovering 88 new BLAPs and doubling the known sample, with detailed analysis of their periods and period changes.

Findings

Discovered 88 new BLAPs, nearly doubling the known sample.

Detected BLAPs with periods between 5 and 76 minutes.

Identified three objects with significant period changes.

Abstract

Blue Large-Amplitude Pulsators (BLAPs) are rare short-period ($\lesssim$80 min) pulsating variable stars exhibiting large-amplitude brightness variations (typically between 0.1 and 0.4 mag). As a recently discovered class of radial-mode pulsators, the origin and nature of these variables remain the subject of ongoing investigations. Here, we present a comprehensive summary of all BLAPs identified in the data of the Optical Gravitational Lensing Experiment (OGLE), including the discovery of 88 new BLAPs in the inner Galactic bulge fields. We performed a systematic search for periodic signals in the $I$-band light curves of more than 400 million stars with magnitudes down to $I = 21$. Our search effectively doubles the number of these variables to almost 200. The detected BLAPs exhibit pulsation periods between roughly 5 and 76 minutes. The analyzed dataset covers a timespan from 2001 to 2024, with some stars observed up to 20,000 times, providing the temporal coverage needed to study period and amplitude variations. We report on three objects that show enormous period changes, at a rate of $10^{-5}$ yr$^{-1}$, which could provide important clues to the evolutionary status of BLAPs. Full dataset is incorporated into the publicly available OGLE Collection of Variable Stars (OCVS), enabling future studies of these enigmatic objects.